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Human health risk due to consumption of vegetables contaminated with carcinogenic polycyclic aromatic hydrocarbons

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Abstract

Purpose Polycyclic aromatic hydrocarbons (PAH) are persistent, toxic, and carcinogenic contaminants present in soil ecosystem globally. These pollutants are gradually accumulating in wastewater-irrigated soils and lead to the contamination of vegetables. Food chain contamination with PAH is considered as one of the major pathways for human exposure. This study was aimed to investigate the concentrations of PAH in soils and vegetables collected from wastewater-irrigated fields from metropolitan areas of Beijing, China. Origin of PAH, daily intake, and health risks of PAH through consumption of contaminated vegetables were studied. Materials and methods Soil samples were collected from the upper horizon (0–20 cm) of both wastewater-irrigated and reference sites and sieved (<2 mm mesh) and then followed by freeze-drying at −50°C and 123 ± 2 Pa. Standing vegetables were also collected from the same sites used for soil sampling and divided into roots and shoots, thoroughly washed with deionized water, and freeze-dried. PAH were extracted using the Soxhlet method with 200 mL DCM for 24 h, and the extracts were cleaned with silica adsorption chromatography prepared with silica gel, alumina, and capped with anhydrous sodium. The final concentrated extracts (soil and vegetable) were analyzed using gas chromatography–mass spectrometry (Agilent 6890). Bioaccumulation factors, daily intake of PAH, and carcinogenicity of PAH were calculated by different statistical equations. Results and discussion Results indicate that the soils and grown vegetables were contaminated with all possible carcinogenic PAH (declared by USEPA 2002) except indeno[1,2,3-c,d]pyrene. The highest concentration (242.9 μg kg−1) was found for benzo(k)fluoranthene (BkF), while lowest (79.12 μg kg−1) for benzo[a]pyrene (BaP). The emission sources of PAH were both pyrogenic and petrogenic in nature. However, the total concentrations of PAH were lower than the permissible limits set by different countries like Canada, Denmark and Germany. Highest total PAH concentration was found in the shoots of Spinacia oleracea L., while lowest in the roots of Raphanus sativus. In this study, the values of total toxic BaP equivalent (TEQ) through consumption of vegetables were found in order of S. oleracea L. > Lactuca sativa L. > Brassica oleracea L. > Brassica napus > Brassica juncea L. > R. sativus L. The data indicate that the daily intake of BaP through consumption of vegetables for adults were lower than virtually safe dose set by the Dutch National Institute for Public Health and the Environment. Conclusions Our findings indicate that PAH concentrations in soil and vegetables were lower than their respective permissible limits set by different organizations. However, the highest intake of total PAH was estimated through consumption of S. oleracea L. for both adults and children.

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... However, these large volumes of wastewater are usually discharged or used with little or no treatment. This can severely risk human health and the environment [9], such as excess nutrients [10] and heavy metals [11] that can negatively cause serious heavy metal pollution of soils and food [12][13][14], risking human health [15][16][17][18]. It can also produce groundwater and surface water pollution [19][20], making water shortage even serious, endangering human survival. ...
... Unfortunately, wastewater irrigation can also be disastrous to soils, depending on the physiochemical characteristics of wastewater. Some wastewater can cause soil heavy metal pollution and organic contamination, which has been reported over the world [14,17,[23][24]. For instance, Liu et al. [23] suggest that sewage irrigation can influence metal distribution and levels in soils, and they also state that soil inhalation and ingestion may become important pathways of human exposure to metal contamination. ...
... They just eat these contaminated products, and then they get ill. Khan and Cao [14] proved that consumption of vegetables contaminated with polycyclic aromatic hydrocarbons (PAH) can be risky to human health. Wang et al. [12], Weber et al. [24], Khan et al. [13], and Srinivasan and Reddy [15] have conducted similar researches to assess the health risks of consuming contaminated agricultural products. ...
... There are various exposure pathways of toxic substances to humans: direct pathways are soil ingestion, dust inhalation, dermal contact; but indirect ingestion through the food chain is one of the most important pathways for the entry of these toxic pollutants into the human body (Khan and Cao 2012). Food chain contamination is of increasing concern because of the adverse impact on the quality of food and health. ...
... Many chemicals are recalcitrant, mutagenic and carcinogenic pollutants, present in the environment as a result of different anthropogenic activities, and are implicated in different types of diseases, including breast, lung and colon cancer in humans (Khan and Cao 2012). ...
... Evaluation of human exposure as a consequence of pollutants translocation from contaminated soils to edible vegetables has been proposed quite recently by Khan and Cao (2012), who suggest to consider separately all the vegetable components. Root concentration factor (RCF), shoot concentration factor (SCF) and fruit concentration factor (FCF) are calculated as follows: ...
Chapter
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Nowadays risk assessment is assuming more and more importance in the solution of problems connected with land sustainability and human health. Indeed, the risk assessment criteria are applied to identify and classify the various sites on the basis of the actual land characteristics, and the potential hazard to exposed population. There are various exposure pathways of toxic substances to general population: direct pathways are soil ingestion, dust inhalation, dermal contact; indirect ingestion through the food chain is one of the most important pathways for the entry of PHEs into the human body. In order to avoid possible consequences to humans and the environment, it is necessary to investigate the source, origin, pathways, distribution in all the environmental compartments, and to ascertain if metal bioaccumulation is likely to occur, affecting human health. Risk assessment procedures include two components, the Environmental Risk Assessment and the Human Health Risk Assessment. The former has been used mainly for comparative and priority setting purposes with reference to contaminated sites. The latter refers to the possible consequences of human exposure to contaminant sources. The ecological risk is generally considered a second priority in comparison to human health risk. Estimate of exposure levels is a central step in Ecological Risk Assessment to evaluate ecotoxicity risks posed by PHEs. For example, agricultural soils contaminated with metals result in elevated uptake and transfer of metals to vegetables; consequently, severe health hazard can be caused by the consumption of metal-contaminated vegetables. Bioaccumulation of heavy metals in edible parts of vegetables is thus responsible for major health concern. Human health risk assessment has been used to determine if exposure to a chemical, at any dose, could cause an increase in the incidence, or adverse effects, on human health. Biological monitoring is a promising method of assessing environmental and human health risk by analysing PHEs concentration in environmental matrixes (e.g. plants, animals), or in human tissues (hairs, nails), or in a biological matrix (blood, urine). Concerning human health, biological monitoring is usually described as the measurement of a particular chemical substance, or a metabolite of that substance, in a suitable biological matrix (e.g. blood, urine, serum, and tissues such as hairs, nails, sweats), that act as an effective biomarker, allowing identification of potential hazards. Examples of how the risk assessment process may be carried out are given with reference to exposure levels and exposure-response relationships for the contaminants of concern.
... However, these large volumes of wastewater are usually discharged or used with little or no treatment. This can severely risk human health and the environment [9], such as excess nutrients [10] and heavy metals [11] that can negatively cause serious heavy metal pollution of soils and food [12][13][14], risking human health [15][16][17][18]. It can also produce groundwater and surface water pollution [19][20], making water shortage even serious, endangering human survival. ...
... Unfortunately, wastewater irrigation can also be disastrous to soils, depending on the physiochemical characteristics of wastewater. Some wastewater can cause soil heavy metal pollution and organic contamination, which has been reported over the world [14,17,[23][24]. For instance, Liu et al. [23] suggest that sewage irrigation can influence metal distribution and levels in soils, and they also state that soil inhalation and ingestion may become important pathways of human exposure to metal contamination. ...
... They just eat these contaminated products, and then they get ill. Khan and Cao [14] proved that consumption of vegetables contaminated with polycyclic aromatic hydrocarbons (PAH) can be risky to human health. Wang et al. [12], Weber et al. [24], Khan et al. [13], and Srinivasan and Reddy [15] have conducted similar researches to assess the health risks of consuming contaminated agricultural products. ...
Article
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Wastewater irrigation is becoming very popular over the world these years, because the amount of wastewater is increasing year by year due to rapid urbanization and industrialization. This paper presents a literature review on the effects of wastewater irrigation on human health. Benefits and risks of wastewater to water safety, soil quality, crop production, and food security were discussed. Wastewater irrigation can have some benefits such as improving soil quality, providing nutrients for plants, and saving expenses of diverting freshwater for irrigation. However, it can also have negative impacts on environment, society, and human beings. It may bring contamination to groundwater, soils, and ecological environment. Most seriously, it may have adverse effects on human health directly and/or indirectly. It is highly recommended that wastewater should be used rationally and scientifically to enlarge the benefits induced by wastewater reuse but reduce its risks.
... EPA 8280 Table 1 Compositions of feedstocks (percentage of the total amount of feedstock) of the ten biogas production lines studied. (2006). The modified method SFS-ISO-17993:2004 was used with PCBs, and the method for PAH-analyses was based on standard ISO 18287. ...
... TBBPA was analyzed using GC/HRMS-technology and HBCD using GC/MS-technology. PFASs were extracted according to methods described by de Voogt et al. (2006) with an extra cleaning step with hexane and analyzed with LC-MS/MS. NP + NPEOs were analyzed after silylation using GC/MS-technology. ...
... According to a UK and a Dutch study, the major contribution of human PAH intake came from cereals (Phillips, 1999). PAH-compounds have a low accumulation potential from soil into plants (Khan and Cao, 2012) and from feed into animals (Fries, 1996). The most important route of contamination of plants by PAHs is atmospheric exposure (Phillips, 1999). ...
Article
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The end products (digestate, solid fraction of the digestate, liquid fraction of the digestate) of ten biogas production lines in Finland were analyzed for ten hazardous organic compounds or compound groups: polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCB(7)), polyaromatic hydrocarbons (PAH(16)), bis-(2-ethylhexyl) phthalate (DEHP), perfluorinated alkyl compounds (PFCs), linear alkylbenzene sulfonates (LASs), nonylphenols and nonylphenol ethoxylates (NP + NPEOs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA). Biogas plant feedstocks were divided into six groups: municipal sewage sludge, municipal biowaste, fat, food industry by-products, animal manure and others (consisting of milling by-products (husk) and raw former foodstuffs of animal origin from the retail trade). There was no clear connection between the origin of the feedstocks of a plant and the concentrations of hazardous organic compounds in the digestate. For PCDD/Fs and for DEHP, the median soil burden of the compound after a single addition of digestate was similar to the annual atmospheric deposition of the compound or compound group in Finland or other Nordic countries. For PFCs, the median soil burden was somewhat lower than the atmospheric deposition in Finland or Sweden. For NP + NPEOs, the soil burden was somewhat higher than the atmospheric deposition in Denmark. The median soil burden of PBDEs was 400 to 1000 times higher than the PBDE air deposition in Finland or in Sweden.With PBDEs, PFCs and HBCD, the impact of the use of end products should be a focus of further research. Highly persistent compounds, such as PBDE- and PFC-compounds may accumulate in agricultural soil after repeated use of organic fertilizers containing these compounds. For other compounds included in this study, agricultural use of biogas plant end products is unlikely to cause risk to food safety in Finland.
... where FIR is the food (vegetable) ingestion rate which was considered as 345 and 232 g fresh weight person-À1 day À1 for adults and children, respectively, as used in the previous studies (Khan andCao 2012, Chauhan andChauhan 2014), C metal is the concentration of toxic metals in rooftop vegetable samples (mg kg À1 ), and BW is the average body weight assuming 63.9 and 32.7 kg for adults and children, respectively, as used in the previous studies (Ge 1992, Khan andCao 2012). ...
... where FIR is the food (vegetable) ingestion rate which was considered as 345 and 232 g fresh weight person-À1 day À1 for adults and children, respectively, as used in the previous studies (Khan andCao 2012, Chauhan andChauhan 2014), C metal is the concentration of toxic metals in rooftop vegetable samples (mg kg À1 ), and BW is the average body weight assuming 63.9 and 32.7 kg for adults and children, respectively, as used in the previous studies (Ge 1992, Khan andCao 2012). ...
Article
Rooftop cultivation of vegetables is considered as a potential food source for urban population. However, rooftop products in the urban area can be contaminated by different types of pollutants like toxic metals and polycyclic aromatic hydrocarbons (PAHs). The present study is the first that investigated the concentrations of toxic metals and PAHs in rooftop soils and vegetables grown in the urban and peri-urban areas of Bangladesh. Red amaranth and Spinach were selected for rooftop cultivation, and both soil and vegetable samples were collected and analyzed for determining the concentrations of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) as toxic metals, while naphthalene, fluorene, phenanthrene, anthracene, pyrene, benzo(a)anthracene, and chrysene as PAHs. The study observed that urban rooftop soil and vegetables were highly contaminated with toxic metals and PAHs as compared to peri-urban rooftop samples. The metal concentrations were found in order of Zn > Cu > Pb > Cd, however, Pb and Cd concentrations in urban vegetables exceeded the safe limit. On contrary, negligible concentrations of PAHs were detected in both urban and peri-urban rooftop vegetables. The values of health risk indices revealed that the concentrations of toxic metals and PAHs in urban rooftop vegetables would not pose any carcinogenic and non-carcinogenic health risks for adults and children and thus are considered to be safe for consumption. The findings of this study will provide scientific evidence to the policy makers and public administrations for urban agriculture based policy formulation as well as will encourage the city dwellers towards urban rooftop agricultural practices.
... where FIR is the food (vegetable) ingestion rate which was considered as 345 and 232 g fresh weight person-À1 day À1 for adults and children, respectively, as used in the previous studies (Khan andCao 2012, Chauhan andChauhan 2014), C metal is the concentration of toxic metals in rooftop vegetable samples (mg kg À1 ), and BW is the average body weight assuming 63.9 and 32.7 kg for adults and children, respectively, as used in the previous studies (Ge 1992, Khan andCao 2012). ...
... where FIR is the food (vegetable) ingestion rate which was considered as 345 and 232 g fresh weight person-À1 day À1 for adults and children, respectively, as used in the previous studies (Khan andCao 2012, Chauhan andChauhan 2014), C metal is the concentration of toxic metals in rooftop vegetable samples (mg kg À1 ), and BW is the average body weight assuming 63.9 and 32.7 kg for adults and children, respectively, as used in the previous studies (Ge 1992, Khan andCao 2012). ...
Article
Full-text available
Rooftop cultivation of vegetables is considered as a potential food source for urban population. However, rooftop products in the urban area can be contaminated by different type of pollutants like toxic metals and polycyclic aromatic hydrocarbons (PAHs). The present study is the first that investigated the concentrations of toxic metals and PAHs in rooftop soils and vegetables grown in the urban and peri-urban areas of Bangladesh. Red amaranth and Spinach were selected for rooftop cultivation, and both soil and vegetable samples were collected and analyzed for determining the concentrations of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) as toxic metals, while naphthalene, fluorene, phenanthrene, anthracene, pyrene, benzo(a)anthracene and chrysene as PAHs. The study observed that urban rooftop soil and vegetables were highly contaminated with toxic metals and PAHs as compared to peri-urban rooftop samples. The metal concentrations were found in order of Zn > Cu > Pb > Cd, however, Pb and Cd concentrations in urban vegetables exceeded the safe limit. On contrary, negligible concentrations of PAHs were detected in both urban and peri-urban rooftop vegetables. The values of health risk indices revealed that the concentrations of toxic metals and PAHs in urban rooftop vegetables would not pose any carcinogenic and non-carcinogenic health risks for adults and children and thus are considered to be safe for consumption. The findings of this study will provide scientific evidence to the policy makers and public administrations for urban agriculture based policy formulation as well as will encourage the city dwellers towards urban rooftop agricultural practices.
... Perfluoroctanoic acid, perfluorooctane sulfonate and perfluorooctane sulphonamide Compost [85] Spinacia oleracea Benzo(k) flouranthene and benzo[a] pyrene Waste-water irrigation [86] Zea mays Acenaphthene and flourene Sewage [74] Brassica oleracea Benzo(k) flouranthene and benzo[a] pyrene Waste-water irrigation [86] Daucus carota Perfluoroctanoic acid, perfluorooctane sulfonate and perfluorooctane sulphonamide Compost [85] Capsicum annuum Phenantrene and Benzo[a]antracene Waste-water irrigation [87] Page 7 of 11 Olowoyo and Mugivhisa Chem. Biol. ...
... Perfluoroctanoic acid, perfluorooctane sulfonate and perfluorooctane sulphonamide Compost [85] Spinacia oleracea Benzo(k) flouranthene and benzo[a] pyrene Waste-water irrigation [86] Zea mays Acenaphthene and flourene Sewage [74] Brassica oleracea Benzo(k) flouranthene and benzo[a] pyrene Waste-water irrigation [86] Daucus carota Perfluoroctanoic acid, perfluorooctane sulfonate and perfluorooctane sulphonamide Compost [85] Capsicum annuum Phenantrene and Benzo[a]antracene Waste-water irrigation [87] Page 7 of 11 Olowoyo and Mugivhisa Chem. Biol. ...
Article
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The use of organic materials as soil nutrients to improve agricultural production is well documented. However, these organic materials may contain toxic pollutants that may bio-accumulate in plant tissues and eventually be consumed by humans. There is a misconception about the use of organic materials (sludge, urine, human waste and urban waste) in agriculture and organic farming. The review work examined the sources and uses of organic material in agriculture from developing countries and the dangers posed by the use of polluted organic materials in agriculture. The review examined through literature the availability and uptake of pollutants in crops that are cultivated from farming activities using organic materials. The review established the possibility of uptake of pollutants from treated waste materials that are used for farming. Some of the pollutants that can be bio-accumulated by plants when cultivated on soil containing these pollutants were documented. The review concluded by establishing the need to create awareness on the possible health risks associated with the use of organic materials if the materials used were polluted. The review also highlighted the importance of educating peasant farmers on the dangers associated with collecting waste materials from untreated sources.
... Several studies have investigated the uptake of PAHs by plants, and the results have shown that the main pathway for the accumulation of PAHs in vegetables is the gaseous deposition (Kipopoulou et al., 1999;Tao et al., 2004b;Voutsa and Samara, 1998;Wild et al., 2004;Wild et al., 1992). In some cases, plants can also accumulate PAHs from contaminated soil through active or passive uptake by plant root (Inam et al., 2016;Khan et al., 2008;Khan and Cao, 2011;Khan et al., 2015;Qamar et al., 2017;Waqas et al., 2014b;Zheng et al., 2014). Wang et al. (2011) reported that root and air uptake pathways are the dominant pathways, and the dominance of one pathway over the other depends on the vegetable, contaminant, and local conditions. ...
... ∑ PAHs concentrations in leafy vegetables were relative higher than those in root vegetables, similar to the results of a study by Khillare et al. (2012), which might be caused by atmospheric deposition (Khillare et al., 2012;Menzie et al., 1992). The concentrations of ∑PAHs were higher than those reported in two other Chinese cities, Shenzhen and Taiyuan, and in Catalonia, Spain (Ding et al., 2013;Falco et al., 2003;Martí-Cid et al., 2008;Martorell et al., 2010;Xia et al., 2010), but lower than those reported in China, and Pakistan (Khan and Cao, 2011;Li, 2007;Waqas et al., 2014a). ...
Article
Halogenated polycyclic aromatic hydrocarbons (HPAHs) are attracting increasing concern because of their greater toxicity than their corresponding parent PAHs. However, human exposure to HPAHs via food consumption is not fully understood. In this study, daily intake via vegetable ingestion of 11 HPAHs and 16 PAHs and subsequent cancer risk were assessed for population in Beijing. A total of 80 vegetable samples were purchased from markets, including five leafy vegetables and three root vegetables. The concentrations of total HPAHs (∑HPAHs) were 0.357-0.874ng/g in all vegetables, lower than that of total PAHs (∑PAHs, 10.6-47.4ng/g). ∑HPAHs and ∑PAHs concentrations in leafy vegetables were higher than those in root vegetables, suggesting that the atmospheric deposition might be the dominant source of PAHs and HPAHs in leafy vegetables. Among the HPAH congeners, 2-BrFle and 9-ClFle were the predominant compounds and frequently detected in the vegetable samples. HPAHs and PAHs were also found in certificated vegetables at the concentrations of 0.466-0.751ng/g and 10.6-38.9ng/g, respectively, which were lower than those in non-certificated vegetables except for spinach. For leafy vegetables from local farms, the ∑PAHs and ∑HPAHs levels in the rape and Chinese cabbage samples significantly decreased with increasing the distance away from the incineration plant. The incremental lifetime cancer risks of HPAHs were below the acceptable risk level (10(-6)), suggesting that there might be little or no risk to consumers from these compounds in vegetables. For all population groups, children were the most sensitive population to PAHs and HPAHs, and their health issues should be paid more attention.
... HOCs are found in the priority list of hazardous substances as listed by the agency for toxic substances and disease registry of USA [1] . Among these compounds, polycyclic aromatic hydrocarbons (PAHs) are more hazardous compounds to human health due to their mutagenic and carcinogenic nature [2,3] . PAHs constitute a class of hazardous organic compounds consisting of two or more fused benzene rings in linear, angular or cluster arrangements. ...
Article
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The solubilization of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, phenanthrene and pyrene by single and mixed anionic dimeric surfactants was investigated and correlated with micellar properties of these surfactants. The surface and micellar properties of single and binary mixed combinations of anionic dimeric surfactants have been studied through surface tension as well as conductivity measurements at 300 K. The associations between their micelle properties and solubilizing efficiency towards PAHs have been quantified and discussed in terms of the molar solubilization ratio (MSR), micelle-water partition coefficient (Km) and standard free energy of solubilization (ΔG0S).The negative value of ΔG0Sexhibits spontaneously the solubilization process. The MSR values increase with the order “pyrene < phenanthrene < naphthalene”. The current study provides significant information for the selection of mixed dimeric surfactants for solubilizing water-insoluble compounds.
... PAHs and their derivatives in the atmosphere, especially nitrated and oxygenated PAHs, are known to be carcinogenic and mutagenic, leading to significant adverse health outcomes upon exposure [48][49][50][51][52]. Given their lipophilic molecular specialty, PAHs can directly penetrate the phospholipid bilayer of the cell membrane [53]. ...
Article
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In order to explore the effects of COVID-19 control measures on the concentration and composition of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs), and to better understand the sources of PM2.5-bound PAHs, PM2.5, samples were collected at two sites in urban and suburban areas of Shanghai before the lockdown, during the lockdown, after the lockdown in 2020, and during the same periods in 2019. The mass concentrations of 21 individual PAHs were determined via GC-MS analysis. While the COVID-19 control measures significantly reduced the absolute concentration of PM2.5-bound PAHs, they had no significant effect on their relative abundances, indicating that the significantly reduced traffic emission may not originally be the major source of PAHs in Shanghai. The differences in the composition of PM2.5-bound PAHs at three different lockdown-related periods may be caused by the gas-particle distribution of semi-volatile PAHs. The similarity in the composition of PM2.5-bound PAHs in different functional areas and different periods brings more uncertainties to the identification of PAH sources using the diagnostic ratios. During the lockdown period, the toxic equivalent concentration of PM2.5-bound PAHs in Shanghai was estimated to decrease by about 1/4, which still exhibits substantial carcinogenic risk upon exposure via inhalation.
... Numerous studies have shown that soil is the main source of exposure to PAHs [13] because 89.9% of these pollutants are accumulated in the soil environment. PAHs present in soil contaminate vegetables and crops, and they can be transferred to the food chain [14][15][16][17][18][19]. Liao [20] also reported that the uptake of organic pollutants by plants is an important part of the assessment of risks from crops grown on contaminated soils. ...
Article
Full-text available
Polycyclic aromatic hydrocarbons (PAHs) are mainly accumulated in soil. Plants secrete enzymes that transform or biodegrade PAHs in soil. Some plant species are more effective in stimulating the biodegradation of these pollutants than other species. This study was undertaken to evaluate the influence of crop rotation on PAH concentrations in soil. Four crops were grown in rotation: sugar beets, spring barley, maize, and spring wheat. Soil samples for the study were obtained from a long-term field experiment established in 1986 in Bałcyny, Poland. The concentrations of PAHs were analyzed in soil samples gathered over a period of 12 years (1998–2009). An attempt was made to evaluate the effect of crop rotation (sugar beets, spring barley, maize, and spring wheat) on PAH concentrations in soil. The content of PAHs in soil samples was measured by gas chromatography with flame ionization detection. Data were processed statistically by repeated measures ANOVA. The concentrations of ∑16 PAHs were lowest in soil after sugar beet cultivation, and highest in soil after maize cultivation. It can be concluded that maize was the plant with the greatest adverse effect on the content of heavy PAH in the soil, a completely different effect can be attributed to spring wheat, which has always been shown to reduce the content of heavy PAH in the soil. Weather conditions affected PAHs levels in soil, and PAH content was highest in soil samples collected in a year with the driest growing season. This arrangement suggests a greater influence of weather conditions than of the cultivated plant.
... The main source of PAHs exposure for nonsmokers or nonworking individuals is the consumption and ingestion of food (Alomirah et al., 2011;Ramalhosa et al., 2012). Vegetables are among the most consumed foodstuffs in the human diet, with the significant intake of PAHs in vegetables emphasized (Khan and Cao, 2012;Tao et al., 2004). In addition, the plant can build up PAHs by active or passive root uptake from contaminated soil (Khan et al., 2015;Waqas et al., 2014). ...
Chapter
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Polycyclic aromatic hydrocarbons (PAHs) are chemicals in the urban environment and are quite worrying because of their carcinogenicity in environmental contamination. PAHs are an omnipresent, environmentally persistent, multi-structure group of several hundred chemical substances, that have varied in toxicity. Substantial hazards to global, environmental, and health exist contamination of soil by harmful substances. The clean-up of toxins with damaging, invasive technology is costly and more critically, often harmful to soil, sediment, or aquifer's natural resource characteristics. PAHs are extremely fat-soluble and are therefore easy to absorb from the mammalian tract system and damage the organs. They are dispersed quickly in a broad range of tissues with a significant tendency to locate the body's fat. PAHs metabolism occurs as a first step through the mixed-function oxidase system mediated by cytochrome P-450, oxidation, or hydroxylatPhytoremediationation is a potential approach for the removal of PAHs from contaminated areas without any harmful effects. Multiple techniques involving various components of pollutant removal from soil were integrated to improve phytoremediation processes. In efforts to eliminate these environmental toxins, several different remediation procedures have been developed. Phytoremediation is among them a safe and cost-effective solution with great potential.
... Numerous studies have shown that soil is the main source of exposure to PAHs [13] because 89.9% of these pollutants are accumulated in the soil environment. PAHs present in soil contaminate vegetables and crops, and they can be transferred to the food chain [14][15][16][17][18][19]. Liao [20] also reported that the uptake of organic pollutants by plants is an important part of the assessment of risks from crops grown on contaminated soils. ...
... Previous studies have investigated the concentrations and distributions of PAEs and PAHs in the environment (Bucheli et al. 2004;Zeng et al. 2008), identified their sources Sosa et al. 2019), assessed the environmental risk of target pollutants (Wen et al. 2018;Khan and Cao 2012;Lu et al. 2020), and correlated these contaminants with soil properties and microbiota (Sun et al. 2018;Wang et al. 2019). These studies were carried out in specific local, contaminated areas. ...
Article
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Purpose Phthalic acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) are of global concern because of their serious environmental impacts. The identification of zones contaminated with PAEs and PAHs in the soil is urgently needed to provide a basis for land use and remediation. Materials and methods Zhejiang Province was used as a typical example to identify contaminated zones by measuring the concentrations of PAEs and PAHs in gridded soil with a 1/6° latitude by 1/4° longitude resolution. Based on the concentrations and spatial distributions of PAEs and PAHs in superficial soil in Zhejiang, the estimation of inventory, and the assessment of ecological risk, the contaminated zones and possible sources of these two groups of pollutants were identified. Results and discussion High spatial variability of PAE concentrations in the surface soils was observed in Zhejiang Province. The areas with high PAE concentrations were in the middle region of Zhejiang where highly urbanized and industrialized. The spatial distribution of PAH in the surface soil of Zhejiang appeared to be uneven. High PAH concentrations in the soil of Zhejiang were mainly measured in plains areas and can be linked to the development of industry and multiple emission sources. Conclusions PAE pollution mainly originated from centralized plastic manufacturing, plastic product use, and plastic waste recycling. PAH contamination was linked to the combustion of fuels in vehicle engines and industrial discharge from a cluster of low-capacity boilers. These results can provide a database and reliable reference information for land use and remediation in other agroindustrial ecotone areas.
... Determining whether plants growing in contaminated soils are capable of significant active root uptake and subsequent translocation of PAHs is important in evaluating the risks from PAH exposure (Mumtaz and George, 1995, pp. 245-246;Khan and Cao, 2012). ...
Chapter
Remediation of sites contaminated with polyaromatic hydrocarbons (PAHs) often involves the use of vascular plants for phytoremediation or restoring ecosystem functions. Because PAHs are potentially carcinogenic, minimizing the quantity of PAHs entering vegetation is critical to reducing risk associated with food-chain contamination. For many years, the general consensus considered the soil-root-shoot pathway to be of minor importance compared to mechanisms involving deposition from the atmosphere. However, more recent studies often attribute greater importance to the soil-root-shoot pathway. The objective of this paper is to review the scientific literature and determine, if possible, the most likely mechanism(s) of PAH assimilation in plant shoots. Studies of plant PAH uptake, direct spectroscopic observations, rigorous numerical modeling, and detailed statistical inference were examined. Some exceptions exist, but the consistent conclusion from mechanistic studies of PAH uptake is that the soil-root-shoot pathway is of minor importance compared to atmosphere-based mechanisms including soil-air-shoot and soil-airborne particle-shoot.
... Since heavy metals often occur in combination with PAHs in soils contaminated by industrial activities, such as e-waste dismantling sites, gas works and coking plants (Zhang et al. 2012;Zhong and Zhu 2013;Abel et al. 2015;Vácha et al. 2015), there is an increasing need to assess the human and environmental risk of mixed heavy metal and PAH pollution (Alternatives NRCC 1994;Lin et al. 2005;Khan and Cao 2012;Zheng et al. 2014). Therefore, efficient and ecologically relevant methods are required to assess the toxicological impacts of combinations of multiple pollutants in soils, such as the determination of pollutant concentrations, toxicity bioassays of heavy metals and PAHs in contaminated soils, and the assessment of ecological risks . ...
Article
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Soil pollution due to the activities of industrial parks, is becoming an increasingly serious issue, particularly throughout China. Therefore, it is essential to explore the soil pollution characteristics and its ecotoxicological effects on model species, such as higher plant species, in typical industrial areas. In this study, concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were examined in the soil collected from 10 sampling sites at a chemical industry park in Nanjing, China. The pollution index was used to assess the heavy metal pollution level of soils, while the hazard index (HI) and carcinogenic risk index (RI) were calculated to assess the human health risk of soil PAHs. In addition, wheat (Triticum aestivum L.) was used as the model species to evaluate the ecotoxicological effects of polluted soil in pot experiments. Results showed that the content of heavy metals and PAHs varied greatly in soil samples, among which the heavy metal pollution at S1, S2 and S3 was the most serious. The health risk assessment of PAHs indicated that non-carcinogenic and carcinogenic values for all soil samples were below the threshold levels. Statistical analysis of the correlation between contaminated soil and toxic effects in wheat found that the significance values of regression equations were all less than 0.05 for chlorophyll content, peroxidase (POD) and amylase (AMS) activity. This indicates that the chlorophyll content, POD and AMS activity in wheat leaves could be suitable biomarkers for evaluation of the combined toxicity of multiple pollutants. This study provides a reference for future research on the risk assessment of soil containing multiple pollutants from industrial chemical parks.
... These chemicals are known to cause toxicity to wildlife and humans even at trace concentrations Wu et al., 2010b). They initiate endocrine disruption: ecotoxic, neurogenic and carcinogenic health disorders in aquatic organisms and humans (Khan and Cao, 2011;Li et al., 2005;Tsutsumi, 2005;Tuyet-Hanh et al., 2010). In humans, these toxic chemicals cause birth defects and reduced fertility, obesity, thyroid effects and brain disorders Sohoni et al., 2001). ...
Thesis
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Waste chemicals arising from poor municipal solid waste management across countries result in negative environmental impacts and health risks. Globally, over 200 infectious and non-communicable diseases, 600 million patient illnesses and 2 million deaths result from microbial and chemical contaminations of food and water. In some developing countries, chemical-related diseases (e.g., “itai-itai”, “chloracne” and “yusho”) have been reported. In 2012, 23% of the global deaths and 22% of the disabilities were attributed to environmental contaminant related risks. In Uganda, ten preventable diseases related to environmental hygiene and food safety contributed to 75% of infant mortality (1997 – 2001). Limited studies on ecological and food chain risk assessments of chemical disease burdens, coupled with weak enforcement of environmental regulations and lack of effective food safety systems have negatively impacted on land and food governance. This has resulted in the co-occurrence of open dumping and urban agriculture, including dumpsite farming. In the Mbale municipality, in Uganda, several qualitative studies have reported more than 50% prevalence of sanitation-related diseases. Only one quantitative study on five soil and two surface water samples have been carried out at the Mbale dumpsite (2007), and no groundwater or food crop risk analysis exists. In this thesis, the literature review (chapter 2) describes the problems associated with poor waste management across countries and identified the critical gaps that present risks to the human population. Also, described is an assessment of food chain contamination due to toxic metals from the Mbale mixed waste dumpsite (Uganda). Food crops on the Mbale dumpsite were used as bio-monitors to assess the presence of aluminium (Al), chromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg) and lead (Pb), and their potential health risks. The first objective of the study was to use 108 Zea mays and Amaranthus cruentus crop samples to assess if crop locations influenced metal uptake across the Mbale dumpsite. The second objective assessed if metal uptake in crops and crop parts were influenced by growth period (maturity age) using eighty-one short-term (2 – 6 months) and long-term (7 - 15, 18 – 72 months) crops from the Mbale dump’s centre and hillslope. The third objective assessed if the single and total dietary exposure risks in individual crop types, combined individual crop types and mixed diets (meal types) were within acceptable levels, using seventy-five short-term crops at the Mbale dump’s centre. The results were compared against World Health Organization food safety guidelines, toxicity limits and the United States Environmental Protection Agency cancer risk categories. It was observed that some metal (Pb, Cr, Al, Zn, Hg, Ni, Mn, Fe, Cu) concentrations in the food crops were above WHO/FAO safe consumption levels and could pose both non-carcinogenic and carcinogenic risks. The mean concentrations of some essential elements (Fe, Al, Zn, Mn and Cu) were higher than for most toxic elements (Cr, Pb, Ni, Co, Se, As, Cd, and Hg), that were only present in trace amounts, except for Al and Se. Metal accumulation in crops depended on crop type and part, with leaves accumulating higher metal concentrations compared to any other part of the plant, for most metals. Furthermore, Al, Zn, Fe, Cr and Co concentrations in crops varied significantly across the dumpsite; and the highest metal accumulation was at the dump centre and in crop leaves, with Zn and Cr concentrations higher at the slope. Metal concentrations in short-term (2 – 6 months) crops were higher than those in long-term (7 – 15 and 18 – 72 months) for most metals, with the highest metal accumulation in short-term crops at the dump centre and in crop leaves at the slope. The estimated daily metal intake, non-carcinogenic and carcinogenic risks were higher in children than adults. The total dietary exposure risks in consuming individual crop type or individual combined crop types were higher than that in meal types (commonly mixed diets). The carcinogenic risks from total metal dietary exposure in meal types and crop types were high (10-3 - 10-2) to very high (10-3 - 100) respectively. Also, the highest risks were via consumption of leafy crops compared to legumes, cereals and fruits. The study concludes with recommendations on the need to create consumer awareness through relevant stakeholder collaborations, inclusion and participation; identifies what crops to grow and where to grow them on the site and outside the urban setting. It also highlights the importance of crop type selection for meal-type combinations. Other identified areas are the need to use scientific evidence to develop potential policies required in enforcing land and food governance, and future research on exposure assessments to further characterize the risks associated with exposure to metal contaminants found in food crops (washed and unwashed) grown on the Mbale dumpsite.
... Such a high concentration would pose severe health risk to humans via direct contact and vapor inhalation. Moreover, strong bioaccumulation of PAHs in food chain has been reported (Khan and Cao, 2012;Meudec et al., 2006). Therefore, it is imperative to develop environmentally friendly and cost-effective remediation techniques to effectively remove PAHs from soil (Lamichhane et al., 2017). ...
Article
Soil washing process enhanced by surfactants is a promising technique in removing organic pollutants from soil. In this work, a simultaneous sorption and biodegradation technique was used to remove 16 PAHs from a soil washing solution (SWS) obtained by rinsing a heavily contaminated soil from a coking plant with Triton X-100 (TX-100). This was done by immobilizing a pyrene-degrading bacterial strain in polyvinyl alcohol-sodium alginate (PVA-SA) hydrogel beads. Removal performance of free bacteria, blank PVA-SA beads and beads with immobilized degrading bacteria at a low, medium and high initial concentration was evaluated. The recycling and removal performance of the used beads were also examined. Our findings showed that hydrogel beads with immobilized bacteria at a medium concentration can remove around 77% ∑16PAHs from SWS in 96 h. The beads can be recycled and reused to treat a new SWS; 32–55% ∑16PAHs was removed in 24 h. The bead provided protection for bacteria against the co-existing substances such as TX-100. The bacteria-immobilized beads are more efficient and sustainable than free bacteria and blank beads due to simultaneous sorption and biodegradation processes, thus providing a solid reference for possible industrial application of bacteria immobilization technique to deal with SWSs with complex composition.
... DI-PAH of individual PAH values obtained for adults were ranged from 0.0001 to 0.00958 μg kg −1 body weight day −1 , 0.00016 to 0.01383 μg kg −1 body weight day −1 , 0.00005 to 0.0109 μg kg −1 body weight day −1 , 0.00001 to 0.003449 μg kg −1 body weight day −1 , 0.000089 to 0.007951 μg kg −1 body weight day −1 , 0.000118 to 0.010897 μg kg −1 body weight day −1 , 0.00003 to 0.001774 μg kg −1 body weight day −1 , 0.000059 to 0.004789 μg kg −1 body weight day −1 for KI, MO, SA, MON, RI, CE, TS and LI respectively. Compared with the virtually safe dose of 0.0005 μg kg −1 body weight day −1 set by the Dutch National Institute for Public Health and Environment (Khan and Cao, 2012), the daily intake of BaP through consumption of A. viridis for adults were ranged from 0.000256 (MON) to 0.00083 μg kg −1 body weight day −1 (SA). The sampling sites KI, SA, RI and LI indicate a daily intake of BaP relatively higher than the safe dose of 0.0005 μg kg −1 body weight day −1 . ...
... These contaminated soil resources can easily lead to the secondary pollution of groundwater bodies (Qiao et al. 2008). Moreover, PAHs are found to be carcinogenic, mutagenic, and teratogenic (Jian et al. 2009;Jian et al. 2011;Khan and Cao 2012). PAHs are hydrophobic, which leads these compounds to be readily retained on the solid phase. ...
Article
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Purpose The ionic and nonionic surfactants have different adsorption-desorption models for polycyclic aromatic hydrocarbons (PAHs) in soil-water system, due to the difference in the composition and charge of the hydrophilic groups. Surfactant eluents retained in the soil may also have a secondary effect on the soil environment. Thus, the aim of the study was to investigate sorption-desorption mechanisms and environmental toxicity of different surfactants in enhancing remediation of soil contaminated with PAHs. Materials and methods The distribution of PAHs between different surfactants and soil is influenced by the surfactant bilayer formation. The average molecular density, Sips isotherm, critical micelle concentration (CMC), and critical washing concentration (CWC) models were used to explore the mechanisms involved in the adsorption-desorption of cationic (cetyltrialkylammonium bromide, CTAB), anionic (sodium dodecyl benzene sulfonate, SDBS), and nonionic (TritonX-100, TX100) surfactants. These models were associated with the surfactant-enhanced remediation (SER) of naphthalene-contaminated soil. The mean concentrations and activity of indigenous bacteria were used to detect the toxic effect of the above surfactants on soil environment. Results and discussion The results of SER experiments showed that there are critical washing points (SDBS = 2.4 CMC, TX100 = 4.6 CMC, CTAB = 3.3 CMC) for different surfactants washing naphthalene (Nap). The values of CWC corresponding to critical washing points were key variables driving the need for added surfactants to remove or immobilize Nap. The CWC of different surfactants could be conveniently predicted by a model based on the surfactant-derived organic carbon. In addition, the mean concentration of viable bacteria in biological culture experiment was highest for TX100, followed by CTAB and SDBS. Conclusions This study revealed the effects of average molecular density and surfactant-derived organic carbon on the distribution of Nap, and suggested a model for calculating CWC of different surfactants, to optimize SER technology. Biological culture experiment indicated that the high concentration and ionic surfactants had a significantly toxic effect on indigenous bacteria.
... collected in the Pearl River Delta (South China). Khan and Cao (2012) calculated RCFs (root/soil concentration factor) and SCFs (shoot/soil concentration factor) for different vegetables grown in metropolitan areas of Beijing (China) and found that the bioaccumulation factors decreased with the increase of ring numbers. Nevertheless, several studies have shown that the major pathway for the accumulation of PAHs in vegetation is atmospheric deposition (Jia et al. 2019). ...
Article
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Urban horticulture and community gardening have become more and more popular in the past years, however, the risk of bioaccumulation of atmospheric polyaromatic hydrocarbons (PAHs) in vegetables grown in polluted areas cannot be neglected. In our study, the No. 227 OECD GUIDELINE FOR THE TESTING OF CHEMICALS: Terrestrial Plant Test: Vegetative Vigour Test was followed to assess foliar uptake of PAHs from aqueous extract of an urban aerosol. Using lettuce (Lactuca sativa) as a test organism, significant accumulation was experienced. The highest bioconcentration factors (BCFs) were experienced for naphthalene and for anthracene, pyrene and fluoranthene showed the lowest bioaccumulation potential. BCF of each PAH showed strong correlation with molecular weight. The standard protocol defined by the Guideline made it possible to assess bioaccumulation pattern under controlled laboratory conditions.
... It is well documented that the dietary intake and ingestion through food is the predominant source of PAH exposure for nonsmokers and non-occupational individuals (Alomirah et al., 2011;Ramalhosa et al., 2012). Vegetables are one of the most consumable food items in the human diet, and the occurrence of PAHs in vegetables have been highlighted due to their high consumption (Khan and Cao, 2011;Tao et al., 2004). Moreover, vegetables can accumulate PAHs from contaminated soil through active or passive root uptake (Inam et al., 2016;Khan et al., 2015;Waqas et al., 2014). ...
Article
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This is a primary investigation on the mitigation of polycyclic aromatic hydrocarbon (phenanthrene as a model PAH) contamination in vegetables including water spinach (Ipomoea aquatica Forsk), pakchoi (Brassica cam-pestris) and Chinese cabbage (Brassica chinensis) using a gfp-labeled PAH-degrading bacterium (RS1-gfp). Effective root colonization led to dense RS1-gfp populations inhabiting the rhizosphere and endosphere of the vegetables, which subsequently led to a reduction in phenanthrene accumulation and risk in vegetables. When compared with the controls without RS1-gfp, the amount of phenanthrene accumulation due to strain RS1-gfp colonization reduced by up to ~93.7% in roots and ~75.2% in shoots of vegetables, respectively. The estimated incremental lifetime cancer risk (ILCR) for adults due to phenanthrene in vegetables was reduced by 24.6%-48% through RS1-gfp inoculation. The proposed method was developed to circumvent the risk of phenanthrene contamination in vegetables by inoculating PAH-degrading bacteria. The findings provide an in-depth understanding of PAH detoxification in agricultural plants grown on contaminated sites by exploiting bacteria like RS1-gfp, which portray both rhizo-and endophytic lifestyles.
... can easily spread from manure to water supplies and can remain viable in the environment for long periods of time (Bowman et al. 2000). These pathogens in contaminated soils may attached to the grown vegetables and cause health risk particularly via leafy vegetables (lettuce) that are consumed in raw or semi-cooked forms (Khan and Cao 2012). ...
Article
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Purpose Antibiotics are growing environmental contaminants leading to public health concern. Antibiotics are commonly used as growth promoters and therapeutic agents in poultry feed that are not completely metabolized in the body tissues of chicken, get deposited in meat as parent compounds, and ultimately excreted via poultry droppings into the environment. These antibiotics in the soil result into the creation of antibiotic resistance in bacteria via activation of antibiotic resistance genes (ARGs). The development of ARGs and antibiotic-resistant bacteria (ARB) lead to huge physical and economic losses, as these bacteria cannot be treated with commonly used antibiotics. Moreover, these antibiotics after entering into food chains seriously affect the human immune system, growth, and metabolism of the body. Therefore, to reduce the future health risks of antibiotics, there is a dire need to understand the fate of poultry antibiotics and spread of ARGs in the soil environment. Materials and methods In this manuscript, we reviewed the existing literature about the antibiotics used in the poultry sector, soil contamination through application of poultry manures, and development of ARB in environment. An attempt has been done to present a better understanding of emerging contaminants (ARGs, ARB) in the soil environment and their associated human health effects. Results and discussion In this paper, we summarized the use of antibiotics in the poultry sector, persistence of antibiotics in animal body, and their release into environment. Transfer mechanism of antibiotics and their metabolites to the human body and their fatal effects have been investigated. Developments of ARB and ARGs in the soil due to excessive use of veterinary antibiotics have been highlighted. Conclusions Poultry antibiotics are causing human health risks by development of ARGs and ARB. Such antibiotic resistance cannot be treated with common antibiotics. Therefore, effective measures are needed to control this emerging problem by improving the efficiency of antibiotics, reducing the spread of resistance genes, and proper monitoring of antibiotics in poultry feed and manure. Manure composting and biochar application are the possible ways to reduce the risk and spread of ARGs in environment due to manure application in agriculture field. The pathways that allow antibiotic, ARGs, and ARB to move through the environment are not fully understood and there is a need for further research to make clear the reservoirs and routes of antibiotic-related contaminants in the ecosystem.
... can easily spread from manure to water supplies and can remain viable in the environment for long periods of time (Bowman et al. 2000). These pathogens in contaminated soils may attached to the grown vegetables and cause health risk particularly via leafy vegetables (lettuce) that are consumed in raw or semi-cooked forms (Khan and Cao 2012). ...
Article
Full-text available
Purpose: Antibiotics are growing environmental contaminants leading to public health concern. Antibiotics are commonly used as growth promoters and therapeutic agents in poultry feed that are not completely metabolized in the body tissues of chicken, get deposited in meat as parent compounds, and ultimately excreted via poultry droppings into the environment. These antibiotics in the soil result into the creation of antibiotic resistance in bacteria via activation of antibiotic resistance genes (ARGs). The development of ARGs and antibiotic-resistant bacteria (ARB) lead to huge physical and economic losses, as these bacteria cannot be treated with commonly used antibiotics. Moreover, these antibiotics after entering into food chains seriously affect the human immune system, growth, and metabolism of the body. Therefore, to reduce the future health risks of antibiotics, there is a dire need to understand the fate of poultry antibiotics and spread of ARGs in the soil environment. Materials and methods: In this manuscript, we reviewed the existing literature about the antibiotics used in the poultry sector, soil contamination through application of poultry manures, and development of ARB in environment. An attempt has been done to present a better understanding of emerging contaminants (ARGs, ARB) in the soil environment and their associated human health effects. Results and discussion: In this paper, we summarized the use of antibiotics in the poultry sector, persistence of antibiotics in animal body, and their release into environment. Transfer mechanism of antibiotics and their metabolites to the human body and their fatal effects have been investigated. Developments of ARB and ARGs in the soil due to excessive use of veterinary antibiotics have been highlighted. Conclusions: Poultry antibiotics are causing human health risks by development of ARGs and ARB. Such antibiotic resistance cannot be treated with common antibiotics. Therefore, effective measures are needed to control this emerging problem by improving the efficiency of antibiotics, reducing the spread of resistance genes, and proper monitoring of antibiotics in poultry feed and manure. Manure composting and biochar application are the possible ways to reduce the risk and spread of ARGs in environment due to manure application in agriculture field. The pathways that allow antibiotic, ARGs, and ARB to move through the environment are not fully understood and there is a need for further research to make clear the reservoirs and routes of antibiotic-related contaminants in the ecosystem.
... The ingestion of food and water are considered as the major route for PAHs intake [7]. The occurrences of PAHs in the raw vegetables and fruits which may due to air pollution were reported [8,9]. The determination of PAHs from food sample is very crucial because of its perilous properties. ...
Article
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An effective analytical method based on microwave-assisted extraction (MAE) and dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-flame ionization detector (GC-FID) was developed for the determination of polycyclic aromatic hydro-carbons (PAHs) in vegetable samples. In most cases, the details of the parameters influencing the efficiency of DLLME in extraction are not well studied. Understanding the reactions of solvents in extraction is the important task on selecting of an appropriate solvent in the process. The effects of parameters affecting the extraction efficiency of DLLME, including extraction solvent and dispersive solvent, extraction time and MAE, such as solvent, microwave power and irradiation time, were studied and explained. The impacts of physio-chemical properties of the selected extraction solvents on the extraction efficiency were also investigated. The results indicated that extraction solvents with low viscosity and low polarity have better extraction efficiency in extraction of PAHs from vegetable sample. No significant difference was observed for the effects of selected dispersive solvents and extraction time on extraction efficiency. In MAE, the types of solvent, microwave power and irradiation time implied some critical effects on the extraction efficiency of DLLME.
... Unfortunately, up to date, such a criterion for 16 priority PAHs in soil is not available in China. Such a high level of PAHs in soils may pose severe health risks to exposed human beings via food consumption, as crops grown on PAH-contaminated soils have been demonstrated to accumulate a certain amount of these contaminants (Khan and Cao, 2011). Jiang et al. (2011) revealed that the total BaPeq (toxic equivalent data based on benzo [a]pyrene) values of ten Dutch target PAHs in 72% agricultural soil samples from Shanghai were higher than their reference total carcinogenic potency. ...
Article
To elucidate the environmental fate of polycyclic aromatic hydrocarbons (PAHs) once released into soil, sixteen humic acids (HAs) and one humin (HM) fractions were sequentially extracted from a peat soil, and sixteen priority PAHs in these humic substances (HSs) were analyzed. It was found that the total concentration of 16 PAHs (∑16PAHs) increased evidently from HA1 to HA16, and then dramatically reached the highest value in HM. The trend of ∑16PAHs in HAs relates to surface carbon and C-H/C-C contents, the bulk aliphatic carbon content and aliphaticity, as well as the condensation enhancement of carbon domains, which were derived from elemental composition, XPS, ¹³C NMR, as well as thermal analyses. HM was identified to be the dominant sink of 16 PAHs retention in soil, due to its aliphatic carbon-rich chemical composition and the highly condensed physical makeup of its carbon domains. This study highlights the joint roles of the physical and chemical properties of HSs in retention of PAHs in soil and the associated mechanisms; the results are of significance for PAH-polluted soil risk assessment and remediation.
... In cases where the separation of plant parts is difficult, element concentration in the whole plant could be used to assess hyperaccumulation, as proposed by Baker and Brooks (1989). As reported by Bini (2014), in particular cases of risk assessment, additional ratios could be useful to further characterize plants, for example the ones proposed by Khan and Cao (2012). ...
Article
This paper reviews the various factors, coefficients and indexes developed to evaluate terrestrial plant performance in respect to phytoremediation. A brief list of indexes includes the Accumulation factor, These indexes represent the result of a ratio calculation between element concentrations in plant parts to that of substrata. In other cases indexes arise from the ratio calculation of element concentrations in two distinct plant parts. In the literature different terms have been attributed to the same ratio and this often represents an overlap in terminology. On the other hand the same term corresponds to several different ratios and this could create confusion and misinterpretation in data comparison. Furthermore, the evaluation of hyperaccumulation, phytostabilization or phytoextraction of plant species is not always performed in the same way. Different plant parts are considered as well as different extraction procedures for both plant and substrata element assessment. As a consequence, a direct comparison between obtained data is not always reliable and possible. In this paper the various available indexes are reviewed, highlighting both the similarity and differences between them with the aim of helping the community in choosing the appropriate term for both data evaluation and comparison. In this author's opinion there is no need of new terms to define indexes. I would stress the need for conformity to the original definitions and criteria.
... In fact, no standards for PAHs in foodstuffs exist in the United States (ATSDR, 2013). Further, these levels are comparable with those found in other food, such as carrots (Daucus carota L.), which ranged from 48 to 94 mg kg −1 (Kipopoulou et al., 1999), and much less than is often found on leafy vegetables, which reach up to 294 mg kg −1 in lettuce (Lactuca sativa L.; Kipopoulou et al., 1999) or 850 mg kg −1 in spinach (Spinacia oleracea L.; Khan and Cao, 2012). Thus, the SPAHs are comparable with food directly consumed by humans on a daily basis (Menzie et al., 1992;Martí-Cid et al., 2008). ...
Article
Successful remediation of oil-contaminated agricultural land may include the goal of returning the land to prespill levels of agricultural productivity. This productivity may be measured by crop yield, quality, and safety, all of which are influenced by soil characteristics. This research was conducted to determine if these metrics are affected in hard red spring wheat (Triticum aestivum L. cultivar Barlow) when grown in soils treated by ex situ thermal desorption (TD) compared with wheat grown in native topsoil (TS). Additionally, TD soils were mixed with TS at various ratios to assess the effectiveness of soil mixing as a procedure for enhancing productivity. In two greenhouse studies, TD soils alone produced similar amounts of grain and biomass as TS, although grain protein in TD soils was 22% (±7%) lower. After mixing TS into TD soils, the mean biomass and grain yield were reduced by up to 60%, but grain protein increased. These trends are likely the result of nutrient availability determined by soil organic matter and nutrient cycling performed by soil microorganisms. Thermal desorption soil had 84% (±2%) lower soil organic carbon than TS, and cumulative respiration was greatly reduced (66 ± 2%). From a food safety perspective, grain from TD soils did not show increased uptake of polycyclic aromatic hydrocarbons. Overall, this research suggests that TD soils are capable of producing safe, high-quality grain yields.
... et al., 2014;Squadrone et al., 2014;Sun et al., 2014) take part in the human intake of POPs. Other potential human sources of POPs could be meat (Hernández et al., 2015) and vegetables (Khan and Cao, 2011), while POPs can be transferred through maternal milk to the infant (Croes et al., 2012;Chen et al., 2015) exposing it to detectable amounts of POPs in the very early stages of life. Infant exposure to such chemicals, either prenatal or postnatal, has been associated with several health issues ranging from growth (Iszatt et al., 2015) and obesity (Tang-Péronard et al., 2014;Vafeiadi et al., 2015) disorders to high blood pressure (Vafeiadi et al., 2015), and effects on the development of nervous (Berghuis et al., 2015), immune, and respiratory (Gascon et al., 2013) systems. ...
Article
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The aim of the present review is to highlight the potential use of marine biocatalysts (whole cells or enzymes) as an alternative bioprocess for the degradation of aromatic pollutants. Firstly, information about the characteristics of the still underexplored marine environment and the available scientific tools used to access novel marine-derived biocatalysts is provided. Marine-derived enzymes, such as dioxygenases and dehalogenases, and the involved catalytic mechanisms for the degradation of aromatic and halogenated compounds, are presented, with the purpose of underpinning their potential use in bioremediation. Emphasis is given on persistent organic pollutants (POPs) that are organic compounds with significant impact on health and environment due to their resistance in degradation. POPs bioaccumulate mainly in the fatty tissue of living organisms, therefore current efforts are mostly focused on the restriction of their use and production, since their removal is still unclear. A brief description of the guidelines and criteria that render a pollutant POP is given, as well as their potential biodegradation by marine microorganisms by surveying recent developments in this rather unexplored field.
... PAHs are of great environmental concerns because of their strong carcinogenicity, teratogenicity, and ecotoxicity. In particular, PAH can be strongly accumulated in crops and subsequently be transferred to humans through the food chain and pose a high hazard to human health (Khan and Cao 2012;Wei et al. 2014 ). Therefore, removal of PAH in contaminated soil is of critical significance to protect human health. ...
Article
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The aim of this study was to investigate the removal of phenanthrene by combination of alfalfa, white-rot fungus, and earthworms in soil. A 60-day experiment was conducted. Inoculation with earthworms and/or white-rot fungus increased alfalfa biomass and phenanthrene accumulation in alfalfa. However, inoculations of alfalfa and white-rot fungus can significantly decrease the accumulation of phenanthrene in earthworms. The removal rates for phenanthrene in soil were 33, 48, 66, 74, 85, and 93% under treatments control, only earthworms, only alfalfa, earthworms + alfalfa, alfalfa + white-rot fungus, and alfalfa + earthworms + white-rot fungus, respectively. The present study demonstrated that the combination of alfalfa, earthworms, and white-rot fungus is an effective way to remove phenanthrene in the soil. The removal is mainly via stimulating both microbial development and soil enzyme activity.
... A conversion factor of 0.085 was used to convert fresh green vegetable weight to dry weight, as described by Rattan et al. (2005). Average daily vegetable intake for adults and children were considered of 0.345 and 0.232 kg person −1 d −1 , respectively, while the average adult and children body weights were considered of 63.9 and 32.7 kg, respectively, as used in the previous studies (Ge, 1992;Wang et al., 2005;Khan and Cao, 2012). ...
... A conversion factor of 0.085 was used to convert fresh green vegetable weight to dry weight, as described by Rattan et al. (2005). Average daily vegetable intake for adults and children were considered of 0.345 and 0.232 kg person −1 d −1 , respectively, while the average adult and children body weights were considered of 63.9 and 32.7 kg, respectively, as used in the previous studies (Ge, 1992;Wang et al., 2005;Khan and Cao, 2012). ...
... Hydrophobic organic contaminants (HOCs), such as polycyclic aromatic hydrocarbons (PAHs), often coexist with heavy metals in industrial soils, including e-waste dismantling sites, gas works, and coking plants (Abel et al. 2015;Vácha et al. 2015;Zhang et al. 2012;Zhong and Zhu 2013). The combined pollution poses risks to the environment and human health (Alternatives 1994;Khan and Cao 2012;Lin et al. 2005;Zheng et al. 2014). For assuring food security and implementing remediation strategies, it is critical to understand the mechanism on the transport and fate of HOCs in the presence of heavy metals in soils. ...
Article
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Purpose Combined pollution by polycyclic aromatic hydrocarbons (PAHs) and heavy metals are commonly found in industrial soils. This study aims to investigate the effect of the coexistence of heavy metals on the sorption of PAHs to soils. We focused specifically on the relationship of the sorption capacity with the estimation of the binding energy between PAHs and heavy metals. Materials and methods The sorption of typical PAHs (naphthalene, phenanthrene, and pyrene) to soils coexisting with heavy metals (Cu(II), Pb(II), and Cr(III)) was characterized in batch sorption experiments. The binding energy between PAHs and heavy metals in aqueous solution was estimated by quantum mechanical (QM) method using density functional theory (DFT) at the M06-2x/def2svp level of theory. Results and discussion Sorption capacity and nonlinearity of the PAHs to the soils were enhanced by the coexisting heavy metals. The extent of increment was positively associated with the hydrophobicity of the PAHs and the electronegativity and radius of the metal cations: Cr(III) > Pb(II) > Cu(II). The cation-π interaction was revealed as an important noncovalent binding force. There was a high correlation between the binding energies of the PAHs and Kf′ (Kf adjusted after normalizing the equilibrium concentration (Ce) by the aqueous solubility (Cs)) (R² > 0.906), indicating the significant role of the cation-π interactions to the improved PAH sorption to soils. Conclusions In the presence of heavy metals, the sorption capacities of naphthalene, phenanthrene, and pyrene to soils were enhanced by 21.1–107 %. The improved sorption capacity was largely contributed from the potent interactions between PAHs and heavy metals.
... Root concentration factors (RCFs) and shoot concentration factors (SCFs) are often used for contaminant concentrations in plants because heavy metal accumulation by plants is one of the main source for pollutants to enter in to food chain. RCFs and SCFs were calculated according to formula adopted from (Khan and Cao 2012). where C root , C shoot , and C soil represent heavy metal concentrations in root, shoot, and soil on dry d.w, respectively. ...
Article
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This study aimed to investigate the lead (Pb) and cadmium (Cd) concentrations in the soil and plants (medicinal and fodder) grown in chromite mining-affected areas, Northern Pakistan. Soil and plant samples were collected and analyzed for Pb and Cd concentrations using atomic absorption spectrometer. Soil pollution load indices (PLIs) were greater than 2 for both Cd and Pb, indicating high level of contamination in the study area. Furthermore, Cd concentrations in the soil surrounding the mining sites exceeded the maximum allowable limit (MAL) (0.6 mg kg(-1)), while the concentrations of Pb were lower than the MAL (350 mg kg(-1)) set by State Environmental Protection Administration (SEPA) for agriculture soil. The concentrations of Cd and Pb were significantly higher (P < 0.001) in the soil of the mining-contaminated sites as compared to the reference site, which can be attributed to the dispersion of toxic heavy metals, present in the bed rocks and waste of the mines. The concentrations of Pb and Cd in majority of medicinal and fodder plant species grown in surrounding areas of mines were higher than their MALs set by World Health Organization/Food Agriculture Organization (WHO/FAO) for herbal (10 and 0.3 mg kg(-1), respectively) and edible (0.3 and 0.2 mg kg(-1), respectively) plants. The high concentrations of Cd and Pb may cause contamination of the food chain and health risk.
... Biosafe-hankkeeseen sisältyi kasvatuskoe, jossa todettiin kuuden eri PFC-yhdisteen voivan kertyä kasvatusmaasta retiisiin. Tarkempi kuvaus koejärjestelyistä ja tuloksista on liitteessä 7. Myös PAH-yhdisteet (Khan & Cao 2012), DEHP (Aranda ym. 1989) ja NP (Sjöström ym. ...
Technical Report
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Concentrations of hazardous organic compounds and pharmaceuticals in biogas plant digestates were analyzed. In addition, the risk for food safety, caused by the use of digestate as a fertilizer in agriculture, was examined. Most of the centralized Finnish biogas plants, which used various waste materials as substrate, took part in the study. The following groups of organic compounds were analyzed: polychlorinated dibenzo-p-dioxins and –furans (PCDD/F), polychlorinated bifenyls (PCB), polyaromatic hydrocarbons (PAH), bis(2-ethylhexyl)phtlalate (DEHP), perfluorinated compounds (PFC), linear alkyl-benzene sulfonate (LAS), nonylphenol and nonylphenol ethoxylate (NP+NPEO), and brominated flame retardants including polybrominated diphenylethers (PBDE), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA). Moreover the occurrence of 25 different pharmaceuticals in digestate was determined. Several hazardous organic compounds and pharmaceuticals were found in all digestates from the biogas plants included in the study. The concentrations varied a lot both between the plants and between samples taken from the same plant at different times. The concentrations measured from the digestates were at the same level than the values found in the literature for wastewater sludge or biogas plant digestates in other European countries. All the digestates produced from various waste materials, such as waste water sludge, municipal bio-waste, manure, and by-products from food industry, contained some hazardous organic compounds. Sta-tistically significant correlations were observed for three different pharmaceuticals when waste water sludge was used as a substrate for biogas production. For the studied compounds, a calculated median soil burden of the compound after a single addition of the digestate as a fertilizer was at the same level to the annual atmospheric deposition of the compound or compound group in Finland or other Nordic countries. However, the soil burden for PBDEs (brominated flame retardants) coming from digestate was 400 – 1000 times higher compared to the annual atmos-pheric deposition. The soil burden for studied compounds coming from liquid fraction of digestate was either lower or at the same level as the soil burden coming from digestate as such or from its solid fraction. The risk for the food safety caused by the fertilizer use of a biogas plant digestate was evaluated based on the literature. According to the risk assessment, agricultural use of biogas plant end products is unlikely to cause significant risk for food safety in Finland for most of the compound groups studied. They are either degraded in the soil, or they are not taken up by the plant and further migrated in the food chain, or the concentration in the soil is at a very low level when also the uptake by the plant is minor. However with PBDEs, PFCs, HBCD and pharmaceuticals, further research is needed to be able to evaluate the risk caused by the fertilizer use of the biogas plant digestates
... Plants grown in PAHs-contaminated soils become contaminated mainly due to root accumulation and acropetal translocation of PAHs (Zezulka et al., 2014;Kim et al., 2014). Thus, improved understanding of the root uptake process and mechanisms is essential to assess plant contamination and subsequent human exposure through the food chain, one of the most important pathways for the entry of PAHs into the bodies of non-smokers (Khan and Cao, 2012;Peng et al., 2013). Kacalkova et al. (Kacalkova and Tlustos, 2011) showed that the highest Phen concentrations were found in sunflower (Helianthus annuus L.) and the highest concentrations of Pyr in maize roots (Zea mays L.) in field experiments. ...
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A novel method for the simultaneous in situ determination of phenanthrene (Phen) and fluoranthene (Fla) adsorbed onto mangrove root surfaces was established using laser-induced time-resolved nanosecond-fluorescence spectroscopy combined with a first-order derivative fluorometry method (D-LITRF). The linear dynamic range, detection limit and recoveries of D-LITRF and laser-induced time-resolved nanosecond fluorescence spectroscopy (LITRF) were of the same order. Using the established method, the transport of Phen and Fla from the mangrove root surface to tissues was simultaneously investigated in situ. The transportation coefficients of the Phen and Fla adsorbed onto the root surface showed a good linear relationship with the content of root lipids, while the inhibition rates showed no significant correlation with the content of root lipids (p> 0.05). Further studies showed that the interaction between Fla and Phen decreased the transport kinetics, especially the slow and very slow transport kinetics. In addition, the coefficients and inhibition rates of the transport of Phen and Fla to Ko root tissues were evaluated at different temperatures. The results acquired by these in situ methods provide new information about how two PAH components are transported from the mangrove root surface to the tissues.
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In fly ash–contaminated soils, metal buildup and translocation and their subsequent uptake in different parts of naturally growing plants were studied. The mean metal levels in soil and plants at uncontaminated site were significantly (p < 0.01) lower than the contaminated site. In polluted soils, metal enrichment factor (EF) was observed in order of Cd > Fe> Cr > Zn > Pb > Cu > Ni > Mn. The shoot enrichment factor (SEF) of Pithecellobium dulce (P. dulce) was Cd > Fe > Zn > Cr > Ni > Cu > Mn > Pb, whereas for Azadirachta indica (A. Indica) and Cassia fistula (C. fistula), the SEF was of the order Fe > Cd > Cr > Zn> Ni > Mn > Cu > Pb, respectively. Root enrichment factor (REF) for P. dulce was Cd > Fe > Zn > Ni > Cu > Cr = Mn > Pb, but in A. indica, the REF was Fe > Cd > Zn > Ni > Mn > Pb > Cu > Cr, and in C. fistula, this order was Fe > Cd > Zn > Ni > Cr > Cu > Mn > Pb. Metal mobilization ratio in plants at both sites were below 1, except Mn and Fe at contaminated site. Single and combined element pollution indexes (SEPI and CPI) and shoot contamination factor (SCF) at contaminated soil were higher than uncontaminated, but root contamination factor (RCF) between sites shows a variable response. From ANOVA results, metal concentration showed significant variation due to site, plants, location, and season interactions.
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The contamination of water resource and food chain by persistent organic pollutants (POPs) constitutes a major environmental and human health concern worldwide. The aim of this study was to investigate the levels of POPs in irrigation water, soil and in Amaranthus viridis (A. viridis) from different gardening sites in Kinshasa to evaluate the potential environmental and human health risks. A survey study for the use of pesticides and fertilizers was carried out with 740 market gardeners. The levels of POPs (including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs)) were analyzed in irrigation water and 144 vegetable samples collected from different gardening sites. The assessment of potential human health risk was estimated by calculating daily intake and toxic equivalency to quantify the carcinogenicity. The results show highest PAH levels in A. viridis from all studied sites. The concentrations of the sum of seven PCBs (Σ7PCBS) congeners in analyzed plants ranged between 15.89 and 401.36 ng g⁻¹. The distributions of OCPs in both water and A. viridis were congener specific, chlorpyrifos-ethyl and p,p′-DDE were predominantly detected. Among PBDEs, only BDE47 was quantified with noticeable concentration in A. viridis, while no PBDEs were detected in irrigation water. Higher estimated daily intake values indicate that consuming leafy vegetables might associate with increased human health risks. However, calculated incremental lifetime cancer risk values indicates no potential carcinogenic risk for the local population. The results of this study provide important information on A. viridis contamination by POPs and strongly recommend implementing the appropriate measures to control the use of chemicals used in studied gardening areas. Thus in Kinshasa, urban agriculture control programs for POPs and fertilizers is very important in order to protect the public health through direct and dietary exposure pathways.
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Irrigation with treated wastewater could produce excessive accumulations within the plant and soil, negatively affecting the yield and production quality. In addition, the presence of biological and chemical contaminants could harm the agricultural environment, as well as the health of farmers and consumers. During this work, the suitability of secondary and tertiary treated wastewater for use in young grapevines was evaluated by studying the effect of the wastewater irrigation on the soil-plant system, crop yield, fruit quality and the presence of inorganic chemical contamination (salts, elements and heavy metals), organic chemical contamination (polycyclic aromatic hydrocarbons) and microbial contamination (E. coli, total coliforms). The results show that tertiary treated wastewater had positive impact on plant growth and yield while secondary treated wastewater had negative impact on fruit safety in comparison with tap water. Sodium levels in soils irrigated with treated wastewater increased at the end of the irrigation period while decreased during the wet season. The total polycyclic aromatic hydrocarbon concentrations in the soils ranged from 363 μg/kg to 374 μg/kg at the end of the experiment for all irrigation treatments applied. The use of tertiary treated wastewater was recommended for the irrigation of young grapevines as an alternative water source secured protection of environment, plant health and fruit quality.
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A reagent-less electrochemical DNA biosensor for rapid non-electroactive polycyclic organic compounds (POCs) screening and detection was proposed. In this method, methylene blue (MB) was incorporated into DNA/chitosan polyion complex membrane and then modified onto a glassy carbon electrode (GCE). The electrochemical analysis for the prepared DNA-MB/chitosan/GCE showed that the modified electrode exhibited high electrochemical activity and stability. The addition of tetracycline hydrochloride (TC), a model analyte of non-electroactive POCs, resulted in an obvious peak current decrease in DNA-MB/chitosan/GCE, and this electrochemical response was affected by the DNA type and MB/DNA ratio in the modified electrodes. Ultraviolet-visible (UV-Vis) absorption spectroscopy was utilized to furthermore investigate the interaction between TC and DNA-MB/chitosan/GCE. As a result, a competitive interaction and displacement effect between TC and the intercalated MB was proposed. In our condition, the prepared DNA-MB/chitosan/GCE showed high sensitivity to POCs and had almost no response to common interferences. Besides, the good stability and reproducibility of the prepared electrode made it suitable for practical use.
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Polycyclic aromatic hydrocarbons (PAHs) are a group of organic environmental pollutants posing a potential risk to human health. This study was constructed to investigate the presence of 16 PAHs in six commonly consumed vegetables collected from the markets in Shandong, China by a quick, easy, cheap, effective, rugged, safe (QuEChERS)-based extraction method coupled with gas chromatography–mass spectrometry (GC–MS). Our results showed that the vegetables were polluted with PAHs at an alarming level, of which celery contained the highest total concentration of PAHs (Σ16 PAH), whereas cucumbers contained the lowest Σ16 PAH. Besides, the dietary exposure of PAHs was assessed in these vegetables based on the maximum Σ16 PAH. The results showed that the populations in Shandong were exposed to 23–213 ng/d of PAHs through these six vegetables, suggesting that vegetables are the major sources of PAHs in the diet. Hence, it is necessary to monitor the PAH levels in vegetables. Our study provides guidance for future legislative actions regarding PAH levels in vegetables in China.
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Background Soil contamination from heavy metals and polycyclic aromatic hydrocarbons (PAHs) released during informal e-waste processing and disposal poses human and ecological health risks in Nigeria. Objectives This study assesses the levels of heavy metals and PAHs in soils of e-waste dumpsites in Lagos and Ibadan, Nigeria. Methods Composite soil samples were collected at depths of 0–15 cm, 15–30 cm and 30–45 cm from major e-waste dumpsites in Lagos and Ibadan and analyzed for lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr) and PAHs to evaluate the potential contaminant contribution from e-waste activities. Control samples were collected at the Botanical Garden, University of Ibadan. Samples were analyzed for heavy metals after acid digestion using atomic absorption spectrophotometry, while PAHs were extracted using cold solvent extraction and quantified by gas chromatography-mass spectrometry. Blank determination and recovery studies were carried out for each metal. Contamination and ecological risks were assessed using soil contamination indices such as contamination factor, geo-accumulation and pollution load indices, and potential ecological risk index to categorize contaminant concentrations and associated impacts. Soil physico-chemical characteristics such as pH and total organic matter were also determined. Results Metals concentrations in the dumpsite soils ranged from 114–2,840 mg/kg and not detectable - 6.50 mg/kg for Pb and Cd, and 42.8–5,390 mg/kg, 27.5–3,420 mg/kg, 11.0–128 mg/kg and 94.0–325 mg/kg for Cu, Zn, Ni and Cr, respectively. Serious metals accumulation was observed at every e-waste dumpsite, as shown by the pollution load index. The potential ecological risk values were between 584 and 10,402 at all of the dumpsites, signifying very high ecological risk. The total PAHs ranged from 1,756–2,224 μg/kg at the 0–15 cm level, 1,664–2,152 μg/kg at 15–30 cm and 278 μg/kg in the top- and sub-soil of the control site. Discussion The total PAHs in the soil of e-waste dumpsites was significantly higher than in the control soil. Conclusions The results of this study indicate that indiscriminate dumping and open burning of e-waste are potential sources of PAH and toxic metal emissions, which can pose serious human health and ecological risks.
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The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed in soil (n=196) and vegetable (n=30) collected from greenhouses, and also in the soil (n=27) collected from agriculture fields close to the greenhouses in Shandong Province, China. The total PAH concentration (∑16PAH) ranged from 152.2 µg/kg to 1317.7 µg/kg, within the moderate range in agricultural soils of China. Three-ring PAHs were the dominant species, with Phe (16.3%), Ace (13.1%), and Fl (10.5%) as the major compounds. The concentrations of low molecular weight (LMW ≤3 rings) PAHs were high in the east and north of Shandong, while the concentrations of high molecular weight (HMW ≥4 rings) PAHs were high in the south and west of the study area. The PAH level in soils in industrial areas (IN) was higher than those in transport areas (TR) and rural areas (RR). No significant difference in concentration of ∑16PAH and composition was observed in soils of vegetable greenhouses and field soils. PAH concentration exhibited a weakly positive correlation with alkaline nitrogen, available phosphorus in soil, but a weakly negative correlation with soil pH. However, no obvious correlation was observed between PAH concentration and organic matter of soil, or ages of vegetable greenhouses. ∑16PAH in vegetables ranged from 89.9 µg/kg to 489.4 µg/kg, and LMW PAHs in vegetables positively correlated with those in soils. The sources of PAHs were identified and quantitatively assessed through positive matrix factorization. The main source of PAHs in RR was coal combustion, while the source was traffic in TR and IN. Moreover, petroleum source, coke source, biomass combustion, or mixed sources also contributed to PAH pollution. According to Canadian soil quality guidelines, exposure to greenhouse soils in Shandong posed no risk to human health.
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Polycyclic aromatic hydrocarbons (PAHs) are typically persistent organic pollutants with hypertoxicity and widespreading, attracting increasing attention in recent years. Six paddy land sites soils irrigated from different rivers in the Nansi Lake area of Shandong Province, China were studied to analyze and assess the source and risk of PAHs. Analysis revealed TPAHs concentrations in topsoil ranging from 57.49 μg kg⁻¹ to 2046.47 μg kg⁻¹, meanwhile, Weishan County (WS) was highly contaminated primarily from coal combustion based on the Nemerow composite index and geochemical indices. Canonical correspondence analysis (CCA) suggested that bacterial species were affected by pH, TPAHs and SOM, while covariables analysis confirmed that most effects of PAHs on bacterial diversity were attributed to the PAHs effect alone rather than the combined effects of PAHs and soil properties. The average daily human exposure (ADE) in children was approximately 2 times higher than that in adults, and the exposure paths values followed a decreasing order, oral intake > skin contact > inhalation. Furthermore, the WS site and another rice test field (TF) presented potential cancer risks and required further investigation. Therefore, the study has important theoretical significance for the control of PAHs pollution in this field, providing a scientific basis for health assessment.
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A review of the literature published in 2012 on topics relating to public and environmental health risks associated with wastewater treatment, reuse, and disposal is presented. This review is divided into the following sections: water and wastewater management, microbial hazards, chemical hazards, wastewater reuse, wastewater treatment plants, wastewater disposal, and sludge and biosolids.
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There is a gradual decline in availability of fresh water to be used for irrigation in India. As a consequence, the use of sewage and other industrial effluents for irrigating agricultural lands is on the rise particularly in peri-urban areas of developing countries. On the other hand, there is increasing concern regarding the exceedance of statutory and advisory food standards for trace metals throughout the world. Hence, a case study was undertaken to assess the long-term effect of sewage irrigation on heavy metal content in soils, plants and groundwater. For this purpose, peri-urban agricultural lands under Keshopur Effluent Irrigation Scheme (KEIS) of Delhi, India were selected where various cereals, millets, vegetable and fodder crops have successfully been grown. Sewage effluents, ground water, soil and plant samples were collected and analysed mainly for metal contents. Results indicated that sewage effluents contained much higher amount of P, K, S, Zn, Cu, Fe, Mn and Ni compared to groundwater. While, there was no significant variation in Pb and Cd concentrations in these two sources of irrigation water and metal content were within the permissible limits for its use as irrigation water. There was an increase in organic carbon content ranging from 38 to 79% in sewage-irrigated soils as compared to tubewell water-irrigated ones. On an average, the soil pH dropped by 0.4 unit as a result of sewage irrigation. Sewage irrigation for 20 years resulted into significant build-up of DTPA-extractable Zn (208%), Cu (170%), Fe (170%), Ni (63%) and Pb (29%) in sewage-irrigated soils over adjacent tubewell water-irrigated soils, whereas Mn was depleted by 31%. Soils receiving sewage irrigation for 10 years exhibited significant increase in Zn, Fe, Ni and Pb, while only Fe in soils was positively affected by sewage irrigation for 5 years. Among these metals, only Zn in some samples exceeded the phytotoxicity limit. Fractionation study indicated relatively higher build-up of Zn, Cu, Fe and Mn in bioavailable pools of sewage-irrigated soils. By and large, tissue metal concentrations in all the crops were below the generalized critical levels of phytotoxicity. Based on the soil to plant transfer ratio (transfer factor) of metals, relative efficiency of some cereals, millet and vegetable crops to absorb metals from sewage and tubewell water-irrigated soils was worked out. Risk assessment in respect of metal contents in some vegetable crops grown on these sewage-irrigated soils indicated that these vegetables can be consumed safely by human.
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Composting may enhance bioremediation of PAH-contaminated soils by providing organic substrates that stimulate the growth of potential microbial degraders. However, the influence of added organic matter (OM) together with the microbial activities on the dissipation of PAHs has not yet been fully assessed. An in-vessel composting-bioremediation experiment of a contaminated soil amended with fresh wastes was carried out. Four different experimental conditions were tested in triplicate during 60 days using laboratory-scale reactors: treatment S (100% soil), W (100% wastes), SW (soil/waste mixture), and SWB (soil/waste mixture with inoculation of degrading microorganisms). A dry mass loss of 35 ± 5% was observed in treatments with organic wastes during composting in all the treatments except treatment S. The dissipation of the 16 USEPA-listed PAHs was largely enhanced from no significant change to 50.5 ± 14.8% (for SW)/63.7 ± 10.0% (for SWB). More obvious dissipation was observed when fresh wastes were added at the beginning of composting to the contaminated soil, without significant difference between the inoculated and non-inoculated treatments. Phospholipid fatty acid (PLFA) profiling showed that fungi and G-bacteria dominated at the beginning of experiment and were probably involved in PAH dissipation. Subsequently, greater relative abundances of G + bacteria were observed as PAH dissipation slowed down. The results suggest that improving the composting process with optimal organic compositions may be a feasible remediation strategy in PAH-contaminated soils through stimulation of active microbial populations.
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The concentrations of 16 polycyclic aromatic hydrocarbons (PAH) were determined in various foodstuffs randomly purchased in Catalonia (Spain) during November and December of 2008. Dietary intake of PAH was subsequently estimated according to age and sex for the general population of Catalonia. The current results were compared with those of previous studies performed in 2000 and 2006. The highest PAH levels corresponded to phenanthrene (18.18 microg/kg), naphthalene (13.31 microg/kg), and pyrene (8.46 microg/kg), whereas the lowest concentrations were those of dibenzo[a,h]anthracene (0.89 microg/kg), indeno[1,2,3-c,d]pyrene (0.94 microg/kg), and benzo[k]fluoranthene (1.00 microg/kg). With respect to the contribution of total carcinogenic PAH, benzo[a]pyrene contributed 47.77% or 48.22%, depending on the TEF value used. By food groups, the current highest levels of total PAH were detected in meat and meat products (38.99 microg/kg), followed by oils and fats (18.75 microg/kg), and dairy products (7.57 microg/kg). The highest contribution to PAH dietary intake corresponded to the group of meat and meat products (4.75 microg/day). The estimated mean dietary intake for a standard male adult (70-kg body weight) was 6.72 microg/day, a lower value than those found in our 2000 (8.42 microg/day), and 2006 surveys (12.04 microg/day). With regard to the results of other recent studies, the current PAH concentrations were comparatively lower.
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Polycyclic aromatic hydrocarbons (PAHs) are possible contaminants in some former industrial sites, representing a potential risk to human health if these sites are converted to residential areas. This work was conducted to determine whether PAHs present in contaminated soils are transferred to edible parts of selected vegetables. Soils were sampled from a former gasworks and a private garden, exhibiting a range of PAH concentrations (4 to 53 to 172 to 1263 and 2526 mg PAHs kg-1 of dry soil), and pot experiments were conducted in a greenhouse with lettuce (Lactuca sativa L. var. Reine de Mai), potato (Solanum tuberosum L. var. Belle de Fontenay), and carrot (Daucus carota L. var. Nantaise). At harvest, above- and below ground biomass were determined and the PAH concentrations in soil were measured. In parallel, plates were placed in the greenhouse to estimate the average PAH-dust deposition. Results showed that the presence of PAHs in soils had no detrimental effect on plant growth. Polycyclic aromatic hydrocarbons were detected in all plants grown in contaminated soils. However, their concentration was low compared with the initial soil concentration, and the bioconcentration factors were low (i.e., ranging from 13.4 x 10(-4) in potato and carrot pulp to 2 x 10(-2) in potato and carrot leaves). Except in peeled potatoes, the PAH concentration in vegetables increased with the PAH concentration in soils. The PAH distribution profiles in plant tissues and in soils suggested that root uptake was the main pathway for high molecular weight PAHs. On the opposite, lower molecular weight PAHs were probably taken up from the atmosphere through the leaves as well as by roots.
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Surface sediments collected from the Savannah River, located in the southeastern state of Georgia, USA, in June–July 1994 were analyzed for individual polycyclic aromatic hydrocarbons (PAHs). Three subdivisions of the river were identified for the study: upstream from, adjacent to, and downstream from the city of Savannah. There was high spatial variability in the total PAH (ΣPAH) concentrations that ranged from 29 to 5,375 ng/g with an average concentration of 1,216 ± 1,161 (SD). Of the three subdivisions, the highest ΣPAH concentrations were in the middle segment, which was adjacent to urban and industrial areas. To elucidate sources, molecular indices based on indices among phenanthrene versus anthracene and fluoranthene versus pyrene were used to determine pyrogenic and petrogenic sources, respectively. These indices have been used by other authors to differentiate sources. In most cases, PAHs in sediments nearest the city of Savannah were of high temperature and pyrogenic origin. These pyrogenic PAHs were highly associated with toxicity to benthic organisms. The two-ringed naphthalene and substituted naphthalenes, which are petroleum-related PAHs, were significantly higher in the lower section of the river relative to the subdivisions. This river segment receives inputs primarily from shipping and boating traffic. Perylene, which is indicative of nonanthropogenic terrestrial inputs of carbon, had the highest concentration among the individual PAHs measured. High perylene concentrations were found at stations located upstream and adjacent to forested terrain and where salinity level was low. To discriminate pattern differences and similarities of individual PAHs among samples, principal component analysis (PCA) was performed on the more hydrophobic and persistent nonalkylated PAHs. These differences and similarities were used to infer perylene origin. PCA was performed on 14 nonalkylated PAHs that was normalized to the sum of nonalkylated PAHs, using a correlation matrix. Generally, the PAHs were separated into group patterns according to chemical and physical properties associated with log K OW, except perylene. Perylene, a five-ringed PAH, was distinctly separated from the other five-ringed PAHs. The sources for perylene are likely from biogenic, terrestrial precursors. The collected data show that pyrogenic PAHs were highly associated with biological effects on benthic organisms, based on bioassay results. Perylene, a nonanthropogenic PAH, was found throughout the river and constituted a large percentage of total PAHs in the upper river.
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The dietary intake of 16 polycyclic aromatic hydrocarbons (PAHs) (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]pyrene) by the general population of Catalonia, Spain, was calculated. Concentrations of PAHs in food samples randomly acquired in seven cities of Catalonia from June to August 2000 were measured. Eleven food groups were included in the study. High-performance liquid chromatography was used to analyze PAHs. The dietary intakes of total and carcinogenic PAHs was calculated for five population groups: children, adolescents, male adults, female adults, and seniors. Among the analyzed PAHs, there was a predominance of phenanthrene (16.7 microg/kg) and pyrene (10.7 microg/kg). By food group, the highest levels of total PAHs were detected in cereals (14.5 microg/kg) and in meat and meat products (13.4 microg/kg). The mean estimated dietary intake of the sum of the 16 PAHs was as follows: male adults, 8.4 microg/day; adolescents, 8.2 microg/day; children, 7.4 microg/day; seniors, 6.3 microg/day; female adults, 6.3 microg/day. The calculated daily intake of PAHs would be associated with a 5/106 increase in the risk for the development of cancer in a male adult with a body weight of 70 kg.
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Sewage and industrial effluents from biological treatment plant have been widely used for agricultural irrigation in north part of China. However, effluents after biological treatment still contain heavy metals and persistent organic contaminants. The persistent organic contaminants accumulated in soil may transfer through the food chains and cause adverse health effects on human or biological effects on soil fauna and flora after long-term application. In present study, field surveys were carried out in the farmlands irrigated by effluents from biological treatment plants that receive sewage wastewater and industrial discharges. Residues of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the soils irrigated using both ground water and effluents were compared. The origins of PAHs in the soils were discussed. The results showed that wastewater irrigation could cause accumulation of PAHs in soils close to the pollution discharge. Significantly higher concentrations of PAHs were observed in the sampling sites close to the entrance of main channel in contrast to those along branches and the reference sites. There was no significant relationship between the accumulation of persistent organic pollutants and organic matter content in soil (TOC). Soil contamination of these persistent organic pollutants as affected by effluent irrigation was characterized by the dominant accumulation of high-molecular-weight PAHs (HMW-PAHs). In the case study, concentration of benzo[a]pyrane (BaP, 45.6 ng/g), indeno[1,2,3-cd]pyrene (IcP, 86.3 ng/g), benzo[g,h,i]perlene (BgP, 66.9 ng/g) could exceed the limits of the soil quality standard for biodegraded soils. In identification of the sources, the IcP/BgP values of PAHs in soils were more close to that in air particulates from coal/coke source (1.09+/-0.03 ng/g) [Dickhut RM, Canuel EA, Gustafson KE, Liu K, Arzayus KM, Walkers E, et al. Automotive sources of carcinogenic polycyclic aromatic hydrocarbons associated with particulate matter in the chesapeake bay region. Environ Sci Technol 2000;34:4635-40]. Therefore, both of the PAHs residues in effluents and emission from a nearby coal/coke plant were responsible. Also in this case study, low levels of the OCPs were observed and were not of significant concern in this wastewater irrigation area. Among the different OCPs analyzed, DDTs (mean 8.41 ng/g) and HCHs (mean 2.91 ng/g) were the major components. From the ratios of DDT/DDTs and beta-HCH/HCHs, it indicated that OCPs residues should be from historical usage.
Article
Currently, a variety of models are available for predicting the uptake, translocation, and elimination of organic contaminants by plants. These models range from simple deterministic risk assessment screening tools to more complex models that consider physical, chemical, and biological processes in a mechanistic manner. This study evaluates the performance of a range of such models and model types against experimental data sets. Three dynamic, three regression-based, and three steady-state and equilibrium models have been selected for evaluation. These models differ in terms of their scope, methodological approach, and complexity. Data from nine published experiments were used to create scenarios to test model performance. These experiments consider plant contamination via both soil and aerial exposure pathways. A total of 19 different organic chemicals were used in the experiments along with 7 different plant species. Model predictions of chemical concentrations in the relevant plant compartments were compared with the experimentally recorded values. The results indicate that dynamic models offer performance advantages for acute exposure durations and for rapidly changing environmental media. Equilibrium/steady-state and regression-based models perform better for chronic exposure durations, where stable conditions are more likely to exist. The selection of an appropriate plant uptake model will therefore be dependent on the requirements of the assessment, the nature of the environmental media, and the duration of the source term. The results generated by the regression-based models suggest that in their current form these models are unsuitable for evaluating the uptake of organic chemicals from the air into plants.
Article
A simple ashing procedure for routine determination of soil organic matter is described. Two hundred fifteen soils from 19 states and Canada were ashed at 500° C and the percent weight loss plotted against the percent organic matter determined by Walkley‐Black titration. The resulting regression equation gave a correlation coefficient of 0.98. The organic matter content of experimental samples ranged from 0.64% to 52.4% as determined by the Walkley‐Black method. The proposed procedure incorporates a computerized weighing system and permits 1600 organic matter determinations per day.
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The polycyclic aromatic hydrocarbon (PAH) burden of various fruit and vegetable species (strawberries, apples, tomatoes, lettuce, kohlrabi, potatoes, parsley and kale) cultivated in allotments in the industrial area of Bitterfeld-Wolfen (Germany) were determined. In addition, the garden soils of the sampling sites were analysed. The total PAH concentrations of fruit and vegetables investigated varied in the range of 1-120 µg/kg fresh weight, with the highest being found in parsley and kale. As the highest concentration of benzo(a)pyrene (BaP) was 0.55 µg/kg in a parsley sample, none of the samples exceeded the recommended BaP limit in vegetable foods of 1 µg/kg. A positive relationship between the total PAH burden and the cultivating site was only found for the more highly contaminated species parsley and kale. The total PAH concentrations in the garden soils ranged from 28 to about 7000 µg/kg dry weight.
Article
Dry deposition is an important path for pollutants entering soil and water. In this study, dustfall samples were collected at four representative sampling sites in the southeastern suburb of Beijing from March, 2005 to January, 2006, with a frequency of about once per month, and were analyzed for 16 USEPA priority PAHs using GC/MS. Results showed that the levels of ∑16PAHs in dustfall samples were 0.72–40.45 µg g− 1. The levels of PHE and DahA were the highest and lowest among the 16 PAH compounds, with annual mean values of 2.07 µg g− 1 and 0.009 µg g− 1, respectively. Two and three ring PAH compounds were the dominant ones in dustfall samples. The distribution patterns of PAH compounds in different rings in dustfall were different from those in TSP and gas phase. Annual average fluxes of dustfall and PAHs were 1 296.67 mg m− 2 d− 1 and 5.14 µg m− 2 d− 1, respectively. There were about 423 387.6 t dustfall and 1.7 t PAHs depositing onto the surface of Tongzhou District in 2005. Impacts of ground dust, meteorologic parameters, air pollution indexes and deposition velocities on PAHs deposition were discussed. Correlation analysis showed that the fluxes of 2–3 ring PAH compounds had significant positive correlation with the concentrations of 2–3 ring PAH compounds in TSP, and the fluxes of 4 ring PAH compounds had significant positive correlation with those in both TSP and gas phase, while no significant correlation existed between the fluxes of 5–6 ring PAH compounds and the concentrations of 5–6 ring PAH compounds in TSP or gas phase. A regression model was established to estimate the PAH fluxes.
Article
PurposePhytoremediation has been recognized as a promising technology for the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils. However, little is known about how plant species and cropping patterns affect the process of phytoremediation removing PAHs. Therefore, the aim of this study was to investigate further the effects of monocultures or mixed cultures of different plant species on PAH phytoremediation. Materials and methodsSoils were sampled from a coke plant in Beijing, and ryegrass, white clover, and celery were selected as the model plants. Pot experiment was conducted in a greenhouse using these plants as mono-, two-, and three-species mixed cultures for 75days. At the end of the experiment, the soil and plant samples were collected for PAH analysis. Moreover, the lipid content and fresh biomass of plants were also determined. Results and discussionThe average remaining percentage of PAHs in mixtures (48%) was significantly lower than those in monocultures (55%) and nonplanted soils (70%). In all treatments, plant-promoted biodegradation accounted for almost 99% plant-enhanced PAH losses, but plant uptake only contributed less than 2%. Between individual PAHs, 2–4-ring PAHs were generally more affected by plant uptake, especially for celery and mixed cultures, while 3–6-ring PAHs were impacted the most by biodegradation which was most enhanced in the presence of multispecies mixtures. ConclusionsOur results suggest that certain multispecies mixtures facilitate the phytoremediation of PAH-contaminated soils over monocultures. Moreover, plant-promoted biodegradation was the major pathway for PAH phytoremediation, whereas plant uptake was the minor one. Both of these pathways were dependent on plant species, cropping pattern, and PAH size. KeywordsCropping pattern–Phytoremediation–Plant-promoted biodegradation–Plant uptake–Polycyclic aromatic hydrocarbons
Article
Atmospheric deposition is the dominant pathway for PAH uptake by vegetables grown in peri-urban areas. Different polycyclic aromatic hydrocarbon (PAH) uptake pathways and the associated health risk were investigated in vegetable samples collected from the Beijing-Tianjin city cluster, China, where irrigation with waste or reclaimed water has been practised for many decades. Sampling comprised 23 diverse sites and the roots and shoots of six types of vegetables. Among the different edible vegetable parts, the highest PAH concentrations were found in radish roots and the lowest in cauliflower heads. Bioconcentration factors (BCFs) for individual PAHs showed a weakly decreasing trend with increasing log K(OW). To investigate whether the air-leaf or soil-root-shoot uptake dominates, the measured values were compared with estimations from a generic one-compartment model. The results and related observations are more consistent with an atmospheric uptake pathway than a soil-uptake pathway. The PAH isomeric ratios are consistent with pyrogenic sources (from combustion of fossil fuel and biomass). A health risk assessment on the consumption of the edible parts of vegetables revealed that all studied vegetables, except for 16% of Chinese cabbage samples, are safe for consumption. The results of this study indicate the potential health risk of consuming vegetables from waste-water irrigated areas of this city cluster and provide new insights regarding the transfer of PAHs in vegetables grown in this region.
Article
In the present report Maximum Permissible Concentrations (MPCs) are derived for 10 Polycyclic Aromatic Hydrocarbons (PAHs). For the aquatic environment MPCs are derived from the available experimental data. For 3 PAHs no experimental data are available. These MPCs are calculated using the QSAR-approach (Van Leeuwen et al., 1992). For soil and sediment the MPCs are derived from the available experimental data. This resulted in only 3 MPCs for soil. These three MPCs for soil are harmonized with the MPCs for the aquatic environment, using the equilibrium partitioning method. The remaining MPCs, 7 for soil and 10 for sediment are calculated from the MPC water also using the equilibrium partitioning method. Because of uncertainties in the mode of action of PAHs, it is at this moment not possible to derive a scientifically underpinned risk limit for the mixture of the 10 PAHs. In dit rapport zijn Maximaal Toelaatbare Risiconivo's (MTR's) voor 10 Polycyclische Aromatische Koolwaterstoffen (PAK's) afgeleid. Voor het aquatisch milieu zijn MTR's afgeleid uit de beschikbare experimentele gegevens. Voor 3 PAK's zijn geen experimentele gegevens beschikbaar. Deze MTR's zijn berekend met behulp van de QSAR-methode (Van Leeuwen et al., 1992). Voor bodem en sediment zijn MTR's afgeleid met behulp van de beschikbare experimentele gegevens. Doordat experimentele gegevens erg schaars zijn, is het voor slechts 3 PAK's mogelijk MTR's af te leiden voor de bodem. Vervolgens zijn deze MTR's voor bodem afgestemd met die voor water met behulp van de evenwichtspartitie-methode. Voor de overige PAK's, 7 voor bodem en 10 voor sediment zijn MTR's afgeleid met behulp van de evenwichtspartitie-methode, waarbij de MTR's voor bodem en sediment worden berekend uit de MTR's voor het aquatische milieu. Omdat er onzekerheden zijn in de werkingsmechanismen voor PAK's is het op dit moment niet mogelijk een wetenschappelijk onderbouwde somnorm voor de 10 PAK's te berekenen.
Article
High performance liquid chromatography coupled to an ultraviolet, diode array or fluorescence detector (HPLC/UV-FLD) has been used to set up a method to detect the 15(+1) EU priority polycyclic aromatic hydrocarbons (PAHs) in food supplements covering the categories of dried plants and plant extracts excluding oily products. A mini validation was performed and the following parameters have been determined: limit of detection, limit of quantification, precision, recovery and linearity. They were in close agreement with quality criteria described in the Commission Regulation (EC) No 333/2007 concerning the PAH benzo[a]pyrene in foodstuffs, except the not fluorescent cyclopenta[c,d]pyrene for which the UV detection leads to a higher limit of detection. Analysis of twenty commercial food supplements covering mainly the class of dried plants was performed to evaluate their PAHs contamination levels and to test the applicability of the method to various plant matrices. Fifty percent of analyzed samples showed concentration exceeding 2 microgkg(-1) for one or more PAHs.
Article
Environmental quality objectives (EQOs) for water, soil, and sediment are derived for polycyclic aromatic hydrocarbons (PAHs). EQOs are an important instrument in the effects-oriented environmental policy of the Dutch Ministry of the Environment. These EQOs should be set in such a way that protection of organisms in all compartments is ensured. As intermedia transport of chemicals occurs, this means that EQOs derived for individual compartments have to be harmonized. EQOs are based on scientifically derived risk limits: maximum permissible concentrations (MPCs) and the negligible concentrations (NCs). MPCs are concentrations above which the risk of adverse effects is considered unacceptable. The NC is defined as the MPC/100 and takes possible effects of combination toxicity due to the presence of other substances into account. In this paper MPCs are derived for haphthalene, anthracene, phenanthrene, fluoranthene, benzo[a]anthracene, chrysene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene. The MPCs for these PAHs are for water 1.2, 0.07, 0.30, 0.30, 0.01, 0.34, 0.04, 0.05, 0.03, and 0.04 micrograms/liter, respectively; for soil 0.14, 0.12, 0.51, 2.6, 0.25, 10.7, 2.4. 0.26, 7.5, and 5.9 mg/kg, respectively; and for sediment 0.14, 0.12, 0.51, 2.6. 0.36, 10.7, 2.4, 2.7, 7.5, and 5.9 mg/kg, respectively.
Article
Currently, a variety of models are available for predicting the uptake, translocation, and elimination of organic contaminants by plants. These models range from simple deterministic risk assessment screening tools to more complex models that consider physical, chemical, and biological processes in a mechanistic manner. This study evaluates the performance of a range of such models and model types against experimental data sets. Three dynamic, three regression-based, and three steady-state and equilibrium models have been selected for evaluation. These models differ in terms of their scope, methodological approach, and complexity. Data from nine published experiments were used to create scenarios to test model performance. These experiments consider plant contamination via both soil and aerial exposure pathways. A total of 19 different organic chemicals were used in the experiments along with 7 different plant species. Model predictions of chemical concentrations in the relevant plant compartments were compared with the experimentally recorded values. The results indicate that dynamic models offer performance advantages for acute exposure durations and for rapidly changing environmental media. Equilibrium/steady-state and regression-based models perform better for chronic exposure durations, where stable conditions are more likely to exist. The selection of an appropriate plant uptake model will therefore be dependent on the requirements of the assessment, the nature of the environmental media, and the duration of the source term. The results generated by the regression-based models suggest that in their current form these models are unsuitable for evaluating the uptake of organic chemicals from the air into plants.
Article
This study was conducted to evaluate the influence of sorbent modification by synthetic, chemical/thermal weathering on the sorptive behavior of polycyclic aromatic hydrocarbons (PAHs). A clean sandy-clay-loam soil was subjected to Soxhlet extraction and PAH sorptive phenomena were evaluated based on quantity and quality changes in soil organic matter (SOM) and clay minerals. Critical changes in sorption capacity were found to depend on the initial PAH concentrations. Above 7 mg/l, weathering increased the PAH in comparison to that of unmodified soil, whereas it decreased when applied below this concentration. Similarly, less PAH was desorbed from the altered soil when PAH was applied above 7 mg/l. Therefore, when PAH was applied below 7 mg/l, quantitative reduction of sorbent amount (i.e., SOM and clay minerals) by soil weathering governed PAH sorptive behavior. However, when the PAH was applied above the critical limit, qualitative modifications in the sorbents facilitated an opposite trend. Sorbent swelling, removal of competing compounds, and possible changes in surface characteristics by Soxhlet extraction, together with increased concentration gradient effects were factors that resulted in dissimilar PAH sorptive phenomena, pivoting at the critical concentration.
Article
Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 microg/g, respectively, with similar pattern. The concentrations of PAH16 and individual compounds in the rhizosphere were significantly higher than those in the bulk soil with mean values of 2.25 and 7.82 microg/g for the two sites, respectively. The contents of both total and dissolved organic matter in the rhizosphere were also higher than those in the bulk soil. Almost all PAH compounds studied were detected in both roots and aerial parts of the vegetables studied. Abundance of higher molecular weight PAHs in vegetable, however, was lower than that in soil. Concentrations of PAH16 in vegetable were higher than those reported in the literature for other areas. It appears that agricultural soils and vegetables in Tianjin, especially those from the site located immediately next to an urban district and irrigated with wastewater for several decades, are severely contaminated by PAHs. Among the eight types of vegetable studied, the highest concentration of PAHs was found in cauliflower. By average, the concentration of PAH16 in the aerial part of vegetables was 6.5 times higher as that in vegetable root, suggesting that foliar uptake is the primary transfer pathway of PAHs from environment to vegetables.
Article
Vegetation plays a key role in the environmental fate of many organic chemicals, from pesticides applied to plants, to the air-vegetation exchange and global cycling of atmospheric organic contaminants. Our ability to locate such compounds in plants has traditionally relied on inferences being made from destructive chemical extraction techniques or methods with potential artifacts. Here, for the first time, two-photon excitation microscopy (TPEM) is coupled with plant autofluorescence to visualize and track trace levels of an organic contaminant in living plant tissue, without any form of sample modification or manipulation. Anthracene-a polynuclear aromatic hydrocarbon (PAH)-was selected for study in living maize (Zea mays) leaves. Anthracene was tracked over 96 h, where amounts as low as approximately 0.1-10 pg were visible, as it moved through the epicuticular wax and plant cuticle, and was observed reaching the cytoplasm of the epidermal cells. By this stage, anthracene was identifiable in five separate locations within the leaf: (1) as a thin (approximately 5 microm) diffuse layer, in the upper surface of the epicuticular wax; (2) as thick (approximately 28 microm) diffuse bands extending from the epicuticular wax through the cuticle, to the cell walls of the epidermal cells; (3) on the external surface of epidermal cell walls; (4) on the internal surface of epidermal cell walls; and (5) within the cytoplasm of the epidermal cells. This technique provides a powerful nonintrusive tool for visualizing and tracking the movement, storage locations, and degradation of organic chemicals within vegetation using only plant and compound autofluorescence. Many other applications are envisaged for TPEM, in visualizing organic chemicals within different matrixes.
Article
Soil contamination with polycyclic aromatic hydrocarbons (PAHs) is an increasing problem in many countries, including China. An extensive and systematic survey has been undertaken to evaluate the contamination with PAHs of urban soils in Beijing, China. Soil samples were collected from campuses of universities, schools and kindergartens, public squares, fallow land and roadsides, and were analyzed for 16 PAHs by GC-MS. There was a high variability in the total PAHs (SigmaPAHs) concentrations, ranging from less than 366 to 27,825 ng g(-1). The highest SigmaPAHs concentrations were found at roadsides and industrial sites. Soil organic carbon (SOC) is one of the important factors that can influence the concentrations of PAHs in soils. It was found that concentrations of SigmaPAHs were significantly correlated with that of soil organic carbon. To trace the sources of PAHs, the ratios of phenanthrene to anthracene and fluoranthene to pyrene were used to identify pyrogenic and petrogenic sources, respectively. In most cases, PAHs in soils in urban areas of Beijing were pyrogenic. These sources included motor vehicle exhausts, industrial activities and coal burning. These data can be further used to assess the health risk associated with soils polluted with PAHs.
Article
Studies were undertaken to assess the impact of wastewater/sludge disposal (metals and pesticides) from sewage treatment plants (STPs) in Jajmau, Kanpur (5 MLD) and Dinapur, Varanasi (80 MLD), on health, agriculture and environmental quality in the receiving/application areas around Kanpur and Varanasi in Uttar Pradesh, India. The raw, treated and mixed treated urban wastewater samples were collected from the inlet and outlet points of the plants during peak (morning and evening) and non-peak (noon) hours. The impact of the treated wastewater toxicants (metals and pesticides) on the environmental quality of the disposal area was assessed in terms of their levels in different media samples viz., water, soil, crops, vegetation, and food grains. The data generated show elevated levels of metals and pesticides in all the environmental media, suggesting a definite adverse impact on the environmental quality of the disposal area. The critical levels of the heavy metals in the soil for agricultural crops are found to be much higher than those observed in the study areas receiving no effluents. The sludge from the STPs has both positive and negative impacts on agriculture as it is loaded with high levels of toxic heavy metals and pesticides, but also enriched with several useful ingredients such as N, P, and K providing fertilizer values. The sludge studied had cadmium, chromium and nickel levels above tolerable levels as prescribed for agricultural and lands application. Bio-monitoring of the metals and pesticides levels in the human blood and urine of the different population groups under study areas was undertaken. All the different approaches indicated a considerable risk and impact of heavy metals and pesticides on human health in the exposed areas receiving the wastewater from the STPs.
Article
To assess how the human exposure to environmental carcinogenic polycyclic aromatic hydrocarbons (PAHs) pollution sources generated from industrial, traffic and rural settings, we present a probabilistic risk model, appraised with reported empirical data. A probabilistic risk assessment framework is integrated with the potency equivalence factors (PEFs), age group-specific occupancy probability and the incremental lifetime cancer risk (ILCR) approaches to quantitatively estimate the exposure risk for three age groups of adults, children, and infants. The benzo[a]pyrene equivalents based PAH concentrations in rural, traffic, and industrial areas associated with age group-specific occupancy probability at different environmental settings are used to calculate daily exposure level through inhalation and dermal contact pathways. Risk analysis indicates that the inhalation-ILCR and dermal contact-ILCR values for adults follow a lognormal distribution with geometric mean 1.04x10(-4) and 3.85x10(-5) and geometric standard deviation 2.10 and 2.75, respectively, indicating high potential cancer risk; whereas for the infants the risk values are less than 10(-6), indicating no significant cancer risk. Sensitivity analysis indicates that the input variables of cancer slope factor and daily inhalation exposure level have the greater impact than that of body weight on the inhalation-ILCR; whereas for the dermal-ILCR, particle-bound PAH-to-skin adherence factor and daily dermal exposure level have the significant influence than that of body weight.
Article
A total of 188 surface soil samples were collected from different types of utilization soils in Tianjin area. Factor analysis and scatter point surface tension spine function interpolation were used to analyze types and spatial distributions of PAH sources of surface soils in Tianjin area. The results showed that most pollution sources were mixed sources including coal burning and petroleum spill. Mixed sources occupied 56.12%, 58.96%, 46.45% and 59.50% in farmland of wastewater irrigation, common farmland, wild land and city greenbelt, respectively. Other pollution sources such as vehicle emission, biogenic conversion, wood burning and natural gas combustion were also significant. The spatial distributions of pollution sources were closely related to geographic location, geographic condition and living habit of indigenes.
Article
In order to better understand land application of sewage sludge, the characterization of heavy metals, PCDD/F and PAHs in sewage sludge was investigated from six different wastewater treatment plants (WWTP) in Beijing City, China. It was found that the total concentrations of Zn in Wujiacun (WJC) sewage sludge, and Cd and Hg in sewage sludge generated from all of the six different places are higher than Chinese regulation limit of pollutants for sludge to be used for agriculture (GB18918-2002). The levels of 16 PAHs that have been categorized as priority pollutants by US EPA in the sewage sludge samples varied from 2467 to 25923 microg/kg (dry weight), the highest values of 25923 microg/kg being found in WJC WWTP. The concentrations of Benzo[a]pyrene were as high as 6.1mg/kg dry weight in WJC sewage sludge, exceeding the maximum permitted content by GB18918-2002. Individual PAH content varies considerably with sewage samples. The ratios of anthracene to anthracene plus phenanthrene (An/178), benz[a]anthracene to benz[a]anthracene plus chrysene (BaA/228), indene[1,2,3-cd]pyrene to indene[1,2,3-cd]pyrene plus benzo[g,h,i]perylene (In/In+BP), and fluoranthene to fluoranthene plus pyrene (Fl/Fl+Py) suggest that petroleum and combustion of fossil fuel were the dominant contributions for the PAHs in sewage sludge. The concentrations of total PCDD/F in the sewage sludge ranged from 330 to 4245 pg/g d.w. The toxicity equivalent concentrations is between 3.47-88.24 pg I-TEQ according to NATO/CCMS, which is below Chinese legislation limit value proposed for land application. The PCDD/F congener/homologue profiles found in the Beijing samples indicated that the high chlorinated PCDD/F contamination might originate mainly from PCP-related source and depositional sources while the low chlorinated PCDD/F homologues could be originating from incineration or coal combustion. The major source of PCDD/Fs in Beijing sludge is still unclear.
Article
The formation of condensed ring polycyclic aromatic hydrocarbons (PAHs) from the pyrolysis of ground tobacco in helium over the temperature range of 350-600 degrees C was investigated. PAH yields in the ng/g range were detected and the maximum yields of all PAHs studied including benzo[a]pyrene (B[a]P) and benzo[a]anthracene (B[a]A) occurred between 500 and 550 degrees C. The pathway to PAH formation in the 350-600 degrees C temperature range is believed to proceed via a carbonization process where the residual solid (char) undergoes a chemical transformation and rearrangement to give a more condensed polycyclic aromatic structure that upon further heating evolves PAH moieties. Extraction of tobacco with water led to a two fold increase in the yields of most PAHs studied. The extraction process removed low temperature non-PAH-forming components, such as alkaloids, organic acids and inorganic salts, and concentrated instead (on a per unit weight basis) tobacco components such as cell wall bio-polymers and lipids. Hexane extraction of the tobacco removed lipophilic components, previously identified as the main source of PAH precursors, but no change in PAH yields was observed from the hexane-extracted tobacco. Tobacco cell wall components such as cellulose, hemicellulose, and lignin are identified as major low temperature PAH precursors. A link between the formation of a low temperature char that evolves PAHs upon heating is established and the observed ng/g yields of PAHs from tobacco highlights a low temperature solid phase formation mechanism that may be operable in a burning cigarette.
Article
Accumulation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) by crop plants from contaminated soils may pose health risks. A greenhouse pot experiment using lettuce (Lactuca satuva L.) as a representative vegetable was conducted to assess the concentrations of PAHs and HMs in vegetables grown in wastewater-contaminated soils. The concentrations of total PAHs were ranged from 1.5 to 3.4 mg kg(-1) in the contaminated soils, while 1.2 mg kg(-1) in the reference soil. Linear regression analyses showed that the relationships between soil and shoot PAH concentrations were stronger for LMW-PAHs (R(2) between 0.51 and 0.92) than for HMW-PAHs (R(2) 0.02 and 0.60), suggesting that translocation for LMW-PAHs is faster than HMW-PAHs. Furthermore, the data imply that root uptake was the main pathway for HMW-PAHs accumulation. The plant shoots were also highly contaminated with HMs, particularly Cd (0.4-0.9 mg kg(-1)), Cr (3.4-4.1 mg kg(-1)), Ni (11.7-15.1 mg kg(-1)) and Pb (2.3-5.3 mg kg(-1)), and exceed the guidance limits set by State Environmental Protection Administration (SEPA), China and the World Health Organization (WHO). This study highlights the potential health risks associated with cultivation and consumption of leafy vegetables on wastewater-contaminated soils.
Article
Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear regression model was used to assess the relationship between total PAH concentrations in soils and soil organic carbon (SOC). A wide range of total PAH concentrations ranging from 1,304 to 3,369 mug kg(-1) in soils collected from different wastewater-irrigated sites in Tianjin, while ranging from 2,687 to 4,916 mug kg(-1) in soils collected from different wastewater-irrigated sites in Beijing, was detected. In general, total PAH concentrations in soils from Beijing sites were significantly higher than those from Tianjin sites, indicating a dominant contribution from both pyrogenic and petrogenic sources. Results indicated that the oral bioaccessibility of PAHs in small intestinal was significantly higher (from P < 0.05 to P < 0.001) than gastric condition. Similarly, the oral bioaccessibility of PAHs in contaminated sites was significantly higher (from P < or = 0.05 to P < 0.001) than in reference sites. Individual PAH ratios (three to six rings), a more accurate and reliable estimation about the emission sources, were used to distinguish the natural and anthropogenic PAH inputs in the soils. Results indicated that PAHs were both pyrogenic and petrogenic in nature. The identification of PAH sources and importance of in vitro test for PAH bioaccessibility were emphasized in this study. The oral bioaccessibility of individual PAHs in soils generally decreased with increasing ring numbers of PAHs in both the gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric conditions to that in the small intestinal condition generally increased with increasing ring numbers, indicating the relatively pronounced effect of bile extract on improving the bioaccessibility of PAHs with relatively high ring numbers characterized by their high K ( ow ) values. Similarly, total PAH concentrations in soils were strongly correlated with SOC, indicating that SOC was the key factor determining the retention of PAHs in soils. Soils were contaminated with PAHs due to long-term wastewater irrigation. PAHs with two to six rings showed high concentrations with a significant increase over reference soils. Based on the molecular indices, it was suggested that PAHs in soils had both pyrogenic and petrogenic sources. It was also concluded that the oral bioaccessibility of total PAHs in the small intestinal condition was significantly higher than that in the gastric condition. Furthermore, the bioaccessibility of individual PAHs in soils generally decreased with the increasing ring numbers in both the gastric and small intestinal conditions. It is suggested that more care should be given while establishing reliable soil criteria for PAHs, especially concerning the health of children who may ingest a considerable amount of PAH-contaminated soil via outdoor hand-to-mouth activities.
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setting maximum levels for certain contaminants in foodstuffs
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