Humans are exposed to a wide range of chemical contaminants from cradle to grave. Evaluating the risk to health from this requires accurate assessment of the timing, pathways, and magnitude of exposure. The Journal of Environmental Exposure Assessment welcomes high quality manuscripts that address all aspects of human exposure to organic and inorganic chemical contaminants. These include but are not limited to: exposure modelling, experimental biomonitoring studies, as well as those examining external exposure via different pathways such as diet, inhalation, drinking water, dermal uptake, and indoor dust ingestion.
Dichlorodiphenyltrichloroethanes (DDTs) are ubiquitous in dust and air, which may be responsible for human dermal exposure to DDT. However, existing DDT exposure studies mainly concentrate on dietary exposure, and studies on skin exposure pathway are lacking. To gain further insight into the human exposure pathway of DDT, skin wipe and food samples were collected in a rural area in southern China, where new input of DDTs was found in both indoor and outdoor environments. The total DDT concentrations in skin wipes and foodstuffs varied from < method quantification limit (MQL) to 1470 ng/m2 and from < MQL to 12.8 ng/g wet weight, respectively. In foodstuffs, egg showed the highest DDT concentration, while forehead showed the highest DDT concentration in the four skin locations. p,p’-DDT was predominant in the hand and forearm wipes, while p,p’-DDE was dominant in the forehead, upper arm, and food samples. The total DDT daily absorption median levels via dermal contact, hand-mouth contact, and food consumption were 0.187, 0.0237, and 0.994 ng/kg/d, respectively. Organic eggs and wild fish contaminated by DDTs released locally are the main sources of human dietary exposure to DDTs, and reducing the intake of contaminated fish and eggs would help to significantly reduce human DDT absorption; in this case, the contribution of dermal exposure cannot be not negligible.
Air pollution is a major environmental and public health issue in urban areas. Biomonitoring using trees has been widely used to determine atmospheric pollution due to its advantages of low cost, high spatial distribution, and accumulation of a wide range of air contaminants. However, challenges exist in applying the data obtained from biomonitoring trees, including differences in pollutant concentrations in samples of the same species from different locations, and the influence of biological and environmental parameters on metal accumulation. This study aims to inform the design of biomonitoring sampling for urban air quality studies and increase their applications to exposure assessment. Specifically, the study evaluates the variation in metal concentration in tree organs of two regionally relevant tree species (Picea pungens and Populus Alba), explores the implications of different aspects of field sampling, such as variation within tree stands, tree age, and develops a reference specimen to establish threshold values for differentiating between background levels and increased exposure. The results provide insight into the complexity of using biomonitoring trees for exposure assessment and the importance of considering multiple factors in study design.
The worldwide production and usage of novel flame retardants increase their exposure to non-human fauna. Animals can accumulate and metabolize these novel flame retardants including novel halogenated flame retardants (NHFRs) and organophosphate flame retardants (OPFRs), which is of considerable significance to their internal exposure and final toxicities. In this review, recent studies on the metabolic pathways and kinetics of the two classes of novel flame retardants and the internal exposure and toxicity of their major metabolites are summarized. The results showed that the metabolic pathways of OPFRs were similar among various animals, while the metabolism kinetics (or toxicokinetics) were variable among species. O-dealkylation, hydroxylation and phase II conjunction were the most likely pathways for OPFRs. NHFRs might be metabolized through the pathways of debromination, hydroxylation, dealkylation, and phase II conjunction. We also suggested that di-alkyl phosphates (DAPs) and hydroxylated OPFRs (OH-OPFRs) were the predominant metabolites in the animal body. DAPs, 2,3,4,5-tetrabromobenzoic acid (TBBA) and 2-ethylhexyl tetrabromophthalate (TBMEHP) have relatively higher internal exposure levels in fauna, which might attribute to their high conversion rate and stability in the body. The metabolism of OPFRs and NHFRs in non-human animals may eliminate their acute toxicity but not their chronic toxicities (especially for endocrine-disrupting effects), which suggests attention should also be paid to the major metabolites. Based on the issues mentioned above, we proposed that the metabolic processes in multitrophic organisms, the transfer of major metabolites across the food web, and the co-exposure of the novel flame retardants and their metabolites in fauna are worth studying in the future.
The growing popularity of electronic cigarettes (e-cig) has raised questions about the health effects of e-cig use, or vaping. Previous studies have reported on the potential of exposure to arsenic (As) and other metal(loid)s from vaping, but little is known about the speciation of As in the inhaled aerosols, an important determinant of toxicity. Inorganic As (iAs) species AsIII and AsV are generally more hazardous than organic As species. This study aimed to investigate total and speciated As in condensed aerosols of popular commercial e-cig products and to compare them with regulatory exposure limits. High-performance liquid chromatography and inductively-coupled plasma mass spectrometry were used for As measurements of e-cig aerosol condensates. The analysis included samples from three types of e-cig devices: MODs, PODs, and disposable pod (d-POD) devices. iAs species were identified in all 23 analyzed e-cig aerosol condensate samples, with the highest aerosol concentrations measured in MODs. The geometric mean (range) iAs concentration of 2.3 (1.2-5.1) µg/m3 observed in MOD devices in this study exceeded the recommended exposure limit of 2 µg/m3 for 15-min or shorter inhalation exposures set by the United States National Institute for Occupational Safety and Health. These preliminary results suggest that iAs species are present in inhalable aerosols of some MOD products at levels above regulatory limits for iAs inhalation.
Despite increasing interest in and use of nanoparticles (NP), the environmental consequences of using NP are poorly understood because most relevant studies have not taken the effects of natural coatings on NP into consideration. The aim of this study was to improve our understanding of the fates of NP in aquatic systems. The fates of silver NP (AgNP) capped with citrate and polyethylene glycol dispersed in ecotoxicological matrices in the presence of environmentally relevant components of natural water (humic substances and extracellular polymeric substances) were investigated. Interactions between AgNP and natural organic matter were evaluated by ultracentrifugation and electrophoretic mobility measurements to assess AgNP dissolution. Humic substances and extracellular polymeric substances both decreased the dissolution rate. The natural organic matter (humic substances and extracellular polymeric substances) provided conditions in which the medium stabilized the NP. The dissolution rate depended on the coating type (citrate or polyethylene glycol), dissolved organic carbon concentration, and particle concentration. The presence of algae and Daphnia affected AgNP conversion, demonstrating the value of research that takes environmentally relevant matrices into consideration. The results improve our understanding of the factors that affect the bioavailabilities of AgNP and therefore improve our ability to evaluate AgNP toxicity. Studies of other NP using the same strategy will improve our understanding of the fates of nanomaterials in the environment and biota.
• Natural organic matter controls silver nanoparticle environmental dissolution/fate;
• Exopolysaccharides and aquatic humic substances both promote AgNP stabilization;
• Capping agents (citrate or polyethylene glycol) change the AgNP dissolution rate;
• AgNP behave differently when considering media for algae and Daphnia bioassays.
The Minamata disease, first identified in Japan in the 1950s, is caused by severe methylmercury (MeHg) poisoning. To prevent the development of this disease, routine evaluation of MeHg levels in blood samples is crucial. The purpose of this research was to explore the use of derivatization and capillary gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) for the quantitative detection of both organic and inorganic mercury in blood samples. Alkyl mercury in standard solutions was extracted as halide salts in toluene with hydrohalic acid. Fat contents in whole blood samples were removed by methyl isobutyl ketone and hexane using a cysteine/alkaline solution and then organic mercury was extracted as a bromide complex using toluene and cupper chloride solution. The linearity of the response ratio vs. concentration curves (R2) was 0.987 for methylmercury bromide and 0.990 for ethylmercury bromide. over the calibration range of 0.02 ng/mL to 20 ng/mL. The recovery of MeHg and ethylmercury (EtHg) was 67.1% and 49.3%, respectively. The concentrations of MeHg in whole blood samples determined using GC with an electron capture detector agreed with those determined using GC-NCI-MS, with a correlation coefficient of 0.923. The mean concentration of MeHg in a certified reference material (NMIJ CRM 7402-a) determined using GC-NCI-MS was 0.64 μg/g, comparable with the certified value of 0.58 μg/g. Our study demonstrates a simple and low-cost approach for analyzing mercury in biological samples, although further optimization is required given the relatively low recovery and the concern about the toxicity of methyl isobutyl ketone.
The global push towards a circular economy (CE) has led to increasing efforts to improve resource utilization efficiency, including plastics recycling. However, the presence of additives, especially those that are toxic, complicates plastics recycling in several ways. Without sufficient controls, the spread of hazardous additives via recycling activities represents a significant public health challenge, particularly among developing nations. This study demonstrates evidence of such uncontrolled recycling, based on an investigation of four household flexible PVC product groups available in Thailand. A versatile pyrolysis/thermal desorption gas chromatography-mass spectrometry (Py/TD-GC-MS) method was employed to simultaneously screen 18 target plasticizers in these products. Di-(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP) are the most frequently detected primary plasticizers. DEHP is dominant in vinyl boots, flooring sheets, and hoses, while DINP is dominant in cable sheaths, likely due to a spill-over effect from the EU Restriction of Hazardous Substances (RoHS) directive. Chlorinated paraffins (CPs) are secondary plasticizers that are also detected in most samples, except for boots. The other plasticizers detected include other ortho-phthalates and non-phthalates. These results provide insight into combinatory patterns of plasticizer ‘cocktails’, that comprise restricted, as-yet-unrestricted, and non-restricted plasticizers, embedded in the same individual samples, with a maximum of seven plasticizers found in a single cable sheath. These findings indicate the existence of potentially risky recycling practices that target embedded plasticizers to save cost, without due consideration of their inherent toxicity. Proper interventions are necessary to ensure that CE and chemical safety can be synergized.
In this study, five surface water and sediment samples were collected from five different points along the course of the Udu River, Niger Delta, Nigeria, which were near the human population. Water samples were liquid-liquid extracted with dichloromethane in a separatory funnel, while sediment samples were Soxhlet extracted using a mixture of acetone, dichloromethane, and n-hexane. Quantification of polychlorinated biphenyls (PCBs) in the extracts was done using gas chromatography-mass spectrometry. The ecological risk of PCBs was assessed by comparing the determined PCB concentrations with established guideline values, while health risk was evaluated using non-cancer and total cancer risk models. From the results obtained, only one congener (PCB-167) was present in water samples, with concentrations ranging from 20-1860 ng L-1. For sediment samples, 28 congeners were detected. The concentration of Ʃ28PCBs and the 12 dioxin-like PCBs (dl-PCBs) ranged from 5.34-16.1 and 1.07-5.36 ng g-1, respectively. The toxicity equivalence values for dl-PCBs varied from 0.0065-0.018. Compared to guideline values for both water and sediment, the PCB concentration obtained in this study does not pose any ecological risk at all except for one sampled point. Similarly, the hazard index values for non-cancer risk evaluation were < 1 at all but one point, while total cancer risk values were between 1 × 10-6 and 1 × 10-4 at all but one sampling point, indicating no potential risk of developing cancer associated with PCBs in water and sediments of the Udu River.
The occurrence and risks of polychlorinated biphenyls (PCBs) in water, sediment, and fish from the Wupa River, Nigeria, were assessed in this study. Water, sediment, and fish were collected from five locations in the Wupa River in November 2019. After extraction with dichloromethane, hexane, and acetone, the PCBs were determined using gas chromatography equipped with a quadrupole mass spectrometer. The hazard index and total cancer risk models were used for risk evaluation of the detected PCBs. The results of this study show that the ∑28 PCB concentrations in the water, sediment, and fish ranged from 0.04-11.42 ng/L, 5032-10132 ng/g, and 64-4254 ng/g, respectively. The hazard index values for children and adults were generally > 1, suggesting a potential non-carcinogenic risk for humans exposed to PCBs from the river. However, the total cancer risk values were above 1 × 10-6 and indicated that there is a carcinogenic risk for humans exposed to the PCBs from Wupa River.
Assessing chemical exposure in home and personal care products (HPCPs) represents an important data need. Key challenges to the assessment are related to limited knowledge in quantifying and characterizing the weight-fraction inclusion level and functionality of chemicals in HPCPs. Publicly available tools have been developed to address these challenges, such as the Chemical and Products database (CPDat). This study aims to evaluate the relative performance of CPDat by comparing estimates of weight-fraction inclusion level and functionality to other relevant data sources. Specifically, estimates obtained from CPDat are evaluated and compared with estimates obtained from marketing analytic data, using Euromonitor Passport for 31 commonly used chemicals found in HPCPs. The results obtained from this exercise suggest relatively good agreement between each of the methods for 10 chemicals (ρ = 0.92; P-value =0.02). When considering all 31 chemical ingredients, however, the correlation observed is generally poor (ρ = 0.46; P-value = 0.1), which is attributed to differences in how the underlying data are obtained for each method. With an emphasis on obtaining data based on mining datasheets for individual products, the application of CPDat is suggested to be useful for higher tiers of assessment, with data obtained from marketing analytics providing valuable input to exposure-based screening models. The insight gained from this study can be used to help guide the appropriate use of data obtained from different sources within a tiered exposure assessment.
The occurrence and behavior of dechlorane plus (DP), an additive chlorinated flame retardant, have been intensively studied since it was identified in 2006. The commercial products of DP are a mixture of two stereoisomers: syn-DP and anti-DP. Stereoselective bioaccumulation of DP isomers in biota was reported in field monitoring and laboratory experiments. This review summarizes stereoselective bioaccumulation of DP in biota samples and provides the potential mechanisms for this stereoselective bioaccumulation. Stereoselective enrichment of syn-DP was widely observed in fish, whereas selective enrichment of anti-DP was mainly found in some birds. This species-specific stereoselective enrichment of DP might reflect that two different types of DP isomer fractionation occurred in bioaccumulation between ectotherms and endotherms. Anti-DP is more readily metabolized through biotransformation in all animals. However, a preferential excretion of anti-DP in fish and syn-DP in birds was observed based on the available data. Both processes determine the DP isomer fractionation in bioaccumulation. A direct comparison in DP composition between biological samples and commercial products was conducted for most studies to determine the occurrence of stereoselective DP enrichment, which may lead to underestimating the potential stereoselective enrichment of DP in organisms. The factors which affected the DP isomer composition in organisms included the tissues or organs used, DP concentration, organisms’ trophic levels occupied, and sex. Inconsistent results were obtained considering the effects of these influence factors. The underlying cause of these inconsistent results is unclear based on present data. Further research on DP biotransformation and interactions between DP and biomacromolecule is needed.
Dust is a widely-used matrix for estimating human exposure to chemicals or as a screening tool for the identification of indoor chemicals of concern. As dust sampling became more common in exposure assessment, techniques used in processing soil have been adapted to dust samples, and separation of dust particles by sieving is common practice. However, there are no defined pore sizes, which results in inconsistent or difficult data interpretation and exposure estimates. Moreover, dust consists of more particle types than soil, particularly fibers, which behave differently during the sieving process. In this study, composite samples from seven microenvironments (homes, apartments, kindergartens, schools, public spaces, offices, and cars) were used to investigate the impact of the separation of dust by sieving on the observed chemical distributions. Dust was sieved to four particle size fractions (1-2 mm, 0.5-1 mm, 0.25-0.5 mm, and < 0.25 mm) and each fraction was analyzed for organic carbon content and polycyclic aromatic hydrocarbons (PAHs), and images of dust samples were taken by optical microscope. We identified irregular distributions across size fractions for carbon and PAHs as well as for fibrous particles. Based on the combination of chemical analyses and microscopy, we recommend careful consideration of pre-processing of dust samples to limit bias in dust exposure assessments, and sieving should be used only when necessary.
Polychlorinated naphthalenes (PCNs) were listed as Persistent organic pollutants in the Stockholm Convention, in May 2015, because of their adverse health and environmental effects. PCNs production began in the early 1900s when they were used extensively in several consumer goods as fire retardants. However, because of their health and environmental implications, the production and use of PCNs chemicals were voluntarily banned in many countries in the 1970s and 1980s. However, PCNs are still detected in different environmental samples including air, water, sediments, soil, indoor dust, biota, consumer products, human diet, blood and serum today, as a result of their historical use and unintentional production. Thus, PCNs can be released into the environment throughout their life cycle. It becomes, therefore, crucial to monitor them in different environmental compartments. To date, about 163 reports on PCNs levels in several matrices have been published in different parts of the world. It was reported that toxic PCNs such as chloronaphthalenes 66, 67 and 73 are prevalent in most samples; thus, there is a need to continuously monitor these congeners in our environment. However, there are sparse studies related to PCNs levels, not only in consumer products, leachates and sediment samples from landfill sites in Africa but also in other matrices, leaving a huge research gap that must be prioritized. To date, only about 3 studies on PCNs have been published in Africa, bearing in mind that there is no documented evidence of any known production of PCNs in the continent. Thus, a wide research gap in PCNs studies still exists in Africa. There is an urgent need, therefore, to conduct studies and establish robust PCNs inventories in Africa. The present review examines the existing knowledge on PCNs levels and trends in Africa, and identifies research gaps that ought to be addressed so that the scale of PCNs distribution in the global environment can be known.
This study compared the concentration of persistent organic pollutants (POPs) in air derived from polyurethane-based passive samplers to those of hair samples collected from humans and sheep. Human scalp hair samples were obtained from 24 healthy individuals and ten sheep (Ovis aries) during indoor and outdoor polyurethane foam plug ambient sampling. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs). ∑PBDE concentrations ranged 0.6-50 ng·g-1 (mean, 18.6 ± 13 ng·g-1) for humans and 0.6-1.4 ng·g-1 (mean, 1.1 ± 0.25 ng·g-1) for sheep. The ∑PAH concentrations were log-normally distributed in human hair ranging 98-2529 ng·g-1 (mean, 460 ± 538 ng·g-1), whereas concentrations for sheep hair samples ranged 168-526 ng·g-1 (mean, 334 ± 117 ng·g-1). Strong correlations (P-values < 0.01) were found between concentrations of PAHs and PBDEs in human and sheep hair with concentrations measured in indoor and outdoor air, respectively. Evidence generated from this preliminary study suggests that hair might be used for the environmental monitoring of POPs in remote sites to provide a first-order estimate of ambient levels. Further studies are required to understand the uptake profiles and validate the use of hair as a sampling medium for POPs in ambient air.
Aim: The elucidation of temporal trends in human exposure to polychlorinated biphenyls (PCBs) and 17 polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) since the previous Irish human milk surveys and to evaluate the impacts of legislative bans and restrictions on human exposure to these compounds.
Methods: Concentrations of PCBs and 17 PCDD/Fs were measured in 16 pools of human milk collected from 92 Irish primiparas participating in the Irish EPA-funded ELEVATE project between October 2016 and April 2018, using Gas-Chromatography coupled with Mass spectrometry.
Results: The geometric mean upper bound concentration of 16 pooled human milk samples [PCDD/Fs + dioxin-like (dl)-PCB TEQ; 4.5 ng kg⁻¹ lipid weight] are on the lower end of those reported internationally. WHO-TEQ PCDD/Fs + dl-PCB are significantly lower (P < 0.005) compared to those reported in the previous Irish human milk studies in 2010 and 2002.
Conclusion: Detected concentrations in this study are comparable to those reported for less industrialised countries in the last WHO/UNEP global surveys for PCDD/Fs. This downward temporal trend likely reflects the impact of regulatory bans and restrictions on the emissions of dioxins and PCBs. While mean upper bound WHO PCDD/F PCB TEQ concentrations are lower than those estimated by EFSA to be associated with adverse health effects in children age 9, maximum upper bound concentrations do exceed EFSA reference concentrations. While the positive health benefits of breastfeeding to both mother and child significantly outweigh potential adverse health effects at reported concentrations, continued action to reduce human body burdens of dioxins and PCBs is required.