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Health Risks of Heavy Metals Uptake by Crops Grown in a Sewage Irrigation Area in China

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Ecological risks of heavy metal toxicity such as Cd, Cu, Pb, Zn, Cr, As, and Hg through crops (wheat and rice) grown in the Tianjin sewage irrigation area in northern China were studied in this paper. Wheat and rice samples as well as related soil samples from 77 select blocks were collected. The second grade of standards for Tianjin soil environmental quality was used for soil risk assessment. Chinese National Food Safe Criterion was used for health risk assessment of wheat and rice grains. Daily intake rate and Target hazard quotient were used for the potential health risk assessment of local population through the intake of wheat and rice grown in the sewage-irrigated site. The results showed that continuous application of wastewater has led to accumulation of heavy metals in the soil, and Cd, Zn, and Hg were the main pollutants. Zn and Cd were more mobile than other metals. Pb in wheat and rice had an ecological risk to human health. As and Hg in some rice samples as well as Cd, Zn, and As in some wheat samples had potential risk. Target hazard quotient (THQ) of individual metal was below 1.0, meaning the relative absence of health risks associated with intake of a single heavy metal through intake of either wheat or rice. THQs of As for wheat and rice would sum up to above 1.0, indicating As may pose a risk to the local population by intake of wheat and rice.
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Introduction
Wastewater irrigation is a widespread practice in the
world and long-term wastewater irrigation may lead to the
accumulation of heavy metals in agricultural soils and
plants [1-9]. Although some of the heavy metals such as Zn,
Mn, Ni, and Cu act as micronutrients at lower concentra-
tions, they become toxic at higher concentrations. The
health risks from heavy metal contamination of soil have
been widely reported [10, 11]. Crops and vegetables grown
in soils contaminated with heavy metals have greater accu-
mulation of heavy metals than those grown in uncontami-
nated soil [12-14]. Intake of crops is an important path of
heavy metal toxicity to humans.
Dietary intake of heavy metals through contaminated
crops may lead to various chronic diseases. Duruibe et al.
suggested that biotoxic effects of heavy metals depend
upon the concentrations and oxidation states of heavy met-
als, the kinds of sources, and the modes of deposition [15].
Severe exposure to Cd may result in pulmonary effects
Pol. J. Environ. Stud. Vol. 24, No. 3 (2015), 1379-1386
Original Research
Health Risks of Heavy Metals Uptake by Crops
Grown in a Sewage Irrigation Area in China
Zuwei Wang1, Xiangfeng Zeng2, 4*, Mingshuo Geng1, Chunyi Chen3, Jianchao Cai5,
Xiaoman Yu2, 4, Yingying Hou1, Hui Zhang1
1Tianjin Key Laboratory of Water Resource and Water Environment, Tianjin Normal University, Tianjin 300387, China
2Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology,
Chinese Academy of Sciences, Shenyang 110016, P.R. China
3Center for Environmental Biotechnology, University of Tennessee, Knoxville 37996, USA
4University of Chinese Academy of Sciences, Beijing 100039, P.R. China
5Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, P.R. China
Received: 30 November 2014
Accepted: 29 December 2014
Abstract
Ecological risks of heavy metal toxicity such as Cd, Cu, Pb, Zn, Cr, As, and Hg through crops (wheat
and rice) grown in the Tianjin sewage irrigation area in northern China were studied in this paper. Wheat and
rice samples as well as related soil samples from 77 select blocks were collected. The second grade of stan-
dards for Tianjin soil environmental quality was used for soil risk assessment. Chinese National Food Safe
Criterion was used for health risk assessment of wheat and rice grains. Daily intake rate and Target hazard quo-
tient were used for the potential health risk assessment of local population through the intake of wheat and rice
grown in the sewage-irrigated site. The results showed that continuous application of wastewater has led to
accumulation of heavy metals in the soil, and Cd, Zn, and Hg were the main pollutants. Zn and Cd were more
mobile than other metals. Pb in wheat and rice had an ecological risk to human health. As and Hg in some rice
samples as well as Cd, Zn, and As in some wheat samples had potential risk. Target hazard quotient (THQ) of
individual metal was below 1.0, meaning the relative absence of health risks associated with intake of a sin-
gle heavy metal through intake of either wheat or rice. THQs of As for wheat and rice would sum up to above
1.0, indicating As may pose a risk to the local population by intake of wheat and rice.
Keywords:heavy metals, health risks, crops, soil, Tianjin
*e-mail: xf6.zeng@gmail.com
DOI: 10.15244/pjoes/35282
such as emphysema, bronchiolitis, and alveolitis. Renal
effects may also result from subchronic inhalation of Cd
[16]. Pb toxicity causes reduction in the haemoglobin syn-
thesis; disturbance in the functioning of kidneys, joints, and
reproductive and cardiovascular systems; and chronic dam-
age to the central and peripheral nervous systems [17].
Higher concentrations of Zn can cause impairment of
growth and reproduction [18].
In Tianjin region, wastewater irrigation is a choice to
resolve the scarcity of agricultural water. But a large
amount of matter enters the soils at the same time, polluting
the soil environment and then threatening lives through the
food chain. There has been research about heavy metals
pollution of the Tianjin sewage-irrigated site. Wang et al.
and Wu et al. studied heavy metals pollution in the sewage-
irrigation area soil of Dagu sewage discharge channel [19,
20]. Shi et al., Zhai, and Dong discussed the risks of heavy
metals on soil and vegetables of sewage-irrigated sites in
Tianjin suburbs [21-23]. Li analyzed heavy metals pollu-
tion of soil and wheat at Beijing sewage discharge channel
sewage-irrigated sites [24]. Ma et al. studied heavy metal
concentrations of winter wheat at each stage in typical
sewage-irrigated sites of Tianjin [25]. Although wheat and
rice are important food crops in Tianjin, there is no pub-
lished research on health risks of heavy metals uptake
through wheat and rice grown in Tianjin sewage-irrigated
sites simultaneously. In the present study, health risk was
ascertained through the calculation of different hazard quo-
tients. Health risk caused by the daily intake of heavy met-
als through contaminated wheat and rice was also assessed.
Materials and Methods
Study Sites
The study was conducted around Tianjin sewage-irri-
gated sites, which have a 20-year history of sewage irriga-
tion. Tianjin sewage-irrigated sites include three main sites
of sewage discharge channel irrigation, namely the Beijing
sewage discharge channel sewage irrigation area (BSIA),
the Dagu sewage discharge channel sewage irrigation area
(DSIA), and North sewage discharge channel sewage irri-
gation area (NSIA) (Fig. 1).
BSIA is located mainly in Wuqing and Beichen districts,
and part in Baodi and Ninghe districts, with an irrigation
area of 8.35×104hm2. The wastewater for irrigation is indus-
trial wastewater and domestic sewage coming from Beijing.
DSIA is located in Xiqing District and Jinnan District with
an irrigation area of 2.33×104hm2, and the wastewater for
irrigation came from Tianjin urban and Xiqing District.
NSIA is located in Dongli District with an irrigation area of
1.2×104hm2, and the wastewater for irrigation is industrial
wastewater coming from Dongli District.
1380 Wang Z., et al.
Fig. 1. A study site map showing the locations of TSIA and related districts.
BD – Baodi District
WQ – Wuqung District
NH – Ninghe District
BC – Beichen District
DL – Dongli District
XQ – Xingqing District
JN – Jinnan District
Beijing
Tianjin
China
N0 10 20
km
In recent years, the sewage-irrigated sites were reduced
due to the reduction of the wastewater amount from Beijing
caused by Chinese national environmental policy and the
advancement of wastewater treatment techniques.
Sampling and Analysis Methods
Representative 24 wheat samples and 29 rice samples
grown in Tianjin wastewater irrigation area (WWI) and 10
wheat samples and 14 rice samples grown in clean water
irrigation area (CWI) were collected randomly from a 5
m×5 m area of different fields in harvest time using the
cinquefoil 5-point snakelike sampling method.
After washing with clean tap water to remove the soil
particles, wheat and rice samples were oven dried at 80ºC
to constant weight. The dried samples were ground, passed
through a 2 mm sieve, and stored in plastic bags at room
temperature before analysis.
At the same time, related soil samples were sampled by
digging out a monolith of 10 cm×10 cm×15 cm size from
the A layer soil and the C layer soil. After transport to the
laboratory, samples were air dried, crushed, passed through
a 2 mm mesh sieve, and stored at ambient temperature for
analysis.
For extraction of heavy metals such as Cd, Cu, Pb, Zn,
and Cr, 1 g dried sample of plant or soil was digested in 15
ml of HNO3, H2SO4, and HClO4mixture (5:1:1) at 80ºC
until a transparent solution was obtained [26]. Water sam-
ples (50 ml) were digested with 10 ml of concentrated
HNO3at 80ºC until the solution became transparent. These
transparent solutions were then filtered through Whatman
No. 42 filter papers and diluted to 50 ml with distilled
water. The concentrations of Cd, Cu, Pb, Zn, and Cr in the
filtrate were determined by inductively coupled plasma
atomic emission spectrometry (ICP-AES, Leeman Labs,
USA), fitted with a specific lamp of particular metal using
appropriate drift blanks. As and Hg concentrations were
determined by atomic florescence (AFS-230).
Quality Control Analysis
The identification of pollutant sources is conducted
with the aid of multivariate statistical analyses, such as cor-
relation analysis, principal component analysis (PCA), and
cluster analysis. Multivariate statistical analyses of the data
in this work were performed with SPSS 12.0 for Windows
(SPSS Inc., Chicago, IL).
Data Analyses
Transfer Factor (TF)
Transfer factor (TF) was calculated to understand the
extent of risk and associated hazard due to wastewater irri-
gation and consequent heavy metal accumulation in an edi-
ble portion of test wheat and rice following Cui et al. [27]:
TF = concentration of metal in edible part/
concentration of metal in soil
Daily Intake Rate (DIR)
Daily intake was calculated by the following equation:
DIR= (Cmetal × Dfood intake)/
Baverage weight
...where Cmetal (mg·kg-1), Dfood intake (kg·person-1), and
Baverage weight (kg·person-1) are the heavy metal concentrations
in wheat grains and rice grains, daily intake of wheat grains
and rice grains, and average body weight, respectively [28,
29]. In the paper, Dfood intake are 0.242 (kg·person-1) for wheat
and 0.235 (kg·person-1) for rice [30], separately. Baverage weight
is 55.9 kg [29].
Target Hazard Quotient (THQ)
For the assessment of health risks through consumption
of wheat and rice grains by the local inhabitants, THQ was
calculated following the methodology described by USEPA
(USEPA 2000). THQ was determined based on formula
[31]:
THQ= 10-3 (EFEDFIRC/RFDWABTA)
...where EFis exposure frequency (365 days·year-1) [32];
EDis the exposure duration (70 years), equivalent to the
average lifetime [33]; FIR is the food ingestion rate
(kg·person-1·day-1); C is the metal concentration in food
(mg·kg-1); RFD is the oral reference dose (mg·kg-1·day-1) from
USEPA (2000) [34]; WAB is the average body weight (55.9
kg), and TAis the average exposure time for noncarcino-
gens (assuming 70 years in this study).
Results and Discussion
Levels of Heavy Metals in Soil
Continuous application of treated and untreated sewage
water to the soil led to higher concentrations of heavy met-
als in the soil at the WWI site as compared to the CWI site
(Table 1). Li has also found higher concentrations of heavy
metals in sewage effluents as compared to clean water irri-
gation [24].
Among all the heavy metals at Tianjin wastewater irri-
gated site, the concentration of Zn was found to be maxi-
mum and Cd was minimum in sewage-irrigated soils. Wang
et al., Dong, and Li found similar trends of highest concen-
trations of Zn and lowest concentrations of Cd in soils [19,
23, 24].
The concentrations of Cd and Hg in Tianjin sewage-irri-
gated soils were higher than those reported by Wang et al.
and Dong, and the concentrations of Cu, Pb, and Cr were
lower [19, 23].
Heavy metals enriched in soils at the WWI sites com-
pared to CWI sites (Fig. 2) shows that Cd and Hg in soils
were enriched obviously, whereas Cu, Pb, Cr, As, and Zn
were enriched slightly.
Health Risks of Heavy Metals... 1381
1382 Wang Z., et al.
The concentrations of heavy metals in soils are not only
related to human activity levels, but controlled by soil tex-
ture. The use of a ratio of concentration of heavy metals in
the A and C layers can eliminate the influence of soil tex-
ture on concentrations of heavy metals. The A/C value of
concentration of heavy metals is shown in Fig. 3.
A/C ratio of Cr and As in soil was close to 1, indicating
they had been not affected by sewage irrigation. A/C ratios
of Cu, Pb, Zn, and Cd in soils were between 1.0 and 2.0,
meaning they had some enrichment in soil after sewage irri-
gation. A/C ratios of Hg were above 2.0, and it enriched
obviously in soil after sewage irrigation.
Among heavy metals at BSIA, concentrations of Cu,
Pb, Zn, and Cr were slightly lower than those reported by
Wang [35], but Cd concentration was slightly higher.
Compared with the heavy metal concentrations in soils at
the CWI site, the concentrations of heavy metals in BSIA
soil were higher by 64.6% for Cd, 18.7% for Cu, 57.5% for
Pb, 37.6% for Zn, 24.6% for Cr, 46.6% for As, and 154.3%
for Hg.
Among heavy metals concentrations in soils at the
DSIA site, the concentrations of Cd, Zn, Cr, As, and Hg in
soils were higher than those reported by Wu et al., but Pb
was lower [20]. The concentrations of heavy metals in soils
were higher by 243.5% for Cd, 28.8% for Cu, 36.5% for
Pb, 85.4% for Zn, 44.4% for Cr, 7.0% for As, and 105% for
Hg.
Among heavy metals in soils at the NSIA site, the con-
centrations of Cu, Pb, Zn, Cr, and As were lower than those
reported by Huang et al., but Cd was higher [36]. The con-
centrations of heavy metals in soils at the NSIA site were
higher by 381.3% for Cd, 17.6% for Cu, 50.7% for Pb,
64.9% for Zn, 15.4% for Cr, 12.8% for As, and 133.3% for
Hg.
The concentrations of heavy metals in soil at DSIA and
NSIA sites were higher than the concentrations at BSIA
site, and the reason may be that there are more rice fields in
DSIA and NSIA, and the intensity of sewage irrigation for
rice fields was higher (Fig. 4).
Table 1. Concentrations of heavy metals in soils and crops such as rice and wheat at the WWI sites.
Element Cd Cu Pb Zn Cr As Hg
Soil
range 0.05-1.17 10.9-61.3 3.8-49.79 62.2-333 40.2-108 5.14-17.7 0.035-1.72
mean 0.46 28.15 15.62 129.05 64.19 11.23 0.52
SD 22.29 9.45 6.34 56.23 12.25 2.88 0.41
Wheat
range 0.025-0.176 2.15-4.16 0.06-0.24 16.21-53.0 0.28-0.62 0.096-0.20 0.001-0.015
mean 0.062 2.99 0.14 27.67 0.49 0.128 0.013
SD 0.020 0.51 0.05 7.33 0.10 0.059 0.006
Rice
range 0.013-0.215 2.62-6.67 0.26-1.73 14.0 -44.3 2.56-5.47 0.046-0.38 0.001-0.257
mean 0.07 4.45 0.62 22.73 3.91 0.166 0.022
SD 0.025 0.59 0.104 2.14 0.64 0.079 0.005
Fig. 2. Enrichment of heavy metals in soils of Tianjin sewage-
irrigated sites.
Fig. 3. A/C value of heavy metals concentrations in soils.
Fig. 4. Mean heavy metal concentrations in wheat and rice field
soil at the WWI site.
WWI/CWI Wheat Field Soil Rice Field Soil
2.5
2.0
1.5
1.0
0.5
0Cd Cu Pb Zn Cr As Hg Cd Cu Pb Zn Cr As Hg
Cu Pb Zn Cd Cr Hg As
Heavy metal concentrations (mg/kg)
1000
100
10
1
0.1
0.01
12
10
8
6
4
2
0
A/C
BSIA
DSIA
NSIA
The concentrations of heavy metals such as Cd, Cu, Pb,
Zn, Cr, As, and Hg in soils at the WWI site were below the
permissible limits of Chinese and EU standards. The con-
centrations of Cd and Hg clearly exceeded the permissible
limits of level of the second grade of the Tianjin Standard
(Table 2) and the concentration of Zn was slightly higher,
suggesting that Cd and Hg were important pollutants in the
soils. They had potential ecological risks, and Zn had, to
some extent, ecological risks.
Levels of Heavy Metals in Wheat Grains
and Rice Grains
Levels of Heavy Metals in Wheat Grains
All the heavy metal concentrations in wheat grains at
the WWI site were much higher compared to the CWI site
(Fig. 5). Li and Ma et al. also found higher concentrations
of heavy metals in wheat grown under wastewater irriga-
tion as compared to those at the CWI site [24, 25]. The con-
centrations of heavy metals in wheat grain grown in the
CWI site were higher by 63.2% for Cd, 3.8% for Cu, 100%
for Pb, 6.6% for Zn, 11.4% for Cr, 326.7% for As, and
18.2% for Hg.
Among heavy metals in wheat grains at the WWI site,
concentrations of Zn were highest and Hg lowest. Similar
results were reported by Yang for wheat grain grown in
Liangfeng sewage-irrigated sites (Beijing) [37]. The con-
centration of Zn of wheat grain was higher than that report-
ed by Zhai [22]. The concentrations of other heavy metals
such as Cd, Cu, Pb, and Cr were lower than those reported
by Zhai [22].
Compared with permissible limits of Chinese Standards
(GB 15618-1995), the mean concentrations of Cd, Cu, Zn,
Cr, As, and Hg in wheat grains were lower at the WWI
sites, whereas Pb concentration was higher by 40%, indi-
cating Pb in wheat grains has a potential ecological risk to
human health. Maximum concentrations of heavy metals,
such as Cd, Zn, and As in some wheat samples exceeded
permissible limits of Chinese Standards, suggesting they
may pose a potential ecological risk to human health.
The mean concentrations of heavy metals were also
lower as compared to the safe limits given by WHO/FAO
(WHO/FAO, 2007) and the safe limits given by commis-
sion regulation (EU, 2008) except for Pb and As (Table 2)
[38].
Levels of Heavy Metals in Rice Grains
Among heavy metals in rice grains at the WWI site,
concentration of Zn was highest and Hg was lowest, fol-
lowed by Cd, As, Pb, Cr and Cu. The mean concentrations
of Zn and Cu were higher than that reported by Zhai but Cr
was lower [22].
All the concentrations of heavy metals in wheat grains
at the WWI site were higher as compared to the CWI site
(Fig. 6), and the concentrations of heavy metals in rice
grains were higher by 27.3% for Cd, 18.7% for Cu, 65.4%
for Pb, 21.6% for Zn, 46.4% for Cr, 54.9% for As, and 40%
for Hg.
The concentrations of Cd, Cu, Zn, and Cr in rice were
lower as compared to the safe limits given by commission
regulations (EU, 2008) and Chinese Standards (GB 15618-
1995), except for Pb, As, and Hg. The concentration of Pb
was higher by 115%, indicating that Pb in wheat grains
may have an ecological risk to human health (Table 2).
Health Risks of Heavy Metals... 1383
Table 2. Guidelines for safe limits of heavy metals (mg·kg-1).
Standards Cd Cu Pb Zn Cr As Hg
Soil
Chinese Standards (second grade)
(GB 15618-1995) 0.6 100 350 300 250D
350P
25D
20P
1.0
Tianjin Standard (second grade) 0.159 43.71 32.83 115 107D
124P
16.64D
14.64P
0.258
European Union Standard (EU2002) 3.0 140 300 300 150 - -
WHO/FAO - - - - - - -
Plant
Chinese Standard
(GB 2762-2005)
wheat 0.1 10 0.2 50 20 0.15 0.02
rice 0.2 10 0.2 50 -0.15 0.02
European Union Standards (EC: No. 629/2008) 0.2 -0.2 - - 0.1 0.02
WHO/FAO 0.2 40 560 -0.15 0.02
D – upland soils, P – paddy soil
0.01
0.1
1
10
100
Cd Cu Pb Zn Cr As Hg
Heavy metal concentration
(mg/kg)
WWI CWI
Fig. 5. Mean concentrations of heavy metals in wheat grains.
Cd Cu Pb Zn Cr As Hg
Heavy metal concentrations (mg/kg)
100
10
1
0.1
0.01
The mean concentrations of As and Hg in rice were slight-
ly higher than the safe limits given by commission regula-
tions (EU, 2008) and Chinese Standards. The ecological
risk to human health can be a big concern. All heavy metal
concentrations were lower as compared to safe limits given
by WHO/FAO (WHO/FAO, 2007) except for As [38].
Maximum concentrations of heavy metals in some rice
samples, such as Cu and Cd, exceeded permissible limits of
Chinese Standards, suggesting they may have potential
ecological risk to human health.
Transfer Factor
Among different metals in wheat grains, Zn showed
highest Transfer Factor (TF) value, followed by Cd, Cu,
Hg, and As (Table 3). The transfer factor of Cr is minimum
followed by Pb. The result showed that Zn and Cd are more
mobile than other metals. Lokeshwari and Chandrappa
have reported that Cd and Zn are retained less strongly by
soils and hence they are more mobile than other metals
[39].
Among different metals in rice grains, Cd showed high-
est TF values followed by Zn, Cu, Hg, and Cr. TF values of
Pb and As were lower. The result showed that Cd and Zn
are more mobile than other metals, which is the same as
wheat grains. TF values of metals in rice were higher than
that in wheat grains except for Zn.
Daily Intake Rate
The degree of toxicity of heavy metals to humans
depends on their daily intake. Heavy metals intake through
wheat and rice grown in the Beijing sewage discharge
channel sewage irrigation area showed slight variations
(Table 3). The standard of FAO/WHO (1999) has estab-
lished a reference value for the tolerable daily intake [38].
Our estimated daily intake rate for all the metals were
below the tolerable daily intake rates. Radwan and Salama
and Khan et al. have also observed no risk due to con-
sumption of common foodstuffs grown in wastewater irri-
gated sites [40].
Target Hazard Quotient (THQ)
The results of estimated target hazard quotient calcula-
tions showed that all heavy metals in plants had no poten-
tial health risk to the local population (Table 3). Although
individual metal THQ (<1.0) values indicated the relative
absence of health risks associated with the intake of a sin-
gle heavy metal through consumption of either wheat or
rice only, the summation of individual THQs of both wheat
and rice was almost 1.0. If individual THQs resulting from
crop consumption are considered, the health risks would be
greater when the THQ values are greater than 1.0. THQs of
As was above 1.0, and consumption of such wheat and rice
may pose a risk to the local population (Table 3). Wang et
al. drew a consistent conclusion when they discussed the
health risks of heavy metals to the general public in Tianjin
regarding consumption of vegetables and fish [29]. Other
metals are less responsible for causing risks to the local
population since the THQs were below 1.0 plants.
Conclusions
Heavy metals were enriched in soils at the WWI sites
compared with the CWI sites. Cd and Hg in soils were
clearly enriched, whereas Cu, Pb, Cr, As, and Zn were
slightly enriched.
1384 Wang Z., et al.
Table 3. TF, DIR, and THQ values of crops.
Elements Cd Cu Pb Zn Cr As Hg
TF Wheat 0.111 0.099 0.008 0.214 0.007 0.012 0.087
Rice 0.242 0.105 0.015 0.181 0.095 0.011 0.100
DIR
Wheat 0.0002 0.0115 0.0011 0.1068 0.0019 0.0005 0.00005
Rice 0.0003 0.0187 0.0018 0.0956 0.0164 0.0005 0.00003
PTDI* 60 300 214 60 – –
THR
Wheat 0.0980 0.1181 0.0111 0.1457 0.0005 0.6742 0.0411
Rice 0.1074 0.1707 0.1650 0.1163 0.0040 0.5626 0.0215
0.2054 0.2888 0.1761 0.2620 0.0045 1.2368 0.0627
*Joint FAO/WHO Expert Committee on Food Additives, 1999; PTDI – Potential tolerable daily intake
Fig. 6. Mean concentrations of heavy metals in rice grains.
Cd Cu Pb Zn Cr As Hg
Heavy metal concentrations (mg/kg)
100
10
1
0.1
0.01
0.001
WWI CWI
The concentrations of Cd and Hg clearly exceeded the
permissible limits of the second grade of Tianjin Standards.
The concentration of Zn was slightly higher, suggesting that
Cd and Hg were important pollutants in the soil and posed
potential ecological risks. Zn had some ecological risks as
well.
The concentrations of Pb in wheat and rice had crossed
the safe limits for human consumption, indicating that Pb
posed ecological risks to human health. The mean concen-
trations of As and Hg in rice were slightly higher than the
safe limits of commission regulation (EU, 2008) and
Chinese Standards, and they had some ecological risks to
human health. The concentrations of heavy metals such as
Cd, Zn, and As in part of the wheat samples, and Cu and Cd
in part of the rice samples exceeded safe limits of Chinese
National Standards, suggesting that they pose a potential
ecological risk to human health.
Heavy metal concentrations varied in wheat and rice
samples, which reflect the differences in their uptake capa-
bilities and their further translocation to edible portion of
the plants. Zn and Cd were more mobile than other metals.
The target hazard quotient of individual metal was
below 1.0, indicating the relative lower health risks associ-
ated with intake of a single heavy metal through consump-
tion of either wheat or rice only. The summation of THQs
of both wheat and rice was above 1.0, indicating that the
consumption of wheat and rice may pose a risk to the local
population.
Thus regular monitoring of heavy metal contamination
in crops grown in wastewater-irrigated sites is necessary.
Consumption of contaminated crops should be avoided in
order to reduce the health risks caused by intake of the con-
taminated crops. The wastewater treatment technology
should be perfected in terms of improving the removal of
heavy metals.
Acknowledgements
This research was funded by the National Nature
Science Foundation of China (No. 40973078), the Geping
Green Action Environmental Research and Education “123
Project” of Liaoning Province, China (CEPF2011-123-1-1),
and the State Scholarship Fund organized by the China
Scholarship Council (CSC2013). We thank reviewers for
their valuable and constructive comments.
References
1. SINGH R. P., AGRAWAL M. Variations in heavy metal
accumulation, growth and yield of rice plants grown at dif-
ferent sewage sludge amendment rates. Ecotox. Environ.
Safe., 73, 632, 2010.
2. SINGH R. P., AGRAWAL M. Potential benefits and risks of
land application of sewage sludge. Waste Manage., 28, 347,
2008.
3. MARKOVIĆ M., CUPAĆ S., ĐUROVIĆ R.,
MILINOVIĆ, J., KLJAJIĆ P. Assessment of heavy metal
and pesticide levels in soil and plant products from agri-
cultural area of belgrade, Serbia. Arch. Environ. Con. Tox.,
58, 341, 2010.
4. LIU W. H., ZHAO J. Z., OUYANG Z. Y., SODERLUND L.,
LIU G. H. Impacts of sewage irrigation on heavy metals dis-
tribution and contamination in Beijing, China. Environ. Int.,
31, 805, 2005.
5. MAPANDA F., MANGWAYANA E. N., NYAMANGARA
J., GILLER K. E. The effect of long-term irrigation using
wastewater on heavy metal contents of soils under vegeta-
bles in Harare, Zimbabwe. Agric. Ecosyst. Environ., 107,
151, 2005.
6. RATTAN R. K., DATTA S. P., CHONKAR P. K., SURIB-
ABU K., SINGH A. K. Long term impact of irrigation with
sewage effluents on heavy metal content in soils, crops and
groundwater – a case study. Agric. Ecosyst. Environ., 109,
310, 2005.
7. JAMALI M. K., KAZI T. G., ARAIN M. B., AFRIDI H. I.,
JALBANI N., MEMON A. R., ANSARI R., SHAH A. The
feasibility of using an industrial sewage sludge produce in
Pakistan as agricultural fertilizer used for cultivation of
Sorghum bicolor L. Arch. Agron. Soil Sci., 53, 659, 2007.
8. JAMALI M. K., KAZI T. G., ARAIN M. B., AFRIDI H. I.,
JALBANI N., MEMON A. R., SHAH A. Heavy metals
from soil and domestic sewage sludge and their transfer to
Sorghum plants. Environ. Chem. Letter, 5, 209, 2008.
9. MORERA M. T., ECHEVERRÍA J., GARRIDO J.
Bioavailability of heavy metals in soils amended with
sewage sludge. Can. J. Soil Sci., 82, 433, 2002.
10. ERIYAMREMU G. E., ASAGBA S.O., AKPOBORIE I. A.,
OJEABURU S. I. Evaluation of lead and cadmium levels in
some commonly consumed vegetables in the Niger-Delta oil
area of Nigeria. B. Environ. Contam. Tox., 75, 278, 2005.
11. NAWAG U. H., QAISAR M., AMIR W., MUHAMMAD I.,
FARIDULLAH, ARSHAD P. Assessment of heavy metals
in wheat plants irrigated with contaminated wastewater. Pol.
J. Environ. Stud., 22, 115, 2013.
12. SHARMA R. K., AGRAWAL M., MARSHALL F. M.
Heavy metals contamination of soil and vegetables in sub-
urban areas of Varanasi, India. Ecotox. Environ. Safe., 66,
258, 2007.
13. SHARMA R. K., AGRAWAL M., MARSHALL F. M.
Heavy metals contamination in vegetables grown in waste-
water irrigation areas of Varanasi, India. B. Environ.
Contam. Tox., 77, 311, 2006.
14. CHANG A. C., PAGE A. L., HYUN H. Cadmium uptake
Swiss for Chard Grown on composted sewage sludge treat-
ed plots: Plateau or time bomb. J. Environ. Qual., 26, 11,
1997.
15. DURUIBE J. O., OGWUEGBU M. D. C., EGWURUQWU
J. N. Heavy metal pollution and human biotoxic effects. Int.
J. Phys. Sci., 2, 112, 2007.
16. YOUNG R. A. Toxicity Profiles: Toxicity Summary for
Cadmium, Risk Assessment Information System. University
of Tennessee (rais. ornl. Gov/ tox/ profiles/ cadmium.html),
2005.
17. OGWUEGBU M. O. C., MUHANGA W. Investigation of
lead concentration in the blood of people in the copper belt
province of Zambia. J. Environ., 1, 66, 2005.
18. NOLAN K. R. Copper toxicity syndrome. J. Orthomol
Physiol., 12, 270, 2003.
19. WANG B., MENG H. T., ZHANG Z., GONG H.Y., JIANG
W. Heavy metals content and potential Ecological risk
assessment in field soil in Tianjin suburbs. Environ. Res.
Test, 4, 11, 2010.
Health Risks of Heavy Metals... 1385
20. WU G. H., SU R. X., LI W. Q., ZHENG H. Q. Source and
enrichment of heavy metals in sewage-irrigation area soil of
Dagu sewage discharge channel. Environ. Sci., 29, 1693,
2008.
21. SHI R. G., ZHOU Q. X., LIU F. Z., ZHAO Y. J., ZHENG
X. Q., ZHANG H. Cadmium accumulation and pollution
risks to human health based on Monto-Carlo model of soil
and vegetable-using vegetable field in Tianjin Suburbs as
example. China Environmental Science, 28, 634, 2008.
22. ZHAI H. Q. Investigation and assessment on heavy metals
in soil and vegetables in sewage irrigation areas. Tianjin
Normal University Master's Thesis, 2010.
23. DONG W. H. Environmental geochemistry of heavy metals
in irrigation water and soil of key areas in Tianjin, China.
China University of Geosciences Master's Thesis, 2007.
24. LI Z. M. Assessment to heavy metals pollution in Tianjin
sewage irrigation area soil and wheat and relative analysis.
Tianjin Normal University Master's Thesis, 2006.
25. MA C. X., WANG Z. R., GAO Q., JIN X. L., HE S. Heavy
metal analysis of winter wheat at each stage in typical
sewage irrigation areas of Tianjin. Environ. Chem., 29, 44,
2010.
26. ALLEN S. E., GRIMSHAW H. M., ROWLAND A. P.
Chemical analysis. In: Moore P. D., & Chapman S. B.,
(Eds.) Methods in Plant Ecology. Blackwell Scientific
Publication, Oxford, London, 285, 1986.
27. CUI Y. J., ZHU Y. G., ZHAI R. H., CHEN D.Y., HUANG
Y. Z., QUI Y., LIANG J. Z. Transfer of metals from near a
smelter in Nanjing, China. Environ. Int., 30, 785, 2004.
28. GE K. Y. The status of and Nutrient and meal of Chinese in
1990s. Beijing People’s Hygiene Press, 1992.
29. WANG X., SATO T., XING B., TAO S. Health risks of
heavy metals to the general public in Tianjin, China via con-
sumption of vegetables and fish. Sci. Total Environ., 350,
28, 2005.
30. WANG X., HUAN G. W., TIAN H. G., DONG S. R., YIN
H. G., CAO X. H. Investigation on dietary of urban residents
in Tianjin from 2000-2004, China. J. Publ. Health, 23, 1245,
2007.
31. CHIEN L. C., HUNG T. C., CHAOANG K. Y., YEH C. Y.,
MENG P. J., SHIEH M. J. Daily intake of TBT, Cu, Zn, Cd
and As for fishermen in Taiwan. Sci. Total Environ., 285,
177, 2002.
32. SINGH A., SHARMA R. K., ETAL M. A., MARSHALL F.
M. Risk assessment of heavy metal toxicity through conta-
minated vegetables from wastewater irrigation area of
Varanasi, India. Trop. Eco., 51, 375, 2010.
33. BENNETT D. H., KASTENBERG W. E., MCKONE T. E.
A multimedia multiple pathway risk assessment of atrazine:
the impact of age differentiated exposure including joint
uncertainty and variability. Reliab. Eng. Sys. Saf., 63, 185,
1999.
34. USEPA. Risk-based concentration table. Philadelphia PA:
United States of Environmental Protection Agency,
Washington D.C., 2000.
35. WANG X. X. Spatial distribution of heavy metals contami-
nation fractions and influence factors in Beijing sewage dis-
charge channel sewage irrigation area of Tianjin. Tianjin
Normal University Master's Thesis, 2012.
36. HUANG J. Y., XU H., LIU S. Y. Comprehensive evolution
on heavy metal pollution in soil of Dabizhuang in Dongli
District of Tianjin. J. AnH. Agri. Sci., 39, (22), 13442, 2011.
37. YANG J., CHEN T. B., ZHENG Y. M., LUO J. F., LIU H.
L., WU W. Y., CHEN Y. C. Dynamic of heavy metals in
wheat grains collected from Liangfeng Irrigation Area,
Beijing and a discussion of availability and human health
risks. Act. Sci. Circum., 25, 1661, 2005.
38. WHO/FAO. Joint FAO/WHO Food Standard Programme
Codex Alimentarius Commission 13th Session. Report of the
Thirty Eight Session of the Codex Committee on Food
Hygiene. Houston, United States of America, ALINORM
07/30/13, 2007.
39. LOKESHWARI H., CHANDRAPPA G. T. Impact of heavy
metal contamination of Bellandur Lake on soil and cultivat-
ed vegetation. Current Science, 91, 620, 2006.
40. RADWAN M. A., SALAMA A. K. Market based survey for
some heavy metals in Egyptian fruits and vegetables. Food
Chem. Toxicol., 44, 1273, 2006.
1386 Wang Z., et al.
... The lowest and highest mean concentrations of Pb in the rice samples analyzed were 0.291 and 0.699 mg/kg respectively for BBR and KWT as shown in Table 3. The concentrations of Pb in all the rice samples irrespective of its variety were found to be higher than maximum limit of 0.2 mg/kg (Fig 1) (Wang et al., 2015). Elevated concentrations of Pb beyond the safe limit are threat to food safety of the consumers, and therefore of health risks to human health. ...
... These results are much lower than maximum limit of 40 mg/kg set by FAO/WHO (2004). In a similar finding, 4.45 mg/kg of Cu was determined in rice samples grown in sewage irrigated soil (Wang et al., 2015). Xu et al. (2006) explained that sources of Cu in rice could be associated with contamination of soil from industries and other anthropogenic sources. ...
... Elevated levels of Cu beyond the safe limit could be of health concern when ingested. Copper is one of the essential micronutrients and its adequate supply for growing plants should be ensured through artificial or organic fertilizers (Itanna, 2002 (Wang et al., 2015). ...
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Accumulation of toxic metals in locally harvested crops is of growing concern due to food safety and the associated health risks. This study evaluates the levels of some heavy metals (Pb, Cd, Fe, Cu and Mn) in white and brown rice samples locally cultivated in Kano using Atomic Absorption Spectrophotometry (AAS). Significant variations were observed (p<0.05), and found to be associated with the differences in rice type. Pb concentrations in all the rice samples analyzed were 0.291±0.024 to 0.699±0.152 mg/kg which surpassed the maximum limit set by FAO/WHO while other metals were below the safe limits, and Cd was not detected in all the rice samples analyzed. Linear discriminant analysis (LDA) revealed that white rice was much associated with Pb along canonical 1, while Fe and Mn were much associated with brown rice as confirmed by F- Ratio analysis. The presence of high levels of toxic metals beyond the maximum limits in the rice varieties might have originated from the fertilizer and other environmental sources which could be of health concern after consumption.
... The concentration of As varied from a minimum 0.673 mg kg −1 in mustard leaves to maximum of 1.589 mg kg −1 in coriander leaves (Table 3). The concentration of arsenic in all the six studied species of leafy vegetables was higher than safe limit of 0.15 mg kg −1 set by WHO (Wang et al., 2015). The concentration of Cd varied from a minimum of 0.190 mg kg −1 in mustard to maximum 0.874 mg kg −1 in spinach. ...
... The concentration of As in fruit and flower vegetables varied from 0.676 mg kg −1 in round gourd to 1.031 mg kg −1 in tomato (Table 3). The concentration of As in all the fruit and flower vegetables was higher than the safe limit of 0.15 mg kg −1 set by WHO (Wang et al., 2015). Cd was detected only in tomato (0.660 mg kg −1 ) among the five fruit and flower vegetables investigated which was higher than safe limit of 0.05 mg kg −1 (FAO/WHO, 2018). ...
... As concentration varied from minimum 0.589 mg kg −1 in onion to maximum 0.757 mg kg −1 in turnip. Arsenic concentration in all the vegetables of this category was higher than safe limit of 0.15 mg kg −1 (Wang et al., 2015). Cd was detected only in turnip (0.300 mg kg −1 ), and it was threefold higher than safe limit of 0.1 mg kg −1 (FAO/WHO, 2018) ( Table 3). ...
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Monitoring of heavy metals in agricultural soils and the crops grown in them is essential to design mitigation strategies to reduce toxic heavy metals in diet and food chains. We determined chromium (Cr), arsenic (As), cadmium (Cd), and lead (Pb) concentrations in the soil–plant system from agricultural fields of Siran Valley, Mansehra, Pakistan, to assess their potential health risk. Although the concentrations of the heavy metals in soils were within the permissible limits for agricultural soils, heavy metal concentrations in many of the vegetables exceeded the recommended safe values. Among the six leafy vegetables tested, all had greater than safe limits for As, four also for Cr and two also for Cd. As level was greater than safe limits in all five fruit and flower vegetables, two had Cr, and one had Pb also at unsafe levels. Among the five tuber, bulb, and root vegetables, As was higher than safe limits in all and Cd in one. The transfer factor in all three categories of vegetables followed the descending order Cd > As > Cr > Pb. Daily intake of metals were within limit set by USEPA for all heavy metals except As. The health risk indices for Cr, As, Cd, and Pb indicated that values greater than 1 for As suggest that the vegetables studied here pose a risk of chronic arsenic poisoning, but other heavy metals do not pose such a risk. Our study reinforces the need for mitigation strategies to reduce unsafe levels of heavy metals in vegetables.
... Heavy metals refer to metals and metalloids that cause pollution and toxicity in the soil (Omran 2016;Hazrat and Ezzat 2018). One major source of heavy metal concentration is long-term sewage irrigation (Zuwei et al. 2015;Kausar et al. 2017;Mohanty et al. 2021;Alnaimy et al. 2021), which is globally used to fill for the decline of surface water and groundwater. Although irrigation with sewage is an opportunity to make up for water scarcity of healthy water for agriculture, sewage in general and untreated sewage is a critical environmental issue around the world (Barakat et al. 2019b). ...
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This paper examines the vertical distribution of heavy metals (As, Cr, Cu, Cd, Pb, Zn, and Fe) in the soil profiles irrigated with sewage from Day River and explores the impact that this sewage has on agricultural soil profile. To this end, three soil profile samples were taken from three unirrigated sites except for rain, and three soil profile samples are collected from sewage irrigated sites in June 2017. Each soil profile is divided into three horizons H1, H2, and H3 at the depth of 0–30, 30–60, and 60–90 cm, respectively. The results of physio-chemical characteristics of the soil show that excessive irrigation with sewage increases organic matter (OM), electrical conductivity (EC), pH, carbonates (CaCO3), and the concentration of all evaluated heavy metals in the soil. In addition, the concentration of all evaluated heavy metals stayed within permissible limits proposed by the World Health Organization (WHO) for unirrigated soil profiles and irrigated soil profiles except for Cd (4.58 mg/kg), Pb (106.26 mg/kg), and As (39.67 mg/kg) in the latter. The vertical distribution of heavy metals demonstrates that the concentration of As, Cr, and Fe increases with the depth, while Pb and Cu decrease downward. In addition, the Cd and Zn have a random distribution. The concentration of heavy metals in the discharged water reveals that the Cd, Pb, and As are gradually decreasing with the depth which confirms that the studied soil retains the heavy metals. The study concludes that sewage irrigation from the Day River contributes to the accumulation of heavy metals and has a dangerous impact on agricultural soil. It is then advisable that local authorities come up with an action plan to treat sewage before discharging it into the Day River.
... Where Pi is the individual pollution index of study metal, C plant/soil/water is the metal concentration in the plant, soil, and water, and C FAO/WHO -standard is the value of the regulatory limit of the heavy metal by FAO/WHO [34][35][36][37]. The classes of contamination are as follows: uncontaminated (PI < 1), low (1 < PI < 2), moderate (2 < PI < 3), strong (3 < PI < 5), and very strong (PI > 5). ...
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The current study focused on quantifying hazardous heavy metals (As, Cd, Cr, Pb, Ni, and Zn) in soil-rice systems near the Buriganga River in Bangladesh to assess their impact on human health and the environment. The mean concentrations of As, Cd, Cr, Ni, and Zn in soil exceeded FAO/WHO acceptable limits, and the metal pollution index (MPI) indicated that all soil samples collected from the rice fields were severely polluted (MPI˃30) than water and rice grain samples. According to the sum of pollution index (SPI) by studied metals, rice grains collected from Kamrangirchor (29.36), Dhakauddan (28.75), and Bosila (18.08) were severely polluted. Mean Bio-concentration factors (BCFs) and Transfer factors (TFgrain/soil) in rice grains were in the following order: Cd (6.034) > Zn (1.752) > Pb (0.697) ˃ Ni (0.666) > Cr (0.135) > As (0.037), and Cd (1.150) > Zn (0.421) > Ni (0.112) ˃ Pb (0.072) > Cr (0.015) > As (0.034) respectively indicating higher accumulation of Cd in rice grain than others toxic heavy metal. The potential ecological risk index (RI) showed that except for water in Kamrangirchar and Keraniganj rice fields, all other rice fields soil and water samples did not pose severe ecological pollution (RI˂110) by different toxic heavy metals. Health risk assessment showed that rice grains are unsafe for human consumption as the carcinogenic health risk (CHR˃10-3) and non-carcinogenic health risk (HI ˃1) quotients seem more than the safe level in all samples collected from rice fields surrounding the Buriganga River. Findings show that heavy metal concentrations are high in rice fields near the Buriganga River, endangering the environment and consumer health.
... Bio was the most effective treatment in decreasing Sb in shoots and roots of green bell pepper with 68.6 and 23.9% decreases, respectively ( Figure 5). However, Sb and Cr in shoots of green bell pepper and wheat grown on amended soils were still exceeding the average levels commonly found in plants growing in uncontaminated soils (Kabata-Pendias 2011); knowing that the permissible levels in wheat are between 0.28 and 0.62 µg·kg −1 for Cr (Wang et al. 2015) and (Bermudez et al. 2011). The maximum permissible levels in vegetables (i.e., green bell pepper) are < 0.1 µg·kg −1 for Cr (Chiroma, Ebewele, and Hymore 2014) and 1 µg·kg −1 for Sb (Choi 2011). ...
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The implementation of organic amendments, such as biochar and compost, can be an effective and innovative environmental friendly option for the recovery of functionality of soils contaminated by potentially toxic elements (PTE). The aim of this study was therefore to assess the influence of a biochar added at 3% w/w (Bio) and its combination with a municipal solid waste compost (MSWC), on the mobility, bioavailability, and phytotoxicity of several (PTE), As (55 mg·kg⁻¹), Sb (84 mg·kg⁻¹), Ni (176 mg·kg⁻¹) and Cr (214 mg·kg⁻¹) present in a contaminated soil (TS). Sequential extraction procedures showed that biochar and its combination with MSWC decreased soil labile PTE, with biochar increasing remarkably their residual fraction compared to TS-soil (+47, 59, 4, and 9% for As, Sb, Cr, and Ni respectively). Amendment addition also favored an increase of the metabolic potential and catabolic versatility of soil microbial communities, as well as soil functionality. Dehydrogenase, β-glucosidase, and urease activities in TS+Bio showed a significant increase (+45, 16, and 21% respectively) with respect to control. Results from a pot experiment showed that all treatments increased the plant yields significantly in the order: Bio>Bio-MSWC>TS (e.g. the shoot length of green bell pepper and wheat grown on Bio increased, respectively, by a factor of 1.8 and 1.2 compared to TS plants). The amendments addition also reduced PTE transfer from root to shoot. Overall, the results obtained indicated that biochar addition at 3% can be an effective environmental friendly strategy for the in situ stabilization of PTE in polluted soils.
... The average values of As in both S1 and S3 were higher than the Thai soil quality standard for agriculture areas (3.9 mg/ kg). Mean values of Cd in S1 and S3 were higher than soil quality standards of Canada (1.4 kg/kg), Chinese (0.6 mg/kg), and Australia (3 mg/kg) and the average earth crust (Australian Department of Environment & Conservation, 2010; Canadian Council of Ministers of the Environment, 2009;Turekian & Wedepohl, 1961;Wang et al., 2015). Moreover, Zn in S3 was over Canadian (29 mg/kg) and Australian (200 mg/ kg) soil standards. ...
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An agricultural land suitability map was developed for rice (Oryza sativa L.) cultivation of land severely contaminated with heavy metals at Mae Tao, Thailand, as a representative area from which more than 300 soil samples and 100 rice grain samples were collected. The average concentrations for As, Cd, Pb, and Zn in the soil were 20.99, 2.66, 19.92, and 115.62 mg/kg, respectively The geo accumulation index (Igeo) values for As, Cd, Pb, and Zn indicated that this area was highly contaminated with Cd. Land suitability maps were developed for three scenarios: I—following conventional factors in the Storie index; II—adding factor D (heavy metal contamination) with the same weighting for four heavy metals; and III—with factor D focusing on As contamination. The results revealed that adding factor D in the Storie index decreased the suitable area for rice cultivation. Taking into account heavy metal contamination of the soil in land suitability mapping, it reduced the areas of highly suited, suited, and marginally suited by 15%. However, the concentration of heavy metals in rice grain in highly suited and suited land was lower than the Codex standard for food safety and quality. This was confirmed by the hazard index (HI) for rice grain planted in scenarios including factor D (HI < 1). Our research should lead to agricultural land management to protect human health from the danger of consuming rice contaminated with heavy metals.
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China has one of the world's fastest-growing economies due to its increase in various industrial activities. A side effect of economic growth is severe environmental problems such as heavy metal contamination of soil and groundwater. Anthropo-genic activities are the main sources of cadmium which is highly mobile and toxic with the potential to bioaccumulate in the ecosystem. It can contaminate ground and river water consequently negatively impacting agriculture and water sources. Anthropogenic source of Cd concentrations in China is 0.002 mg/L in drinking water, 0.102 mg/kg in soil, and 0.23-0.96 mg/ kg in paddy soil. Geological trends and health implications of cadmium contamination in Human, southern China were analyzed. Source, transportation, and various conventional remediation processes exist today and can be categorized as biological, physical, and chemical. Using nanoparticle technology, it has been found that adsorption capacities can be 3 to 4 times higher compared to using powdered activated carbon. From the experiment carried out, a maximum adsorption capacity of 10.86 mg/g for cadmium was obtained. Cadmium intake in south China populations occurred at an alarming rate and most children were at greater risk of being affected. Therefore, cadmium contamination should be taken seriously by the responsible authorities.
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Heavy metal deposition in crops irrigated with wastewater is a serious environmental issue in many developing countries. This research looked at the probable health impacts of chromium (Cr) in water, soil, and food crop samples. The concentration of Cr was measured in samples taken from three sites: Sargodha City, Sahiwal, and Shahpur. Chromium levels were found to vary from 0.011 to 0.067 mg/L in water, to 0.223–2.49 in soil, and from 0.17 to 1.74 mg/kg in crops, respectively. Cr levels in the water, soil, and crops met World Health Organization requirements. Crop samples showed a positive correlation with soil chromium concentrations. There was a wide range in the bioconcentration factor (BCF), pollution load index (PLI), enrichment factor (EF), daily metal intake (DIM), health risk index (HRI), and target hazard quotient (THQ), which were all between 0.16 and 1.79. The BCF and EF were greater than one, which proves a high level of Cr mobility and metal enrichment. The PLI, DIM, HRI, and THQ of metal values were less than one, indicating that toxic metals were present in lower quantities in food crops and had no carcinogenic effects on consumers. Consistent monitoring of water quality, crops, soil, and better agricultural practices that inhibit metals from entering agricultural food reduce the potential health risks to consumers.
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In many countries, where wastewater irrigation has become a common practice, the accumulation of heavy metals by crops has been regarded as a severe environmental hazard. The evaluation of the toxic element lead (Pb) in water, agricultural soils and food crops, and their potential damage to human health, is the focus of the present study. Samples of eleven food crops, soil, with three treatments, waste, canal, and tube well waters, were collected from three feeding sites, Sargodha city, Sahiwal, Shahpur, and evaluated for Pb concentration. The results indicates that the range of Pb in the water, soil and crop samples were from 0.023 to 0.039 mg/L, 2.932-13.687 mg/kg and 1.241-4.825 mg/kg, respectively. The metal concentration was significantly higher (P < 0.001) in wastewater treated soil and crop samples that exceed the permissible limit of the World Health Organization (WHO). There is a positive correlation between the Pb concentration in the soil and crop samples. The pollution load index and enrichment factor are greater than 1, indicating a high level of soil contamination and the influence of natural and anthropogenic sources of Pb metal accumulation in soils. The bioconcentration factor (BCF), daily intake of metal (DIM), health risk index (HRI) and metal values are less than 1, indicating that toxic Pb are present in lower quantities in food crops and had no health risks to consumers. In wastewater treated soils, there is a significant accumulation of Pb toxicity. Therefore, it is vitally important to address Pb contamination and its potential entrance route into the human food chain.
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Concerns over water contamination have prompted a review of the hazards posed by waterborne contaminants. The use of wastewater irrigated wheat grains and the rate of water irrigation to the crops is a crucial aspect that includes comprehensive approach, covering both human and environmental health. Although, water usage enormously depends on spatial factor such as geographic location, but long term consumption of grains grown in contaminated soil may surpass permissible intake of essential elements. Therefore, this study was conducted in randomly selected districts of Punjab, Pakistan to assess the Zinc (Zn) content in water, soil and in various parts of cereal crop wheat (Triticum aestivum L.) during two consecutive growing seasons. The present study estimated significant concentration of Zn range between 0.83 µg/l to 0.93 µg/l in various water regimes, which was minimum in groundwater. Therefore, highest Zn concentration in IWW irrigated soil was recorded during the second cropping season with value of 42.33 mg/kg, however, PLI and BAF were estimated less than 1. The Zn concentration in roots, shoot and grain was ranging in decreasing range of 30.70–35.99 mg/kg, 23.96–25–53 mg/kg and 3.32–7.49 mg/kg respectively. From current study we can conclude that, usage of wastewater in specific proportion to freshwater did not cause any harmful effects and therefore it’s safe to reduce chemical fertilizer cost. However, further investigations are recommended to revealed physiological and molecular aspects.
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A market basket survey was carried out with the aim to assess the levels of lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) in various fruits and vegetables sold in Egyptian markets. Atomic absorption spectrometry was used to estimate and evaluate the levels of these metals. The results of this survey showed that the average concentrations detected were ranged from 0.01 to 0.87, 0.01 to 0.15, 0.83 to 18.3 and 1.36 to 20.9 mg/kg for Pb, Cd, Cu and Zn, respectively. The highest mean levels of Pb, Cd, Cu and Zn were detected in strawberries, cucumber, date and spinach, respectively. The levels of the metals compare with those reported for similar fruits and vegetables from some other parts of the world. The daily intakes of Pb, Cd, Cu and Zn through fruits and vegetables have also been estimated. They are found to be below the recommended tolerable levels proposed by [Joint FAO/WHO Expert Committee on Food Additives 1999. Summary and conclusions. In: 53rd Meeting, Rome, June 1-10, 1999] and may not constitute a health hazards for consumers.
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The recycling of sewage sludge to agricultural land results in the slow accumulation of potentially toxic heavy metals in soils. A greenhouse experiment was conducted to determine the bioavailability of Cu, Ni, Pb and Zn applied to soils in urban anaerobically stabilized sewage sludge. The soils were Lithic Haplumbrept (Lh), Calcixerollic Xerochrept (Cx1 and Cx2) and Paralithic Xerorthent (Px). Sunflower plants (Helianthus annuus L) were grown in the soils following amendment with the sludge. The addition of sewage sludge markedly increased the average dry weight of the plants in the soils that had lower yields without sludge addition (Lh, Cx2, and Px). The acid pH of the Lh soil favoured the bioavailability of Zn from sewage sludge. The bioavailability of Cu was greater in the alkaline soils than in the acidic soil (Lh), which can be attributed to the high organic matter content of the Lh soil which complexes Cu and impairs its uptake by the plants. The concentration of metals in the plants increased with the sewage sludge dose. The effect of the soil type on the metal concentration in plants was greater that the effect of the dose.
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Some heavy metals have bio-importance as trace elements but, the biotoxic effects of many of them in human biochemistry are of great concern. Hence, there is the need for proper understanding of the conditions, such as the concentrations and oxidation states, which make them harmful, and how biotoxicity occurs. It is also important to know their sources, leaching processes, chemical conversions and their modes of deposition to pollute the environment, which essentially supports lives. Literature sources point to the fact that these metals are released into the environment by both natural and anthropogenic sources, especially mining and industrial activities, and automobile exhausts (for lead). They leach into underground waters, moving along water pathways and eventually depositing in the aquifer, or are washed away by run-off into surface waters thereby resulting in water and subsequently soil pollution. Poisoning and toxicity in animals occur frequently through exchange and co-ordination mechanisms. When ingested, they combine with the body's biomolecules, like proteins and enzymes to form stable biotoxic compounds, thereby mutilating their structures and hindering them from the bioreactions of their functions. This paper reviews certain heavy metals and their biotoxic effects on man and the mechanisms of their biochemical activities.
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In certain areas of Varanasi city, waste water from Dinapur sewage treatment plant is used for irrigating vegetable plots. We quantified the concentrations of heavy metals, viz. Cd, Cr, Cu, Ni, Pb and Zn in soil, vegetables and the waste water used for irrigation. The waste water used for irrigation had the highest concentration of Zn followed by Pb, Cr, Ni, Cu and Cd. Continuous application of waste water for more than 20 years has led to accumulation of heavy metals in the soil. Consequently, concentrations of Cd, Pb and Ni have crossed the safe limits for human consumption in all the vegetables. Percent contribution of fruit vegetables to daily human intake for Cu, Ni, Pb and Cr was higher than that of leafy vegetables, while the reverse was true for Cd and Zn. Target hazard quotient showed health risk to the local population associated with Cd, Pb and Ni contamination of vegetables. Therefore, to reduce the health risk and the extent of heavy metal contamination, steps must be taken for efficient treatment of sewage. Regular monitoring of heavy metals in the vegetables grown in waste water irrigated areas is also necessary.
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Based on a large scale survey of cadmium concentration in soil and vegetables in Tianjin five suburbs, the characteristics of cadmium levels in soil and vegetables were analyzed. In addition, absorption capability of soil cadmium with different vegetable species was researched. Risk of vegetable soil cadmium to human health through soil-vegetable-body was assessed by Monte-Carlo technique. The data of soil cadmium complies with the log normal distribution. Cadmium concentrations in soils ranged from 0.04 to 3.2 mg/kg, with arithmetic mean, median of 0.31 mg/kg and 0.24 mg/kg. Compared with the background cadmium concentrations of soil from tianjin, the arithmetic mean of soil cadmium was higher, there appeared to be a significant accumulation of cadmium in soil collected from fields that produce vegetables. In all of the vegetable species, wild cabbage, brassica juncea, cucmuls sativus, cucurbita pepo, lycopersicon esculentum, solanum, bean and allium fistulosum has the samples that the cadmium concentration is higher than the maximum levels of cadmium in food. The synthetically ration of the cadmium contents exceeding criterion is 7.6 percents. CHAID system cluster analysis on the cadmium bioconcentration factor (BCF) in vegetables indicated that the samples could be separated into four groups based on BCF and there were significant difference between the four groups. The assessed results by Monte-Carlo model testify that there was significant risk to human health under heavy metal pollution soil.
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In the present study we evaluate the feasibility of using untreated industrial sewage sludge by liming before use as a fertilizer, produced in Pakistan. In a pots experiment, limed industrial sewage sludge (LSW) and non-limed sewage sludge (NLSW), were amended with soil separately and grown sorghum. After maturity, the sorghum grains were analysed for total contents of potentially toxic metals (TPTM), As, Cd, Cr, Cu, Ni, Pb and Zn. The proportion of different mobility fractions of each element in LWS and NLSW, a modified BCR sequential extraction procedure (Community Bureau of Reference) and single extractions with mild extractants (deionized water and CaCl2) were used. In LSW, the availability of most of the elements under study was reduced, probably due to the increased pH of soil, while this was the reverse in the cases of Cd and Cu, their mobility was slightly increased by lime-treated sludge. The sorghum grains grown in LSW have low level As, Cr, Ni, Pb and Zn as compared to grains grown in NLSW, except Cu and Cd, which, however, never exceeded legal limits. Thus the research showed that liming, by augmenting soil alkalinity, allows a safe agricultural use even of industrial sludge, which is environmentally hazardous for its great content of heavy metals.