Environmental exposure to POPs and heavy metals in urban children from Dhaka, Bangladesh

Relationships between growth indicators, liver and kidney function markers, and blood concentrations of essential and potentially toxic elements in environmentally exposed young children

Environmental exposure to multiple metals and metalloids is widespread, leading to a global concern relating to the adverse health effects of mixed-metals exposure, especially in young children living around industrial areas. This study aimed to quantify the concentrations of essential and potentially toxic elements in blood and to examine the potential associations between multiple elements exposures, growth determinants, and liver and kidney function biomarkers in children living in several industrial areas in Dhaka, Bangladesh. The blood distribution of 20 trace elements As, Ag, Bi, Br, Cd, Co, Cr, Cu, I, Mn, Hg, Mo, Ni, Pb, Se, Sb, Tl, V, U, and Zn, growth determinants such as body mass index and body fats, blood pressure, liver and kidney injury biomarkers including serum alanine aminotransferase and alkaline phosphatase activities, serum calcium, and creatinine levels, blood urea nitrogen, and hemoglobin concentrations, and glomerular filtration rate were measured in 141 children, aged six to 16 years. Among these elements, blood concentrations of Ag, U, V, Cr, Cd, Sb, and Bi were measured below LOQs and excluded from subsequent statistical analysis. This comprehensive study revealed that blood concentrations of these elements in children, living in industrial areas, exceeded critical reference values to varying extents; elevated exposure to As, Pb, Br, Cu, and Se was found in children living in multiple industrial areas. A significant positive association between elevated blood Tl concentration and obesity (β = 0.300, p = 0.007) and an inverse relationship between lower As concentration and underweight (β = -0.351, p < 0.001) compared to healthy weight children indicate that chronic exposure to Tl and As may influence the metabolic burden and physical growth in children. Concentration-dependent positive associations were observed between the blood concentrations of Cu, Se, and Br and hepatic- and renal dysfunction biomarkers, an inverse association with blood Mo and I level, however, indicates an increased risk of Cu, Se, and Br-induced liver and kidney toxicity. Further in-depth studies are warranted to elucidate the underlying mechanisms of the observed associations. Regular biomonitoring of elemental exposures is also indispensable to regulate pollution in consideration of the long-term health effects of mixed-elements exposure in children.

Blood lead levels of children exposed to e-waste: a systematic review and meta-analysis

Blood lead levels (BLLs) have been decreasing worldwide for decades. However, systematic reviews and quantitative syntheses of BLLs in electronic waste (e-waste)-exposed children are lacking. To summarize temporal trend of BLLs among children in e-waste-recycling areas. Fifty-one studies met the inclusion criteria and included participants from six countries. Meta-analysis was performed using the random-effects model. Results showed that among e-waste-exposed children, the total geometric mean (GM) BLL was 7.54 μg/dL (95% CI: 6.77, 8.31). Children's BLLs displayed a decreasing temporal trend, from 11.77 μg/dL in phase I (2004-2006) to 4.63 μg/dL in phase V (2016-2018). Almost 95% of eligible studies found that children exposed to e-waste had significantly higher BLLs than reference groups. The difference of children's BLLs between the exposure group and the reference group was from 6.60 μg/dL (95% CI: 6.14, 7.05) in 2004 to 1.99 μg/dL (95% CI: 1.61, 2.36) in 2018. For subgroup analyses, except for Dhaka and Montevideo, the BLLs of children from Guiyu in the same survey year were higher than those of children from other regions. Our findings indicate that the gap between BLLs of children exposed to e-waste and those of reference group children is closing, and we appeal that the critical value for blood lead poisoning in children should be lowered in key e-waste-dismantling areas of developing countries, such as Guiyu.

A comprehensive review on magnetic carbon nanotubes and carbon nanotube-based buckypaper for removal of heavy metals and dyes

Industrial effluents contain several organic and inorganic contaminants. Among others, dyes and heavy metals introduce a serious threat to drinking waterbodies. These pollutants can be noxious or carcinogenic in nature, and harmful to humans and different aquatic species. Therefore, it is of high importance to remove heavy metals and dyes to reduce their environmental toxicity. This has led to an extensive research for the development of novel materials and techniques for the removal of heavy metals and dyes. One route to the removal of these pollutants is the utilization of magnetic carbon nanotubes (CNT) as adsorbents. Magnetic carbon nanotubes hold remarkable properties such as surface-volume ratio, higher surface area, convenient separation methods, etc. The suitable characteristics of magnetic carbon nanotubes have led them to an extensive search for their utilization in water purification. Along with magnetic carbon nanotubes, the buckypaper (BP) membranes are also favorable due to their unique strength, high porosity, and adsorption capability. However, BP membranes are mostly used for salt removal from the aqueous phase and limited literature shows their applications for removal of heavy metals and dyes. This study focuses on the existence of heavy metal ions and dyes in the aquatic environment, and methods for their removal. Various fabrication approaches for the development of magnetic-CNTs and CNT-based BP membranes are also discussed. With the remarkable separation performance and ultra-high-water flux, magnetic-CNTs, and CNT-based BP membranes have a great potential to be the leading technologies for water treatment in future.

Sources of Blood Lead Exposure in Rural Bangladesh

Lead (Pb) exposure is a major public health problem worldwide. Although high levels of Pb in blood in Bangladesh have been documented, the dominant Pb sources contributing to human exposure in rural Bangladesh have not been determined. Here, we first obtained blood from pregnant women from three rural Bangladeshi districts who were previously assessed by a case-control and sampling study, and we then conducted semistructured in-depth interviews to understand Pb exposure behavior and finally collected samples of the suspected Pb sources. We measured the Pb isotopic composition of both potential Pb sources and 45 blood samples in order to understand which of three sources predominate: (1) food from Pb-soldered cans, (2) turmeric, or (3) geophagous materials (clay, soil, or ash). The Pb isotope ratios of the three sources are distinct (p = 0.0001) and blood isotope ratios are most similar to turmeric. Elevated lead and chromium (Cr) concentrations in turmeric and a yellow pigment used in turmeric processing are consistent with reported consumption behavior that indicated turmeric as a primary contributor to blood Pb. The Pb isotopic composition analyses combined with a case-control and sampling approach provides evidence that turmeric adulterated with the yellow Pb-bearing pigment is the main Pb exposure source in these districts and illustrates the need to assess drivers and practices of turmeric adulteration, as well as the prevalence of adulteration across South Asia.

Removal of heavy metals from water sources in the developing world using low-cost materials: A review

Heavy metal contamination is a growing concern in the developing world. Inadequate water and wastewater treatment, coupled with increased industrial activity, have led to increased heavy metal contamination in rivers, lakes, and other water sources in developing countries. However, common methods for removing heavy metals from water sources, including membrane filtration, activated carbon adsorption, and electrocoagulation, are not feasible for developing countries. As a result, a significant amount of research has been conducted on low-cost adsorbents to evaluate their ability to remove heavy metals. In this review article, we summarize the current state of research on the removal of heavy metals with an emphasis on low-cost adsorbents that are feasible in the context of the developing world. This review evaluates the use of adsorbents from four major categories: agricultural waste; naturally-occurring soil and mineral deposits; aquatic and terrestrial biomass; and other locally-available waste materials. Along with a summary of the use of these adsorbents in the removal of heavy metals, this article provides a summary of the influence of various water-quality parameters on heavy metals and these adsorbents. The proposed adsorption mechanisms for heavy metal removal are also discussed.

Recent history of persistent organic pollutants (PAHs, PCBs, PBDEs) in sediments from a large tropical lake

²¹⁰Pb-dated sediment cores and surface sediments from Lake Chapala (LC), Mexico, were analyzed to assess the temporal trends in concentrations and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs). Total sediment concentrations of PAHs (95-1,482 ng g^-1), PCBs (9-27 ng g^-1) and PBDEs (0.2-2.5 ng g^-1) were indicative of moderate to intense contamination. The POP concentrations have progressively increased since the 1990s. The light molecular weight PAHs, and the prevalence of PCB congeners with low-chlorination levels (e.g., di- to tri-CB) and low-to medium-brominated (tri- to penta-BDE) PBDEs in most sections of the sediment profiles, suggested that these POPs have most likely reached these sediments by long-range atmospheric transport from distant sources; although the significant presence of heavier PAH, PCB and PBDE congeners in the topmost sediments, indicate that other nearby and local sources (soil erosion from the catchment, urban and industrial wastewaters discharges, as well as navigation) might have also contributed to the recent input of POPs to LC. Taking into account the relevance of LC as regional freshwater supply and commercial fishing ground, the potential risk posed by the organic contaminated sediments to the biota and human population should not be underestimated.

Children's Environmental Health in South and Southeast Asia: Networking for Better Child Health Outcomes

Children are particularly vulnerable to environmental hazards because they receive higher doses of pollutants in any given environment and often do not have equitable access to social protection mechanisms such as environmental and health care services. The World Health Organization established a global network of collaborating centres that address children’s environmental health (CEH). The network developed a focus on low- and middle-income countries (LMICs) and is broadening its reach by conducting regional workshops for CEH.

Urinary metals and metal mixtures in Bangladesh: Exploring environmental sources in the Health Effects of Arsenic Longitudinal Study (HEALS)

INTRODUCTION

Environmental exposure to toxic metals and metalloids is pervasive and occurs from multiple sources. The Health Effects of Arsenic Longitudinal Study (HEALS) is an ongoing prospective study predominantly focused on understanding health effects associated with arsenic exposure from drinking water. The goal of this project was to measure a suite of elements in urine to better understand potential exposure patterns and to identify common environmental sources of exposure among this semi-rural Bangladeshi population.

METHODS

In a random sample of 199 adult HEALS participants (50% female), the concentrations of 15 urinary elements (As, Ba, Cd, Co, Cs, Cu, Mn, Mo, Ni, Pb, Se, Sr, Tl, W, Zn) were assessed by Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) to assess commonalities with sociodemographic characteristics and potential sources of exposure. We used principal component analysis (PCA) with varimax normalized rotations, and hierarchical cluster analysis (CA), using Ward's method with Euclidean distances, to evaluate these relationships.

RESULTS

PCA and CA showed similar patterns, suggesting 6 principal components (PC) and 5 clusters: 1)PC: Sr-Ni-Cs/ CA: Sr-Ni-Co; 2) Pb-Tl/Pb-Tl-Se-Cs; 3) As-Mo-W/As-Mo-W; 4) Ba-Mn/Ba-Mn; 5) Cu-Zn/Cu-Zn-Cd; and 6) Cd. There was a strong significant association between the As-Mo-W PC/cluster and water arsenic levels (p < 0.001) and between the Cd PC and betel nut use (p = 0.003). The Sr-Ni-Cs PC was not related to any of the socio-demographic characteristics investigated, including smoking status and occupation. The first PC, Sr-Ni-Cs, explained 21% of the variability; the third PC, As-Mo-W, explained 12.5% of the variability; and the sixth PC, Cd, explained 10% of the variability. Day laborers appeared to have the highest exposure.

CONCLUSIONS

Groundwater and betel nut use are likely important sources of metal and metalloid exposure in this population. These findings will guide future exposure assessment research in Bangladesh and future epidemiologic research investigating the degree to which metal mixtures play a role in disease development.

Prevalence of elevated blood lead levels among pregnant women and sources of lead exposure in rural Bangladesh: A case control study

Prenatal and early childhood lead exposures impair cognitive development. We aimed to evaluate the prevalence of elevated blood lead levels (BLLs) among pregnant women in rural Bangladesh and to identify sources of lead exposure. We analyzed the BLLs of 430 pregnant women randomly selected from rural communities in central Bangladesh. Fifty-seven cases were selected with the highest BLLs, ≥ 7 μg/dL, and 59 controls were selected with the lowest BLLs, < 2 μg/dL. An exposure questionnaire was administered and soil, rice, turmeric, water, traditional medicine, agrochemical, and can samples were analyzed for lead contamination. Of all 430 women, 132 (31%) had BLLs > 5 μg/dL. Most women with elevated BLLs were spatially clustered. Cases were 2.6 times more likely than controls to consume food from a can (95% CI 1.0-6.3, p = 0.04); 3.6 times more likely to use Basudin, a specific brand of pesticide (95% CI 1.6-7.9, p = 0.002); 3.6 times more likely to use Rifit, a specific brand of herbicide (95% CI 1.7-7.9, p = 0.001); 2.9 times more likely to report using any herbicides (95% CI 1.2-7.3, p = 0.02); and 3.3 times more likely to grind rice (95% CI 1.3-8.4, p = 0.01). Five out of 28 food storage cans were lead-soldered. However, there was minimal physical evidence of lead contamination from 382 agrochemical samples and 129 ground and unground rice samples. Among 17 turmeric samples, one contained excessive lead (265 μg/g) and chromium (49 μg/g). Overall, we found evidence of elevated BLLs and multiple possible sources of lead exposure in rural Bangladesh. Further research should explicate and develop interventions to interrupt these pathways.

Dietary patterns and serum of DDT concentrations among reproductive-aged group of women in Bangladesh

This research was conducted in order to propose ways to reduce human exposure to DDT, especially for women of reproductive age in Bangladesh, and to find a relation between DDT exposure levels in serum and questionnaire information including sociodemographic and food frequency (FFQ). In this study, a significant relationship was found between the education level and BMI, and the serum p,p'-DDE concentration. This result suggests that people with higher education (relating to higher income) and BMI in Bangladesh actively buy expensive foodstuff, like meat and/or fatty fish, which relates to a higher fat intake. Additionally, a weak positive relationship between p,p'-DDE concentration in serum and the frequency of beef consumption was observed among the nullipara women subgroup. In a previous study, beef and fish showed large contributions on DDT intake of Bangladesh population. Those results suggest that the control of fatty food consumption such as meat (beef) and marine fish might help to regulate the levels of DDT.

Serum concentrations of organochlorine compounds and predictors of exposure in children living in agricultural communities from South-Eastern Spain

BACKGROUND

Information on exposure levels to organochlorine compounds (OCs) in child population is limited, despite their greater vulnerability to the adverse health effects of these chemicals.

OBJECTIVE

To determine serum concentrations of 10 OCs (including organochlorine pesticides and polychlorinated biphenyls -PCBs-) in children living in agricultural communities from Almería (South-Eastern Spain), and to identify the main predictors of exposure related to socio-economic characteristics, diet and lifestyle.

METHODS

A cross-sectional study was conducted on 133 children aged 6-11 years selected from public schools of the study area. OCs compounds were determined in serum samples by GC/ECD. Anthropometric measures were obtained during sample collection. Information on sociodemographic characteristics, parental occupation, residential history, lifestyle and frequency of food consumption, among other relevant factors, was obtained by questionnaires administered to the mothers.

RESULTS

Geometric means of serum concentrations (ng/ml) were 0.11 for β-hexachloro-cyclohexane (β-HCH), 0.09 for endosulfan, 0.20 for endosulfan-ether, 0.51 for hexachorobenzene (HCB), 0.08 for mirex, 0.06 for oxychlordane, 0.36 for p,p'-DDE, 0.20 for PCB 138, 0.36 for PCB 153, and 0.45 for PCB 180. Percentage of samples above the limit of detection (0.05 ppb) ranged from 32 (β-HCH) to 100 (HCB). A high variability in OC levels depending on the compound was observed between our results and others found in similar studies carried out in children. Variables related to fish consumption were found to be the major dietary determinant of PCB 138, p,p´-DDE, endosulfan-α, β-HCH, mirex and oxychlordane levels.

CONCLUSIONS

Children participating in this study showed detectable levels of many OC, despite these compounds are no longer used. Their presence in children serum can be explained by their high lipophilicity and environmental persistence, leading to contamination of fatty food. In this line, fish consumption seemed to be the most relevant determinant of OC levels found in our study.

In vitro study on the joint hepatoxicity upon combined exposure of cadmium and BDE-209

Joint toxicity is an important issue during the risk assessment of environmental pollutants. Contamination of heavy metals and persistent organic pollutants (POPs) under the environmental and biological settings poses substantial health risk to humans. Although previous studies demonstrated the co-occurrence of cadmium and decabrominated diphenyl ether (BDE-209) in environmental mediums, food chains and even human body, their potentially joint toxicities remain elusive thus far. Our investigation here with respect to the hepatotoxicity in vitro clearly demonstrated that combined exposure of cadmium and BDE-209 aggravated the injuries in hepatocytes, which was evidenced by the additive effects on the induction of remarkable morphological alternations, LDH release, cell apoptosis and necrosis, impairment of mitochondrial activity and transmembrane potential. Enhanced ROS production was one of the mechanisms for cell apoptosis and death upon joint treatment. Additionally, more cadmium-treated cells underwent apoptosis than BDE-209-treated cells while more ROS was generated with BDE-209 treatment, indicating that other mechanisms might be involved in cadmium-induced apoptosis. Our results would be helpful for evaluating the joint-hepatotoxicity upon combined exposure of cadmium and BDE-209 as well as investigating the underlying mechanisms.

Lead Exposure Assessment among Pregnant Women, Newborns, and Children: Case Study from Karachi, Pakistan

Lead (Pb) in petrol has been banned in developed countries. Despite the control of Pb in petrol since 2001, high levels were reported in the blood of pregnant women and children in Pakistan. However, the identification of sources of Pb has been elusive due to its pervasiveness. In this study, we assessed the lead intake of pregnant women and one- to three-year-old children from food, water, house dust, respirable dust, and soil. In addition, we completed the fingerprinting of the Pb isotopic ratios (LIR) of petrol and secondary sources (food, house-dust, respirable dust, soil, surma (eye cosmetics)) of exposure within the blood of pregnant women, newborns, and children. Eight families, with high (~50 μg/dL), medium (~20 μg/dL), and low blood levels (~10 μg/dL), were selected from 60 families. The main sources of exposure to lead for children were food and house-dust, and those for pregnant women were soil, respirable dust, and food. LIR was determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) with a two sigma uncertainty of ±0.03%. The LIR of mothers and newborns was similar. In contrast, surma, and to a larger extent petrol, exhibited a negligible contribution to both the child’s and mother’s blood Pb. Household wet-mopping could be effective in reducing Pb exposure. This intake assessment could be replicated for other developing countries to identify sources of lead and the burden of lead exposure in the population.

Exposure Assessment to Environmental Chemicals in Children from Ciudad Juarez, Chihuahua, Mexico

It has been demonstrated that the human biomonitoring of susceptible populations is a valuable method for the identification of critical contaminants. Therefore, the purpose of this study was to assess the exposure profile for arsenic (As), lead (Pb), mercury (Hg), 1-hydroxypyrene (1-OHP), 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) in children living in Ciudad Juarez, Chihuahua, Mexico (a major manufacturing center in Mexico). In 2012, we evaluated a total of 135 healthy children living in Ciudad Juarez since birth. The total PBDEs levels ranged from nondetectable (< LOD) to 215 ng/g lipid, with a mean total PBDEs level of 29.5 ± 53.0 ng/g lipid (geometric mean ± standard deviation). The mean total PCBs level in the study participants was 29.0 ± 10.5 ng/g lipid (range 4.50-50.0 ng/g lipid). The mean concentration of total DDT (DDT + DDE) was 11.9 ± 6.70 ng/g lipid (range 3.00-26.0 ng/g lipid). The mean 1-OHP levels was 1.2 ± 1.1 µmol/mol creatinine (range <LOD to 3.90 µmol/mol creatinine). Regarding heavy metals levels, the mean urinary As levels was 19.5 ± 3.07 µg/g creatinine, for urinary mercury the levels ranged from <LOD to 11.5 µg/L, with a mean value of 2.10 µg/L, and finally, the mean blood lead level was 4.20 ± 3.80 µg/dL. In conclusion, our data indicate high exposure levels to chemicals analyzed in the children living in the study community. Therefore, a biomonitoring program for the surveillance of the child population in Ciudad Juarez is necessary.

Modulation of aryl hydrocarbon receptor-regulated enzymes by trimethylarsine oxide in C57BL/6 mice: In vivo and in vitro studies

Arsenic is a worldwide environmental pollutant that is associated with skin and several types of internal cancers. Recent reports revealed that arsenic biomethylation could activate the toxic and carcinogenic potential of arsenic. Therefore, we investigated the effect of trimethylarsine oxide (TMAO) on the activation of AhR-regulated genes in vivo and in vitro. In vivo, C57BL/6 mice received TMAO (13mg/kg i.p.) with or without the prototypical AhR ligand, TCDD (15μg/kg), then the livers were harvested at 6 and 24h post-treatment. In vitro, isolated hepatocytes from C57BL/6 mice were treated with TMAO (5μM) in the absence and presence of TCDD (1nM) for 6 and 24h. Our in vivo results demonstrated that, TMAO alone increased Cyp1a1, Cyp1a2, Cyp1b1, Nqo1, Gsta1, and Ho-1 at mRNA level. Upon co-exposure to TMAO and TCDD, TMAO potentiated the TCDD-mediated induction of Cyp1a1, Cyp1b1, and Nqo1 mRNA levels. Western blotting revealed that, TMAO alone increased Cyp1a1, Cyp1a2, Nqo1, Gsta1/2, and Ho-1 protein levels, and potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1b1 protein level. In addition, TMAO alone significantly increased Cyp1a1, Cyp1a2, Nqo1, Gst, and Ho-1 activities and significantly potentiated the TCDD-mediated induction of Cyp1a1 activity. At the in vitro level, TMAO induced Cyp1a1 and potentiated the TCDD-mediated induction of Cyp1a1 at mRNA, protein and activity levels. In addition, TMAO increased the nuclear localization of AhR and AhR-dependent XRE-driven luciferase activity. Our results demonstrate that the TMAO, modulates AhR-regulated genes which could potentially participate, at least in part, in arsenic induced toxicity and carcinogenicity.

Temporal trends in concentrations and total serum burdens of organochlorine compounds from birth until adolescence and the role of breastfeeding

INTRODUCTION

The aims of the present study are to assess the temporal trends of organochlorine compounds (OCs) concentrations and total serum burdens from birth until adolescence and the influence of breastfeeding in these temporal trends.

METHODS

In 1997 two birth cohort studies were set up in Ribera d'Ebre (N=102) and the island of Menorca (N=482), Spain. Concentrations (ng/mL) of OCs [pentachlorobenzene (PeCB), four isomers of hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (4,4'-DDT), dichlorodiphenyldichloroethylene (4,4'-DDE) and seven polychlorobiphenyl congeners (Σ7PCBs)] were measured in cord blood and at the age of 4 and 14years. The total serum burdens (ng) of these compounds were estimated based on the total blood volume (mL) of children at the different ages. We compared median concentrations and total serum burdens of these OCs at the different time-points of follow-up between children of Ribera d'Ebre and Menorca and between breastfed and non-breastfed children.

RESULTS

From birth until adolescence concentrations of all OCs drastically reduced. These reductions were mainly derived from the dilution of OCs, associated to an increase in total blood volume of children at the age of 4 and 14years. Despite the reduction in OCs concentrations, the total serum burdens of 4,4'-DDE and Σ7PCBs, were higher in adolescents than at birth. Increases in OCs total serum burden occurred both in breastfed and non-breastfed children, but were significantly higher in the first.

CONCLUSIONS

Even after decades of banning OCs production and use, current young generations in westernized countries are still bioaccumulating these compounds. Given the potential health effects of OCs, especial attention should be paid in the control of secondary emissions in the environment and in the control of food production and contamination. In countries with endemic malaria it is important to work towards effective alternatives to the use of DDT.

S100β in heavy metal-related child attention-deficit hyperactivity disorder in an informal e-waste recycling area

Exposure to lead even at low levels correlates with attention-deficit/hyperactivity disorder (ADHD). However, lead-contaminated environments are often contaminated with other heavy metals that could exacerbate lead-induced ADHD. We conducted this study to evaluate the relationship between multiple heavy metals and child behaviors, and the involvement of S100 calcium-binding protein β (S100β) expression in child ADHD in Guiyu, an internationally-known e-waste contaminated recycling town. Two hundred and forty kindergarten children, 3- to 7-years of age, who lived in Guiyu, were recruited for this study. Child behavioral assessment was derived from parent and teacher ratings. Serum S100β was assayed by an enzyme-linked immunosorbent assay (ELISA). Lead (Pb), cadmium (Cd) and manganese (Mn) levels in whole blood were measured using graphite furnace atomic absorption spectrometry (GFAAS). The prevalence of children with ADHD symptoms in Guiyu was 18.6%, with the percentage of children suspected to have behavior problems being 46.2% or 46.5%, based on the Rutter parents' or teachers' scale scores, respectively. Child blood levels of Pb, Cd, and Mn correlated with certain behavioral abnormalities, such as conduct problems and antisocial behavior. Serum S100β levels were associated with heavy metal levels in blood, and certain behavioral abnormalities. These findings suggest that exposure to various environmental heavy metals in Guiyu might result in child behavior disorders. Results also indicate that S100β may provide information for laboratory evaluation of neurotoxicity.

Role of fruits, grains, and seafood consumption in blood cadmium concentrations of Jamaican children with and without Autism Spectrum Disorder

Human exposure to cadmium has adverse effects on the nervous system. Utilizing data from 110 age- and sex-matched case-control pairs (220 children) ages 2-8 years in Kingston, Jamaica, we compared the 75th percentile of blood cadmium concentrations in children with and without Autism Spectrum Disorder (ASD). In both univariable and multivariable Quantile Regression Models that controlled for potential confounding factors, we did not find any significant differences between ASD cases and typically developing (TD) controls with respect to the 75th percentile of blood cadmium concentrations, (P > 0.22). However, we found a significantly higher 75th percentile of blood cadmium concentrations in TD Jamaican children who consumed shellfish (lobsters, crabs) (P <0.05), fried plantain (P <0.01), and boiled dumpling (P <0.01). We also observed that children living in Jamaica have an arithmetic mean blood cadmium concentration of 0.16μg/L which is similar to that of the children in developed countries and much lower than that of children in developing countries. Although our results do not support an association between blood cadmium concentrations and ASD, to our knowledge, this study is the first to report levels of blood cadmium in TD children as well as those with ASD in Jamaica.

DDT and DDE concentrations in the blood of Mexican children residing in the southeastern region of Mexico

The aim of this study was to assess the levels of dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in the blood of children living in the southeastern region of Mexico. In this study, we found high levels of DDT and its principal metabolite (DDE) in the blood of children residing in the communities studied. The levels of total DDT found in our study ranged from 4,676.4 ng/g lipid to 64,245.2 ng/g lipid. All of the children in the study had detectable levels of DDT and/or DDE. In conclusion, our data indicate that children living within the study areas are exposed to high levels of DDT and DDE. Moreover, these results can be used as a trigger to revisit local policies on environmental exposures.

DDT, DDE, and 1-hydroxypyrene levels in children (in blood and urine samples) from Chiapas and Oaxaca, Mexico

The aim of this study was to evaluate the DDT, DDE, and 1-hydroxypyrene exposure levels of children living in communities located in southeastern Mexico. The study communities were Lacanja and Victoria in Chiapas state and Ventanilla in Oaxaca state. Children living in Lacanja had total blood DDT levels (mean ± SD, 29,039.6 ± 11,261.4 ng/g lipid) that were significantly higher than those of children in Victoria (10,220.5 ± 7,893.1 ng/g lipid) and Ventanilla (11,659.7 ± 6,683.7 ng/g lipid). With respect to the 1-hydroxypyrene levels in urine samples, the levels in Lacanja (4.8 ± 4.1 μg/L or 4.5 ± 3.9 μmol/mol creatinine) and Victoria (4.6 ± 3.8 μg/L or 3.9 ± 3.0 μmol/mol Cr) were significantly higher than levels found in Ventanilla (3.6 ± 1.4 μg/L or 2.5 ± 0.5 μmol/mol Cr). In conclusion, our data indicate high levels of exposure in children living in the communities studied in this work. The evidence found in this study could be further used as a trigger to revisit local policies on environmental exposures.

Implications of global climate change for the assessment and management of human health risks of chemicals in the natural environment

Global climate change (GCC) is likely to alter the degree of human exposure to pollutants and the response of human populations to these exposures, meaning that risks of pollutants could change in the future. The present study, therefore, explores how GCC might affect the different steps in the pathway from a chemical source in the environment through to impacts on human health and evaluates the implications for existing risk-assessment and management practices. In certain parts of the world, GCC is predicted to increase the level of exposure of many environmental pollutants due to direct and indirect effects on the use patterns and transport and fate of chemicals. Changes in human behavior will also affect how humans come into contact with contaminated air, water, and food. Dietary changes, psychosocial stress, and coexposure to stressors such as high temperatures are likely to increase the vulnerability of humans to chemicals. These changes are likely to have significant implications for current practices for chemical assessment. Assumptions used in current exposure-assessment models may no longer apply, and existing monitoring methods may not be robust enough to detect adverse episodic changes in exposures. Organizations responsible for the assessment and management of health risks of chemicals therefore need to be more proactive and consider the implications of GCC for their procedures and processes.

Occurrence and levels of organochlorine compounds in human breast milk in Bangladesh

In low-income countries, the use of some organochlorine pesticides is still common in order to increase food production. Monitoring the chemical exposure is an important step in risk-reducing strategies. This is the first study to report concentrations of organochlorines in breast milk of women from Bangladesh where farming is the main income source. Organochlorines such as p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD (i.e., ∑DDT), HCB, α-, β- and γ-HCH, trans-chlordane, cis-chlordane, oxy-chlordane, trans-nonachlor, cis-nonachlor, mirex and polychlorinated biphenyls (CB 28, 52, 99, 101, 105, 114, 118, 123, 128, 138, 141, 149, 153, 156, 157, 163, 167, 170, 180, 183, 187, 189, 194) were analyzed in breast milk collected in 2002 from 72 first-time mothers (median age 20years) living in the rural area Matlab, Bangladesh. While the concentrations of PCBs and many of the pesticides were low, the concentrations of p,p'-DDT and its metabolite p,p'-DDE were high (median 349 and 1645ngg(-1)lipid, respectively) in comparison to other countries. The median value of ∑DDT was 2123ngg(-1)lipid. The estimated daily exposure to p,p'-DDT, p,p'-DDE and ∑DDTs was 10, 30 and 42μgkg(-1) body weight, respectively, in 3months old infants. The p,p'-DDE/p,p'-DDT ratio ranged from 1 to 23, where 58% of the mothers had a ratio below 5 indicating recent or ongoing DDT exposure. This study reports infant exposure and maternal body burden of organochlorines through breast milk. Although the findings give no reason to limit breast-feeding, it is essential to identify the main exposure sources and find means to decrease the exposure.

Source and risk assessment of PCBs in sediments of Fenhe reservoir and watershed, China

The concentrations of polychlorinated biphenyls (PCBs) in sediments from the Fenhe reservoir and watershed were detected at 28 sites in wet and dry seasons. The ∑(123)PCBs ranged from n.d. to 126.49 ng g(-1) dw. The dominated congeners were tri-PCBs (34.29%) and tetra-PCBs (24.05%). In the Fenhe reservoir, ∑(123)PCBs presented a decreasing trend, while percentages of low chlorinated congeners showed an increasing trend. For the temporal variations, PCBs homologues profiles of sediment samples and spatial distribution of ∑(123)PCBs for the two periods were similar (with CD = 0.021 and r(2) = 0.999 respectively), although PCBs concentrations in the wet season were significantly higher than in the dry season. PCA was applied to analyze the possible sources for PCBs, suggesting that PCBs might be mainly influenced by Aroclor 1016 and 1242. Compared with 3 established sediment quality guidelines, levels of PCBs in sediments of the investigated watershed might have a potential biological impact, especially in the wet season.