Hormonal, liver, and renal function associated with electronic waste (e-waste) exposure in Dhaka, Bangladesh.

Electronic waste (e-waste) contains numerous metals and organic pollutants that have detrimental impacts on human health. We studied 199 e-waste recycling workers and 104 non-exposed workers; analyzed blood, urine, and hair samples to measure heavy metals, hormonal, liver, and renal function. We used quantile regression models to evaluate the impact of Pb, Cd, and Hg on hormonal, liver and renal function, and the role of DNA oxidative damage in mediating the relationship between exposures and outcomes. Exposed workers had higher blood lead (Pb) (median 11.89 vs 3.63 µg/dL), similar blood cadmium (Cd) (1.04 vs 0.99 µg/L) and lower total mercury (Hg) in hair (0.38 vs 0.57 ppm) than non-exposed group. Exposed workers also had elevated median concentrations of total triiodothyronine (TT3), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urinary albumin, albumin creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were significantly higher than non-exposed group (p≤0.05). Sex hormones including luteinizing hormone, follicle stimulating hormone, estrogen, progesterone and testosterone concentrations were not significantly different between exposed and non-exposed (all p≥0.05). The median concentration of ALT was 4.00 (95% CI: 0.23, 7.77), urinary albumin was 0.09 (95% CI: 0.06, 0.12) and ACR was 1.31 (95% CI: 0.57, 2.05) units higher in the exposed group compared to non-exposed group. Pb was associated with a 3.67 unit increase in the ALP (95% CI: 1.53, 5.80), 0.01 unit increase in urinary albumin (95% CI: 0.002, 0.01), and 0.07 unit increase in ACR (95% CI: 0.01, 0.13). However, no hormonal, renal, and hepatic parameters were associated with Cd or Hg. Oxidative DNA damage did not mediate exposure-outcome relationships (p≥0.05). Our data indicate e-waste exposure impairs liver and renal functions secondary to elevated Pb levels. Continuous monitoring, longitudinal studies to evaluate the dose-response relationship and effective control measure are required to protect workers from e-waste exposure.

Systematic literature review of heavy metal contamination of the Nigerian environment from e-waste management: Associated health and carcinogenic risk assessment.

E-waste -the aftermath of large amount of electrical and electronic equipment ferried into Africa from which Nigeria receives a significant chunk, is composed of components known to be hazardous to health. Composition of series of heavy metals (HMs) in e-waste is traceable to many health conditions including cancer which is hitherto incompletely understood. This study harmonizes primary data on HMs from e-waste in different Nigerian environmental media including the air, soil, surface dust, water and plant. We estimated the possible health implications, single and aggregative soil and water pollution indices both in adult and children categories, carcinogenic and non-carcinogenic risks secondary to HM exposure and mapped out the possible mechanism of carcinogenesis. Analysis showed that soil, water, surface dust and plant matrices in Nigerian environment are variedly but considerably contaminated with combination of HMs. The significantly high values of the hazard quotient and hazard index of both water and surface dust matrices are indicative of adverse health effect of the non-carcinogenic risk. The highest HQ is generated by Pb and Cr through dermal exposure to soil and surface dust with mean values of 1718.48, 1146.14, 1362.10 and 1794.61 respectively among Nigerian children followed by the oral exposure. This pattern of observation is similar to that obtained for adult category. HI due to Pb and Cr in soil constitutes the highest HI (2.05E+03 and 1.18E+03 respectively) followed by surface dust. However, this study precipitates the observation that children are more at health risk than adults in contaminated environment. Carcinogenic risk also follows the same pattern of expression in the Nigerian environment. We conclude that exposure to e-waste poses significant carcinogenic and non-carcinogenic health risks and the induction of toxicity may be mediated via DNA damage, oxidative stress and inflammatory/immune cells dysfunction in Nigerian environment.

Unexpectedly high levels and health risks of atmospheric polychlorinated biphenyls in modern mechanical dismantling of obsolete electrical equipment: Investigations in a large integrated e-waste dismantling industrial estate.

Large industrial estates for electrical and electronic waste (e-waste) mechanical dismantling and recycling are gradually replacing outmoded small factories and intensive domestic workshops for e-waste manual and chemical dismantling. However, the air pollution and health risks of persistent organic pollutants during the modern mechanical processing of e-waste, especially obsolete electrical equipment, still remain unclear. Here, unexpectedly high levels (409.3 ng/m3) and health risks of airborne polychlorinated biphenyls (PCBs) were found during the mechanical processing of obsolete electric equipment or parts in a large integrated dismantling industrial estate, which is comparable to or a dozen times higher than those reported during chemical processing. In contrast, the levels (936.0 pg/m3) and health risks of particulate polybrominated diphenyl ethers (PBDEs) were all lower than those of previous studies. PCB emissions (44.9-3300.5 ng/m3) varied significantly across six mechanical dismantling places specifically treating waste motors, electrical appliances, hardware, transformers, and metals, respectively. The high PCB content and mass processing number of obsolete electrical equipment probably result in the highest PCB emissions from the mechanical dismantling of obsolete motors, followed by waste electrical appliances and metals. The PCB non-cancer and cancer risks associated with inhalation and dermal exposure in different mechanical dismantling places were all above the given potential risk limits. In particular, the health risks of dismantling obsolete motor exceeded the definite risk levels. Little difference in PCB emissions and health risks between working and non-working time suggested the importance of PCB volatilization from most e-waste. Such high PCB emissions and health risks of PCBs undoubtedly posed a severe threat to frontline workers, but fortunately, they decreased significantly with the increasing distance from the industrial estate. We highlight that PCB emissions and associated health risks from obsolete electrical equipment with high PCB content during mechanical dismantling activities should be of great concern.

Elevated levels of biomarkers of oxidative stress and renal injury linked to nitrogenous flame retardants exposure in e-waste dismantling site: A case study in China.

Nitrogenous flame retardants (NFRs) have aroused worldwide public concern as their nephrotoxic effect. However, knowledge regarding the pathogenesis mechanism of their exposure to induce kidney injury remains largely unknown. In this study, eight NFRs, four oxidative stress biomarkers (OSBs), and one kidney injury biomarker, namely neutrophil gelatinase-associated lipocalin (NGAL), were measured in urine specimens collected from residents living around e-waste disassembly and reference areas, representing two exposure scenarios. Significant higher concentrations of Σ8NFR (median: 70.6 vs. 33.8 µg/g Cre) and five biomarkers (124 vs. 97.4 µg/g Cre) were found in urines of populations living in e-waste site compared to those in the reference site (p < 0.05). Primary NFRs exhibited significant positive associations with OSBs and NGAL regardless of the population examined, implying that chronic NFRs exposure could induce oxidative stress and kidney damage. By using structure equation model, we found that oxidative stress, particularly DNA and RNA oxidation mediated 16.1% of the total effect of NFRs on NGAL in e-waste related people, but not on the general population. Overall, this study suggests long-term chronic exposure to NFRs can induce oxidative stress and renal injury in humans but the pathogenesis mode may be scenario-specific.

Metal Levels, Genetic Instability, and Renal Markers in Electronic Waste Workers in Thailand.

BACKGROUND: Informal electronic waste (e-waste) recycling is an increasingly important industry worldwide. However, few studies have studied the health risks in this group of workers. OBJECTIVE: To assess the associations between occupational exposures to metals and genetic instability and renal markers among e-waste recycling workers. METHODS: We recruited informal e-waste recycling workers from a community in northeastern Thailand. Participants completed a questionnaire, several health measurements, and provided urine and blood samples, which we then analyzed for a number of metals including lead (Pb), cadmium (Cd), and manganese (Mn). Samples were analyzed for a marker of RNA and DNA damage (ie, oxidative stress), 8-hydroxy-2'-deoxyguanosine (8-OHdG). Glomerular filtration rate (GFR) and fractional excretion of calcium (FECa%) were measured as markers of renal function. Correlations and regression models were used to assess associations between these various factors. RESULTS: We found significantly higher levels of Cd and Pb in blood of men compared with those in women. Men who worked >48 hours/week had significantly higher levels of 8-OHdG compared with men who worked ≤48 hours/week. Smoking was significantly associated with higher blood Pb and Cd concentrations among men. CONCLUSION: Our results suggest gender differences in both blood concentrations of metals associated with e-waste recycling and smoking and highlight potentially elevated oxidative stress associated with longer work hours. Health promotion efforts are needed among informal e-waste recyclers to reduce possible risks of renal damage and cancer.

Alterations in platelet indices link polycyclic aromatic hydrocarbons toxicity to low-grade inflammation in preschool children.

BACKGROUND: Environmental exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) can disturb the immune response. However, the effect of PAHs on low-grade inflammation related to platelets in humans is unknown. OBJECTIVES: We investigated the association of PAH exposure with low-grade inflammation and platelet parameters in healthy preschoolers. METHODS: The present study recruited 239 participants, aged 2-7 years, from an electronic-waste (e-waste)-exposed (n = 118) and a reference (n = 121) area. We measured ten urinary PAH metabolites, four types of immune cells and cytokines, and seven platelet parameters, and compared their differences between children from the two groups. Spearman correlation analysis was performed to explore the potential risk factors for PAH exposure and the associations between urinary monohydroxylated PAHs (OH-PAHs) and biological parameters. Associations between urinary PAH metabolites and platelet indices were analyzed using quantile regression models. Mediation analysis was used to understand the relationship between urinary total hydroxynaphthalene (ΣOHNa) and interleukin (IL)-1ß through seven platelet indices, as mediator variables. RESULTS: We found higher urinary monohydroxylated PAH (OH-PAH) concentrations, especially 1-hydroxynaphthalene (1-OHNa) and 2-hydroxynaphthalene (2-OHNa), in children from the e-waste-exposed group than in the reference group. These were closely associated with child personal habits and family environment. A decreased lymphocyte ratio and increased pro-inflammatory cytokines, such as gamma interferon-inducible protein (IP)-10 and IL-1ß, were found in the e-waste-exposed children. After adjustment for confounding factors, significantly negative correlations were found between levels of mean platelet volume (MPV), platelet distribution width (PDW), platelet-large cell ratio (P-LCR) and ratio of mean platelet volume to platelet count (MPVP) and OH-PAHs. In addition, ΣOHNa was positively associated with IL-1ß mediated through MPV, PDW, P-LCR, and ratio of platelet count to lymphocyte count (PLR). CONCLUSIONS: Platelet indices were significantly associated with the changes in urinary OH-PAH levels, which may can be regarded as effective biomarkers of low-grade inflammation resulting from low PAH exposure in healthy children.

Ambient fine particulate matter inhibits innate airway antimicrobial activity in preschool children in e-waste areas.

Ambient fine particulate matter (PM2.5) is a risk factor for respiratory diseases. Previous studies suggest that PM2.5 exposure may down-regulate airway antimicrobial proteins and peptides (AMPs), thereby accelerating airway pathogen infection. However, epidemiological research is scarce. Hence, we estimated the associations between individual PM2.5 chronic daily intake (CDI) and the levels of the airway AMP salivary agglutinin (SAG), as well as peripheral leukocyte counts and pro-inflammatory cytokines, of preschool children in Guiyu (an e-waste area) and Haojiang (a reference area located 31.6 km to the east of Guiyu). We recruited 581 preschool children from Guiyu and Haojiang, of which 222 were included in this study for a matching design (Guiyu: n = 110 vs. Haojiang: n = 112). Air PM2.5 pollution data was collected to calculate individual PM2.5 CDI. The mean concentration of PM2.5 in Guiyu was higher than in Haojiang, resulting in a higher individual PM2.5 CDI. Concomitantly, saliva SAG levels were lower in Guiyu children (5.05 ng/mL) than in Haojiang children (8.68 ng/mL), and were negatively correlated with CDI. Additionally, peripheral counts of white blood cells, and the concentrations of interleukin-8 and tumor necrosis factor-alpha, in Guiyu children were greater than in Haojiang children, and were positively associated with CDI. Similar results were found for neutrophils and monocytes. To our knowledge, this is the first study on the relationship between PM2.5 exposure and innate airway antimicrobial activity in children, in an e-waste area, showing that PM2.5 pollution may weaken airway antimicrobial activity by down-regulation of saliva SAG levels, which might accelerate airway pathogen infection in children.

Blood lead and cadmium levels associated with hematological and hepatic functions in patients from an e-waste-polluted area.

Chronic exposures to toxic trace metals have hazardous effects on human health, especially exposure to lead (Pb) and cadmium (Cd). Blood Pb and Cd reflect toxicity on human health. A total of 267 hospitalized patients, of which 158 were from Guiyu (exposed group) in China, and 109 from Jinping (reference group), were recruited in this study. Blood Pb and Cd were measured by graphite furnace atomic absorption spectrometry. Blood Pb and Cd levels from the exposed group were both higher than in the reference group. Blood Pb levels are positively associated with blood Cd levels from the two groups. Blood Pb and Cd levels are associated with elevated hematological and hepatic parameters in patients from the exposed and reference groups. The results suggest toxic trace metals may increase liver metabolic burden, inducing abnormal liver function.

Bioremediation of triphenyl phosphate in river water microcosms: Proteome alteration of Brevibacillus brevis and cytotoxicity assessments.

Triphenyl phosphate (TPHP), an organophosphate flame retardant, was detected in river water samples collected from an electronic waste recycling area in Guiyu, Southern China. The concentrations of TPHP ranged from not detected to 347.2 ng/L, with an average of 138.8 ng/L. The bioaugmentation potential of Brevibacillus brevis on TPHP biodegradation by aerobic microcosms contained in river water from Guiyu was assessed. The results showed that TPHP degradation efficiency was significantly improved to 97.9% by bioaugmentation with B. brevis after 96 h incubation. A total of 182 significantly changed proteins in B. brevis were identified and quantified by isobaric tags for relative and absolute quantification (iTRAQ) in response to TPHP stress. The differentially expressed proteins were mainly associated with energy metabolism, lipid metabolism, cell wall biosynthesis, amino acid transport, and metabolism. The identification that proteins of B. brevis respond to TPHP existence provides novel insights into biodegradation mechanisms of bacteria under environmental stress. Additionally, cytotoxicity assays indicated that the degrading intermediates of TPHP, namely diphenyl phosphate and phenyl phosphate, were less cytotoxic to human HepG2 cells compared with TPHP. Collectively, these findings suggest that aerobic bioaugmentation with degrading microorganisms is a potential strategy for in situ treatment of TPHP-contaminated sites.

Genomic instability in adult men involved in processing electronic waste in Northern China.

BACKGROUND: Managing and recycling electronic waste (e-waste), while useful and necessary, has resulted in significant contamination of several environments in China. The area around Tianjin, China has become one of the world's largest e-waste disposal centers, where electronics are processed by manually disassembly or burning, which can result in serious exposure of workers to a multitude of toxicants. OBJECTIVE: The present study assessed potential genomic damage in workers involved in recycling e-waste. METHODS: To detect cytogenetic and DNA damage, chromosomal aberrations (CA), cytokinesis blocking micronucleus (CBMN) and the comet assay were performed. Concentrations of some trace elements, markers of oxidative stress and polychlorinated biphenyls (PCBs) in whole blood or serum were measured, and relationships among the markers described above, age, and duration of exposure were analyzed. The profiles of expression of genes in lymphocytes in peripheral blood were assessed to determine the status of the regulation of genes involved in genome stability. RESULTS: Concentrations of 28 PCB congeners in the whole blood of the exposed group were significantly (P<0.001) greater than those in the control individuals. Frequency of CA (8.01%) and CBMN (26.3‰) in lymphocytes and the level of DNA damage in the lymphocytes and spermatozoa of the exposed men were also significantly (P<0.0001) greater than those of the controls. There were significant relationships between CA, CBMN, DNA damage and duration of exposure. Concentrations of malondialdehyde (MDA) and lead (Pb) in the blood serum were significantly greater, but activities of superoxide dismutase (SOD), glutathione (GSH) and concentrations of calcium (Ca) and magnesium (Mg) were lower in the serum of the exposed men. MDA, Pb, Ca and Mg were associated with the duration of exposure to handling e-waste. In males involved in handling of e-waste, there were 13 genes - ATM, ATR, ABL1, CHEK1, CHEK2, GADD45A, CDK7, GTSE1, OGG1, DDB1, PRKDC, XRCC1 and CCNH - for which expression of mRNA was up-regulated and 7 genes - BRCA1, GTF2H1, SEMA4A, MRE11A, MUTYH, PNKP and RAD50 - for which the expression of mRNA was down-regulated. CONCLUSIONS: A strong correlation between indicators of damage of DNA, which could result in instability of the genome, and duration of processing e-waste was observed. If proper procedures are not followed, there are significant risks to the health of the individuals involved in such activities.

Maternal urinary cadmium levels during pregnancy associated with risk of sex-dependent birth outcomes from an e-waste pollution site in China.

This study was to investigate whether exposure to cadmium (Cd) during pregnancy is associated with an increased risk of adverse birth outcomes in a sex-dependent manner. Cd concentrations in maternal urine (U-Cd) samples were measured in 237 subjects from Guiyu (e-waste area) and 212 subjects from Haojiang. A significance level of p <0.05 was used for all analyses. The maternal U-Cd levels in Guiyu residents were significantly higher than Haojiang. We found significant inverse associations between U-Cd concentrations and birth anthropometry (birth weight, birth length, Head Circumference and Apgar scores with 1min and 5 mins) in female neonates, but no significant associations were observed in male neonates except Apgar (1min) score after adjustment. The association was more pronounced among female neonates than male neonates, suggesting an association between Cd and adverse birth outcomes may be sex-specific.

Elevated inflammatory Lp-PLA2 and IL-6 link e-waste Pb toxicity to cardiovascular risk factors in preschool children.

Cardiovascular toxicity of lead (Pb) manifests primarily as an effect on blood pressure and eventual increased risk of atherosclerosis and cardiovascular events. Therefore, we investigated vascular inflammatory biomarkers and cardiovascular effects of Pb-exposed children. A total of 590 children (3-7 years old) were recruited from Guiyu (n = 337), an electronic waste (e-waste)-exposed group, and Haojiang (n = 253), a reference group, from November to December 2016. We measured child blood Pb levels (BPbs), and systolic and diastolic blood pressure. Pulse pressure was calculated for the latter two. Serum biomarkers including lipid profiles and inflammatory cytokines, and plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) were detected. Unadjusted regression analysis illustrated that higher ln-transformed BPb associated with lower systolic blood pressure and pulse pressure. After adjustment for various confounders, the relational degree of lnBPb and blood pressure measures became slightly attenuated or not significant. Elevated BPb was associated with higher Lp-PLA2, interleukin (IL)-6, triglycerides (TG) and lower high-density lipoprotein (HDL). Lp-PLA2 remained inversely associated with pulse pressure and HDL, but positively with ratios of total cholesterol to HDL (Tc/HDL) and low-density lipoprotein to HDL (LDL/HDL). IL-6 was associated negatively with systolic blood pressure, pulse pressure and HDL, and positively associated with TG, Tc/HDL and LDL/HDL. The mediation effect of biomarkers on the association of BPb with pulse pressure was insignificant except for Lp-PLA2. Available data supports the conclusion that e-waste-exposed children with higher BPbs and concomitant abnormal measures of cardiovascular physiology have an augmented prevalence of vascular inflammation, as well as lipid disorder.

Potential health risk for residents around a typical e-waste recycling zone via inhalation of size-fractionated particle-bound heavy metals.

Health risk of residents dwelling around e-waste recycling zones has been a global concern, but has not been adequately examined. The present study was intended to evaluate the potential health risk of residents through inhalation exposure to size-fractionated particle-bound heavy metals in a typical e-waste recycling zone, South China. Anthropogenic metals (Zn, Se, Pb, Sb, As, and Cd) were predominantly enriched in fine particles (Dp<1.8µm), whereas the crustal elements (Ti, Fe, and Co) tended to accumulate in coarse particles (Dp>1.8µm). Although the daily inhalation intakes of the target metals were significantly lower than those through food consumption and ingestion of house dust, the hazard quotients of total metals for adults (95% CI: 1.0-5.5) and children (95% CI: 3.0-17) were greater than 1. Moreover, the incremental lifetime cancer risks of five carcinogenic metals (Cr, Co, Ni, As, and Cd) for adults and children were 1.3×10(-3) (95% CI: 4.1×10(-4)-3.0×10(-3)) and 3.9×10(-3) (95% CI: 1.3×10(-3)-8.6×10(-3)), respectively, substantially higher than the acceptable cancer risk range of 10(-6)-10(-4). All these findings suggested that health risks were high for local residents dwelling around the e-waste recycling zone through inhalation exposure to particle-bound heavy metals, for both adults and children.

Health risks of polycyclic aromatic hydrocarbons via fish consumption in Haimen bay (China), downstream of an e-waste recycling site (Guiyu).

Guiyu, China has been one of the largest e-waste recycling sites of the world for more than 20 years. Abundant data show that local dwellers there suffered from severe health risks from e-waste contaminants. In this study, polycyclic aromatic hydrocarbons (PAHs) were used as candidates to test the contamination levels and their possible adverse effects on residents in Haimen Bay, the estuary of Lian River (less than 30km from Guiyu), which has been totally neglected. The concentrations of 16PAHs were determined in collected marine fish with a median ΣPAH concentration of 1478ng/g (wet weight), and the contamination may be mainly influenced by Lian River runoff, specifically from Guiyu. The lifetime excess cancer risk for local dwellers was much higher than the serious risk level (10(-4)). More seriously, outflows of PAHs from the e-waste recycling site (Guiyu) seemed to exert health risks of a much larger scale of population downstream.

Environmental risk assessment of CRT and PCB workshops in a mobile e-waste recycling plant.

The mobile e-waste recycling equipment was chosen as the object of this study, including manual dismantling, mechanical separation of cathode ray tubes (CRTs), and printed circuit boards (PCBs) in the two independent workshops. To determine the potential environmental contamination, the noise, the heavy metals (Cu, Cd, Pb), and the environmental impacts of the e-waste recycling processes in the two workshops of the mobile plant have been evaluated in this paper. This study determined that when control measures are employed, the noise within the two workshops (<80 dB) will meet the national standards. In the CRT workshop, Pb was the most polluting metal, with 2.3 µg/m(3) and 10.53 mg/g in the air and floor dust, respectively. The result of a health risk assessment shows that noncancerous effects are possible for Pb (hazard index (HI) = 3.54 in the CRT workshop and HI = 1.27 in the PCB workshop). The carcinogenic risks to workers for Cd are relatively light in both the workshops. From the results of life cycle assessment (LCA), it can be seen that there was an environmental benefit from the e-waste recycling process as a whole.

The bioavailability and adverse impacts of lead and decabromodiphenyl ether on soil microbial activities.

Lead (Pb) and decabromodiphenyl ether (BDE209) are the main pollutants at electronic waste (e-waste) recycling sites (EWRSs), and their potential toxic effects on soil organisms have received extensive attention. However, the impact on soil microorganisms of joint exposure to the two chemicals remains almost unknown. Therefore, indoor incubation tests were performed to explore the adverse impacts of Pb and BDE209 on soil microbial activities and chemical transformation for the first time. The results have demonstrated that BDE209 was barely degraded in all treated groups, indicating that the presence of Pb hardly affected BDE209 dissipation. The fractions analysis according to Tessier suggested that Pb gradually transformed towards more stable fractions in the slightly alkaline soil, thus reducing the bioavailability of Pb. Additionally, increased Pb doses caused significantly higher bioavailability (p < 0.05), and the same trend was clearly observed after simultaneous exposure to BDE209. Generally, single Pb or BDE209 exposure markedly inhibited (p < 0.05 or 0.01) soil microbial biomass C (C mic), while soil basal respiration (SBR) indicated the opposite response trend (inhibition or stimulation for BDE209 or Pb alone, respectively). Compared to the controls, Pb dramatically (p < 0.01) facilitated soil metabolic quotient (qCO2) during the incubation period. After joint exposure to Pb and BDE209, C mic generally declined with increasing exposure concentration, following certain dose-response relationships. However, SBR and qCO2 were highly significantly stimulated (p < 0.01), and more doses of Pb and BDE209 resulted in higher values. The results of these observations have provided a basic understanding of the potential ecological risk of Pb and BDE209 in soil at EWRSs.

Significant accumulation of persistent organic pollutants and dysregulation in multiple DNA damage repair pathways in the electronic-waste-exposed populations.

Electronic waste (e-waste) has created a worldwide environmental and health problem, by generating a diverse group of hazardous compounds such as persistent organic pollutants (POPs). Our previous studies demonstrated that populations from e-waste exposed region have a significantly higher level of chromosomal aberrancy and incidence of DNA damage. In this study, we further demonstrated that various POPs persisted at a significantly higher concentration in the exposed group than those in the unexposed group. The level of reactive oxygen species and micronucleus rate were also significantly elevated in the exposed group. RNA sequencing analysis revealed 31 genes in DNA damage responses and repair pathways that were differentially expressed between the two groups (Log2 ratio >1 or <-1). Our data demonstrated that both females and males of the exposed group have activated a series of DNA damage response genes; however many important DNA repair pathways have been dysregulated. Expressions of NEIL1/3 and RPA3, which are critical in initiating base pair and nucleotide excision repairs respectively, have been downregulated in both females and males of the exposed group. In contrast, expression of RNF8, an E3 ligase involved in an error prone non-homologous end joining repair for DNA double strand break, was upregulated in both genders of the exposed group. The other genes appeared to be differentially expressed only when the males or females of the two groups were compared respectively. Importantly, the expression of cell cycle regulatory gene CDC25A that has been implicated in multiple kinds of malignant transformation was significantly upregulated among the exposed males while downregulated among the exposed females. In conclusion, our studies have demonstrated significant correlations between e-waste disposing and POPs accumulation, DNA lesions and dysregulation of multiple DNA damage repair mechanisms in the residents of the e-waste exposed region.

Bioaccessibility and health risk of heavy metals in ash from the incineration of different e-waste residues.

Ash from incinerated e-waste dismantling residues (EDR) may cause significant health risks to people through ingestion, inhalation, and dermal contact exposure pathways. Ashes of four classified e-waste types generated by an incineration plant in Zhejiang, China were collected. Total contents and the bioaccessibilities of Cd, Cu, Ni, Pb, and Zn in ashes were measured to provide crucial information to evaluate the health risks for incinerator workers and children living in vicinity. Compared to raw e-waste in mixture, ash was metal-enriched by category incinerated. However, the physiologically based extraction test (PBET) indicates the bioaccessibilities of Ni, Pb, and Zn were less than 50 %. Obviously, bioaccessibilities need to be considered in noncancer risk estimate. Total and PBET-extractable contents of metal, except for Pb, were significantly correlated with the pH of the ash. Noncancer risks of ash from different incinerator parts decreased in the order bag filter ash (BFA) > cyclone separator ash (CFA) > bottom ash (BA). The hazard quotient for exposure to ash were decreased as ingestion > dermal contact > inhalation. Pb in ingested ash dominated (>80 %) noncancer risks, and children had high chronic risks from Pb (hazard index >10). Carcinogenic risks from exposure to ash were under the acceptable level (<10(-6)) both for children and workers. Exposure to ash increased workers' cancer risks and children's noncancer risks. Given the risk estimate is complex including toxicity/bioaccessibility of metals, the ways of exposure, and many uncertainties, further researches are required before any definite decisions on mitigating health risks caused by exposure to EDR incinerated ash are made.

Risks of toxic ash from artisanal mining of discarded cellphones.

The potential environmental and human health impacts of artisanal mining of electronic waste through open incineration were investigated. A market-representative set of cellphones was dismantled into four component categories-batteries, circuit boards, plastics and screens. The components were shredded, sieved and incinerated at 743-818 °C. The concentrations of 17 metals were determined using U.S. EPA methods 6010C (inductively coupled plasma-atomic emission spectrometry; 6020A (inductively coupled plasma-mass spectrometry, or 7471B and 7470A (cold-vapor atomic absorption). EPA Method 8270 (gas chromatography/mass spectrometry) was used to identify polyaromatic hydrocarbon compounds and polybrominated diphenyl ethers. EPA Method 8082A was used to measure polychlorinated biphenyls and EPA Method 8290 was used for dioxin/furans in the residue ash. The life cycle assessment model USEtox(®) was used to estimate impacts of the ash residue chemicals on human health and the ecosystem. Among metals, copper in printed circuit boards had the highest ecotoxicity impact (1610-1930PAFm(3)/kg); Beryllium in plastics had the highest impact on producing non-cancer diseases (0.14-0.44 cases/kg of ash); and Nickel had the largest impact on producing cancers (0.093-0.35 cases/kg of ash). Among organic chemicals, dioxins from incinerated batteries produced the largest ecotoxicological impact (1.07E-04 to 3.64E-04PAFm(3)/kg). Furans in incinerated batteries can generate the largest number of cancers and non-cancer diseases, representing 8.12E-09 to 2.28E-08 and 8.96E-10 and 2.52E-09 cases/kg of ash, respectively. The results reveal hazards of burning discarded cellphones to recover precious metals, and pinpoints opportunities for manufacturers to reduce toxic materials used in specific electronic components marketed globally.