E-waste Site Research Articles

Aerobic and anaerobic biodegradation of BDE-47 by bacteria isolated from an e-waste-contaminated site and the effect of various additives

Degradation experiments are conducted to specifically compare the degradation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) by aerobic and anaerobic strains isolated from real e-waste sites contaminated by BDE-47. The effect of carbon sources, inducers and surfactants on the degradation was examined to strengthen such a comparison. An aerobic strain, B. cereus S1, and an anaerobic strain, A. faecalis S4, were obtained. The results indicated that BDE-47 could be used as the sole carbon source by B. cereus S1 and A. faecalis S4 under aerobic and anaerobic conditions, respectively. The degradation of BDE-47 by B. cereus S1 and A. faecalis S4 was illustrated a first-order kinetics process obtaining a removal efficiency of 61.6% and 51.6% with a first-order rate constant of 0.0728 d−1 and 0.0514 d−1, and corresponding half-life of 8.7 d and 13.5 d, respectively. The addition of carbon sources (yeast extract, glucose, acetic acid and ethanol) and inducers (2,4-dichlorophenol, bisphenol A and toluene) promoted BDE-47 degradation by both B. cereus S1 and A. faecalis S4 under aerobic and anaerobic conditions, while hydroquinone as the inducer inhibited the degradation. All of the surfactants tested (CTAB, Tween 80, Triton X-100, rhamnolipid and SDS) showed inhibitory effect. BDE-47 degradation by B. cereus S1 under aerobic condition was more efficient than A. faecalis S4 under anaerobic condition whether with or without the additives. The results of the study indicated that in the field sites contaminated by BDE-47, the aerobic condition can be more favorable for BDE-47 removal and the degradation can be further enhanced by applying suitable carbon sources and inducers.

OPFRs in e-waste sites: Integrating in silico approaches, selective bioremediation, and health risk management of residents surrounding

A multilevel index system of organophosphate flame retardant bioremediation effect in an e-waste handling area was established under three bioremediation scenarios (scenario I, plant absorption; scenario II, plant–microbial combined remediation; scenario III, microbial degradation). Directional modification of OPFR substitutes with high selective bioremediation was performed. The virtual amino acid mutation approach was utilised to generate high-efficiency selective absorption/degradation mutant proteins (MPs) in a plant–microbial system under varying conditions. In scenario III, the MP's microbial degrading ability to replace molecules was increased to the greatest degree (165.82%). Appropriate foods such as corn, pig liver, and yam should be consumed, whereas the simultaneous consumption of high protein foods such as pig liver and walnut should be avoided; sweet potato and yam are believed to be prevent OPFRs and substitute molecules from entering the human body through multiple pathways for reduced genotoxicity of OPFRs in the populations of e-waste handling areas (the reduction degree can reach 85.12%). The study provides a theoretical basis for the development of ecologically acceptable OPFR substitutes and innovative high-efficiency bioremediation MPs, as well as for the reduction of the joint toxicity risk of multiple ingestion route exposure/gene damage of OPFRs in high OPFR exposure sites.

Key factors controlling colloids–bulk soil distribution of polybrominated diphenyl ethers (PBDEs) at an e-waste recycling site: Implications for PBDE mobility in subsurface environment

Accumulation of polybrominated diphenyl ethers (PBDEs) in surface soils at elevated concentrations is common at e-waste recycling sites. Even though highly insoluble, migration of PBDEs into the vadose zone and groundwater is possible, due to their association with soil colloids. Here, we show that upon equilibration with artificial rainwater surface and subsurface soil samples collected at an e-waste recycling site release significant quantities of colloids, with the total concentrations of 14 PBDE congeners as high as 990 ng/g dw. The concentrations of different congeners vary markedly in the colloids, and that of BDE-209 is the highest in all the samples. Notably, even the colloids released from the soil collected at a depth of 95–105 cm contain high concentrations of PBDEs. Preferential binding of PBDEs to soil colloids is observed, with the colloids-soil distribution coefficients above 10 in certain cases. The extent of preferential binding displays no apparent correlation with the relative hydrophobicity of the PBDEs, nor can it be explained simply by considering the higher specific surface area, pore volume, and clay content of the soil colloids than the respective bulk soil. Principal component analysis shows that multiple soil properties are collectively responsible for the preferential distribution of PBDEs. Specifically, the differences in pore volume, soil organic carbon content, and pore size between colloids and soils are likely the major factors affecting the distribution of high-concentration PBDEs, whereas the differences in clay content, pore volume and specific surface area are the key factors affecting the distribution of low-concentration PBDEs. The findings clearly show that colloids are an important medium with which PBDEs are associated at contaminated sites, and underline the need of understanding colloid-facilitated transport of PBDEs at e-waste sites.

Presence of Novel and Legacy Flame Retardants and Other Pollutants in an E-Waste Site in China and Associated Risks

Presence of Novel and Legacy Flame Retardants and Other Pollutants in an E-Waste Site in China and Associated Risks

Heavy metal contamination and bioaccumulation in Khorat snail-eating turtles (Malayemys khoratensis) from an e-waste recycling activity site in Thailand

Turtles, as a long-lived reptile, have been used as important tools to study heavy metal contamination because the accumulation of pollutants in the turtles is indicative of human health and ecological risks. The purpose of this study was to examine 10 heavy metals, including Fe, Mn, Zn, Cu, Cr, Ni, As, Pb, Cd and Hg, in the surface waters, sediments, gastropods, and Khorat snail-eating turtle (Malayemys khoratensis) blood and to investigate the bioaccumulation factor (BAF) influenced by the heavy metal e-waste recycling activities in the area. Heavy metals were analyzed using inductively coupled plasma–mass spectrometry (ICP–MS). The mean concentrations of heavy metals were Fe > Mn > Zn > As > Ni > Pb > Hg in the surface waters, Fe > Mn > Zn > Cr > Pb > Ni > Cu > As > Hg in the sediments, Fe > Mn > Zn > Cu > Cr > Ni > As = Pb > Cd = Hg in gastropods and Fe > Zn > Cu > Ni > Cr > Hg > Pb in turtle blood. Noteworthy, the highest concentration of toxic heavy metal in surface water was As (0.0020 ± 0.0006 mg/L) while Cr was highest in sediments (10.6320 ± 2.3711 mg/kg), gastropods (0.9563 ± 0.3426 mg/kg) and turtle bloods (0.0706 ± 0.0131 mg/L). Zn had the highest BAF concentration in turtle blood (7,958.4240 ± 6,798.5850 L/kg) and significant bioaccumulation potential. This study presented that heavy metal pollution from e-waste recycling sites can accumulate in freshwater turtles and implies that the rice field ecosystems around the e-waste recycling activity site were contaminated with toxic heavy metals. Therefore, the local people and wildlife inhabiting the areas were exposed to toxicity risks from toxic heavy metals from unsafe recycling activities.

Effects of soil-extractable metals Cd and Ni from an e-waste dismantling site on human colonic epithelial cells Caco-2: Mechanisms and implications

E-wastes release toxic metals including Cd, Cu, Ni, Pb and Zn into nearby soils during dismantling process. However, their adverse effects and the associated mechanisms on human intestinal epithelium are poorly understood. In this study, their toxic effects on human colonic epithelial cells Caco-2 and the underlying mechanisms were assessed basing on three soils from Wenling e-waste dismantling site. Since soil-extractable metals are more available for gastrointestinal absorption, we used phosphate buffer saline solution to extract metals at solid to liquid ratio of 1:2. Among metals, total Cd and Ni exceeded the risk screening values in three soils, being 3.8–8.8 and 42.4–155 mg/kg. Furthermore, high extractable-metals at 5.9, 1.9, and 0.87 mg/kg Cd (20–67%) and 4.6, 6.4, and 12.4 mg/kg Ni (3.6–29%) were observed for Soil-1, -2 and -3, respectively. All three extracts triggered cytotoxicity, with Soil-2 showing the strongest inhibition of cell viability. Higher production of reactive oxygen species and stronger inhibition of antioxidant enzymes SOD1 and CAT were observed in Soil-2 and -3. Upregulation of proinflammatory mediators (IL-1β, IL-8 and TNF-α) and apoptosis-regulatory genes (GADD45α, Caspase-3, and Caspase-8) were observed. Our data suggest that soil extracts induced cytotoxicity, oxidative damage, inflammatory response, and cell apoptosis in Caco-2 cells, indicating soil ingestion from e-waste dismantling site may adversely impact human health.

Investigating the metal contamination status from recycling e-waste sites from Dakar, Senegal

In Senegal, processes employed for recycling e-wastes result in release of so-called heavy metals in the environment. In this study, the metal distribution and concentrations of soils collected from four e-waste recycling areas located in the Dakar area are presented. Measurements are performed using portable X-ray fluorescence and laser-induced breakdown spectroscopy (LIBS) to obtain a complete analysis of the soil, including major and trace elements (i.e., mg/kg). Levels of zinc, copper, manganese, and iron in soils are high but contrasted ranging from 66mg/kg for Cu in Mbeubeuss landfill to more than 1000mg/kg for Mn and 10,000mg/kg for Zn. Lower values are obtained for chromium and lead (Cr = 207mg/kg and Pb = 181mg/kg). The most elevated average lead values (i.e., 2935mg/kg and 1427mg/kg) are obtained from the e-waste recycling sites located in the urban area of Dakar: Reubeuss and Pikine, respectively. Specific element fingerprints are obtained from each of the studied areas. To evaluate human exposure to the main metals, vegetables grown outside the large e-waste landfill were analyzed. The values obtained for Cr, Cu, Fe, Mn, Sr, and Zn are low, ranging from 0.11 to 9.66mg/kg for chromium in turnip and iron in beetroots, respectively. The calculated health risk index remains below unit for all vegetables, which means no potential risk of vegetable consumption for human health. The data provided useful information to estimate contaminations and their origin. Therefore, in order to ensure food safety, continuous monitoring of the vegetables grown in the vicinity of recycling areas is needed.

Heavy metals in fish nearby electronic waste may threaten consumer's health. Examples from Accra, Ghana

Electronic waste sites are rich in heavy metals contained in electronic and electric equipment waste and pose a risk of pollution if metals enter in the environment nearby. The Korle lagoon, located in the center of Accra, is receiving waste effluents from industries, households and the adjacent e-waste burning site Agbogbloshie which is the biggest in the country. Thus, the risk of heavy metal contamination of the water body and subsequent uptake in the aquatic food chain is particularly relevant. Small-scale fishing, not entering the commercial chain, occurs in the lagoon despite its consideration of biologically dead. We assessed if the exposure to heavy metals through these fish consumption is posing higher health risks than fish sold on Ghanaian markets. Using ICP-MS technology, we quantified concentrations of As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn in fish caught from the Korle Lagoon (Trachinotus ovatus, Mugil curema and Mugil cephalus) and compared them to fish from the Tema Newtown fishing market (Scomber colias, Pseudotolithus senegallus). Cobalt and lead concentrations, typical e-waste metals, were higher in fish from the Korle lagoon, even though they were of lower trophic level. Calculated risk indices revealed risk of elevated arsenic and mercury exposure, particularly through T. ovatus from the Korle lagoon, if consumed daily as it is common in the region. This study suggests the need of monitoring programs of Ghanaian catch, with a special focus in environmental risk areas like Korle lagoon to ensure human food safety.

Occupational exposures to particulate matter and PM2.5-associated polycyclic aromatic hydrocarbons at the Agbogbloshie waste recycling site in Ghana

Electronic waste (e-waste) disposal and recycling activities such as burning and smelting can emit particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and other pollutants that expose workers and nearby communities. At informal e-waste recycling facilities, both emission controls and protective measures for workers are absent. This study characterizes personal exposures (breathing zone) of PM and PAHs of e-waste workers at the large Agbogbloshie e-waste site in Accra, Ghana. We collected gravimetric and optical measurements of PM2.5 and PM10 using shift samples for workers and for an age- and gender-matched reference population. PM2.5 filters were analyzed for 26 PAHs using gas chromatography/mass spectroscopy. Among e-waste workers, PM2.5 and PM10 concentrations were 99 ± 56 and 218 ± 158 µg/m3 (median ± interquartile range, optical measurements), respectively; these levels were 78 and 57% higher, respectively, than levels measured at a fixed site that was centrally located at the waste site. In the reference community, breathing zone PM2.5 and PM10 levels were lower, 49 ± 20 and 131 ± 108 µg/m3, respectively, and the fraction of coarse PM was larger. We detected all 26 target PAHs, of which naphthalene and phenanthrene were the most abundant. PAH concentrations were weakly correlated to PM levels, but PAH abundances, representing the fraction of PAH mass to the total PM2.5 mass collected, were strongly and inversely correlated to PM levels, suggesting multiple and different sources of PAHs and PM that affected exposures. Both PM and PAH levels were elevated for workers performing burning and dismantling, and both exceeded standards or risk-based guidelines, e.g., lifetime excess cancer risks for several PAHs were in the 10−4 to 10−6 range, indicating the need to reduce emissions as well as provide respiratory protection. The study emphasizes the importance of using personal and shift samples to accurately characterize worker exposure.

Toxic chemicals from uncontrolled e-waste recycling: Exposure, body burden, health impact

Uncontrolled electronic-waste (e-waste) recycling processes have induced serious environmental pollution and human health impacts. This paper reviewed studies on the wide range of toxic chemicals through the use of primitive recycling techniques, their transfer to various ecological compartments, and subsequent health impacts. Results indicated that local food items were heavily polluted by the pollutants emitted, notably heavy metals in vegetables, rice, fish and seafood, and persistent organic pollutants (POPs) in livestock. Dietary exposure is the most important exposure pathway. The associations between exposure to e-waste and high body burdens of these pollutants were evident. It seems apparent that toxic chemicals emitted from e-waste activities are causing a number of major illnesses related to cardiovascular, digestive and respiratory systems, according to the information provided by a local hospital (Taizhou, an e-waste recycling hot spot in China). More epidemiological data should be made available to the general public. It is envisaged that there are potential dangers of toxic chemicals passing on to the next generation via placental transfer and lactation. There is a need to monitor the development and health impacts of infants and children, born and brought up in the e-waste sites.

Assessment of heavy metal contamination and health risk from indoor dust and air of informal E-waste recycling shops in Dhaka, Bangladesh

With the digital revolution across the world, including in low- and middle-income countries (LMICs) like Bangladesh, the global burden of electronic waste (e-waste) is increasing. Consequently, the environmental and human health implications of informal e-waste recycling practices in LMICs are becoming a cause for concern. Here we report the indoor dust and air contamination from e-waste derived heavy metals in the e-waste recycling shops in Dhaka, the capital of Bangladesh. Representative heavy metals including Pb, Cu, Ni, Cr, and Mn were measured in dust and air samples collected from three different e-waste shops located in two different sites in Dhaka. Concentrations of these heavy metals were found to be as much as orders of magnitude higher in the e-waste sites than in areas with no e-waste recycling activities. The geo-accumulation index (Igeo) calculated for these metals also indicated moderate to severe pollution of the e-waste shops, especially for Pb and Cu. The calculated health quotient (HQ) and hazard index (HI) for these metals indicate towards potential severe health risk of the workers due to the release and exposure to Pb from the e-wastes. These results emphasize the need for more direct evidence of contaminant exposure, body burden, and health impacts of the e-waste workers in Bangladesh, along with the need for interventions to ensure the health and safety of these workers.

Evaluation of heavy metal exposure pathways on children from an informal e-waste processing village in Viet Nam

Attempts were made to assess the contributions of different pathways of heavy metal exposure to the carcinogenic and non-carcinogenic risks based on the field samplings and questionnaire surveys of children residing in an informal e-waste processing village and a reference village in Viet Nam. The results showed that the ingestion of cooked rice contributed the most (69.20 − 99.60%), followed by the ingestion of soil (0.32 − 29.53%), to the environmental health risks of exposure to a mixture of Pb, Cd, Cr, Ni, and As in children from the two villages. Ingestion of drinking water and dermal contact of soil, however, contributed negligibly. It was found that the non-carcinogenic risk of each heavy metal from four pathways was less than 1, with Ni (0.48), As (0.44), Cd (0.23), Cr (0.19), and Pb (0.14), meaning these heavy metals are unlikely to cause an adverse non-carcinogenic risk to a child. It was also found that the carcinogenic risks for each heavy metal, except that for dermal contact of soil to children were higher than the benchmark value of 10−6 set by USEPA, indicating the likelihood of carcinogenic risks to children, especially to those aged 8 − 10 years. Children whose parents were engaging in e-waste processing activities and those who lived in a distance less than 10 m from an e-waste processing site sustained greater carcinogenic and non-carcinogenic risks.

Halogenated flame retardants in wild, prey-sized mud carp from an e-waste recycling site in South China, 2006–2016: Residue dynamics and ecological risk assessment

The crude e-waste recycling has been regulated in China since the late 2000s; however, information on the recent levels and the ecological risks of e-waste derived contaminants such as halogenated flame retardants (HFRs) in the e-waste sites are limited. We therefore examined the concentrations of several HFRs in wild, prey-sized mud carps collected from a typical e-waste site in 2006, 2011 and 2016, to understand the exposure dynamics and ecological risk of these chemicals. Several ecological and biological parameters including δ15N, δ13C, body size and lipid content of the fish were also examined, to ensure an overall uniformity of the sample set among the sampling years. Among the HFRs measured, polybrominated diphenyl ethers (PBDEs) were detected at the highest concentrations (contributing >90% to ∑HFRs), followed by Dechlorane Plus (DPs), polybrominated biphenyls (PBBs), and alternative brominated flame retardants (ABFRs). The fish concentrations of ∑PBDEs, ∑PBBs and ∑DPs significantly dropped by 65%, 57% and 53% from 2006 to 2011, and 12%, 74% and 51% from 2011 to 2016, respectively; likely reflecting the positive impact of the environmental regulations on crude e-waste recycling. The ∑ABFRs concentrations were also decreased by 80% from 2006 to 2011, but increased by 127% from 2011 to 2016; suggesting possible fresh input of these novel HFRs in recent years. In addition to the changes in the HFR concentrations, contaminant profiles in the fish were also changed, possibly due to environmental degradation of the HFRs. Despite our conservative method of risk assessment, we found that PBDEs posed an important risk both for the mud carp and for piscivorous wildlife that inhabit the e-waste site.

Effects of Electronic and Electrical Waste-Contaminated Soils on Growth and Reproduction of Earthworm (Alma nilotica).

Informal recycling of electronic waste (e-waste) contaminates local environments with metals and other organic compounds. The adverse effects on native earthworm populations are poorly understood. The objective of the present study was to determine metal concentrations in soils from e-waste activity sites in Douala (Cameroon) and assess the effects of these soils on the growth and reproduction of the local earthworm, Alma nilotica. Concentrations of nine metals (arsenic [As], cadmium [Cd], cobalt [Co], chromium [Cr], copper [Cu], mercury [Hg], nickel [Ni], lead [Pb], and zinc [Zn]) were measured in soil samples collected from eight e-waste activity and two non-e-waste sites. Earthworms were then exposed to these soils in the laboratory following test guidelines of the Organisation for Economic Co-operation and Development. Metal concentrations in the e-waste-contaminated soils were significantly higher than in the non-e-waste soils. The e-waste soils were found to have a different soil metal profile (Cu > Pb > Zn > Cr > Ni > Co > As > Cd > Hg) from that of the non-e-waste soils (Zn > Cr > Cu > Pb > Ni > As > Cd > Co > Hg). Earthworm growth and reproduction were significantly inhibited in organisms exposed to soils from e-waste sites. Reproduction was particularly affected, with a mean of 8 ± 5.6 offspring/10 worms in the e-waste-exposed worm groups compared with 90.5 ± 0.7 in non-e-waste soil worms. Notably, earthworm growth recovered during depuration in clean soil, indicating the possibility of remediation activities. The results demonstrate that soils at e-waste sites can affect the health of resident worm populations, which may be more sensitive than temperate species. They also highlight the potential of a bioassay-based approach in monitoring risks at e-waste sites. Environ Toxicol Chem 2022;41:287-297. © 2021 SETAC.

Mixed bromine/chlorine transformation products of tetrabromobisphenol A: Potential specific molecular markers in e-waste dismantling areas

Mixed bromine/chlorine transformation products (ClyBrxBPAs) of tetrabromobisphenol A (TBBPA) were recently identified for the first time in an electronic waste (e-waste) dismantling site. To determine whether these compounds can be used as specific molecular markers of e-waste dismantling activities, the environmental occurrences and distributions of TBBPA and its transformation products including debromination products (BrxBPAs) and ClyBrxBPAs were analyzed in soil samples from three sites in China: Guiyu (an e-waste site), Qingyuan (a former e-waste site now mainly used for old wire and cable recycling), and Shouguang (a flame retardant production base). Levels of the target analytes in Guiyu were significantly higher than in Qingyuan and Shouguang. BrxBPAs and ClyBrxBPAs were widely detected in Guiyu at concentrations between 1 and 4 orders of magnitude lower than their parent compound TBBPA. The highest concentration was found in an e-waste dismantling park, with lower concentrations in surrounding area. The levels of ClyBrxBPAs in Qingyuan were much lower, indicating that the ClyBrxBPAs may come from the processing of wires and cables, but not rule out the incubation on their own in soils. None of ClyBrxBPAs were detected in Shouguang. ClyBrxBPAs may thus be useful as specific molecular markers for determining the intensity of e-waste dismantling activities.

Assessment of heavy metals concentration in soils and plants from electronic waste dumpsites in Lagos metropolis.

E-waste is a global environmental problem that must not be underestimated. To ascertain the environmental pollution status of electronic waste dumpsites, an assessment of seasonal variation in concentrations of heavy metals in the soils and plants in electronic waste dumpsites in Lagos metropolis was undertaken during the two major seasons (wet and dry seasons) in Nigeria. The soils and plants samples collected in August during the rainy season and December during the dry season were digested using aqua regia, a wet digestion method. The heavy metal concentrations were quantified with flame atomic absorption spectrophotometer (FAAS) fitted with a hollow cathode lamp (Perkin-Elmer AA Analyst 200) using an air-acetylene flame. The soil samples and the plants analyzed were found to have high concentrations of heavy metals. All the plants analyzed were identified and classified as excluders and accumulators of heavy metals based on their shoot/root quotients. The results obtained experimentally were analyzed using statistical and multivariate techniques. The soil quality of the study area was evaluated using correlation factor, pollution load index, and geoaccumulation index. The heavy metal assessment in comparison with the EU and Canadian standards for both agricultural and residential soils showed that the e-waste dumping sites are highly polluted. The results obtained for both the soil and plants analyzed confirmed the great impact of the hazardous components of e-waste on the ecosystem.

E-Waste in Africa: A Serious Threat to the Health of Children.

Waste electronic and electrical equipment (e-waste) consists of used and discarded electrical and electronic items ranging from refrigerators to cell phones and printed circuit boards. It is frequently moved from developed countries to developing countries where it is dismantled for valuable metals in informal settings, resulting in significant human exposure to toxic substances. E-waste is a major concern in Africa, with large sites in Ghana and Nigeria where imported e-waste is dismantled under unsafe conditions. However, as in many developing countries, used electronic and electrical devices are imported in large quantities because they are in great demand and are less expensive than new ones. Many of these used products are irreparable and are discarded with other solid waste to local landfills. These items are then often scavenged for the purpose of extracting valuable metals by heating and burning, incubating in acids and other methods. These activities pose significant health risks to workers and residents in communities near recycling sites. E-waste burning and dismantling activities are frequently undertaken at e-waste sites, often in or near homes. As a result, children and people living in the surrounding areas are exposed, even if they are not directly involved in the recycling. While toxic substances are dangerous to individuals at any age, children are more vulnerable as they are going through important developmental processes, and some adverse health impacts may have long-term impacts. We review the e-waste situation in Africa with a focus on threats to children’s health.

The changes of essential trace elements in residents from an e-waste site and the relationships between elements and hormones of the hypothalamic-pituitary-thyroid (HPT) axis

The heavy metals pollution and related health issues were widely reported in e-waste sites, while the impacts of e-waste exposure on the essential trace elements have been neglected. The aim of this study was focused on the internal Cu, Fe, Mn and Zn levels in the residents from an e-waste site and the potential endocrine disrupting effects of these essential trace elements on the hypothalamic-pituitary-thyroid (HPT) axis. This was a cross-sectional study that 87 subjects were recruited from the e-waste site and 81 from the reference site. The results indicated that the e-waste exposed group had significantly lower Fe, Mn level when compared with the reference group (p < 0.05). Cu and Zn were also lower in the exposed group but the differences were not statistically significant. The exposed group had significantly higher TSH level and Fe was significantly associated with TSH in the females (β (95% CI): − 1.892 (−3.309, −0.475), p = 0.009), rather than in males or all subjects. The exposed group also showed oxidative stress which was indicated by the increased concentrations of MDA and 8-iso-PG. It was further indicated the elevated MDA was mediated by the increase of TSH in the females but not directly related to Fe. In conclusion, the e-waste exposed group showed a decrease of essential trace elements, an increase of TSH and oxidative stress. The decreased Fe was related to the elevated TSH in the females, which further indirectly mediated the increase of oxidative stress. The results suggested that the internal exposure levels and the potential health effects of the essential trace elements in populations from e-waste sites should be of more concern. And the women might be more vulnerable and they need more protection to against the adverse health effects from e-waste.

Strategies of cadmium and copper uptake and translocation in different plant species growing near an E-waste dismantling site at Wenling, China.

This study aimed to explore the interactions between cadmium (Cd) and copper (Cu) during uptake and translocation in plants growing in soil polluted with heavy metals derived from electronic waste (E-waste). We collected the roots, stems, leaves, and root-surrounding soils of ten dominant plant species growing in farmland near an E-waste dismantling site, and analyzed their Cd and Cu concentrations. Among the ten plant species, Echinochloa crus-galli (L.) P. Beauv., Cucurbita moschata (Duch. ex Lam.) Duch. ex Poiret, Phragmites australis (Cav.) Trin. ex Steud., and Benincasa hispida (Thunb.) Cogn. accumulated Cd (2.40-4.56 mg kg-1) and Cu (19.60-35.21 mg kg-1) in the roots. In Polygonum hydropiper L. and Sesbania cannabina (Retz.) Poir., the Cd (0.50-0.81 mg kg-1) and Cu (11.04-15.55 mg kg-1) concentrations were similar among the three organs. Glycine max (L.) Merr. accumulated more Cu in the roots (16.42 mg kg-1) than in the stems (5.61 mg kg-1) and leaves (7.75 mg kg-1), and accumulated Cd at similar levels in the three organs (0.65-0.99 mg kg-1). Sesamum indicum L., Bidens pilosa L., and Solidago decurrens Lour. accumulated Cd at similar levels among the three organs (0.16-3.34 mg kg-1) and accumulated less Cu in the stems (6.89-8.28 mg kg-1) than in the roots (12.61-21.63 mg kg-1) and leaves (12.93-22.38 mg kg-1). S. indicum had a stronger capacity to accumulate and translocate Cd and Cu according to transfer coefficient and translocation factor. The concentrations of Cd and Cu in soils were significantly positively correlated with those in the roots (p<0.01) but not those in the stems and leaves. We detected significantly positive correlations between Cd and Cu concentrations in the roots and leaves (p<0.01) but not in the stems. These results suggest that there is a synergetic strategy of Cd and Cu transport from soils to the roots and from the roots to the leaves, while the stems may not be the key organ controlling Cd and Cu transport in plants. These findings have important implications for the phytoremediation of soils contaminated with Cd and Cu, the mechanisms of plant Cd and Cu transport, and the food safety of agricultural products.

Airborne volatile organic compounds at an e-waste site in Ghana: Source apportionment, exposure and health risks

Informal e-waste recycling processes emit various air pollutants. While there are a number of pollutants of concern, little information exists on volatile organic compounds (VOCs) releases at e-waste sites. To assess occupational exposures and estimate health risks, we measured VOC levels at the Agbogbloshie e-waste site in Ghana, the largest e-waste site in Africa, by collecting both fixed-site and personal samples for analyzing a wide range of VOCs. A total of 54 VOCs were detected, dominated by aliphatic and aromatic compounds. Mean and median concentrations of the total target VOCs were 46 and 37 μg/m3 at the fixed sites, and 485 and 162 μg/m3 for the personal samples. Mean and median hazard ratios were 2.1 and 1.4, respectively, and cancer risks were 4.6 × 10-4 and 1.5 × 10-4. These risks were predominantly driven by naphthalene and benzene; chloroform and formaldehyde were also high in some samples. Based on the VOC composition, the major sources were industry, fuel evaporation and combustion. The concentration gradient across sites and the similarity of VOC profiles indicated that the e-waste site emissions reached neighboring communities. Our results suggest the need to protect e-waste workers from VOC exposure, and to limit emissions that can expose nearby populations.