Effects of PCBs and PBDEs on thyroid hormone, lymphocyte proliferation, hematology and kidney injury markers in residents of an e-waste dismantling area in Zhejiang, China

E-waste: mechanisms of toxicity and safety testing

Currently, information on the toxicity profile of the majority of the identified e-waste chemicals, while extensive and growing, is admittedly fragmentary, particularly at the cellular and molecular levels. Furthermore, the toxicity of the chemical mixtures likely to be encountered by humans during and after informal e-waste recycling, as well as their underlying mechanisms of action, is largely unknown. This review paper summarizes state-of-the-art knowledge of the potential underlying toxicity mechanisms associated with e-waste exposures, with a focus on toxic responses connected to specific organs, organ systems, and overall effects on the organism. To overcome the complexities associated with assessing the possible adverse outcomes from exposure to chemicals, a growing number of new approach methodologies have emerged in recent years, with the long-term objective of providing a human-based and animal-free system that is scientifically superior to animal testing, more effective, and acceptable. This encompasses a variety of techniques, typically regarded as alternative approaches for determining chemical-induced toxicities and holds greater promise for a better understanding of key events in the metabolic pathways that mediate known adverse health outcomes in e-waste exposure scenarios. This is crucial to establishing accurate scientific knowledge on mixed e-waste chemical exposures in shorter time frames and with greater efficacy, as well as supporting the need for safe management of hazardous chemicals. The present review paper discusses important gaps in knowledge and shows promising directions for mechanistically anchored effect-based monitoring strategies that will contribute to the advancement of the methods currently used in characterizing and monitoring e-waste-impacted ecosystems.

A Review of the Association between Exposure to Flame Retardants and Thyroid Function

Flame retardants have been shown to cause widespread physiological effects, in particular on endocrine organs such as the thyroid. This review aims to provide an overview of the literature on the association between flame retardants and thyroid function within humans. A search in the National Library of Medicine and National Institutes of Health PubMed database through January 2024 yielded 61 studies that met the inclusion criteria. The most frequently analyzed flame retardants across all thyroid hormones were polybrominated diphenyl ethers (PBDEs), in particular BDE-47 and BDE-99. Ten studies demonstrated exclusively positive associations between flame retardants and thyroid stimulating hormone (TSH). Six studies demonstrated exclusively negative associations between flame retardants and TSH. Twelve studies demonstrated exclusively positive associations for total triiodothyronine (tT3) and total thyroxine (tT4). Five and eight studies demonstrated exclusively negative associations between flame retardants and these same thyroid hormones, respectively. The effect of flame retardants on thyroid hormones is heterogeneous; however, the long-term impact warrants further investigation. Vulnerable populations, including indigenous people, individuals working at e-waste sites, firefighters, and individuals within certain age groups, such as children and elderly, are especially critical to be informed of risk of exposure.

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.

In vivo exposure to electronic waste (e-waste) leachate and hydraulic fracturing fluid adversely impacts the male reproductive system

Human health effects can arise from unregulated manual disassembly of electronic waste (e-waste) and/or hydraulic fracturing fluid spills. There is limited literature on the effects of e-waste and hydraulic fracturing wastewater exposure on the male reproductive system. Thus, this proof-of-concept study begins to address the question of how wastewater from two potentially hazardous environmental processes could affect sperm quality. Therefore, three groups of eight-week-old adult mice were exposed (5 d/wk for 6 wks) via a mealworm (Tenebrio molitor and Zophabas morio) feeding route to either: (1) e-waste leachate (50% dilution) from the Alaba Market (Lagos, Nigeria); (2) West Virginia hydraulic fracturing flowback (HFF) fluid (50% dilution); or, (3) deionized water (control). At 24-hours (hr), 3 weeks (wk), or 9-wk following the 6-wk exposure period, cohorts of mice were necropsied and adverse effects/persistence on the male reproductive system were examined. Ingestion of e-waste leachate or HFF fluid decreased number and concentration of sperm and increased both chromatin damage and numbers of morphological abnormalities in the sperm when compared to control mice. Levels of serum testosterone were reduced post-exposure (3- and 9-wk) in mice exposed to e-waste leachate and HFF when compared to time-matched controls, indicating the long-term persistence of adverse effects, well after the end of exposure. These data suggest that men living around or working in vicinity of either e-waste or hydraulic fracturing could face harmful effects to their reproductive health. From both a human health and economic standpoint, development of prevention and intervention strategies that are culturally relevant and economically sensitive are critically needed to reduce exposure to e-waste and HFF-associated toxic contaminants.

Effects of Benzo (a) Pyrene and 2,2',4,4'-Tetrabromodiphenyl Ether Exposure on the Thyroid Gland in Rats by Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy

Benzo[a]pyrene (B[a]P) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are widespread environmental pollutants and can destroy thyroid function. We assessed the biochemical changes in the thyroid tissue of rats exposed to B[a]P and BDE-47 using attenuated total reflection Fourier-transform infrared spectroscopy combined with support vector machine(SVM). After B[a]P and BDE-47 treatment in rats, the structure of thyroid follicles was destroyed and epithelial cells were necrotic, indicating that B[a]P and BDE-47 may lead to changes of the thyroid morphology of the rats. These damages are mainly related to C=O stretch vibrations of lipids (1743 cm-1), as well as the secondary structure of proteins [amide I (1645 cm-1) and amide II (1550 cm-1)], and carbohydrates [C-OH (1138 cm-1), C-O (1106 cm-1, 1049 cm-1, 991 cm-1), C-C (1106 cm-1) stretching] and collagen (phosphodiester stretching at 922 cm-1) vibration modes. When SVM was used for classification, there was a substantial separation between the control and the exposure groups (accuracy = 96%; sensitivity = 98%; specificity = 87%), and there was also a major separation between the exposed groups (accuracy = 93%; sensitivity = 94%; and specificity = 92%).

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Toxic ties: Unraveling the complex relationship between endocrine disrupting chemicals and chronic kidney disease

Environmental pollution is inherently linked to several metabolic diseases and high mortality. The kidney is more susceptible to environmental pollutants compared to other organs as it is involved in concentrating and filtering most of these toxins. Few epidemiological studies revealed the intrinsic relationship between exposure to Endocrine Disrupting Chemicals (EDCs) and CKD development. Though EDCs have the potential to cause severe pathologies, the specific molecular mechanisms by which they accelerate the progression of CKD remain elusive. In particular, our understanding of how pollutants affect the progression of chronic kidney disease (CKD) through the gut-kidney axis is currently limited. EDCs modulate the composition and function of the gut microbial community and favor the colonization of harmful gut pathogens. This alteration leads to an overproduction of uremic toxin and membrane vesicles. These vesicles carry several inflammatory molecules that exacerbate inflammation and renal tissue damage and aggravate the progression of CKD. Several experimental studies have revealed potential pathways by which uremic toxin further aggravates CKD. These include the induction of membrane vesicle production in host cells, which can trigger inflammatory pathways and insulin resistance. Reciprocally, CKD can also modulate gut bacterial composition that might further aggravate CKD condition. Thus, EDCs pose a significant threat to kidney health and the global CKD burden. Understanding this complicated issue necessitates multidisciplinary initiatives such as strict environmental controls, public awareness, and the development of novel therapeutic strategies targeting EDCs.

A mechanistic and kinetic investigation on the oxidative thermal decomposition of decabromodiphenyl ether

The thermal processes of materials containing decabromodiphenyl ether (BDE-209) normally result in the exposure of BDE-209 to high-temperature environments, generating a series of hazardous compounds. However, the evolution mechanisms of BDE-209 during oxidative thermal processes remain unclear. Thus, this paper presents a detailed investigation on the oxidative thermal decomposition mechanism of BDE-209 by utilizing density functional theory methods at the M06/cc-pVDZ theoretical level. The results show that the barrierless fission of the ether linkage dominates the initial degradation of BDE-209 at all temperatures, with branching ratio over 80%. The decomposition of BDE-209 in oxidative thermal processes is mainly along BDE-209 → pentabromophenyl and pentabromophenoxy radicals → pentabromocyclopentadienyl radicals → brominated aliphatic products. Additionally, the study results on the formation mechanisms of several hazardous pollutants indicate that the ortho-phenyl-type radicals created by ortho-C-Br bond fission (branching ratio reached 15.1% at 1600 K) can easily be converted into octabrominated dibenzo-p-dioxin and furan, which require overcoming the energy barriers of 99.0 and 48.2 kJ/mol, respectively. The O/ortho-C coupling of two pentabromophenoxy radicals also acts as a non-negligible pathway for the formation of octabrominated dibenzo-p-dioxin. The synthesis of octabromonaphthalene involves the self-condensation of pentabromocyclopentadienyl radicals, followed by an intricately intramolecular evolution. Results presented in this study can enhance our understanding of the transformation mechanism of BDE-209 in thermal processes, and offer an insight into controlling the emissions of hazardous pollutants.

Regional variation of polybrominated diphenyl ethers in East Asian finless porpoises in the East China Sea

Certain polybrominated diphenyl ethers (PBDEs) have been banned for years, however, they still possess the potential to harm marine cetaceans. In this study, 56 East Asian finless porpoises (EAFPs) collected from three locations of the East China Sea between 2009 and 2011, were analyzed to determine the presence of typical PBDE congeners. Among all the samples, BDE47 was the main congener, constituting ∼48.3 % of the ΣPBDEs. Significant variations (p < 0.01) in PBDE abundance were observed among different regions (Pingtan: 172.8 ng/g, Lvsi: 61.2 ng/g and Ningbo: 32.9 ng/g). In addition, there was a significant positive correlation between PBDE abundance and male body length. The general ΣPBDEs concentration of this population was lower compared to other populations and cetaceans. Although combined risk assessments indicated a low risk to porpoise health, long-term surveillance is essential as PBDEs are not completely banned.

Individual and mixtures of polychlorinated biphenyls and organochlorine pesticides exposure in relation to metabolic syndrome among Chinese adults

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are commonly detected in humans due to their persistence and bioaccumulation, and are suspected risk factors for metabolic syndrome (MetS). However, most studies have focused on individual rather than combined exposure. We explored the associations between individual and combined PCBs/OCPs exposure and MetS to better assess the health effects of PCBs and OCPs. This cross-sectional study included 1996 adults from Wuhan, China. A total of 338 participants fulfilled criteria for MetS. Eight PCBs and OCPs were detected in >50 % of the samples. Most of the hexachlorocyclohexanes (HCHs) in the serum were derived from the recent environmental input of lindane, while the high levels of dichlorodiphenyltrichloroethane (DDTs) were mainly due to historical use. Multivariate linear regression analyses revealed that β-HCH, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), PCB-52, PCB-153, and PCB-180 were positively correlated with increased odds of MetS. The profiles of the PCBs and OCPs associated with the different components of MetS were distinct. Furthermore, quantile-based g computation (qgcomp) analyses showed that PCB and OCP mixtures were positively associated with the risk of MetS, and p,p'-DDE was the largest contributor to our model. These findings suggest that PCB and OCP concentrations, both individually and as mixtures, are associated with MetS risk. Prospective studies are needed to confirm these results.

Associations between serum polychlorinated biphenyls, halogen flame retardants, and renal function indexes in residents of an e-waste recycling area

E-waste handling activities release large quantities of polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) into the surrounding area, creating a high exposure risk for local residents. However, the possibility of PCBs and HFRs exposure contributing to renal injury has not been extensively studied. To fill this knowledge gap, we conducted an epidemiological analysis of adolescents and adults recruited from an e-waste recycling area and a control area. Some PCBs and HFRs compounds were statistically significantly associated with the levels of β₂-microglobulin (β₂-MG), blood urea nitrogen (BUN), serum creatinine (SCr), and uric acid, with thyroid hormone-related genes found to partly mediate these associations. The interactions of PCBs and HFRs with metals also influenced renal function indexes. Exposure to high concentrations of PCBs and HFRs resulted in higher levels of β₂-MG and lower levels of BUN and SCr in the exposed group. As indicated by the elevated β₂-MG levels, high exposure to PCBs and HFRs may increase the risk of early renal injury for adolescents. These findings help to clarify the impacts of PCBs and HFRs on renal function and highlight the need to protect the health of residents in regions impacted by e-waste handling activities.

The Relationship between Typical Environmental Endocrine Disruptors and Kidney Disease

Endocrine disrupting chemicals (EDCs) are exogenous substances that alter the endocrine function of an organism, to result in adverse effects on growth and development, metabolism, and reproductive function. The kidney is one of the most important organs in the urinary system and an accumulation point. Studies have shown that EDCs can cause proteinuria, affect glomeruli and renal tubules, and even lead to diabetes and renal fibrosis in animal and human studies. In this review, we discuss renal accumulation of select EDCs such as dioxins, per- and polyfluoroalkyl substances (PFAS), bisphenol A (BPA), and phthalates, and delineate how exposures to such EDCs cause renal lesions and diseases, including cancer. The regulation of typical EDCs with specific target genes and the activation of related pathways are summarized.

Accumulative levels, temporal and spatial distribution of common chemical pollutants in the blood of Chinese adults

China has been in a rapid development period in recent decades, the mass production and use of chemical industrial products and pesticides have resulted in a large amount of pollutants in the environment. These pollutants enter the human body through environmental exposure and dietary intake, causing adverse health effects. Although many of them have been banned and restricted in the production and use in China, these pollutants still remain in the human body due to their high persistence and strong bioaccumulation. In this review, we aim to reveal the accumulation levels and profiles, as well as the temporal and spatial distribution of common chemical pollutants including chlorinated paraffins (CPs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers, organophosphorus flame retardants (OPFRs), new halogenated flame retardants (NHFRs), polychlorinated biphenyls, phthalic acid esters, perfluorinated compounds, bisphenols, organophosphorus pesticides and pyrethroid insecticides in the blood (including whole blood, serum and plasma) of Chinese adults by extracting 93 related studies published from 1990 to 2021. Results have shown that CPs, OCPs and PAHs were the main pollutants in China, the levels of short-chain chlorinated paraffin, p,p'-DDE and phenanthrene in blood even reached 11,060.58, 740.41 and 498.28 ng/g lipid respectively. Under the strict control of pollutants in China, the levels of most pollutants have been on a downward trend except for perfluoro octanoate and perfluoro nonanoate. Besides, OPFRs, NHFRs and PAHs may have a potential upward trend, requiring further research and observation. As for spatial distribution, East China (Bohai Bay and Yangtze River Delta) and South China (Pearl River Delta) were the major polluted regions due to their fast development of industry and agriculture.

Network Toxicology Guided Mechanism Study on the Association between Thyroid Function and Exposures to Polychlorinated Biphenyls Mixture

Polychlorinated biphenyls (PCBs) are persistent and highly toxic pollutants, which can accumulate in organisms and produce toxic effects, especially damaging the function of thyroid hormones. So far, the molecular mechanism of PCBs mixture and their metabolites interfering with thyroid hormones has not been studied thoroughly except for individual compounds. In this study, PubMed, Web of Science, and STITCH databases were used to search PCBs and their corresponding target proteins. The intersection of PCBs and thyroid hormone dysfunction target proteins was obtained from GeneCards. The “compounds-targets-pathways” network was constructed by Cytoscape software. And KEGG and Go analyses were performed for key targets. Finally, molecular docking was used to verify the binding effect. Four major active components, five key targets, and 10 kernel pathways were successfully screened by constructing the network. Functional enrichment analysis showed that the interference was mediated by cancer, proteoglycans, PI3K-Akt, thyroid hormone, and FoxO signaling pathways. The molecular docking results showed that the binding energies were less than -5 kcal·mol-1. PCBs and their metabolites may act on the key targets of MAPK3, MAPK1, RXRA, PIK3R1, and TP53. The toxic effect of sulfated and methyl sulfone PCBs is greater. The method of screening targets based on the simultaneous action of multiple PCBs can provide a reference for other research. The targets were not found in previous metabolite toxicity studies. It also provides a bridge for the toxic effects and experimental research of PCBs and their metabolites in the future.

Transcriptomics-based analysis of co-exposure of cadmium (Cd) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) indicates mitochondrial dysfunction induces NLRP3 inflammasome and inflammatory cell death in renal tubular epithelial cells

Environmental pollution often releases multiple contaminants resulting in as yet largely uncharacterized additive toxicities. Cadmium (Cd) is a widespread pollutant that induces nephrotoxicity in animal models and humans. However, the combined effect of Cd in causing nephrotoxicity with 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a typical congener of polybrominated diphenyl ethers (PBDEs), has not been evaluated and mechanisms are not completely clear. Here, we applied transcriptome sequencing analysis to investigate the combined toxicity of Cd and BDE-47 in the renal tubular epithelial cell lines HKCs. Cd or BDE-47 exposure decreased cell viability in a dose-dependent manner, and exhibited cell swelling and rounding similar to necrosis, which was exacerbated by co-exposure. Transcriptomic analysis revealed 2191, 1331 and 3787 differentially-expressed genes following treatment with Cd, BDE-47 and co-exposure, respectively. Interestingly, functional annotation and enrichment analyses showed involvement of pathways for oxidative stress, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and inflammatory cell death for all three treatments. Examination of indices of mitochondrial function and oxidative stress in HKC cells showed that the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and intracellular calcium ion concentration [Ca²⁺]i were elevated, while superoxide dismutase (SOD) and mitochondrial membrane potential (MMP) were decreased. The ratio of apoptotic and necrotic cells and intracellular lactate dehydrogenase (LDH) release were increased by Cd or BDE-47 exposure, and was aggravated by co-exposure, and was attenuated by ROS scavenger N-Acetyl-L-cysteine (NAC). NLRP3 inflammasome and pyroptosis pathway-related genes of NLRP3, adaptor molecule apoptosis-associated speck-like protein (ASC), caspase-1, interleukin-18 (IL-18) and IL-1β were elevated, while gasdermin D (GSDMD) was down-regulated, and protein levels of NLRP3, cleaved caspase-1 and cleaved GSDMD were increased, most of which were relieved by NAC. Our data demonstrate that exposure to Cd and BDE-47 induces mitochondrial dysfunction and triggers NLRP3 inflammasome and GSDMD-dependent pyroptosis leading to nephrotoxicity, and co-exposure exacerbates this effect, which could be attenuated by inhibiting ROS. This study provides a further mechanistic understanding of kidney damage, and co-exposure impact is worthy of concern and should be considered to improve the accuracy of environmental health assessment.

Effects of Polybrominated Diphenyl Ethers on Hormonal and Reproductive Health in E-Waste-Exposed Population: A Systematic Review

Electronic waste management is a global rising concern that is primarily being handled by informal recycling practices. These release a mix of potentially hazardous chemicals, which is an important public health concern. These chemicals include polybrominated diphenyl ethers (PBDEs), used as flame retardants in electronic parts, which are persistent in nature and show bioaccumulative characteristics. Although PBDEs are suspected endocrine disruptors, particularly targeting thyroid and reproductive hormone functions, the relationship of PBDEs with these health effects are not well established. We used the Navigation Guide methodology to conduct a systematic review of studies in populations exposed to e-waste to better understand the relationships of these persistent flame retardants with hormonal and reproductive health. We assessed nineteen studies that fit our pre-determined inclusion criteria for risk of bias, indirectness, inconsistency, imprecision, and other criteria that helped rate the overall evidence for its quality and strength of evidence. The studies suggest PBDEs may have an adverse effect on thyroid hormones, reproductive hormones, semen quality, and neonatal health. However, more research is required to establish a relationship of these effects in the e-waste-exposed population. We identified the limitations of the data available and made recommendations for future scientific work.

Composition changes, releases, and potential exposure risk of PBDEs from typical E-waste plastics

Since Stockholm Convention listed polybrominated diphenyl ethers (PBDEs) as persistent organic pollutants and banned their addition, alternative halogen flame retardants (AHFRs) have been substituted for PBDEs. This study systematically investigates the change trends of PBDEs and AHFRs from typical e-waste plastics and dust, as well as clarifying human exposure risks of PBDEs in formal and informal e-waste recycling enterprises, repair store and residential building. The results show that the PBDEs levels in five typical types of e-waste vary in the range of 1.08 × 10^-3-30.8 μg/g, meeting the requirements of RoHS regulation. Compared with the residential buildings (1.49-1.68 μg/g), PBDEs in the dust from the formal and informal e-waste recycling enterprises are much higher, ranging from 4.70 to 536 μg/g. BDE-209 is the main congener in most e-waste plastic and dust samples. Meanwhile, AHFRs have become the important composition (3.5-61.5%) in e-waste plastics, while its contribution is lower in dust, implying the higher enrichment efficiency of PBDEs. For PBDEs exposure, the dust intake risk of PBDEs is much higher than skin contact for the workers, and the highest hazard quotient (HQ) value (1.40 × 10^-1) and cancer risk (CR) value (1.21 × 10^-7) both imply safe exposure levels.

Polychlorinated naphthalene concentrations in human serum caused by unintentional production and emissions, and potential effects of polychlorinated naphthalenes on thyroid hormones

The concentrations of 75 polychlorinated naphthalene (PCN) congeners in 95 human serum samples from the Fengjiang electronic waste dismantling area and Huangyan District in Taizhou City (Zhejiang Province, China) were determined. Thyroid hormone (FT3, FT4, TSH, and TRH) concentrations in the samples were also determined. The total PCN concentrations in the samples from Fengjiang and Huangyan were 1.29 × 10⁴-4.28 × 10⁵ and 8.29 × 10²-6.45 × 10⁵ pg/g lipid, respectively. The less-chlorinated (Cl_1-3) PCN concentrations were relatively high in all of the samples, and the concentrations in the samples from the two areas were not significantly different. The sums of the combustion-related PCN congener concentrations were significantly higher in the samples from Fengjiang than in the samples from Huangyan, and the sums of the more-chlorinated (Cl_4-8) PCNs were slightly higher in the samples from Fengjiang than in the samples from Huangyan. The relationship between the PCN concentration and age indicated that electronic waste controls have decreased human exposure to PCNs but that attention should still be paid to exposure to less-chlorinated PCNs. The main PCN congeners that contributed to the toxic equivalent concentrations were markedly different for the samples from Fengjiang and Huangyan. CN-66/67 was dominant for the Fengjiang samples and CN-10 was dominant for the Huangyan samples. Attention should be paid to the risks posed by less-chlorinated PCNs to human health. CN-1, CN-2, and CN-20 concentrations are related to human thyroid hormone levels, and the relationships between less-chlorinated PCN concentrations and thyroid hormone concentrations should be further studied.

Forty years studies on polychlorinated biphenyls pollution, food safety, health risk, and human health in an e-waste recycling area from Taizhou city, China: a review

E-waste generation has become a serious environmental challenge worldwide. Taizhou of Zhejiang Province, situated on the southeast coastline of China, has been one of the major e-waste dismantling areas in China for the last 40 years. In this review, we focused on the polychlorinated biphenyl (PCB) trends in environmental compartments, burden and impact to humans, food safety, and health risk assessment from Taizhou, China. The review suggested that PCBs showed dynamic trends in air, soil, water, biodiversity, and sediments. Soils and fish samples indicated higher levels of PCBs than sediments, air, water, and food items. PCB levels decreased in soils with the passage of time. Agriculture soils near the e-waste recycling sites showed more levels of total PCBs than industrial soils and urban soils. Dioxin-like PCB levels were higher in humans near Taizhou, suggesting that e-waste pollution could influence humans. Compared with large-scale plants, simple household workshops contributed more pollution of PCBs to the environment. Pollution index, hazard quotient, and daily intake were higher for PCBs, suggesting Taizhou should be given priority to manage the e-waste pollution. The elevated body burden may have health implications for the next generation. The areas with stricter control measures, strengthened laws and regulations, and more environmentally friendly techniques indicated reduced levels of PCBs. For environment protection and health safety, proper e-waste dismantling techniques, environmentally sound management, awareness, and regular monitoring are very important.

Health consequences of exposure to e-waste: an updated systematic review

Electronic waste (e-waste) contains numerous chemicals harmful to human and ecological health. To update a 2013 review assessing adverse human health consequences of exposure to e-waste, we systematically reviewed studies reporting effects on humans related to e-waste exposure. We searched EMBASE, PsycNET, Web of Science, CINAHL, and PubMed for articles published between Dec 18, 2012, and Jan 28, 2020, restricting our search to publications in English. Of the 5645 records identified, we included 70 studies that met the preset criteria. People living in e-waste exposed regions had significantly elevated levels of heavy metals and persistent organic pollutants. Children and pregnant women were especially susceptible during the critical periods of exposure that detrimentally affect diverse biological systems and organs. Elevated toxic chemicals negatively impact on neonatal growth indices and hormone level alterations in e-waste exposed populations. We recorded possible connections between chronic exposure to e-waste and DNA lesions, telomere attrition, inhibited vaccine responsiveness, elevated oxidative stress, and altered immune function. The existence of various toxic chemicals in e-waste recycling areas impose plausible adverse health outcomes. Novel cost-effective methods for safe recycling operations need to be employed in e-waste sites to ensure the health and safety of vulnerable populations.

Acceleration of polychlorinated biphenyls remediation in soil via sewage sludge amendment

Bioremediation of polychlorinated biphenyls (PCBs) is impeded by difficulties in massively cultivating bioinoculant. Meanwhile, sewage sludge is rich in pollutant-degrading microorganisms and nutrients, drawing our attention to investigate their potential to be used as a supplement for bioremediation of PCBs. Here we reported extensive microbial reductive dechlorination of PCBs by waste activated sludge (WAS) and digestion sludge (DS), which were identified to harbor multiple putative organohalide-respiring bacteria (i.e., Dehalococcoides, Dehalogenimonas, Dehalobacter, and uncultivated Dehalococcoidia) and PCB reductive dehalogenase genes (i.e., pcbA4 and pcbA5). Consequently, amendment of 1-20% (w/w) fresh WAS/DS enhanced the attenuation of PCBs by 126-544% in a soil microcosm compared with the control soil, with the fastest dechlorination of PCBs being achieved when spiked with 20% fresh WAS. Notably, dechlorination pathways of PCBs were also changed by sludge amendment. Microbial and physicochemical analyses revealed that the enhanced dechlorination of PCBs by sludge amendment was largely attributed to the synergistic effects of sludge-derived nutrients, PCB-dechlorinating bacteria, and stimulated growth of beneficial microorganisms (e.g., fermenters). Finally, risk assessment of heavy metals suggests low potential ecological risks of sludge amendment in soil. Collectively, our study demonstrates that sewage sludge amendment could be an efficient, cost-effective and environment-friendly approach for in situ bioremediation of PCBs.

Polybrominated diphenyl ethers in the environment: a wake-up call for concerted action in India

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants (POPs) used as flame retardants in the products utilized in day-to-day life. Their bioaccumulation, low volatility, and high persistence in the environment have led to their global spread even to remote and distant regions. The present study identifies gaps in the investigation of the neurotoxic potential of PBDEs, their effects on brain development, toxicokinetic, and their potential as a carcinogen. In India, to date, only human breast milk was assessed for levels of PBDEs, and it is suggested that other human tissues can also be explored. No data on the reproductive toxicity of PBDEs are reported from Indian cohorts. Long-range transport and deposition of PBDEs in colder regions necessitates monitoring of Himalayan regions in India. An inventory of PBDEs is required to be made for addressing the worrisome situation of the unregulated import of E-waste from the developed countries in India. The study also emphasizes providing guidelines for the articulation of policies regarding sound surveillance and management of PBDE production, consumption, and release in the Indian context. It is recommended that a separate cell for monitoring and follow-up of PBDEs should be established in India. Also, the development of better alternatives and environment-friendly remediation technologies for PBDEs is the need of the hour.

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.

Human exposure to PBDEs in e-waste areas: A review

Polybrominated biphenyl ethers (PBDEs) are commonly added to electronic products for flame-retardation effects, and are attracting more and more attentions due to their potential toxicity, durability and bioaccumulation. This study conducts a sysmtematic review to understand the human exposure to PBDEs from e-waste recycling, especially exploring the exposure pathways and human burden of PBDEs as well as investigating the temporal trend of PBDEs exposure worldwide. The results show that the particular foods (contaminated fish, poultry, meat and breast milk) ingestion, indoor dust ingestion and indoor air inhalation may be key factors leading to human health risks of PBDEs exposure in e-waste recycling regions. Residents and some vulnerable groups (occupational workers and children) in e-waste recycling areas may face higher exposure levels and health risks. PBDE exposure is closely related to exposure level, exposure duration, e-waste recycling methods, and dietary customs. High levels of PBDEs are found in human tissues (breast milk, hair, blood (serum), placenta and other tissues) in e-waste areas, at far higher levels than in other areas. Existing data indicate that PBDE exposure levels do not present any apparent downward trend, and will possibly cause serious human diseases. More epidemiological studies are still needed to provide a solid basis for health risk assessment.

Polybrominated diphenyl ethers and decabromodiphenyl ethane in paired hair/serum and nail/serum from corresponding chemical manufacturing workers and their correlations to thyroid hormones, liver and kidney injury markers

We detected the polybrominated diphenyl ethers (PBDEs) or decabromodiphenyl ethane (DBDPE) in paired hair-serum and nail-serum samples collected from the corresponding chemical manufacturing workers. The levels of decabrominated diphenyl ether (BDE-209) or DBDPE in the serum, hair and nail samples were all significantly higher than those reported in other studies, and the "work place" (pretreatment or posttreatment workshop) was the primary influencing factor that affected the levels of specific BFRs in vivo. For BDE-209 workers, the BDE-209 in both the hair and nail samples were significantly and positively related to the BDE-209 in the serum, indicating that both hair and nails can be used as noninvasive biomatrices to reflect internal exposure to BDE-209. In DBDPE workers, hair rather than nails was more suitable for use as a noninvasive biomatrix to infer the DBDPE exposure level. A series of serum biomarkers reflecting thyroid hormones and liver and kidney injuries were tested to calculate the correlations between hair or nail BFR levels and the levels of the biomatrices. The BDE-209 in the hair samples was significantly and positively correlated with the total protein (TP), and the nail BDE-209 level was significantly and positively related to the total bilirubin (TBIL), indirect bilirubin (IDBIL) and uric acid (UA). The DBDPE in hair was significantly and positively correlated with the thyroid hormones free triiodothyronine (fT3) and total triiodothyronine (tT3) and kidney injury markers, including blood urea nitrogen (BUN), creatinine (CRE) and cystatin C (Cys-C). In addition, the nail DBDPE levels were significantly and positively correlated with the albumin/globulin (A/G), BUN, CRE and Cys-C but negatively correlated with the TP and globulin (GLO). Our findings provide preliminary evidence that hair and nails can be used as noninvasive biomatrices for assessing internal BFR exposure and health damage in occupational workers.

The relationship between perinatal exposure to dioxins and serum steroid hormone levels in preschool-aged children at an e-waste region in China

Perinatal exposure to dioxins affects steroid hormone synthesis. The purpose of the present study was to evaluate the associations between perinatal exposure to dioxins and serum steroid hormone levels in preschool-aged children from an e-waste recycling region in China. In the present study, we enrolled 50 pairs of mothers and infants from the Taizhou, Luqiao region in 2015. Of the 50 pairs of mothers and infants, 42 pairs participated in this study when the children were 4 years old. We measured breast milk dioxin concentrations using high-resolution gas chromatography/mass spectrometry. Additionally, we used liquid chromatography-tandem mass spectrometry to measure the concentrations of progesterone, testosterone, androstenedione (A-dione), and dehydroepiandrosterone (DHEA) in serum samples from the 4-year-old children. We used multivariate linear regressions to assess the associations between dioxin congeners and steroid hormones. Results were reported as beta estimates and 95% confidence intervals by bootstrapping. We observed sex-related differences between breast milk dioxins and serum steroid hormone levels in 4-year-old children. An increase in breast milk dioxins was associated with a decrease in testosterone in serum samples from boys. Similarly, an increase in breast milk dioxins was associated with a decrease in progesterone levels in serum samples from girls. However, dioxins were not associated with changes in the levels of testosterone, DHEA, or A-dione in girls. Based on these results, we conclude that perinatal exposure to dioxins modifies steroidogenesis in preschool-aged children. However, the long-term impact of dioxins requires further large-scale studies to assess these effects in school-going children and adolescents.

The association between dioxins and steroid hormones in general adult males: a cross-sectional study in an e-waste region of China

As observed among residents in electronic waste (e-waste) recycling areas, dioxins can disrupt the homeostasis of endocrine hormones and the balance of thyroid hormones. Few studies, however, have examined whether e-waste recycling activities influence steroid hormone equilibrium in the general adult male population. This study evaluated the association between steroid hormones and the physical burdens of dioxins in the general adult male population residing in an e-waste region. In September 2017, 74 adult males residing in an e-waste dismantling region were enrolled in the current study. Approximately 10 mL of blood was collected from each adult male, and the serum samples were separated through centrifugation. Then, the levels of dioxin and steroid hormones in the serum of the participants were measured. We treated dioxin levels as categorical variables in the general linear model according to quartiles (25, 50, and 75 percentile). Comparing the findings with a reference group (< 25th percentile), we noted significantly higher dehydroepiandrosterone (DHEA) level in men with low serum polychlorinated dibenzofuran-toxic equivalent (PCDFs-TEQ) level between 3.80 and 6.31 pg/g lipid (1933 vs. 1447 pg/ml) and low polychlorinated dibenzo-p-dioxins and dibenzofurans-TEQ (PCDD/PCDFs-TEQ) between 8.57 and 15.11 pg/g lipid (1996 vs. 1360 pg/ml). Moreover, a significantly higher androstenedione (A-dione) level was found in men whose serum PCDFs-TEQ ≥ 11.34 pg/g lipd (2404 vs. 1848). What's more, there were significantly higher 3β-hydroxysteroid dehydrogenase (3β-HSD) concentrations in low- and high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) groups (1.30-1.67 and ≥ 2.64 pg-TEQ/g lipid, respectively with 719 and 807 vs. 496, respectively). Our findings suggest that specific dioxin exposure may disturb normal DHEA, A-dione levels, and enzyme activity in the general adult male population in an e-waste region of China.

Activation of integrated stress response and disordered iron homeostasis upon combined exposure to cadmium and PCB77

Both cadmium and polychlorinated biphenyls (PCBs) can induce diverse detrimental effects on human health. Though these compounds co-exist in various environmental contexts and in the human body, studies on their joint toxicities are limited. Activation of the integrated stress response (ISR) and iron homeostasis are crucial for erythropoiesis. The impact of cadmium and PCBs on the ISR activation and iron homeostasis of erythroid progenitors is unknown. We investigated the adverse effects and mechanisms of CdCl₂ and PCB77 on HEL cells, a human cell model of erythroid progenitors. We found that at high concentrations of CdCl₂ and PCB77, cytotoxicity and apoptosis of HEL cells were mainly induced by CdCl₂. At low concentrations of CdCl₂ and PCB77, iron homeostasis inside HEL cells was disturbed by both of these two compounds. Both CdCl₂ and PCB77 activated ISR to combat stress, which at high concentration was mainly induced by ROS, leading to apoptosis, and at low concentration was partly induced by disordered iron homeostasis. The patterns of ISR activation and iron homeostasis disorder were different between CdCl₂ and PCB77. Their combined exposure exhibited synergetic effect on activating ISR but antagonistic effect on disturbing iron homeostasis. Our study demonstrates some previously unrecognized harmful characteristics and mechanisms of cadmium and PCB77.

Occurrence and congener profiles of polybrominated diphenyl ethers in green mussels (Perna viridis) collected from northern South China Sea and the associated potential health risk

Polybrominated diphenyl ether (PBDE) contamination has become a major concern over the effects on human health. In the present study, we collected widely consumed green mussels (Perna viridis) samples from the northern South China Sea (NSCS) to investigate the occurrence, spatial distribution, congener profiles as well as potential risk of 18 PBDEs. All the target PBDEs were detected in green mussel samples, indicating their ubiquitous distribution. The concentrations of the total 18 PBDE_S (ΣPBDEs) in all samples varied from 6.96 to 55.6 ng/g lipid weight (lw), with BDE-47 and BDE-209 being the predominant PBDE congeners. Overall, the ΣPBDEs pollution in green mussels from NSCS was at a moderate to high level in comparison with the PBDEs pollution worldwide. The dietary exposure of the local population in South China to PBDEs via consuming green mussels was estimated to be 0.30-0.80 ng/kg body weight (bw)/day. Evaluation of the exposure risk for BDE-47, 99, 153 and 209 indicated that health risks due to green mussel consumption are substantially lower than the U.S. EPA minimum concern level.

Occurrence, gas-particle partitioning, and sources of polybrominated diphenyl ethers in the atmosphere over the Yangtze River Estuary, East China Sea

To investigate the occurrence, gas-particle partitioning, and potential sources of polybrominated diphenyl ethers (PBDEs) in the atmosphere over the Yangtze River Estuary, gas and particle samples were collected at the remote Huaniao Island, East China Sea, during a whole year from 2013 to 2014. Nine PBDEs, with total atmospheric concentration of Σ₉BDEs of 20.3 ± 26.5 pg/m³, were found in both the gas and particle phases in most samples. BDE-209 dominated both the gas and particle phases, which is consistent with the PBDE usage record in China. Seasonal variation of particle-phase Σ₉BDEs was observed, with the highest concentration in winter and the lowest in summer; however, a reversed seasonal trend was observed in the gas phase. Correlation analysis between log K_p and log K_OA suggested that the gas-particle (G/P) partitioning was in a non-equilibrium state, particularly for BDE-209 throughout the year. The K_OA-based adsorption model prediction performed relatively well for the particle-phase fraction of Br_<10-BDEs, but largely overestimated BDE-209. A steady-state model could be superior to predict G/P partitioning of BDE-209 based on annual values, though with the exception of summer samples. A relatively higher gas-phase distribution for BDE-209 than high-brominated BDEs was observed, especially in summer, when it reached 73%, implying a sustained input of gas-phase BDE-209. The potential source contribution function showed that the possible source regions for BDE-209 included Shandong and Jiangsu Provinces (the main BDE-209 production regions in China), the Yangtze River Delta region, and the southeastern coastal areas (which hosts intensive electronic waste recycling activities).

Disruption of thyroid hormone regulated proteins and gene expression by polychlorinated biphenyls, polybrominated diphenyl ethers and new flame retardants in residents of an e-waste region

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and new flame retardants (NFRs) are known thyroid hormone (TH) disruptors, but their disrupting mechanisms in humans are not completely understood. In this study, we aimed to explore the disrupting mechanisms of the aforementioned chemicals via examining TH-regulated proteins and gene expression in human serum. Adult participants from an e-waste dismantling (exposed group) and a control region (control group) in South China provided blood samples for the research. Some compounds of PCBs, PBDEs, and NFRs showed strong binding affinity to the thyroid-stimulating hormone (TSH), thyroglobulin, thyroxine-binding globulin (TBG), gene expression of TH receptor α (TRα) and β, and iodothyronine deiodinase I (ID1). The highly exposed individuals had lower levels of TBG, TSH, and expression of TRα, but higher expression of ID1 than those of the control group. The disruption of TH-regulated proteins and gene expression suggested the exertion of different and, at times, even contradictory effects on TH disruption. However, no statistically significant difference was found in the TH levels between the exposed and the control group, implying that the TH disruption induced by these chemicals depends on the combined influence of multiple mechanisms. Gene expression appears to be an effective approach for investigations of TH disruption and the potential health effects.

Thyroid endocrine status and biochemical stress responses in adult male Wistar rats chronically exposed to pristine polystyrene nanoplastics

Toxicity evaluations of micro- or nano-sized plastics in rodent species commonly employed for toxicity analyses based on which risk assessment for humans could be performed are still largely lacking. Given this knowledge gap, the present work was aimed at determining the potential impact of chronic exposure to polystyrene nanoplastics (PS NPs) on the thyroid endocrine status and biochemical stress in a rat model. Young adult male rats were orally administered with PS NPs (1, 3, 6 and 10 mg kg^-1 day^-1) for five weeks. Thyroid hormones (THs) l-thyroxine (T4), l-triiodothyronine (T3), l-free triiodothyronine (FT3), and l-free thyroxine (FT4) as well as thyroid stimulating hormone (TSH) serum levels of normal rats and those exposed to PS NPs were compared. Serum levels of high-density lipoprotein (HDL), low-density lipoprotein (LDL), cholesterol, and creatinine, as well as glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) enzymes were also measured. Exposure to PS NPs suppressed the serum levels of T3 and circulating levels of THs, whereas TSH increased significantly. Though exposure to PS NPs did not affect the molar ratios of T3/T4, it induced a slight, but significant, increase in FT3/FT4. In addition, exposure to plastic nanoparticles showed signs of nephrotoxicity induction and kidney injury in exposed organisms as can be inferred from the significantly higher serum levels of creatinine in exposed groups. Our results provide clear evidence of an association between exposure to plastic NPs and thyroid endocrine disruption as well as metabolic deficit, and generate new leads for future research efforts.

Depressive Symptoms After PCB Exposure: Hypotheses for Underlying Pathomechanisms via the Thyroid and Dopamine System

Polychlorinated biphenyls’ (PCB) exposure has been reported to be associated with depressive symptoms, which is correlated to lower dopamine- (DA) and thyroxine-concentrations (T4). T4 is necessary for DA-synthesis and it binds to transthyretin (TTR) being transported into the brain. PCBs can displace T4 by binding to TTR itself, being transported into the brain and disturbing DA-synthesis, where depressive symptoms might occur. Consequently, the free T4-concentration (fT4) increases when PCBs bind to TTR. The interaction of PCBs with fT4 and its associations with the main DA metabolite, homovanillic acid (HVA), and depressive symptoms were investigated. In total, 116 participants (91.6% men) were investigated, who took part in three annual examinations (t1–t3) of the HELPcB health surveillance program. Blood was collected for measuring PCBs, hydroxy PCBs (OH-PCBs), and fT4 and urine for HVA. Depressive Symptoms were assessed with a standardized questionnaire. Interactions were tested cross-sectionally with multiple hierarchical regressions and longitudinally with mixed effect models. Related to HVA, an interaction was cross-sectionally found for lower-chlorinated PCBs (LPCBs) and dioxin-like PCBs (dlPCBs); longitudinally only for LPCBs. Related to depressive symptoms, the interaction was found for LPCBs, dlPCBs, and OH-PCBs; longitudinally again only for LPCBs. The results give first hints that a physiological process involving the thyroid and DA system is responsible for depressive symptoms after PCB exposure.

Dioxin-like PCB 126 Increases Systemic Inflammation and Accelerates Atherosclerosis in Lean LDL Receptor-Deficient Mice

Exposure to dioxins and related persistent organic pollutants likely contributes to cardiovascular disease (CVD) risk through multiple mechanisms including the induction of chronic inflammation. Epidemiological studies have shown that leaner individuals may be more susceptible to the detrimental effects of lipophilic toxicants because they lack large adipose tissue depots that can accumulate and sequester these pollutants. This phenomenon complicates efforts to study mechanisms of pollutant-accelerated atherosclerosis in experimental animal models where high-fat feeding and adipose expansion limit the bioavailability of lipophilic pollutants. Here, we investigated whether a model dioxin-like pollutant, PCB 126, could increase inflammation and accelerate atherosclerosis in Ldlr-/- mice fed a low-fat atherogenic diet. We fed Ldlr-/- mice the Clinton/Cybulsky diet (10% kcal fat, 0.15% cholesterol) and sacrificed mice at 8, 10, or 12 weeks postPCB (2 doses of 1 μmol/kg) or vehicle gavage. To characterize this novel model, we examined the effects of PCB 126 on markers of systemic inflammation, hematological indices, fatty livers, and atherosclerotic lesion size. Mice exposed to PCB 126 exhibited significantly increased plasma inflammatory cytokine levels, increased circulating biomarkers of CVD, altered platelet, and red blood cell counts, increased accumulation of hepatic fatty acids, and accelerated atherosclerotic lesion formation in the aortic root. PCB 126 also increased circulating neutrophils, monocytes, and macrophages as determined by flow cytometry analysis. Exposure to dioxin-like PCB 126 increases inflammation and accelerates atherosclerosis in mice. This low-fat atherogenic diet may provide a useful tool to study the mechanisms linking exposure to lipophilic pollutants to increased risk of CVD.

Human Sex Hormone Disrupting Effects of New Flame Retardants and Their Interactions with Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, a Case Study in South China

Even though sex hormone disrupting effects of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are widely understood, similar effects associated with new flame retardants (NFRs) have not been so well studied. This study aimed to explore the sex hormone disruption of NFRs and their interactions with PCBs and PBDEs through the conduct of an ecological study in an e-waste dismantling and control region in South China. Questionnaires and blood samples were collected from local adult residents. Results of generalized additive model and linear regression analyses indicate that several species of NFRs showed similar disrupting effects with PBDE congeners on female follicle-stimulating hormone (FSH) and male testosterone. Judged by the curved shape and statistical significance, ΣNFR (sum of 8 species of NFRs) showed stronger disrupting effects on male testosterone and female FSH compared to ΣPBDE (sum of 13 congeners of PBDEs). The interactions induced by NFRs complicated the original sex hormone disruption led by PCBs and PBDEs. The disrupting effects and interactions induced by NFRs decreased female FSH levels in the exposed group. Comprehensive evaluation is needed to provide the evidence base for judging the health risks arising from the increased usage of NFRs.

Temporal trends in dioxin-like polychlorinated biphenyl concentrations in serum from the general population of Shandong Province, China: A longitudinal study from 2011 to 2017

Temporal changes in the concentrations of dioxin-like (DL) polychlorinated biphenyls (PCBs) in environmental and biological matrices in China are not well understood. We determined the DL-PCB concentrations in pooled serum samples from the general population of Weifang City, Shandong Province, China in 2011 (n = 305) and 2017 (n = 495). The total DL-PCB concentration was 3.48 ± 1.31 ng/g lipid (mean ± standard deviation) in 2011 and 2.82 ± 1.73 ng/g lipid (19% lower) in 2017, but the difference was not statistically significant (p = 0.347). The DL-PCB concentrations and toxic equivalent concentrations were much lower in the serum from Weifang residents than have been found in serum from the inhabitants of other parts of the world. The concentrations of most of the DL-PCB congeners followed different downward temporal trends, but the PCB-118 concentration was higher in 2017 than in 2011. The temporal changes in the PCB concentrations and compositions in the samples from the general population of Weifang indicated that there may a new source of unintentionally produced PCBs in Weifang.

Association between serum polybrominated diphenyl ethers, new flame retardants and thyroid hormone levels for school students near a petrochemical complex, South China

As surrogates of polybrominated diphenyl ethers (PBDEs), new flame retardants (NFRs) include a series of chlorinated and brominated flame retardants. Though the NFRs are thought to induce similar thyroid hormone (TH) disrupting effects as PBDEs, few studies have focused on them. Given the increasing levels of NFRs in the environment, more in depth investigation of the potential TH disrupting effects of NFRs is warranted. This research involved a health survey to collect data and examine the associations between PBDEs, NFRs and TH. 174 school students lived near a petrochemical complex in South China participated in the survey, completing questionnaires and providing blood samples. Thirteen congeners of PBDEs, eight species of NFRs, TH and thyroid-stimulating hormone (TSH) were measured. The median levels of ΣPBDE (sum of thirteen congeners of PBDEs) and ΣNFR (sum of eight species of NFRs) for students were 140 and 240 ng g^-1 lipid, respectively. Nonmonotonic relationships were observed between quartile levels of PBDEs, NFRs and corresponding TH. In contrast to ΣPBDE that was positively associated with triidothyrine (T₃) level, ΣNFR was not statistically associated with TH. ΣPBDE + NFR (sum of thirteen congeners of PBDEs and eight species of NFRs) was significantly associated with T₃ level.

Polybrominated diphenyl ethers (PBDEs) and hydroxylated PBDEs in human serum from Shanghai, China: a study on their presence and correlations

Polybrominated diphenyl ethers (PBDEs) are becoming a public health concern because of their potential toxicity, from endocrine disruption system to neurodevelopmental impairments. Nonetheless, information on their levels in human blood is scarce. In this study, human serum samples collected in Shanghai, China, were analyzed for the concentrations of PBDEs and their hydroxylated metabolites (OH-PBDEs). Eight PBDE congeners and six OH-PBDE congeners were quantified in serum samples by gas chromatography with mass spectrometry (GC-MS) and high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). As a result, total PBDE concentration ranged from 0.280 to 12.330 ng g^-1 on a lipid weight basis lw (median: 1.100 ng g^-1 lw) and the total OH-PBDE level ranged from 0.045 to 0.363 ng g^-1 (lw) (median: 0.187 ng g^-1 lw). Among them, BDE-47 and 6-OH-BDE-47 were the predominant PBDEs and OH-PBDEs, respectively. In addition, based on the results of the Bartelett X ² test, BDE-47 significantly (p < 0.05) correlated with BDE-28, BDE-100, BDE-85, and BDE-154, whereas 3'-OH-BDE-7 significantly (p < 0.01) correlated with 3-OH-BDE-47, 2-OH-BDE-68, and 6'-OH-BDE-99. Among all donors, no significant association between age and PBDEs (or OH-PBDEs) was found. Further research on the exposure routes in the environment and metabolic processing of PBDEs in human blood is necessary.

Endocrine Disruptors and Health Effects in Africa: A Call for Action

BACKGROUND

Africa faces a number of unique environmental challenges. Unfortunately, it lacks the infrastructure needed to support the comprehensive environmental studies that could provide the scientific basis to inform environmental policies. There are a number of known sources of endocrine-disrupting chemicals (EDCs) and other hazardous chemicals in Africa. However, a coordinated approach to identify and monitor these contaminants and to develop strategies for public health interventions has not yet been made.

OBJECTIVES

This commentary summarizes the scientific evidence presented by experts at the First African Endocrine Disruptors meeting. We describe a "call to action" to utilize the available scientific knowledge to address the impact of EDCs on human and wildlife health in Africa.

DISCUSSION

We identify existing knowledge gaps about exposures to EDCs in Africa and describe how well-designed research strategies are needed to address these gaps. A lack of resources for research and a lag in policy implementation slows down intervention strategies and poses a challenge to advancing future health in Africa.

CONCLUSION

To address the many challenges posed by EDCs, we argue that Africans should take the lead in prioritization and evaluation of environmental hazards, including EDCs. We recommend the institution of education and training programs for chemical users, adoption of the precautionary principle, establishment of biomonitoring programs, and funding of community-based epidemiology and wildlife research programs led and funded by African institutes and private companies. https://doi.org/10.1289/EHP1774.

Pollution Status and Human Exposure of Decabromodiphenyl Ether (BDE-209) in China

Decabromodiphenyl ether (BDE-209/decaBDE) is a high-production-volume brominated flame retardant in China, where the decaBDE commercial mixture is manufactured in Laizhou Bay, Shandong Province, even after the prohibition of penta- and octaBDE mixtures. The demand for flame retardants produced in China has been increasing in recent years as China not only produces electronic devices but also has numerous electronic waste (e-waste) recycling regions, which receive e-wastes from both domestic and foreign sources. High concentrations of BDE-209 have been observed in biotic and abiotic media in each of the different areas, especially within the decaBDE manufacturers and e-waste recycling areas. BDE-209 has been viewed as toxic and bioaccumulative because it might debrominate to less brominated polybrominated diphenyl ethers (PBDEs) (lower molecular weight and hydrophobicity), which are more readily absorbed by organisms. The highest concentration of PBDEs in dust within urban areas reached 40 236 ng g^-1 in the Pearl River Delta, and BDE-209 contributed the greatest proportion to the total PBDEs (95.1%). Moreover, the maximum hazard quotient was found for toddlers (0.703) for BDE-209, which was close to 1. This suggests that exposure to BDE-209 might lead to increased potential for adverse effects and organ harm (e.g., the lungs) through inhalation, dust ingestion, and dermal absorption, especially for the group of toddlers compared to others. In daily food and human tissues, the amount of BDE-209 was also extensively detected. However, the toxicity and adverse effect of BDE-209 to humans are still not clear; thus, further studies are required to better assess the toxicological effects and exposure scenarios, a more enhanced environmental policy for ecological risks regarding BDE-209 and its debrominated byproducts in China.

Decreased lung function with mediation of blood parameters linked to e-waste lead and cadmium exposure in preschool children

Blood lead (Pb) and cadmium (Cd) levels have been associated with lower lung function in adults and smokers, but whether this also holds for children from electronic waste (e-waste) recycling areas is still unknown. To investigate the contribution of blood heavy metals and lung function levels, and the relationship among living area, the blood parameter levels, and the lung function levels, a total of 206 preschool children from Guiyu (exposed area), and Haojiang and Xiashan (reference areas) were recruited and required to undergo blood tests and lung function tests during the study period. Preschool children living in e-waste exposed areas were found to have a 1.37 μg/dL increase in blood Pb, 1.18 μg/L increase in blood Cd, and a 41.00 × 10⁹/L increase in platelet counts, while having a 2.82 g/L decrease in hemoglobin, 92 mL decrease in FVC and 86 mL decrease in FEV₁. Each unit of hemoglobin (1 g/L) decline was associated with 5 mL decrease in FVC and 4 mL decrease in FEV₁. We conclude that children living in e-waste exposed area have higher levels of blood Pb, Cd and platelets, and lower levels of hemoglobin and lung function. Hemoglobin can be a good predictor for lung function levels.

Distribution of PBDEs, HBCDs and PCBs in the Brisbane River estuary sediment

To date, very little or no data exist in literature for some brominated flame retardants (BFRs) and polychlorinated biphenyls in Queensland sediments. These pollutants were measured in the sediments along the Brisbane River estuary. The target compounds were regularly detected in measurable concentrations: PBDEs=33.3-97.8% (n=45), PCBs=94.1-100% (n=51) and HBCDs=79-98% (n=48). Consistently, >90% of the observed ∑₈PBDE concentration was attributed to BDE-209. Mean PBDE levels (ng/g dry wt.) were: 4.4±3.2 (∑₈PBDE) and 4.4±3.0 (BDE-209) across 22 sampling sites. The mean ∑₇PCB and ∑HBCD were 5.4±4.5 and 1.0±1.5ng/g dry wt. respectively. The 25% (α-HBCD), 8% (β-HBCD) and 67% (γ-HBCD) diastereoisomer contributions observed were consistent with values reported in the literature. Contaminant levels are fairly distributed along the River and were generally low compared to similar studies around the world.

Current halogenated flame retardant concentrations in serum from residents of Shandong Province, China, and temporal changes in the concentrations

The residents of Shandong Province, China, are exposed to high concentrations of halogenated flame retardants because large amounts of halogenated flame retardants are produced in the province. We determined the concentrations of eight polybrominated diphenyl ether congeners (PBDEs), seven novel brominated flame retardants (NBFRs), and the two dechlorane plus isomers (DPs) in serum from residents of Shandong Province. The aim was to identify temporal trends in the concentrations of these pollutants. The mean total concentrations of PBDEs, NBFRs and DPs were 41, 2.2 and 2.1ng/g lipid in pooled serum samples collected in 2014, and were 32, 3.5 and 3.1ng/g lipid in pooled serum samples collected in 2015, respectively. Decabromodiphenyl ether was the dominant PBDE congener in all of the samples. The novel brominated flame retardant and dechlorane plus concentrations were between one and two orders of magnitude lower than the PBDE concentrations. The PBDE concentrations in serum decreased significantly between 2007 and 2015, but the pentabromobenzene, pentabromotoluene, and dechlorane plus concentrations were relatively stable.

Disruption of thyroid hormone (TH) levels and TH-regulated gene expression by polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and hydroxylated PCBs in e-waste recycling workers

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) are the primary toxicants released by electronic waste (e-waste) recycling, but their adverse effects on people working in e-waste recycling or living near e-waste sites have not been studied well. In the present study, the serum concentrations of PBDEs, PCBs, and hydroxylated PCBs, the circulating levels of thyroid hormones (THs), and the mRNA levels of seven TH-regulated genes in peripheral blood leukocytes of e-waste recycling workers were analyzed. The associations of the hormone levels and gene expression with the exposure to these contaminants were examined using multiple linear regression models. There were nearly no associations of the TH levels with PCBs and hydroxylated PCBs, whereas elevated hormone (T₄ and T₃) levels were associated with certain lower-brominated BDEs. While not statistically significant, we did observe a negative association between highly brominated PBDE congeners and thyroid-stimulating hormone (TSH) levels in the e-waste workers. The TH-regulated gene expression was more significantly associated with the organohalogen compounds (OHCs) than the TH levels in these workers. The TH-regulated gene expression was significantly associated with certain PCB and hydroxylated PCB congeners. However, the expression of most target genes was suppressed by PBDEs (mostly highly brominated congeners). This is the first evidence of alterations in TH-regulated gene expression in humans exposed to OHCs. Our findings indicated that OHCs may interfere with TH signaling and/or exert TH-like effects, leading to alterations in related gene expression in humans. Further research is needed to investigate the mechanisms of action and associated biological consequences of the gene expression disruption by OHCs.

Human amniotic fluid contaminants alter thyroid hormone signalling and early brain development in Xenopus embryos

Thyroid hormones are essential for normal brain development in vertebrates. In humans, abnormal maternal thyroid hormone levels during early pregnancy are associated with decreased offspring IQ and modified brain structure. As numerous environmental chemicals disrupt thyroid hormone signalling, we questioned whether exposure to ubiquitous chemicals affects thyroid hormone responses during early neurogenesis. We established a mixture of 15 common chemicals at concentrations reported in human amniotic fluid. An in vivo larval reporter (GFP) assay served to determine integrated thyroid hormone transcriptional responses. Dose-dependent effects of short-term (72 h) exposure to single chemicals and the mixture were found. qPCR on dissected brains showed significant changes in thyroid hormone-related genes including receptors, deiodinases and neural differentiation markers. Further, exposure to mixture also modified neural proliferation as well as neuron and oligodendrocyte size. Finally, exposed tadpoles showed behavioural responses with dose-dependent reductions in mobility. In conclusion, exposure to a mixture of ubiquitous chemicals at concentrations found in human amniotic fluid affect thyroid hormone-dependent transcription, gene expression, brain development and behaviour in early embryogenesis. As thyroid hormone signalling is strongly conserved across vertebrates the results suggest that ubiquitous chemical mixtures could be exerting adverse effects on foetal human brain development.

Substance flow analysis and environmental releases of PBDEs in life cycle of automobiles

Polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants, have been widely used in many applications in industry such as automobiles, textiles, and electronics. This study focused on a quantitative substance flow analysis (SFA) of PBDEs in automobiles in order to identify their flow by life cycle and treatment pathways of PBDEs-containing materials in end-of-life vehicles (ELVs) in Korea. In addition, this study has estimated environmental releases of PBDEs in automobiles by life cycle in Korea. During this study, PBDEs were analyzed for the samples collected from several ELVs treatment facilities using X-ray fluorescence and gas chromatography/mass spectrometry (GC/MS) methods. The system boundary for SFA of PBDEs ranged from manufacturing/trade to disposal stage of automobiles by life cycle. Based on the result of the SFA, it was found that the amount of PBDEs in automobiles were the highest in use stage (7748ton/year), followed by production stage (1743ton/year) in 2014. In disposal stage, automobile shredded residues (ASR) and seat fabrics were the main components with relatively high levels of PBDEs in ELVs. The major treatment methods of such components included incineration (84%), energy recovery (9%), and landfilling (6%). This research indicates that PBDEs were emitted the highest amount from interior components during the use stage of automobiles, followed by recycling processes such as dismantling and shredding. This study suggests that PBDEs in ASR and seat fabrics should be properly managed to prevent the widespread dispersion in the environment.