Human exposure levels of PAEs in an e-waste recycling area: Get insight into impacts of spatial variation and manipulation mode

Biomonitoring and health risk assessment of exposure to phthalate esters in waste management workers

Humans are at risk of exposure to phthalates due to the widespread use of plasticized plastics, and one of the major concerns is occupational exposure. The present study investigated occupational exposure to phthalates at one of the greatest solid waste management sites in the second-largest country in the Middle East. Carcinogenic and non-carcinogenic health risks were assessed by human biomonitoring (HBM). The concentration of phthalate esters was determined using gas chromatography-mass spectrometry (GC-MS), and the daily intake (DI) of phthalate was calculated based on the adjusted urinary creatinine concentrations. Moreover, carcinogenic and non-carcinogenic risks were assessed. Monte Carlo simulations were performed for uncertainty and sensitivity analysis. The highest concentration recorded was 130.80 µg/g creatinine for mono-ethyl phthalate (MEP) among the composting group, while the lowest concentration was 0.49 µg/g creatinine for Monobenzyl phthalate (MBzP) among the office group. All estimates of daily intake were below the reference concentration, and differences between the DI at site sections were statistically significant (p < 0.05). The non-carcinogenic risk level was negligible. The excess lifetime cancer risk (ELCR) values corresponding to di-(2-ethylhexyl) phthalate (DEHP) exposure were 2.07E-04 among the composting group and 2.07E-04 among the processing group, posing a definite risk. The carcinogenic risk value among the office group was in a possible risk category with ELCR values of 9.75 E-05. The on-site workers of waste management sites can be highly exposed to phthalates, and their health risk is considerable. Appropriate measures and interventions should be considered to reduce occupational exposure to phthalates.

Phthalate Biomarkers Composition in Relation to Fatty Liver: Evidence from Epidemiologic and in vivo studies

Phthalates, classified as environmental endocrine disruptors, pose potential toxicity risks to human health. Metabolic dysfunction-associated fatty liver disease is one of the most widespread liver diseases globally. Compared to studies focusing on metabolic disorders in relation to pollutants exposure, the impact of individual factors such as fatty liver on the in vivo metabolism of pollutants is always overlooked. Therefore, this study measured concentrations and composition of phthalate monoesters (mPAEs) in human urine samples, particularly those from fatty liver patients. Furthermore, we induced fatty liver in male Wistar rats by formulating a high-fat diet for twelve weeks. After administering a single dose of DEHP at 500 mg/kg bw through gavage, we compared the levels of di-2-ethylhexyl phthalate (DEHP), its metabolites (mDEHPs) and three hepatic metabolic enzymes, namely cytochrome P450 enzymes (CYP450), UDP glucuronosyltransferase 1 (UGT1), and carboxylesterase 1 (CarE1), between the normal and fatty liver rat groups. Compared to healthy individuals (n = 75), fatty liver patients (n = 104) exhibited significantly lower urinary concentrations of ∑mPAEs (median: 106 vs. 166 ng/mL), but with a higher proportion of mono-2-ethylhexyl phthalate in ∑mDEHPs (25.7 % vs. 9.9 %) (p < 0.05). In the animal experiment, we found that fatty liver in rats prolonged the elimination half-life of DEHP (24.61 h vs. 18.89 h) and increased the contents of CYP450, CarE1, and UGT1, implying the common but differentiated metabolism of DEHP as excess lipid accumulation in liver cells. This study provides valuable information on how to distinguish populations in biomonitoring studies across a diverse population and in assigning exposure classifications of phthalates or similar chemicals in epidemiologic studies.

Crosstalk between aryl hydrocarbon receptor and Wnt/β-catenin signaling pathway: Possible culprit of di (2-ethylhexyl) phthalate-mediated cardiotoxicity in zebrafish larvae

Typical plasticizer di (2-ethylhexyl) phthalate (DEHP) has been demonstrated to induce cardiotoxicity in zebrafish, but the potential molecular mechanisms involved have not been fully elucidated. Aryl hydrocarbon receptor (AhR), an essential protein for inducing developmental abnormalities, has been demonstrated to be activated by DEHP in other species, but whether the AhR signaling pathway also contributes to DEHP-mediated cardiac developmental toxicity in zebrafish remains unclear. Firstly, molecular docking simulations initially confirmed the possibility that DEHP has AhR agonistic activity. To further confirm this conjecture, this work analyzed the changes of cardiac-related indexes in zebrafish stressed by DEHP at individual, protein, and gene levels. The results showed that DEHP mediated cardiac phenotypic developmental defects, increased CYP1A1 activity, and oxidative stress as well as significant changes in the expression levels of key proteins and genes of AhR, Wnt/β-catenin, and Nrf2-Keap1 signaling pathways. Notably, the addition of AhR inhibitors effectively alleviated the above negative effects, indicating that the AhR signaling pathway and its crosstalk with the Wnt/β-catenin signaling pathway is an essential pathway for DEHP-mediated cardiac developmental toxicity. Overall, this work enriches the molecular mechanism of DEHP-mediated cardiac developmental defects in zebrafish and provides a reliable biomarker for future environmental risk assessment of DEHP.

First evidence of occupational and residential exposure to bisphenols associated with an e-waste dismantling site: A case study in China

Bisphenol A and its structural analogues (BPs) are widely used chemicals in electronics devices. To get insight into the occupational exposure to the full-time employees compared with the residents, urinary BPs in workers dismantling e-waste and in nearby residents were compared. Only 4 BPs among the tested 8 congeners, bisphenol AF (BPAF), bisphenol A, bisphenol S (BPS), and bisphenol F (BPF), were extensively detected with the detection frequencies of 100%, 99%, 98.7%, 51.3%. The median concentration of bisphenol A was 8.48 ng/mL, followed by BPAF (1.05 ng/mL), BPS (0.115 ng/mL), and BPF (0.110 ng/mL). The 4 detected BPs had a median concentration (Σ4BPs) ranging from 0.950 to 64.5 ng/mL in all volunteers, with a median value of 10.2 ng/mL. Result indicated the median concentration of ∑4BPs in worker's urine was significantly higher (14.2 ng/mL) than those in residents in nearby towns (4.52 ng/mL and 5.37 ng/mL) (p < 0.05), suggesting a BPs' occupational exposure risk related to e-waste dismantling. Besides, urinary ∑4BPs' median concentrations for the employees in family workshops (14.5 ng/mL) were significantly higher than those in plants with centralized management (9.36 ng/mL). Among volunteers, higher ∑4BPs were observed in groups of aged above 50 years, males, or body weight under average with no significant correlations. The estimated daily intake of bisphenol A did not exceed the reference dose (50 μg/kg bw/day) recommended by the U.S. Food and Drug Administration. In this research, excess levels of BPs were recorded for the full-time employees in e-waste dismantling sites. Strengthened standards could support public health initiatives for full-time worker protection and reduce take-home BPs to family members.

Phthalates and phthalate metabolites in urine from Tianjin and implications for platelet mitochondrial DNA methylation

Background

Phthalates (PAEs) are important synthetic substances in plastics, attracting much attention due to their potential effects on the cardiovascular system.

Methods

In this study, urine and blood samples from 39 individuals were collected in Tianjin, China. Phthalates and phthalate metabolites (mPAEs) were analyzed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography-mass spectrometry (HPLC-MS), respectively. The polymerase chain reaction (PCR) products from bisulfite-treated mitochondrial DNA (mtDNA) samples were analyzed using pyrosequencing technology.

Results

The detection frequencies for 9 PAEs varied from 2.56 to 92.31%, and those for 10 mPAEs varied from 30.77 to 100%. The estimated daily intakes (EDIs) and cumulative risk of PAEs were calculated based on the experimental statistics of urinary PAEs and mPAEs. For PAEs, the HIRfD (hazard index corresponding to reference doses) values of 10.26% of participants and the HITDI (hazard index corresponding to tolerable daily intake) values of 30.77% of participants were estimated to exceed 1, suggesting a relatively high exposure risk. The mtDNA methylation levels in the MT-ATP8 and MT-ND5 were observed to be lower than in the MT-ATP6. Mono-ethyl phthalate (MEP) and MT-ATP8 were positively correlated with triglyceride levels (p < 0.05). Based on the association of PAEs, mtDNA methylation, and triglycerides, the mediating role of mtDNA methylation between PAEs and cardiovascular diseases (CVDs) was analyzed in this study, but no mediated effect was observed.

Conclusion

The effects of PAE exposure on cardiovascular diseases (CVDs) should be investigated further.

Fate of phthalates in a river receiving wastewater treatment plant effluent based on a multimedia model

Phthalic acid esters (PAEs) can enter environment media by secondary effluent discharge from wastewater treatment plants (WWTP) into receiving rivers, thus posing a threat to ecosystem health. A level III fugacity model was established to simulate the fate and transfer of four PAEs in a study area in Tianjin, China, and to evaluate the influence of WWTP discharge on PAEs levels in the receiving river. The results show that the logarithmic residuals of most simulated and measured values of PAEs are within one order of magnitude with a good agreement. PAEs in the study area were mainly distributed in soil and sediment phases, which accounted for 84.66%, 50.26%, 71.96% and 99.09% for dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), respectively. The upstream advection accounted for 77.90%, 93.20%, 90.21% and 90.93% of the total source of DMP, DEP, DBP and DEHP in the river water, respectively, while the contribution of secondary effluent discharge was much lower. Sensitivity analysis shows that emission and inflow parameters have greater influences on the multimedia distributions of PAEs than physicochemical and environmental parameters. Monte Carlo analysis quantifies the uncertainties and verifies the reliability of the simulation results.

Phthalates in dormitory dust and human urine: A study of exposure characteristics and risk assessments of university students

Phthalate diesters (PAEs) are prevalent and potentially toxic to human health. The university dormitory represents a typical and relatively uniform indoor environment. This study evaluated the concentrations of phthalate monoesters (mPAEs) in urine samples from 101 residents of university status, and the concentrations of PAEs in dust collected from 36 corresponding dormitories. Di-(2-ethylhexyl) phthalate (DEHP, median: 68.0 μg/g) was the major PAE in dust, and mono-ethyl phthalate (47.9 %) was the most abundant mPAE in urine. The levels of both PAEs in dormitory dust and mPAEs in urine were higher in females than in males, indicating higher PAE exposure in females. Differences in lifestyles (dormitory time and plastic product use frequency) may also affect human exposure to PAEs. Moreover, there were significant positive correlations between the estimated daily intakes of PAEs calculated by using concentrations of PAEs in dust (EDI_D) and mPAEs in urine (EDI_U), suggesting that PAEs in dust could be a significant source of human exposure to PAEs. The value of EDI_D/EDI_U for low molecular weight PAEs (3-6 carbon atoms in their backbone) was lower than that of high molecular weight PAEs. The contribution rate of various pathways to PAE exposure illustrated that non-dietary ingestion (87.8 %) was the major pathway of human exposure to PAEs in dust. Approximately 4.95 % of university students' hazard quotients of DEHP were >1, indicating that there may be some health risks associated with DEHP exposure among PAEs. Furthermore, it is recommended that some measures be taken to reduce the production and application of DEHP.

National-scale urinary phthalate metabolites in the general urban residents involving 26 provincial capital cities in China and the influencing factors as well as non-carcinogenic risks

Phthalates (PAEs) are widely used in daily products but can cause a variety of adverse effects in humans. Few studies have been carried out on human internal exposure levels of PAEs on a large-scale, especially in developing countries. In the present study, 1161 urine samples collected from residents of 26 provincial capitals in China were analyzed for nine phthalate metabolites (mPAEs). The chemicals were widely detected, and the median specific gravity adjusted urinary concentration of Σ₉mPAEs was 278 μg/L. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the main parent PAEs that the residents were exposed to. Demographic characteristics, such as age and educational level, were significantly associated with PAE exposure. Children and the elderly had higher mPAE levels. Subjects with lower educational levels were more frequently exposed to DnBP and DEHP. However, mono-ethyl phthalate showed the opposite trend, i.e., higher concentrations in subjects aged 18-59 years and with higher educational levels. Geographic differences were detected at the national scale. Residents in northeastern and western China had higher levels of mPAEs than those in central China, most likely because of different industrial usage of the chemicals and different living habits and living conditions of the residents. Health risk assessment showed that hazard indices of PAEs ranged from 0.07 to 9.34, with 20.0% of the subjects being concern for potential non-carcinogenic risk as assessed by Monte Carlo simulation. DEHP and DnBP were the primary contributors, representing 96.7% of total risk. This first large-scale study on PAE human internal exposure in China provides useful information on residents' health in a developing country, which could be used for chemical management and health protection.

Human exposure to BTEX emitted from a typical e-waste recycling industrial park: External and internal exposure levels, sources, and probabilistic risk implications

Benzene, toluene, ethylbenzene, and xylene (BTEX) can be released during extensive activities associated with the disposal of electronic waste (e-waste), which might pose deleterious health effects on workers. In this study, pollution profiles of BTEX in air and their urinary excretive profiles in occupational workers were investigated in a typical e-waste recycling industrial park. The results showed that the workers in the park were generally exposed to high levels of BTEX. The median levels of urinary metabolites were approximately 6-orders of magnitude higher than those of unmetabolized BTEX, indicating that pollutants efficiently metabolize at those occupational levels. The analytes presented differential profiles in external and internal exposure. Among the metabolites, significant correlation (p < 0.05) was observed between N-acetyl-S-benzyl-L-cysteine (S-BMA) concentration and atmospheric individual BTEX derived from the e-waste recycling area, suggesting that S-BMA is a potential marker for BTEX exposure to e-waste occupational workers. Notably, 95.2 % of all the workers showed a cumulative carcinogenic risk induced by BTEX exposure via inhalation, with 99.9 % of the carcinogenic risk distribution based on concentration of benzene metabolite (N-acetyl-S-(phenyl)-L-cysteine) exceeding 1.0E-6. This study holds potential in providing valuable inferences for the development of remediation strategies focusing on BTEX exposure reduction to protect workers' health at e-waste recycling industries.

Occupational exposure to organophosphate esters in e-waste dismantling workers: Risk assessment and influencing factors screening

Organophosphate esters (OPEs) are increasingly added in electronic products as alternative flame retardants, which may result in high occupational exposure of electronic waste recycling employees. This study investigated occupational exposure to OPEs in an e-waste recycling site in northern China, with intent to explore the impacts of occupational exposure and dismantling manipulation mode. Human urine samples from three sites with different distances from the core dismantling area, including employees from family workshops and plants with centralized management and residents from nearby areas, were collected and analyzed for OPEs' metabolites (mOPEs). The urinary ∑mOPEs' median concentrations (0.910 ng/mL) of all employees were significantly higher than those of residents in Ziya Town (0.526 ng/mL) and Jinghai downtown (0.600 ng/mL), suggesting the risk of occupational OPEs' exposure associated with e-waste dismantling. However, the spatial variation was insignificant for residents with different distances from the e-waste recycling site. Besides, OPEs' exposure levels were significantly affected by manipulation modes and the urinary ∑mOPEs' median concentrations in the employees of family workshops (1.05 ng/mL) were significantly higher than those in plants with centralized management (0.667 ng/mL). The result suggests that mechanical dismantling and active ventilating measures can reduce the OPEs' occupational exposure risk. Moreover, ∑mOPEs were higher in volunteers with age above 50 years old and in the underweight subgroup. Finally, different categories of mOPEs in human urine showed associations with corresponding OPEs in dust samples in the same area.

On the formation chemistry of brominated polycyclic aromatic hydrocarbons (BrPAHs)

Brominated polycyclic aromatic hydrocarbons (BrPAHs) have been consistently detected in various environmental matrices, and measured at alarming rates in stack emissions. However, formation mechanisms and bromination patterns of BrPAHs remain unclear. This contribution constructs detailed mechanistic pathways for the synthesis of selected BrPAHs (namely bromine-bearing naphthalene, acenaphthylene, anthracene, and phenanthrene). Mapped-out pathways follow the Bittner-Howard's route in the hydrogen abstraction acetylene addition (HACA) mechanism, in which a second C₂HBr molecule is added to the first one. Constructed kinetic model portrays temperature-dependent profiles of major and minor species. Direct loss of an H atom from the acetylenic fragment appears to be more important at elevated temperatures, when compared with further addition of C₂HBr cuts or ring-cyclization reactions. The occurrence of closed-shell Diels-Alder pathway should be inhibited owing to sizable enthalpic barriers. Fukui Indices for electrophilic substitutions (f^-1) establish bromination' s pattern of selected BrPAHs. The diradical character of BrPAHs coupled with electron-deficient C(Br) sites, render BrPAHs as potent precursors for the formation of environmentally persistent free radicals (EPFRs). Findings reported herein shall be useful in comprehending the formation chemistry of BrPAHs, a less-investigated category of toxicants in thermal systems.

HBM4EU Occupational Biomonitoring Study on e-Waste-Study Protocol

Workers involved in the processing of electronic waste (e-waste) are potentially exposed to toxic chemicals. If exposure occurs, this may result in uptake and potential adverse health effects. Thus, exposure surveillance is an important requirement for health risk management and prevention of occupational disease. Human biomonitoring by measurement of specific biomarkers in body fluids is considered as an effective method of exposure surveillance. The aim of this study is to investigate the internal exposure of workers processing e-waste using a human biomonitoring approach, which will stimulate improved work practices and contribute to raising awareness of potential hazards. This exploratory study in occupational exposures in e-waste processing is part of the European Human Biomonitoring Initiative (HBM4EU). Here we present a study protocol using a cross sectional survey design to study worker’s exposures and compare these to the exposure of subjects preferably employed in the same company but with no known exposure to industrial recycling of e-waste. The present study protocol will be applied in six to eight European countries to ensure standardised data collection. The target population size is 300 exposed and 150 controls. Biomarkers of exposure for the following chemicals will be used: chromium, cadmium and lead in blood and urine; brominated flame retardants and polychlorobiphenyls in blood; mercury, organophosphate flame retardants and phthalates in urine, and chromium, cadmium, lead and mercury in hair. In addition, the following effect biomarkers will be studied: micronuclei, epigenetic, oxidative stress, inflammatory markers and telomere length in blood and metabolomics in urine. Occupational hygiene sampling methods (airborne and settled dust, silicon wristbands and handwipes) and contextual information will be collected to facilitate the interpretation of the biomarker results and discuss exposure mitigating interventions to further reduce exposures if needed. This study protocol can be adapted to future European-wide occupational studies.

Assessment of dust trace elements in an e-waste recycling area and related children's health risks

Children from Guiyu, an electronic waste (e-waste) recycling town, are exposed to trace elements via dust. However, the source, pathways, and influence factors of house dust and the association of house dust with child inflammation in an e-waste recycling area are not well-known. This study investigated dust trace elements in children's living environment and the associations of house dust trace elements with influence factors and child inflammation. A total of 108 dust samples from children's residences, roads, and kindergartens in Guiyu (an exposed area) and Haojiang and Shantou urban areas (reference areas) were collected and analyzed, as well as children's questionnaire data. The Mann-Whitney U test found there were higher trace element concentrations in road dust (Co, Ni, and Cu), kindergarten dust (Al, V, Mn, Co, Ni, and Zn), and house dust (V, Co, Cu, As, and Cd) in Guiyu than in Haojiang and Shantou urban areas (P < 0.05). Our analysis showed that house dust and road dust have similar distribution patterns of trace elements. Spearman's correlations showed close relationships among quantities of trace elements (P < 0.05). Higher trace element concentrations in dust were found in houses that used indoor shoe cabinets and opened windows frequently (P < 0.05). In houses of children with airway inflammation, higher dust Ba concentrations were found (P < 0.05), and if their fathers did not work with e-waste, we found higher dust Pb concentrations (Mann-Whitney U test, P < 0.05). Health assessments showed a high risk of exposure through ingestion and an acceptable risk of exposure through inhalation of dust trace elements for children. However, relationships between airway inflammation and house dust trace elements showed the inhalation risk might be underestimated. This study suggests trace element exposure via dust poses a health risk for children living in e-waste recycling areas.

Prevalence of phthalate alternatives and monoesters alongside traditional phthalates in indoor dust from a typical e-waste recycling area: Source elucidation and co-exposure risk

This study first discovered the prevalence of phthalate (PAE) alternatives and PAE monoesters alongside traditional PAEs with elevated concentrations in indoor dust from typical e-waste recycling industrial park and adjacent communities. Among nine PAEs, high-molecular-weight (HMW) PAEs dominated over low-molecular-weight (LMW) PAEs in e-waste dust, with total concentrations (∑₉PAEs) ranging from 170 to 5300 μg g^-1. The diisononyl phthalate (DiNP) was identified as the most abundant PAE in e-waste dust, with over 10 times higher median concentration than that measured in home dust. Total concentrations of three PAE alternatives ranged from 20 to 1600 μg g^-1 in e-waste dust, which were 3-10 times higher than the measured levels in home dust. A total of 13 monoesters were all identified in all samples with total concentrations of 4.7-59 μg g^-1, and biodegradation of diesters was recognized as the major source of monoesters present in indoor dust. Significant correlations between the concentrations of PAE alternatives and the HMW PAEs were observed (p < 0.05), indicating that they are being simultaneously used in electronic and electrical products. The occupationally high co-exposure of e-waste dismantling workers to multiple PAEs and PAE alternatives as well as their monoesters should be of concern.

From inequitable to sustainable e-waste processing for reduction of impact on human health and the environment

Recycling of electric and electronic waste products (e-waste) which amounted to more than 50 million metric tonnes per year worldwide is a massive and global operation. Unfortunately, an estimated 70-80% of this waste has not been properly managed because the waste went from developed to low-income countries to be dumped into landfills or informally recycled. Such recycling has been carried out either directly on landfill sites or in small, often family-run recycling shops without much regulations or oversights. The process traditionally involved manual dismantling, cleaning with hazardous solvents, burning and melting on open fires, etc., which would generate a variety of toxic substances and exposure/hazards to applicators, family members, proximate residents and the environment. The situation clearly calls for global responsibility to reduce the impact on human health and the environment, especially in developing countries where poor residents have been shouldering the hazardous burden. On the other hand, formal e-waste recycling has been mainly conducted in small scales in industrialized countries. Whether the latter process would impose less risk to populations and environment has not been determined yet. Therefore, the main objectives of this review are: 1. to address current trends and emerging threats of not only informal but also formal e-waste management practices, and 2. to propose adequate measures and interventions. A major recommendation is to conduct independent surveillance of compliance with e-waste trading and processing according to the Basel Ban Amendment. The recycling industry needs to be carefully evaluated by joint effort from international agencies, producing industries and other stakeholders to develop better processes. Subsequent transition to more sustainable and equitable e-waste management solutions should result in more effective use of natural resources, and in prevention of adverse effects on health and the environment.

The internal exposure of phthalate metabolites and bisphenols in waste incineration plant workers and the associated health risks

Many hazardous substances can be released during incineration of municipal solid waste (MSW), which pose a potential threat to human health. As additives, phthalates (PAEs) and bisphenols (BPs), which are widely used in daily goods, are likely to be present in the released hazardous substances. In the present study, we investigated the urinary levels of phthalate metabolites (mPAEs) and BPs in workers in an MSW incineration plant (the exposed group) and in residents 8 km away (the control group) in Shenzhen, China. The results showed that the median total urinary concentration of mPAEs in workers was significantly higher than that in residents (1.02 × 10³ vs. 375 ng/mL). However, there was no significant difference between workers and residents for BPs. Among the mPAEs measured, the most abundant compound was mono-n-butyl phthalate in both exposed and control groups. Monoethyl phthalate and monomethyl phthalate might be potential markers for MSW incineration because of significantly high levels in the exposed group. The workers engaged in different types of workshops showed no significant differences in the urinary levels of mPAEs, also for BPs. It was worth noting that 70.8% of workers were at risk of the non-carcinogenic effects caused by PAEs with diethylhexyl phthalate having the highest risk. Actions should be taken to reduce the risks caused by these hazardous chemicals.