Halogenated and organophosphorous flame retardants in surface soils from an e-waste dismantling park and its surrounding area: Distributions, sources, and human health risks

Composition profiles of halogenated flame-retardants in the surface soils and in-situ cypress leaves from two chemical industrial parks

There is limited information available regarding the investigation on typical organic pollutants between the soil and in-situ grown plant leaves. This study is to reveal whether the pollution characteristics of soil and leaves can reflect the long-term and short-term pollution situation, and to find the differences between halogenated flame-retardants in the surface soils and in-situ cypress leaves. Polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), and decabromodiphenyl ethane (DBDPE) in were investigated in two different industrial parks, which were located at the largest brominated flame-retardant-manufacturing center in Weifang, China. These chemicals were frequently detected with high median concentrations of PBDEs (1.22 × 10³ ng/g) and DBDPE (227 ng/g) in the soil samples, and DBDPE (881 ng/g) and PBDEs (461 ng/g) in the in-situ cypress leaves. The DP concentration was 1-4 orders of magnitude lower than the other two chemicals in both the matrices. Different composition profiles of the chemicals in soil and cypress leaves were observed. The PBDEs and DBDPE were found to be the predominant species in soils and cypress leaves, respectively. In comparison, the LG industrial parks had higher concentrations of PBDEs and DBDPE in both the soils and cypress leaves. No significant correlations were observed for these chemicals between the soil and leaf samples, although significant correlations (p < 0.05) were observed for several PBDE congeners among all samples from the industrial parks and a separate industrial park. The results indicated that the soil was not the important source of these chemicals in leaves. A large proportion of DBDPE was preferentially present in cypress leaves, which revealed the situation of recent pollution. The results deepen the understanding of chemical distribution characteristics among different environmental matrices in soils and leaves.

Comprehensive characterization of halogenated flame retardants and organophosphate esters in settled dust from informal e-waste and end-of-life vehicle processing sites in Vietnam: Occurrence, source estimation, and risk assessment

Information about the co-occurrence of halogenated flame retardants (HFRs) and organophosphate esters (OPEs) in the environment of informal waste processing areas is still limited, especially in emerging and developing countries. In this study, OPEs and HFRs including polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), and chlorinated flame retardants (CFRs) were determined in settled dust from Vietnamese e-waste recycling (WR) and vehicle processing (VP) workshops. Pollutant concentrations decreased in the order: OPEs (median 1500; range 230-410,000 ng/g) ≈ PBDEs (1200; 58-250,000) > NBFRs (140; not detected - 250,000) > CFRs (13; 0.39-2200). HFR and OPE levels in the WR workshops for e-waste and obsolete plastic were significantly higher than in the VP workshops. Decabromodiphenyl ether and decabromodiphenyl ethane are major HFRs, accounting for 60 ± 26% and 25 ± 29% of total HFRs, respectively. Triphenyl phosphate, tris(2-chloroisopropyl) phosphate, and tris(1,3-dichloroisopropyl) phosphate dominated the OPE profiles, accounting for 30 ± 25%, 25 ± 16%, and 24 ± 18% of total OPEs, respectively. The OPE profiles differed between WR and VP dust samples, implying different usage patterns of these substances in polymer materials for electric/electronic appliance and automotive industries. Human health risk related to dust-bound HFRs and OPEs in the study areas was low.

Heterologous spatial distribution of soil polycyclic aromatic hydrocarbons and the primary influencing factors in three industrial parks

Soil polycyclic aromatic hydrocarbons (PAHs) generated from industrial processes are highly spatially heterologous, with limited quantitative studies on their main influencing factors. The present study evaluated the soil PAHs in three types of industrial parks (a petrochemical industrial park, a brominated flame retardant manufacturing park, and an e-waste dismantling park) and their surroundings. The total concentrations of 16 PAHs in the parks were 340-2.43 × 10³, 26.2-2.63 × 10³, and 394-2.01 × 10⁴ ng/g, which were significantly higher than those in the surrounding areas by 1-2 orders of magnitude, respectively. The highest soil PAH contamination was observed in the e-waste dismantling park. Nap can be considered as characteristic pollutant in the petrochemical industrial park, while Phe in the flame retardant manufacturing park and e-waste dismantling park. Low molecular weight PAHs (2-3 rings) predominated in the petrochemical industrial park (73.0%) and the surrounding area of brominated flame retardant manufacturing park (80.3%). However, high molecular weight PAHs (4-6 rings) were enriched in the other sampling sites, indicating distinct sources and determinants of soil PAHs. Source apportionment results suggested that PAHs in the parks were mainly derived from the leakage of petroleum products in the petroleum manufacturing process and pyrolysis or combustion of fossil fuels. Contrarily, the PAHs in the surrounding areas could have been derived from the historical coal combustion and traffic emissions. Source emissions, wind direction, and local topography influenced the PAH spatial distributions.

Decadal Journey of E-Waste Recycling: What Has It Achieved?

E-waste recycling has been a hot topic around the world. This Feature revisits the issues raised by our previous Feature 10 years ago, i.e., the environmental, economic, and social benefits of e-waste recycling, using China as an example. The decadal journey of e-waste recycling has witnessed a giant leap from haphazard disposal initially to regulated disassembly presently. Specific successful stories include cleaned environment and reduced human exposure, significant advantages of urban mining over mineral mining, additional employment opportunities, and improved legislation system related to e-waste recycling. Strict legislation systems related to e-waste management based on the principle of Extended Producer Responsibility are key to the sustainable development of the e-waste recycling sector in China. The experiences and lessons learned in China would provide valuable guidelines for other developing countries.

Identification of specific halogenated polycyclic aromatic hydrocarbons in surface soils of petrochemical, flame retardant, and electronic waste dismantling industrial parks

Halogenated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) have received tremendous attention due to their high toxicity. To identify the emission pattern of Cl/Br-PAHs from various industrial productions, understand the formation mechanisms and the influence on the surroundings, this study investigated the surface soils of three typical industrial parks. Generally, traces of Cl-PAHs were much lower than Br-PAHs. The mean Cl-PAH concentrations followed the trend of petrochemical industrial park (3.12 ng/g), brominated flame retardant (BFR) manufacturing park (1.48 ng/g), and electronic waste dismantling park (0.26 ng/g). However, the BFR manufacturing park had the highest mean Br-PAH concentration (21.6 ng/g), significantly higher than the other two parks. Generally, higher levels of the chemicals were found in the parks than in their surroundings, except for the electronic waste dismantling park. The massive addition of chlorine additives in crude oil and its by-products, plus the enormous quantity of brominated brines used in BFR productions, favor Cl/Br-PAH formation. Analyzing the homolog compositions of Cl/Br-PAHs suggested that 3- or 4-ring Cl/Br-PAHs were typically come from the petrochemical industrial park and electronic waste dismantling park. Contrarily, 4- or 5-ring Cl/Br-PAHs were predominantly come from the BFR manufacturing activity. This study provides fingerprints to trace the Cl/Br-PAH emissions during industrial production and analyzes the formation mechanism.

Sub-chronic ecotoxicity of triphenyl phosphate to earthworms (Eisenia fetida) in artificial soil: Oxidative stress and DNA damage

As a flame retardant, triphenyl phosphate (TPHP) is commonly added to various daily products. Due to its easy diffusion, TPHP pollution has become a global concern. Despite the wide focus on environmental risk, the sub-chronic ecotoxicity of TPHP in soil organisms remains unclear. In this study, the artificial soil exposure method was used to analyze the oxidative stress and DNA damage in earthworms with 0, 20, 40, 60 and 80 mg/kg TPHP treatments through the response of reactive oxygen species (ROS), antioxidant and detoxifying enzymes, malondialdehyde (MDA) and olive tail moment (OTM) at 7, 14, 21 and 28 days. Throughout the experimental period, the results showed that the ROS content in earthworms treated with 20, 40, 60 and 80 mg/kg TPHP treatments increased by 9.43-18.37 %, 6.07-25.73 %, 7.71-42.61 % and 8.22-46.70 %, respectively, compared to the control treatment. Meanwhile, the activities of antioxidant and detoxification enzymes in earthworms with all TPHP treatments were significantly activated after exposure for 7 and 14 days, and then inhibited at 21 and 28 days. Despite the protection of antioxidant enzymes and detoxification enzymes, MDA content in earthworms with the 20 mg/kg treatment still significantly increased at 7 and 14 days of exposure, as well as in the other three treatments. Compared to the control treatment, the obviously higher OTM values in earthworms with TPHP treatments possibly indicated a genotoxicity of TPHP in earthworms. Furthermore, the integrated biomarker response index (IBRv2) revealed that earthworms showed an obvious biochemical response TPHP-contaminated soil, which was strongly correlated with TPHP concentrations and exposure time. This study provides insights into the TPHP hazard in the soil environment and offers a reference to assess its environmental risk to soil ecosystems.

Riverine transport dynamics of PBDEs and OPFRs within a typical e-waste recycling zone: Implications for sink-source interconversion

Despite ample evidence on spreading of e-waste derived hazardous materials, riverine transport of organic contaminants from e-waste recycling zones to surrounding areas has not been evaluated. To address this issue, passive and grab sampling methods were used to assess sediment-water diffusion and horizontal transport of polybrominated diphenyl ethers (PBDEs) and organophosphorus flame retardant (OPFRs) at upstream and downstream sites of two rivers in a typical e-waste recycling zone. Sediment acted as a source of BDE-17 with fluxes of 0.007-0.04 ng m^-2 d^-1 at all sampling sites. BDE-47 and BDE-99 reached equilibrium between overlying water and sediment porewater. Sediment interconverted from a sink at the upstream site to a source of OPFRs at the downstream site with a flux varying between -7.3 and 234 ng m^-2 d^-1. The amounts of OPFRs (11-45 g d^-1) via horizontal riverine transport were greater than those of PBDEs (0.68-2 g d^-1). The vertical sediment-water diffusion of PBDEs and OPFRs was not significant compared to horizontal riverine transport. The annual riverine outputs of PBDEs and OPFRs from the downstream sites were 250-330 g and 12,000-16,500 g, respectively, indicating the significance of riverine transport of organic contaminants from e-waste recycling zones to surrounding areas.

Debromination process of Br-containing PS of E-wastes and reuse with virgin PS

High Br-containing polystyrene (PS) plastics are generated in large quantities during the dismantling of waste CRT TVs. Debromination and reuse of Br-containing PS plastics is a critical technical challenge. Here, we demonstrate a method for combining alkaline hydrothermal debromination and co-blending granulation to achieve the regeneration of high Br-containing PS plastics. The results show the bromine concentration in PS was reduced from 49,300 mg/kg to 7420 mg/kg and from 169,000 mg/kg to 9340 mg/kg, with a removal efficiency of 84.95% at least. Then, we co-blended the debromination PS products (1 part) with qualified normal PS plastics (9 parts) for granulation. Compared to the qualified normal PS, the physical properties of the co-blended plastics remained stable in terms of the melt index, tensile strength, flexural strength andflexural modulus, which made it have good application prospects. Meanwhile, the Br concentration of co-blended PS plastics were further reduced to less than 1000 mg/kg. In summary, we provide a promising outlook of alkaline hydrothermal and co-blending (1 +9) granulation as an efficient approach for Br-containing PS plastics upgrading recycling. NOVELTY STATEMENT: This study provides a novel method for combining alkaline hydrothermal treatment and co-blending modification granulation process to achieve the upgrading recycling of Br-containing waste plastics. The results show the Br concentration in PS was reduced from 169,013 ppm to 9344 ppm, with a removal efficiency of 94.47%. The debromination PS products (1 part) were blended with qualified normal PS plastics (9 parts) for granulation. Compared to the qualified normal PS, the physical properties of the co-blended plastics remained basically stable, which made it have good application prospects. Also, the reuse of waste plastic can make contribution for the carbon reduction.

Major contaminants of emerging concern in soils: a perspective on potential health risks

Soil pollution by the contaminants of emerging concern (CECs) or emerging contaminants deserves attention worldwide because of their toxic health effects and the need for developing regulatory guidelines. Though the global soil burden by certain CECs is in several metric tons, the source-tracking of these contaminants in soil environments is difficult due to heterogeneity of the medium and complexities associated with the interactive mechanisms. Most CECs have higher affinities towards solid matrices for adsorption. The CECs alter not only soil functionalities but also those of plants and animals. Their toxicities are at nmol to μmol levels in cell cultures and test animals. These contaminants have a higher propensity in accumulating mostly in root-based food crops, threatening human health. Poor understanding on the fate of certain CECs in anaerobic environments and their transfer pathways in the food web limits the development of effective bioremediation strategies and restoration of the contaminated soils and endorsement of global regulatory efforts. Despite their proven toxicities to the biotic components, there are no environmental laws or guidelines for certain CECs. Moreover, the information available on the impact of soil pollution with CECs on human health is fragmentary. Therefore, we provide here a comprehensive account on five significantly important CECs, viz., (i) PFAS, (ii) micro/nanoplastics, (iii) additives (biphenyls, phthalates), (iv) novel flame retardants, and (v) nanoparticles. The emphasis is on (a) degree of soil burden of CECs and the consequences, (b) endocrine disruption and immunotoxicity, (c) genotoxicity and carcinogenicity, and (d) soil health guidelines.

Comprehensively screening of citric acid ester (CAE) plasticizers in Chinese foodstuffs, and the food-based assessment of human exposure risk of CAEs

An increasing number of studies on the toxicities of citric acid esters (CAEs)-a class of so-called "safe" alternative plasticizers-have highlighted the urgent need to understand their contamination profiles in foodstuffs and the corresponding potential risks to human health. This study determined the concentrations of 8 target CAEs in 105 foodstuff samples, grouped into 6 food categories, collected from Nanjing City, China, in 2020. All eight CAEs were detected in at least one of the analyzed samples and had detection frequencies (DFs) of 5-47%. The DFs and distribution profiles of the target CAEs varied among different food categories; for example, cereals had the highest DF (92%), while meat/fish contained the highest mean total concentration of CAEs (8.35 ng/g wet weight (ww)). Among the target CAEs, acetyl tributyl citrate (ATBC) had the highest DF (47%), and tributyl citrate (TBC) exhibited the highest mean concentration (1.24 ng/g ww). Based on the food ingestion route, the estimated total daily intake (EDI) values of the target CAEs for adults under average- and high-exposure scenarios were 38.3 ng/kg of body weight (bw) and 111 ng/kg bw, respectively, which were attributed to the high percentage contributions of TBC (50.6%) and ATBC (23.7%). In addition, a suspect and characteristic fragment-dependent screening strategy was applied to the foodstuff data, and a novel CAE, monoethyl citrate (MEC, CAS: 4552-00-5), with a DF of 34% was tentatively identified. Overall, this study provides novel and comprehensive information regarding the pollution status of CAEs in foodstuffs.

Similarities and differences among the responses to three chlorinated organophosphate esters in earthworm: Evidences from biomarkers, transcriptomics and metabolomics

The wide use of chlorinated organophosphate esters (Cl-OPEs) as additive flame retardants has aroused concern about their potential risks on ecosystem and human health. However, knowledge about the toxicity of Cl-OPEs on soil organisms remains limited. In this study, earthworms, Eisenia fetida, were exposed to three representative Cl-OPEs, i.e., tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-1-methylethyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) in artificial soil. Using a combination of biochemical indicators (biomarkers), transcriptomics, and metabolomics, we compared the Cl-OPE-induced toxicity to E. fetida and provide new insight into the related molecular mechanism. All three Cl-OPEs elicited immune defense by the earthworms, as evidenced by increased acid phosphatase and alkaline phosphatase activities, and the genes involved in immune-related pathways (e.g., lysosomal and interleukin-17 signaling pathways). Furthermore, no effects on acetylcholinesterase activity were observed among the three Cl-OPEs. However, the TCPP and TDCPP treatments significantly decreased the neurotransmitter serotonin, suggesting the potential neurotoxicity of Cl-OPEs. Although TCEP affected the genes involved in carbohydrate and amino acid metabolism, the changes in the corresponding metabolites were not statistically significant. In contrast, exposure to TCPP and TDCPP induced oxidative stress, and affected xenobiotic metabolism and energy metabolism, leading to the decreased body weight in E. fetida. Based on these toxic effects, TCPP and TDCPP were more severely toxic than TCEP, despite their structural similarity. Given that the use of TCEP has been tightly regulated, our results suggest the potentially toxic effects of TCPP and TDCPP should not be ignored in future risk assessments of flame retardants.

A review of organophosphate esters in soil: Implications for the potential source, transfer, and transformation mechanism

Organophosphate esters (OPEs) are widely used around the world as flame retardants and plasticizers with a growing production in the last 15 years due to the phase-out of polybrominated diphenyl ethers. Multiple papers reported the occurrences of OPEs in various environmental matrices and elevated concentrations of OPEs (0.1-10,000 ng/g dry weight) were documented in different types of soils which were regarded as both the "sink" and "source" of OPEs. In this study, the source, transfer, and transformation mechanisms of OPEs are systematically reviewed from the perspective of the soil environment. The wet/dry deposition, air-soil exchange, sewage irrigation, sludge application, and indirect oxidization of organophosphate antioxidants are the possible sources of OPEs in soil. Meanwhile, the OPEs in the soil environment may also migrate into other environmental media via plant uptake, air-soil exchange, desorption, and infiltration to cause relevant ecological risk, which depends much on the chemical properties of these compounds. The trimethylphenyl phosphate (TMPP) (mixture of isomers) and triphenyl phosphate (TPHP), which have strong hydrophobicity, pose a higher ecological risk for the soil environment than other OPEs. Further, the hydrolysis, indirect photolysis, and biodegradation of OPEs in the soil environment may be affected by the soil pH, organic acid, dissolved metals and metal oxides, active oxygen species, and microorganisms significantly. Besides that, the human exposure risks of OPEs from the soil are limited compared to those via indoor dust and food ingestion pathways. Finally, this study identifies the knowledge gaps and generated the future perspectives of the OPEs in soil.

Formal waste treatment facilities as a source of halogenated flame retardants and organophosphate esters to the environment: A critical review with particular focus on outdoor air and soil

Extensive use of halogenated flame retardants (HFRs) and organophosphate esters (OPEs) has generated great concern about their adverse effects on environmental and ecological safety and human health. As well as emissions during use of products containing such chemicals, there are mounting concerns over emissions when such products reach the waste stream. Here, we review the available data on contamination with HFRs and OPEs arising from formal waste treatment facilities (including but not limited to e-waste recycling, landfill, and incinerators). Evidence of the transfer of HFRs and OPEs from products to the environment shows that it occurs via mechanisms such as: volatilisation, abrasion, and leaching. Higher contaminant vapour pressure, increased temperature, and elevated concentrations of HFRs and OPEs in products contribute greatly to their emissions to air, with highest emission rates usually observed in the early stages of test chamber experiments. Abrasion of particles and fibres from products is ubiquitous and likely to contribute to elevated FR concentrations in soil. Leaching to aqueous media of brominated FRs (BFRs) is likely to be a second-order process, with elevated dissolved humic matter and temperature of leaching fluids likely to facilitate such emissions. However, leaching characteristics of OPEs are less well-understood and require further investigation. Data on the occurrence of HFRs and OPEs in outdoor air and soil in the vicinity of formal e-waste treatment facilities suggests such facilities exert a considerable impact. Waste dumpsites and landfills constitute a potential source of HFRs and OPEs to soil, and improper management of waste disposal might also contribute to HFR contamination in ambient air. Current evidence suggests minimal impact of waste incineration plants on BFR contamination in outdoor air and soil, but further investigation is required to confirm this.

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

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

Pollution profiles and human health risk assessment of atmospheric organophosphorus esters in an e-waste dismantling park and its surrounding area

Recycling e-waste has been recognized as an important emission source of organophosphate triesters (tri-OPEs) and organophosphate diesters (di-OPEs), but the presence of di-OPEs in atmosphere has not been studied. Herein, tri-OPEs and di-OPEs in atmosphere of an e-waste dismantling park and surrounding area in South China were monitored for three consecutive years. Thirteen tri-OPEs and seven di-OPEs were identified. In 2017, 2018, and 2019, tri-OPE concentrations in e-waste dismantling park were 1.30 × 10⁸, 4.60 × 10⁶, and 4.01 × 10⁷ pg/m³, while di-OPE concentrations were 1.14 × 10³, 1.10 × 10³, and 0.35 × 10³ pg/m³, respectively, which were much higher than the surrounding area. Tri-OPEs and di-OPEs generated during e-waste dismantling affected surrounding area through diffusion. Triphenyl phosphate (TPhP) and diphenyl phosphate (DPhP) were the predominant congeners of tri-OPEs and di-OPEs, respectively. Additionally, TPhP concentration was extremely higher than other tri-OPEs, so TPhP could be used as an indicator of e-waste dismantling. Spearman correlation analysis showed significant correlations between DPhP and TPhP (R² = 0.53, p < 0.01), bis-(1-chloro-2-propyl) phosphate (BCIPP) and tris(2-chloropropyl) phosphate (TCIPP) (R² = 0.49, p < 0.01), as well as dibutyl phosphate (DBP) and tributyl phosphate (TBP) (R² = 0.53, p < 0.01), indicating that they had the same source. Further, non-carcinogenic risk of them to people via inhalation was acceptable and non-carcinogenic risk of tri-OPEs decreased year by year in surrounding area.

Exploring source footprint of Organophosphate esters in the Bohai Sea, China: Insight from temporal and spatial variabilities in the atmosphere from June 2014 to May 2019

Organophosphate esters (OPEs) are still produced and used in large quantities in the world-wide, and the environmental burden and behavior have generated widespread concern, especially in some large-scale waterbodies. This study conducted a comprehensive assessment on the temporal and spatial variabilities and budget of OPEs to trace the source for the Bohai Sea (BS), based on a 5-year seasonal monitoring campaign (June 2014 to May 2019) of 12 atmospheric sites around the BS and our previous studies. The average concentration of Σ₁₀OPEs in atmosphere during the sampling period was 7.65 ± 6.42 ng m^-3, and chlorinated OPEs were the major compounds. The Seasonal-Trend decomposition procedure based on Loess (STL) analyzed that during the 5-year sampling period, the atmospheric concentrations of Σ₁₀OPEs had a slightly increasing trend with a rate of + 0.092 ng m^-3 yr^-1, and the seasonal concentrations had a distinct seasonal distribution. The highest concentration of Σ₁₀OPEs was observed at the sampling site of Dalian, followed by Tianjin, Yantai, and Beihuangcheng. The estimation of the fugacity ratios and air-water gas exchange fluxes established that the concentration levels of two major components of chlorinated OPEs (tris-(2-chloroethyl) phosphate (TCEP) and tris-(1-chloro-2-propyl) phosphate (TCPP)) in the atmosphere were dominated by their volatilization from BS's seawater (1.24 ± 0.46 t yr^-1 for TCEP and 5.15 ± 2.15 t yr^-1 for TCPP), with 73% deriving from the coastal seawater. The budget assessment suggested that the volatile fluxes of TCEP and TCPP accounted for 8% and 29% of their storages (15.6 ± 5.32 t for TCEP and 17.6 ± 6.70 t for TCPP) in the BS seawater, which were mainly contributed by continental river input (20% for TCEP and 42% for TCPP). The efforts indicated that river inputs of TCEP and TCPP needed to be paid more attention for the improvement of environmental quality of the BS.

Current pollution status, spatial features, and health risks of legacy and emerging halogenated flame retardants in agricultural soils across China

Soil is a major reservoir and a secondary source of semi-volatile organic chemicals, while studies on the pollution status of halogenated flame retardants (HFRs) in agricultural soils are limited. In this study, a total of twenty-five chemicals including novel brominated flame retardants (NBFRs), polybrominated diphenyl ethers (PBDEs), and dechlorane plus (DPs) was analyzed in the agricultural soils across China to investigate the occurrence, spatial distribution, potential sources, influencing factors and their associated human health risks. The results showed that BDE-209 (125-130,183 pg/g, dry weight, d.w.) was the most abundant flame retardant of PBDEs, followed by decabromodiphenyl ethane (DBDPE) (9.27-22,864 pg/g, d.w.). Meanwhile, the DPs (anti-DP plus syn-DP) were in the range of ND-1229 pg/g (d.w.), and the range of f_anti values (the concentration of anti-DP divided by the sum of the concentrations of two isomers) in this study greatly matched those of commercial products, suggesting the effect of proximity to the source region. The higher levels of HFRs were found in Eastern and Southern regions of China. Spatial distribution implied that e-waste recycling activities and plastic processing have shown more importance in releasing legacy flame retardants (FRs) into the environment than the manufacturing process, while all are important for novel FRs. Correlation analysis between influencing factors and HFRs indicated that the distribution of most pollutants was more affected by anthropogenic source factors than environmental factors. The results of the principal component analysis demonstrated that deca-BDE and its alternative products were the major contributors to the sources of HFRs pollution. Human health risks assessment via oral intake and dermal contact pathways presented that the selected pollutants posed a no-carcinogenic risk to children and adults. It is worth noting that supervision of the disposal process of the NBFRs should be strengthened in the future.

Organophosphate esters in surface soils from a heavily urbanized region of Eastern China: Occurrence, distribution, and ecological risk assessment

Organophosphate esters (OPEs) pose increasing concerns for their widespread distribution in soil environments and potential threat to human health. In this study, we investigated the occurrence and associated risks of seven OPEs in surface soils and the potential influence of human activities on soil OPE contamination in a heavily urbanized region of the Yangtze River Delta in Eastern China. All target OPEs were detected in the soil samples (100% of samples) reflecting their widespread distribution in the study region. The total OPE concentration (the sum of the seven OPEs) ranged from 162.7 to 986.0 ng/g on a dry weight basis, with a mean value of 469.3 ± 178.6 ng/g. Tris (2-butoxyethyl) phosphate was the main compound, accounting for 67-78% of the total OPE concentration. Ecological risk assessment showed that tris(2-chloroisopropyl) phosphate, tris(2,3-dichloropropyl) phosphate, tris(2-butoxyethyl) phosphate, and tris(2-ethylhexyl) phosphate posed a medium potential risk to terrestrial biota (0.1 < risk quotient <1). The human exposure estimation showed insignificant risks to local population. Redundancy analysis revealed that the individual and total OPE contaminations were positively correlated with human activity parameters. The total OPE concentrations were positively correlated to population density (R² = 0.38, P < 0.001), and urban land use percentage (R² = 0.39, P < 0.001), while negatively correlated to forest land use percentage (R² = 0.59, P < 0.001), suggesting a significant contribution of human disturbance to OPE pollution. These results can facilitate OPE contamination control and promote sustainable soil management in urbanized and industrialized regions.

Health risk assessment and development of human health ambient water quality criteria for PBDEs in China

Polybrominated diphenyl ethers (PBDEs) are not only a class of highly efficient brominated flame retardants (BFRs) but also a class of typical persistent organic pollutants (POPs) that are persistent and widely distributed in various environmental media. This study examined the concentrations of PBDEs in five environmental media (water, soil, air, dust, and food) and two human body media (human milk and blood) in China from 2010 to 2020. In addition, this study conducted multi-pathway exposure health risk assessments of populations of different ages in urban, rural, key regions, and industrial factories using the Monte-Carlo simulation. Finally, the human health ambient water quality criteria (AWQC) of eight PBDEs were derived using Chinese exposure parameters and bioaccumulation factors (BAFs). The results showed that the eastern and southeastern coastal regions of China were heavily polluted by PBDEs, and the variation trends of the ΣPBDEs concentrations in the different exposure media were not consistent. PBDEs did not pose a risk to urban and rural residents in ordinary regions, but the hazard indexes (HIs) for residents in key regions and occupational workers exceeded the safety threshold. Dust exposure was the primary exposure pathway for urban and rural residents in ordinary regions, but for residents in key regions and occupational workers, dietary exposure was the primary exposure pathway. BDE-209 was found to be the most serious individual PBDE congener in China. The following human health AWQC values of the PBDEs were derived: drinking water exposure: 0.233-65.2 μg·L^-1; and drinking water and aquatic products exposure: 8.51 × 10^-4-1.10 μg·L^-1.

Organophosphate flame retardants, tetrabromobisphenol A, and their transformation products in sediment of e-waste dismantling areas and the flame-retardant production base

Due to the prohibition of polybrominated diphenyl ethers, organophosphate flame retardants (OPFRs) and tetrabromobisphenol A (TBBPA) have become emerging flame retardants. However, knowledge about their occurrence, especially their transformation products, is still limited. This study collected sediment samples from two rivers, i.e., Lianjiang River (located at an e-waste dismantling area) and Xiaoqing River (situated at a flame retardant production base), to investigate the occurrence, composition, and spatiality distribution of OPFRs, TBBPA, and their transformation products. Both targets were detected in the Lianjiang River in the range of 220-1.4 × 10⁴ and 108-3.1 × 10³ ng/g dw (dry weight) for OPFRs and TBBPA, and 0.11-2.35 and 4.8-414 ng/g dw for their respective transformation products, respectively. The concentrations of OPFRs and TBBPA in the Xiaoqing River ranged from 4.15 to 31.5 and 0.76-2.51 ng/g dw, respectively, and no transformation products were detected. Different compositional characteristics of OPFRs and distinct spatial distribution from mainstream and tributary observed between the two rivers are attributed to the difference in the local industries. Spatial distribution and principal component analysis indicated that e-waste dismantling activities could be a vital source of local pollution. Besides, the confluence of tributaries seemed to determine the contaminant levels in the Xiaoqing River. Also, concentration ratios and Spearman's correlation between metabolites and parent chemicals were analyzed. Low concentration ratios (3.6 ×10^-4 to 0.16) indicated a low transformation degree, and Spearman's correlation analysis suggested transformation products were partly stemming from commercial products. Considering the limited study of these transformation products, more studies on their sources, transform mechanism, and toxicity are required.

Identifying Citric Acid Esters, a Class of Phthalate Substitute Plasticizers, in Indoor Dust via an Integrated Target, Suspect, and Characteristic Fragment-Dependent Screening Strategy

Citrate acid esters (CAEs) have been proposed as a class of phthalate substitute plasticizers; however, information on their occurrence in indoor environments is rare. By using liquid chromatography coupled with a quadrupole-Orbitrap mass spectrometer, we developed an integrated strategy that can be applied for target, suspect, and characteristic fragment-dependent screening of CAEs. In n = 50 indoor dust samples collected from Nanjing City (China), three CAEs, namely, acetyl tributyl citrate (ATBC; mean: 412,000 ng/g), tributyl citrate (TBC, 11,600 ng/g), and triethyl citrate (TEC, 10,900 ng/g), exhibited the greatest contamination levels. Total concentrations of CAEs (∑₈CAEs) were statistically significantly (p < 0.01) greater than those of common organophosphate triesters (OPTEs), a class of ubiquitous contaminants in dust. Suspect and characteristic fragment-dependent screening (m/z 111.0078 ([C₅H₃O₃]⁺) and m/z 129.0181 ([C₅H₅O₄]⁺)) of CAEs were further conducted for the same batch of samples. We tentatively identified six novel CAEs, and the most frequent and abundant CAE was fully identified as tributyl aconitate (TBA). Statistically significant correlation relationships were observed on dust levels between TBA vs ATBC (r = 0.650; p < 0.01) and TBA vs TBC (r = 0.384; p < 0.01), suggesting their similar sources in dust samples.

Identifying Dermal Uptake as a Significant Pathway for Human Exposure to Typical Semivolatile Organic Compounds in an E-Waste Dismantling Site: The Relationship of Contaminant Levels in Handwipes and Urine Metabolites

Dermal exposure to semivolatile organic compounds (SVOCs) has recently attracted widespread attention; understanding these exposures is particularly important for people whose skin is frequently exposed to different pollution surfaces. In this study, handwipes were collected from exposed occupational workers and local residents near a typical electronic waste (e-waste) dismantling area; urine samples were also sampled. The wipes were analyzed for three typical SVOCs: polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and organophosphate flame retardants (OPFRs). The median levels of PAHs, OPFRs, and PBDEs in handwipes from e-waste dismantlers were 96.0, 183, and 238 ng, respectively. The analytes were higher in the handwipes collected from workers than those from residents, indicating that they were subjected to greater dermal exposure during primitive e-waste dismantling activities. Among the three SVOCs, the strongest correlation was found between triphenyl phosphate (TPhP) in handwipes and diphenyl phosphate (DPhP) in paired urine; the next strongest correlations were between PAHs and PBDEs and their corresponding urinary metabolites. The results showed that TPhP contributed the highest exposure to e-waste dismantlers via dermal exposure. Our research highlights the importance of dermal exposure to TPhP, which should be considered in future exposure risk assessments.

Assessment of Pre-Treatment Techniques for Coarse Printed Circuit Boards (PCBs) Recycling

Waste electrical and electronic equipment or e-waste generation has been skyrocketing over the last decades. This poses waste management and value recovery challenges, especially in developing countries. Printed circuit boards (PCBs) are mainly employed in value recovery operations. Despite the high energy costs of generating crushed and milled particles of the order of several microns, those are employed in conventional hydrometallurgical techniques. Coarse PCB pieces (of order a few centimetres) based value recovery operations are not reported at the industrial scale as the complexities of the internal structure of PCBs limit efficient metal and non-metal separation. Since coarse PCB particles’ pre-treatment is of paramount importance to enhance metal and non-metal separations, thermal, mechanical, chemical and electrical pre-treatment techniques were extensively studied. It is quite evident that a single pre-treatment technique does not result in complete metal liberation and therefore several pre-treatment flowsheets were formulated for coarse PCB particles. Thermal, mechanical and chemical pre-treatments integrated flowsheets were derived and such flowsheets are seldom reported in the e-waste literature. The potential flowsheets need to be assessed considering socio-techno-economic considerations to yield the best available technologies (BAT). In the wider context, the results of this work could be useful for achieving the United Nations sustainable development goals.

Highly effective removal of bisphenol A by greigite/persulfate in spiked soil: Heterogeneous soil/water system balance and degradation

The degradation of bisphenol A (BPA) in spiked soil was studied to investigate persulfate (PS) activation by the environment-friendly heterogeneous material greigite for removing organic pollutants from soil. The effects of the PS and greigite doses were investigated, and the BPA degradation rate in the lateritic red soil was lower than that in kaolin. Notably, 500 mg/kg of BPA could be effectively removed by the flower-like greigite (FLG)/PS system in 30 min. The difference in BPA degradation in kaolin and the lateritic red soil was negligible, thus indicating that the contents of components such as total organic matters in the lateritic red soil did not affect the BPA degradation rate of the FLG/PS system considerably. Furthermore, the distribution processes of BPA in the soil and liquid phase were also investigated in detail. The results showed that the water contents were a key factor in the distribution and degradation of BPA. The transfer of BPA from kaolin to the liquid phase was simpler than that from the lateritic red soil to the liquid phase. BPA might be transferred to the liquid phase first and then degraded by the FLG/PS system in that phase. Regarding BPA degradation in the lateritic red soil, BPA was degraded in the soil and liquid phases at the same time. This study proposed a pathway for BPA degradation in soil slurries by heterogeneous material/PS systems for first time, providing a deeper understanding of the degradation mechanism of organic pollutants in soil and new methods for soil remediation.

Uptake and translocation of organophosphate esters by plants: Impacts of chemical structure, plant cultivar and copper

Organophosphate esters (OPEs) are normally used as flame retardants, plasticizers and lubricants, but have become environmental pollutants. Because OPEs are normally present alongside heavy metals in soils, the effects of interactions between OPEs and heavy metals on plant uptake of OPEs need to be determined. In this study, we investigated the effects of OPEs chemical structure, plant cultivar and copper (Cu) on the uptake and translocation of OPEs by plants. The bioaccumulation of OPEs varied among plant cultivars. They were preferentially enriched in carrot, with the lowest concentrations observed in maize. OPEs with electron-ring substituents (ER-OPEs) exhibited a higher potential for root uptake than did OPEs with open-chain substituents (OC-OPEs), which could be attributed to the higher sorption of ER-OPEs onto root charged surfaces. This was explained by the stronger noncovalent interactions with the electron-rich structure of ER-OPEs. The presence of Cu slightly reduced the distinct difference in the ability of roots to take up OC-OPEs and ER-OPEs. This was explained by the interactions of Cu ions with the electron-rich structure of ER-OPEs, which suppressed the sorption of ER-OPEs on the root surface. A negative relationship between the logarithms of the translocation factor and octanol-water partition coefficient (K_ow) was observed in treatments with either OPEs only or OPEs + Cu, implying the significant role of hydrophobicity in the OPEs acropetal translocation. The results will improve our understanding of the uptake and translocation of OPEs by plant cultivars as well as how the process is affected by the chemical structure of OPEs and Cu, leading to improvements in the ecological risk assessment of OPEs in the food chain.

Organophosphorus flame retardants in breast milk from Beijing, China: Occurrence, nursing infant's exposure and risk assessment

Organophosphorus flame retardants (OPFRs) are widely used chemicals, whereas data on OPFRs in human being is limited. In this study, thirteen OPFRs were measured in 105 breast milk samples collected from Beijing mothers in 2018. The ∑₁₃OPFRs ranged from <LOD to 106 ng mL^-1 (<LOD-6700 ng g^-1 lipid weight (lw)), with a median value 10.6 ng mL^-1 (157 ng g^-1 lw). The most abundant compound was tris(2-ethylhexyl) phosphate (TEHP), followed by triphenyl phosphate (TPhP) and 2-ethylhexyl diphenyl phosphate (EHDPP). The detecting frequencies and contamination levels of OPFRs in our study were higher than those reported in other studies, which indicated that China is one of the most affected regions by OPFRs. In addition, OPFR levels in our study were found to be higher than levels of brominated flame retardants (BFRs) in human milk from China. Based on regression analyses, mothers' personal characters, including age, pregnancy, residing/working location, and educational level were found to be impact factors of some OPFRs in breast milk. Estimated daily intakes (EDI) of the OPFRs for nursing infants via human milk ingest were calculated, and the mean EDIs of the 13 OPFRs ranged from 2.62 to 1640 ng kg^-1 bw d^-1. Since the mean and max EDIs of most OPFRs were lower than corresponding reference doses (RfDs), the daily OPFR intake for most nursing infants would not cause significant health concerns. However, the max EDIs of two OPFRs, TPhP and EHDPP, with values of 1.09 × 10⁴ and 2190 ng kg^-1 bw d^-1, respectively, were higher than their corresponding RfDs. To our knowledge, this is the first report on the occurrence of OPFRs in human milk from China.

Pollution of plastic debris and halogenated flame retardants (HFRs) in soil from an abandoned e-waste recycling site: Do plastics contribute to (HFRs) in soil?

Electronic waste (e-waste) recycling site may be a "hotspot" for pollution of plastic debris, which has not been well studied. Eighteen halogenated flame retardants (HFRs) were measured in plastics and soil separated from twenty soil samples, respectively, from an abandoned e-waste recycling site. Abundances and concentrations of plastic debris ranged from 600 to 14,200 particles/kg and 0.24-153 mg/g, respectively, which were at the high end in literature. Blue, black, and red were main plastic colors, and acrylonitrile-butadiene-styrene (ABS) was the main type of plastics. Polybrominated diphenyl ether (PBDE) 209 was the main chemical, with median concentrations of 6.22-40.6 μg/g in soil and 28.1-47.2 μg/g in plastics, respectively. Contributions of HFRs in plastics were less than 10% in total HFR masses in bulk soil samples. Exposure values to HFRs from plastics via soil ingestion and dermal contact with soil were generally two orders of magnitude lower than those from soil. The results indicate that plastics in soil have little contribution to total HFR burden in soil and human exposure risks to HFRs in this study. However, ecological risks of plastics to terrestrial wildlife in e-waste sites should be paid attention.

Ornamental houseplants as potential biosamplers for indoor pollution of organophosphorus flame retardants

We investigated the occurrence, compositions, and partitioning behaviors of organophosphorus flame retardants (OPFRs) in indoor dust, air, and ornamental plants in Dalian, China, to evaluate the possibility of using houseplants as indoor biosamplers of OPFRs. The mean concentrations of OPFRs in the indoor air, dust, and plant samples were 14.9 ng/m³, 18,000 ng/g, and 345 ng/g, respectively. Tris(2-chloroisopropyl) phosphate (TCIPP) was the dominant congener in all kinds of samples. Significant correlation was found between the concentrations of tris(1,3-dichloroisopropyl) phosphate (TDCIPP) in indoor air and plants, suggesting that ornamental plant can be used as a sentinel for certain OPFRs in the indoor air. We developed a predictive model to assess the partitioning coefficients of OPFRs between indoor air and plant. The lipid content in leaf cuticle instead of leaf organic matter was used to improve the accuracy and reliability of this assessment. Using this model, we can estimate the OPFR concentrations in the indoor air based on their concentrations measured in the corresponding indoor plant. The estimated air concentrations were generally comparable with the measured concentrations, especially for those with octanol-air partition coefficient log K_oa <11.6. Indoor plants can also provide a more holistic understanding of OPFR occurrence within a home due to the relatively long-term air-foliage partitioning. The results suggest that under certain conditions indoor ornamental plants have the potential to be used as the biosamplers of OPFRs in the indoor environment due to their convenience and low-cost.

Temporal trends of legacy and novel brominated flame retardants in sediments along the Rhône River corridor in France

Brominated flame retardants (BFRs) are anthropogenic compounds that are ubiquitous in most manufactured goods. Few legacy BFRs have been recognised as persistent organic pollutants (POPs) and have been prohibited since the 2000s. However, most BFRs continue to be used despite growing concerns regarding their toxicity; they are often referred to as novel BFRs (nBFRs). While environmental contamination due to chlorinated POPs has been extensively investigated, the levels and spatiotemporal trends of BFRs are comparatively understudied. This study aims to reconstruct the temporal trends of both legacy and novel BFRs at the scale of a river corridor. To this end, sediment cores were sampled from backwater areas in four reaches along the Rhône River. Age-depth models were established for each of them. Polychlorinated biphenyls (PCBs), legacy BFRs (polybrominated diphenyl ethers - PBDEs, polybrominated biphenyls - PBBs and hexabromocyclododecane - HBCDDs) and seven nBFRs were quantified. Starting from the 1970s, a decreasing contamination trend was observed for PCBs. Temporal trends for legacy BFRs revealed that they reached peak concentrations from the mid-1970s to the mid-2000s, and stable concentrations by the mid-2010s. Additionally, individual concentrations of nBFRs were two to four orders of magnitude lower than those of legacy BFRs. Their temporal trends revealed that they appeared in the environment in the 1970s and 1980s. The concentrations of most of these nBFRs have not decreased in recent years. Thus, there is a need to comprehend the sources, contamination load, repartition in the environment, and toxicity of nBFRs before their concentrations reach hazardous levels.

Spatial occurrence and composition profile of organophosphate esters (OPEs) in farmland soils from different regions of China: Implications for human exposure

The environmental load of organophosphate ester (OPE) flame retardants has caused a series of problems due to their extensive use. The soil matrix, as an ultimate sink for organic pollution, plays a vital part in the fate of OPEs in the environment. In this study, the spatial occurrence, composition profile and health risk of 13 OPE species in farmland soils from four provinces of China were characterized. Excluding tris(2,3-dibromopropyl) phosphate (TDBPP) and ethylhexyl diphenyl phosphate (EHDPP), the remaining eleven OPEs had a high detection frequency (DF) ranging from 60% to 100%. The range of total OPE (ΣOPE) concentrations were 62.3-394 ng/g dry weight (dw), with a median of 228 ng/g dw. Among these OPEs, tris(2-ethylhexyl) phosphate (TEHP) with a median of 143 ng/g dw) was the predominant species, followed by tricresyl phosphate (TCP; median of 20.1 ng/g dw) and tris(2-chloroethyl) phosphate (TCEP; median of 17.9 ng/g dw). In terms of geographical distribution, significantly lower OPEs levels were found in samples from Heilongjiang (159 ± 47.0 ng/g dw) than in those of Guangxi (264 ± 66.0 ng/g dw), Henan (252 ± 74.5 ng/g dw) and Hubei (242 ± 52.8 ng/g dw) provinces. Principal component analysis and Spearman's correlations were used to reveal potential sources of OPEs in the different provincial regions. Health risk exposure to OPEs in farmland soils was at an acceptable level (<1.20 × 10^-5 for non-carcinogenic risk to children as the most sensitive age group; and <6.47 × 10^-10 for carcinogenic risk to adults as the most sensitive age group) at the present detected concentrations. However, TCEP and TEHP, the predominant risk contributors, should be paid more attention.

Polybrominated Diphenyl Ethers and Heavy Metals in a Regulated E-Waste Recycling Site, Eastern China: Implications for Risk Management

Serious pollution of multiple chemicals in irregulated e-waste recycling sites (IR-sites) were extensively investigated. However, little is known about the pollution in regulated sites. This study investigated the occurrence of 21 polybrominated diphenyl ethers (PBDEs) and 10 metals in a regulated site, in Eastern China. The concentrations of PBDEs and Cd, Cu, Pb, Sb, and Zn in soils and sediments were 1-4 and 1-3 orders of magnitude lower than those reported in the IR-sites, respectively. However, these were generally comparable to those in the urban and industrial areas. In general, a moderate pollution of PBDEs and metals was present in the vegetables in this area. A health risk assessment model was used to calculate human exposure to metals in soils. The summed non-carcinogenic risks of metals and PBDEs in the investigated soils were 1.59-3.27 and 0.25-0.51 for children and adults, respectively. Arsenic contributed to 47% of the total risks and As risks in 71.4% of the total soil samples exceeded the acceptable level. These results suggested that the pollution from e-waste recycling could be substantially decreased by the regulated activities, relative to poorly controlled operations, but arsenic pollution from the regulated cycling should be further controlled.

Human exposure to halogenated and organophosphate flame retardants through informal e-waste handling activities - A critical review

Informal electrical and electronic waste (e-waste) handling activities constitute a potentially important source of halogenated (HFRs) and organophosphate flame retardants (OPFRs) to the environment and humans. In this review, two electronic databases (ScienceDirect and Web of Science Core Collection) were searched for papers that addressed this topic. A total of 82 relevant studies (including 72 studies selected from the two databases and 10 studies located from the references of the first 72 selected studies) were identified that reported on human external and internal exposure to HFRs and OPFRs arising as a result of informal e-waste handling activities. Compared to the general population, higher levels of external exposure (i.e., inhalation, ingestion, and dermal absorption) and internal exposure (i.e., blood serum, hair, breast milk, urine, and other human matrices) to HFRs and OPFRs were identified for e-waste recyclers and residents inhabiting e-waste dismantling and recycling zones, especially for younger adults and children. Food intake and dust ingestion were the dominant exposure pathways for the majority of brominated flame retardants (BFRs) and dechlorane plus (DP); while inhalation was identified as the most significant pathway of human exposure to OPFRs in informal e-waste sites. The majority of research to date has focused on China and thus future studies should be conducted in other regions such as Africa and South Asia. Other suggested foci of future research are: examination of exposure via dermal contact with e-waste, dietary exposure of local populations to OPFRs, confirmation of the existence of and cause(s) of the higher body burdens of females compared with males amongst populations impacted by informal e-waste handling, and characterisation of exposure of such populations to chlorinated paraffins.

A pilot study of organophosphate esters in surface soils collected from Jinan City, China: implications for risk assessments

Data monitoring is a prerequisite for the occurrence of organophosphate esters (OPEs) in the soil environment in light of their potential toxicity, bioaccumulation, and environmental persistence. In this study, we determined the concentrations and profiles of OPEs in surface soils collected from Jinan City, East China. The soil concentrations of ΣOPE (sum of all OPEs) were in the range of 2.55-581 ng/g dry weight (dw), with an average value of 106 ng/g dw. Industrial soils (mean: 433 ng/g dw) had significantly higher levels of ΣOPE compared with those in urban (42.1 ng/g dw) and farmland soils (7.89 ng/g dw) (p < 0.01), suggesting that industrial activity is an important source of OPEs to ambient soil environment. Tris(1-chloro-2-propyl) phosphate (TCIPP), triphenyl phosphate (TPHP), and tris(2-butoxyethyl) phosphate (TBOEP) were the most abundant OPEs in industrial soils, contributing 30%, 25%, and 20% of ΣOPE, respectively. Principal component analysis revealed that TCIPP, TPHP, and TBOEP in soils derived from respective industrial activities. As compared with other cities within China, the surface soil of Jinan City was mildly contaminated by OPEs, and its human exposure and eco-toxicological risks were found to be negligible. Our study provides current contamination status of OPEs in soils across the multiple functional regions of Jinan, which could be used to support the authorities to make relevant regulations.

A review of the transplacental transfer of persistent halogenated organic pollutants: Transfer characteristics, influential factors, and mechanisms

Persistent halogenated organic pollutants (HOPs) are a class of toxic chemicals, which may have adverse effects on fetuses via transplacental transfer from their mothers. Here, we review reported internal exposure levels of various HOPs (organochlorinated pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, short- and medium-chain chlorinated paraffins, and per- and poly-fluoroalkyl substances) in placenta, and both maternal and umbilical cord sera. We also present analyses of the transplacental transfer and placental distribution characteristics of each class of compounds, and discuss effects of several factors on the transfer and accumulation efficiencies of HOPs, as well as the main mechanisms of HOPs' transfer across the placental barrier. Reported compound-specific transplacental transfer efficiencies and distribution efficiencies, expressed as umbilical cord:maternal serum and placental:maternal serum concentration ratios (R_CM and R_PM, respectively), are summarized. Average published R_CM values of the HOPs range from 0.24 to 3.08 (lipid-adjusted) and from 0.04 to 3.1 (based on wet weights), and are highest for perfluoroalkylcarboxylates (PFCAs) and tetrabromobisphenol A. Average published R_PM values range from 0.14 to 1.02 (lipid-adjusted) and from 0.30 to 1.4 (based on wet weights). The broad R_CM and R_PM ranges may reflect effects of various factors, inter alia physicochemical properties of HOPs, metabolic capacities of mothers and fetuses, placental maturity, and differential expression of influx/efflux transporters in the placenta. Generally, HOPs' R_CM values decline linearly with molecular size, and are curvilinearly related to solubility. Plasma protein binding affinity and the difference between maternal and fetal metabolic capacities may also affect some HOPs' transfer efficiencies. HOPs' molecular size may be influential. Transplacental transport of HOPs likely occurs mostly through passive diffusion, although influx/efflux transporters expressed on maternal and/or fetal sides of the placenta may also facilitate or hinder their transport. Overall, the review highlights clear gaps in our understanding of mechanisms involved in HOPs' transplacental transport.

Temporal trends of "old" and "new" persistent halogenated organic pollutants in fish from the third largest freshwater lake in China during 2011-2018 and the associated health risks

The study aimed to investigate temporal trends of "old" and "new" persistent halogenated organic pollutants (HOPs) in Taihu Lake, the third largest freshwater lake in China, and the associated health risks. Five fish species were consecutively collected from the lake every year during 2011-2018. HOPs including 37 polychlorinated biphenyls (PCBs), 10 organochlorine pesticides (OCPs), short- and medium-chain chlorinated paraffins (SCCPs and MCCPs), 19 polybrominated diphenyl ethers (PBDEs), and 10 new brominated flame retardants (NBFRs), were measured. The results showed that all the HOPs were detected, with MCCPs and NBFRs showing the highest and lowest concentrations, respectively. The levels of SCCPs and MCCPs were several orders of magnitude higher than those of the other HOPs. There were obvious increasing trends for SCCPs, MCCPs, and hexachlorobenzene, but a decreasing trend for PBDEs. No obvious increasing or decreasing trends were observed for the other HOPs. The present study indicated that the use of NBFRs to replace PBDEs was not yet clearly observed. Fish consumption did not result in non-carcinogenic risks, but posed low carcinogenic risks, with PCBs and DDTs being the highest-risk contaminants because of historical residues. This is the first study for the temporal variations of the HOPs in the lake.