Characterization of polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDDs/Fs) in environmental matrices from an intensive electronic waste recycling site, South China

Hydrogen-Donor-Controlled Polybrominated Dibenzofuran (PBDF) Formation from Polybrominated Diphenyl Ether (PBDE) Photolysis in Solutions: Competition Mechanisms of Radical-Based Cyclization and Hydrogen Abstraction Reactions

Polybrominated dibenzofurans (PBDFs) are characteristic dioxin-like products of polybrominated diphenyl ether (PBDE) photolysis. In this study, competition mechanisms of radical-based cyclization and hydrogen abstraction reactions are proposed in PBDF formation. Commonly, the ortho C-Br bond dissociation during photolysis generates aryl radicals, which undergo intramolecular cyclization to form PBDFs or hydrogen abstraction with hydrogen donors (such as organic solvents and water) to form lower brominated PBDEs. By using 2,4,4'-tribromodiphenyl ether (BDE-28) as the model reactant, the experimental PBDF formation ratios in various solutions are explained quantitatively by the calculated rate constants of cyclization and hydrogen abstraction reactions using the density functional theory (DFT) method. The solvent effect of pure and mixed solvents on PBDF formation is illustrated successfully. The structure-related hydrogen donation ability for hydrogen abstraction controls the bias of competition reactions and influences PBDF formation. Water resulted to be the most significant generation of PBDFs. Fulvic and humic acid display higher hydrogen donation ability than small-molecule organics due to the partitioning effect in aqueous solution. Quantitative structure-activity relationship (QSAR) models of the calculated rate constants for 512 cyclization and 319 hydrogen abstraction reactions using 189 PBDEs as the initial reactants in water are established, revealing the high risk of PBDF formation in aqueous solution.

Polybrominated dibenzo-p-dioxins/furans and their chlorinated analogues in sediments from a historical hotspot for both brominated flame retardants and organochlorine pesticides

Polybrominated dibenzo-p-dioxin/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) in the environment are closely related to their precursors, brominated flame retardants (BFRs) and organochlorine pesticides (OCPs). However, their change trends following the regulation of BFRs and OCPs remain incompletely characterized. Here, we examined PBDD/Fs and PCDD/Fs in sediments from a historical hotspot for both BFRs and OCPs, namely the Pearl River Delta (PRD), China. PBDD/Fs showed ubiquity in these samples but significantly lower concentrations than PCDD/Fs. Spatially, the occurrence of PBDD/Fs was positively correlated with local development levels and sediments from highly urbanized/industrialized areas showed higher and increasing PBDD/F concentrations. Polybrominated diphenyl ether (PBDE)-related products/industries were the greatest PBDD/F contributors to the PRD, followed by bromo-phenol/benzene-related products/industries. PCDD/Fs in PRD sediments showed significant positive correlations with local grain planting area, yield, and pesticide consumption. The historical use of pentachlorophenol (PCP)/PCP-Na and biomass open-burning were the leading PCDD/F sources of the PRD agricultural/rural areas, where the concentrations and toxic equivalent quantities (TEQs) of PCDD/Fs in sediments changed very little over the past decade. Anthropogenic thermal processes involved in metallurgy, waste incineration, and vehicles were the greatest PCDD/F contributors in the PRD urban/industrial areas, where the PCDD/F concentrations in sediments almost doubled over the last decade. This finding indicates the increasing PCDD/F contributions of industrial and municipal activities in the PRD, despite the implementation of strict emission standards. Over sixty percent of the samples showed TEQs that surpassed the low-risk threshold specified for mammalian life by the U.S. EPA (2.5 pg TEQ g^-1) and warrant continuous attention.

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.

PCDD/Fs and PBDD/Fs in sediments from the river encompassing Guiyu, a typical e-waste recycling zone of China

Severe pollution of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and their brominated analogues (PBDD/Fs) was frequently reported for the waters located near unregulated e-waste recycling areas. However, the migrations of these high-level dioxins via waterways and their potential threats to the lower reaches were seldom investigated. In this study, we analyzed PCDD/Fs and PBDD/Fs in 27 surficial sediments collected from the Lian River encompassing the Guiyu, China e-waste recycling zone, and investigated their distributions, sources, migration behaviors and risks. Both PCDD/Fs and PBDD/Fs in these sediments exhibited a spatial trend of Guiyu > Guiyu downriver > Guiyu upriver, illustrating that the Guiyu e-waste recycling activities were the uppermost dioxin contributors in this watershed. Sediments from different Guiyu villages demonstrated big gaps in PCDD/F concentrations and congener compositions, and the reason was attributed to the diverse e-waste recycling activities practiced in these villages. Sediments near the e-waste open-burning areas demonstrated extremely high PCDD/F concentrations and unique PCDD/F profiles featured by low-chlorinated PCDFs (tetra- to hexa-), which is quite different from the OCDD-dominant PCDD/F profile found in most of the Lian River sediments. The geographical distributions of PCDD/F concentrations and profiles illustrate that the substantial amount of PCDD/Fs in Guiyu sediments were mainly retained in local and vicinal water bodies. The principal component analysis (PCA) results further confirm that the high-level PCDD/Fs in Guiyu sediments exhibited quite limited translocations downstream and therefore exerted little influences on the lower reaches. Pentachlorophenol use in history, ceramic industry and vehicle exhaust were diagnosed as the major PCDD/F sources for most sediments of the Lian River. Total toxicity equivalent quantities (TEQs) of 70% of the Lian River sediments surpassed the high-risk limit specified for mammalian life by the U.S.EPA (25 pg TEQ g^-1), and most of these sediments were from Guiyu and its near downstream, which merit continuous attention and necessary remediation measures.

Polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) in soil around municipal solid waste incinerator: A comparison with polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs)

Polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) share similar toxicities and thermal origins, e.g., municipal solid waste incinerator (MSWI). Recently, PBDD/Fs from MSWI attracted rising concern because their important precursors, i.e., brominated flame retardants (BFRs), were frequently found in various wastes for landfill or MSWI feedstock. So far, however, little is known about PBDD/Fs and their associated risks in the vicinal environments of MSWI. Here we analyzed PBDD/Fs and PCDD/Fs in 29 soil samples collected around a multiyear large-scale MSWI, and compared their spatial distributions, sources and risks. PBDD/Fs demonstrated comparable concentrations and toxic equivalent quantities (TEQs) to PCDD/Fs in these samples. Spatially, both the concentrations of PBDD/Fs and PCDD/Fs decreased outwards from the MSWI, and exhibited significant linear correlations with the distances from the MSWI in the southeast downwind soil, suggesting the influence of the MSWI on its vicinal soil environment. However, the existence of other dioxin sources concealed its influence beyond 6 km. PBDD/Fs in the soils were characterized by highly-brominated PBDFs, especially Octa-BDF, and their sources were diagnosed as the MSWI and diesel exhaust; PCDD/Fs, however, were dominated by highly-chlorinated PCDDs, particularly Octa-CDD, and were contributed individually or jointly by the MSWI, automobile exhaust and pentachlorophenol (PCP)/Na-PCP. The non-carcinogenic risks of dioxins in all the soil samples were acceptable, but their carcinogenic risks in 17% of the samples were unacceptable. These samples were all located close to the MSWI and highways, therefore, the land use of these two high-risk zones should be cautiously planed.

Comprehensive screening of polybromochlorodibenzo-p-dioxins, dibenzofurans as mixed halogenated compounds in wastewater samples from industrial facilities by GC×GC/ToFMS and post-data processing

An enormous number of pollutants must be investigated to be able to understand which types threaten human health and environmental biota. In this study, we propose a workflow for screening polybromochlorodibenzo-p-dioxins and dibenzofurans (PBCDD/Fs), which are compounds that have thousands of isomers and congeners, by combining measurement of a sample without any in-laboratory-cleanup with the results of comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry and post-data processing. This process can be regarded as "in silico sample cleanup." The post-data processing stage comprises two methods in which the extracted mass spectra are matched to exact mass and isotopic ratios specified as formulae and filtering via mass deficiency. We applied this workflow to wastewater samples from industrial facilities to identify mixtures of halogenated dioxins. As a result, it was estimated that dioxins in an absolute quantity of 10-500 pg could be detected with sufficient accuracy by recovery testing of a standard mixture against sample crude extracts. Tri- to octa-halogenated dioxins were detected in 8 of 13 samples. Leachate from an industrial landfill was found to contain relatively large numbers of PBCDD/Fs, and several congeners were found in wastewater from an industrial fabric facility that handles decabromodiphenyl ether. The workflow, including the post-data processing method developed and applied in this study, has the advantage that additional identifications can be performed at any time from a single set of measurement data. This also enables the screening of substances that have thousands of homologous isomers, such as chlorinated and brominated dioxins, as well as other non-halogenated compounds.

Polybrominated dibenzo-p-dioxins and furans (PBDD/Fs): Contamination in food, humans and dietary exposure

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) have been recognised as environmental pollutants for decades but their occurrence in food has only recently been reported. They elicit the same type of toxic response as analogous polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) with similar potencies and effects, and share similar origins - inadvertent production during combustion and occurrence as by-products in industrial chemicals. Surprisingly, PBDD/Fs have received considerably less attention than PCDD/Fs, perhaps because determination requires a higher degree of analytical competence, a result of the higher adsorptivity and lability associated with carbon-bromine bonding. For most populations, the principal exposure pathway is dietary intake. The PBDD/F toxicity arising from occurrence in foods has often been expressed as toxic equivalents (TEQs) using the same scheme developed for PCDD/Fs. This approach is convenient, but resulting TEQ estimates are more uncertain, given the known differences in response for some analogous congeners and also the different patterns of PBDD/F occurrence confirmed by the newer data. Further studies to consolidate potency factors would help to refine TEQ estimates. Characteristically, most foods and human tissues show more frequent and higher PBDF concentrations relative to PBDDs, reflecting major source patterns. Occurrence in food ranges from <0.01 to several thousand pg/g (or up to 0.3 pg TEQ/g whole weight) which is comparable to PCDD/F occurrence (ΣPBDD/F TEQs are underestimated as not all relevant congeners are included). Plant based foods show higher PBDD/F: PCDD/F TEQ ratios. Reported PBDD/F dietary intakes suggest that some population groups, particularly young children, may exceed the revised tolerable weekly intake for dioxin-like contaminants (2 pg TEQ/kg bw/week), even for mean consumption estimated with lower bound data. It is evident that the omission of PBDD/Fs from the TEQ scheme results in a significant underestimation of the cumulative toxicity and associated risk arising from this mode of action.

Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC Technical Report)

The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare Earth elements), and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern, due to widespread illegal shipments; weak environmental, as well as health and safety, regulations; lack of technology; and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan, and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora, and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders seeking to devise integrated management strategies to tackle this global environmental concern.

Fate and migration of polybrominated diphenyl ethers in a workshop for waste printed circuit board de-soldering

Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑₈PBDEs in TSP and PM_2.5 in the workshop were 20.3 ng/m³ (24.7 μg/g) and 16.1 ng/m³ (115 μg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑₆PBDEs at the stack outlet (416 pg/m³) after gas treatment were lower than those in the stack pipe (1310 pg/m³) and hood inside (7440 pg/m³). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑₆PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.

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.

A review of sustainable e-waste generation and management: Present and future perspectives

Studies on sustainable management of waste from electrical and electronic equipment (or e-waste) have gained increasing attention from researchers around the world in recent years, with investigations into various aspects of e-waste management were investigated. Studies on e-waste generation by previous papers have been reviewed to provide an overview of the current research progress and recommendations for future research. The relevant existing studies were collected from various databases. Using content analysis, three main aspects of the existing studies were evaluated: the distribution and trends of the publications, the scope and boundaries of the studies, and the current research practices and research applications. Although there was a significant increasing trend of the amount of research on the evaluation of e-waste generation, however, the number of publications based on the countries of origin was still small. Another limitation was found related to the differences in the selection of research subjects and the level of analysis resulted in variations in the scopes and boundaries of the existing studies. Various other research areas were investigated further based on their research findings, but the analysis of various methodological aspects was complicated due to the increasing number of newly developed methodologies and the lack of comprehensive and up-to-date reviews on this research area. Additionally, there was also a need to evaluate emerging and/or older technology, which led electrical appliances to be overlooked. We found that comprehensive and up-to-date reviews of the methodological aspects of e-waste generation are still lacking. Based on the research gaps and limitations discussed, recommendations for future research were made.

Severe dioxin-like compound (DLC) contamination in e-waste recycling areas: An under-recognized threat to local health

Electrical and electronic waste (e-waste) burning and recycling activities have become one of the main emission sources of dioxin-like compounds (DLCs). Workers involved in e-waste recycling operations and residents living near e-waste recycling sites (EWRS) are exposed to high levels of DLCs. Epidemiological and experimental in vivo studies have reported a range of interconnected responses in multiple systems with DLC exposure. However, due to the compositional complexity of DLCs and difficulties in assessing mixture effects of the complex mixture of e-waste-related contaminants, there are few studies concerning human health outcomes related to DLC exposure at informal EWRS. In this paper, we have reviewed the environmental levels and body burdens of DLCs at EWRS and compared them with the levels reported to be associated with observable adverse effects to assess the health risks of DLC exposure at EWRS. In general, DLC concentrations at EWRS of many countries have been decreasing in recent years due to stricter regulations on e-waste recycling activities, but the contamination status is still severe. Comparison with available data from industrial sites and well-known highly DLC contaminated areas shows that high levels of DLCs derived from crude e-waste recycling processes lead to elevated body burdens. The DLC levels in human blood and breast milk at EWRS are higher than those reported in some epidemiological studies that are related to various health impacts. The estimated total daily intakes of DLCs for people in EWRS far exceed the WHO recommended total daily intake limit. It can be inferred that people living in EWRS with high DLC contamination have higher health risks. Therefore, more well-designed epidemiological studies are urgently needed to focus on the health effects of DLC pollution in EWRS. Continuous monitoring of the temporal trends of DLC levels in EWRS after actions is of highest importance.

Thermal degradation and pollutant emission from waste printed circuit boards mounted with electronic components

Waste printed circuit boards mounted with electronic components (WPCB-ECs) are generated from electronic waste dismantling and recycling process. Air-borne pollutants, including particulate matter (PM) and volatile organic compounds (VOCs), can be released during thermal treatment of WPCB-CEs. In this study, organic substances from WPCB-ECs were pyrolyzed by both thermo-gravimetric analysis (TGA) and in a quartz tube furnace. We discovered that board resin and solder coating were degraded in a one-stage process, whereas capacitor scarfskin and wire jacket had two degradation stages. Debromination of brominated flame retardants occurred, and HBr and phenol were the main products during TGA processing of board resin. Dehydrochlorination occurred, and HCl, benzene and toluene were detected during the pyrolysis of capacitor scarfskin. Benzene formation was found only in the first degradation stage (272-372 °C), while toluene was formed both in the two degradation stages. PM with bimodal mass size distributions at diameters of 0.45-0.5 and 4-5 μm were emitted during heating WPCB-ECs. The PM number concentrations were highest in the size ranges of 0.3-0.35 μm and 1.6-2 μm. The research produced new data on pollutant emissions during thermal treatment of WPCB-ECs, and information on strategies to prevent toxic exposures that compromise the health of recyclers.

Influence of soil physicochemical properties on the depth profiles of perfluoroalkylated acids (PFAAs) in soil along a distance gradient from a fluorochemical plant and associations with soil microbial parameters

The widespread use of perfluoroalkylated acids (PFAAs) has led to a global presence in the environment, in which they accumulate and may cause detrimental effects. Although soils are known sinks for many persistent organic pollutants, still little is known on the behaviour of PFAAs in soils. Furthermore, studies that examine the relationships between PFAA concentrations and soil microbial parameters are scarce. The 3 M fluorochemical plant near Antwerp has been characterized as a PFAAs hotspot. In the present study, we examined the vertical distribution of 15 PFAAs and their associations with multiple physicochemical soil properties along a distance gradient from this hotspot. Additionally, we tested the relationships between PFAA concentrations in the top soil with soil respiration, microbial activity and microbial biomass. Our results show that both perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) concentrations were elevated in the subsurface layer (up to 50 cm), after which concentrations decreased again, suggesting a downward migration of both analytes in the soil. This downward movement might pose a potential threat for the contamination of the groundwater and, consequently, organisms that rely on this water for consumption. The soil concentrations were influenced by multiple physicochemical properties of the soil, which suggests differences in bioavailability and sorption/desorption capacities between different soil types. We did not observe any influence of PFAA contamination in the top soil on microbial activity and biomass nor soil respiration.

Emission characteristics of polychlorinated, polybrominated and mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, PBDD/Fs, and PBCDD/Fs) from waste incineration and metallurgical processes in China

Typical thermal processes are common sources of polychlorinated, polybrominated and mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, PBDD/Fs, and PBCDD/Fs); however, very few reports have investigated their coemission. To clarify the emission characteristics of these DD/Fs, two municipal waste incinerators (MWIs), three hazardous waste incinerators (HWIs), one cement kiln coprocessing municipal waste incinerator (CMWI), one secondary copper smelter (SCu), and one iron and steel sintering smelter (ISS) in China were investigated. In total, 17 congeners of PCDD/Fs, 14 congeners of PBDD/Fs, and 12 congeners of PBCDDs in stack flue gases from these thermal processes were analyzed using a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) in this study. PCDD/Fs, PBDD/Fs and PBCDD/Fs were detectable in all samples, with total concentrations of 911-5.15 × 10³ pg/Nm³ (80.2-414 pg TEQ/Nm³). The concentrations of each DD/F were similar within the same type of facility and varied among different types of facilities. The contributions of PBDD/Fs and PBCDD/Fs to the total concentrations exceeded that of PCDD/Fs in some cases, such as in HWIs and SCu. In general, the ∑Cl_4-7 CDFs and ∑Cl_7-8 CDDs, 1,2,3,4,6,7,8-HpBDF, and 1-B-2,3,7,8-TeCDD and 2-B-1,3,7,8-TeCDD were the dominant congeners in the PCDD/F, PBDD/F, and PBCDD/F mass concentrations, respectively. Several other congeners present at low mass concentrations, such as 1,2,3,4,7,8-HxBDF, have potential as major contributors to the TEQs due to their high toxic equivalency factors. These results reveal the necessity of synergistically inhibiting the occurrences of PCDD/Fs, PBDD/Fs, and PBCDD/Fs from these sources and provide valuable information for use in the source identification of these pollutants in the environment.

Cutting down on the ozone and SOA formation as well as health risks of VOCs emitted from e-waste dismantlement by integration technique

Elimination of volatile organic compounds (VOCs) in the e-waste dismantling industry by an integration technique of spray tower-electrostatic precipitation-photocatalysis was conducted to investigate its application possibility for reducing formation of O₃ and secondary organic aerosols (SOAs) as well as exposure risk. Results revealed the average 5.4 × 10² μg m^-3 of VOCs with the top two groups being aromatic hydrocarbons (AHs, 55.93%) and halogenated hydrocarbons (HHs, 33.33%), contributing to 1.3 × 10³ and 3.0 × 10⁴ μg m^-3 of the O₃ and SOA (OFP and SOAFP) formation potential, respectively. Furthermore, 86.47% of OFP and 99.87% of SOAFP were ascribed to AHs, in which toluene ranked first (35.30% and 48.07%). The highest removal efficiency (76.92%) for VOCs by the integrated technique resulted in excellent prevention efficiencies of OFP (71.54%) and SOAFP (80.62%). Occupational cancer risk assessment found that HHs (62.63%) and AHs (36.93%) were the top two contributors. After the treatment by the integrated technique, 55.44% of the total risk index was reduced with the accumulation of few low-concentrated and more toxic AHs (e.g. 6.6 μg m^-3 benzene on average). All results suggest that controlling AH and HH emissions from the e-waste dismantling source could efficiently prevent atmospheric secondary pollution and human exposure risk to industrial emission.

Effects of perinatal dioxin exposure on development of children: a 3-year follow-up study of China cohort

The purpose of this study was to investigate the longitudinal effects of perinatal exposure to dioxin on physical growth in a 3-year follow-up study. In 2015, 27 mother-infant pairs living in an electronic waste (e-waste) dismantling region and 35 pairs living in a control region were enrolled in the present study. Breast milk samples were collected at 4 weeks after birth. Physical growth, including weight, height, and head and chest circumferences, was measured at 6 months and 3 years of age. Dioxin levels in the breast milk were measured by gas chromatography/high-resolution mass spectrometry. Levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and toxic equivalency values in maternal breast milk of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and PCDDs/PCDFs were significantly higher in women residing in the e-waste dismantling region. In 3-year-old boys, inverse associations were found between height and PCDDs-TEQ. In girls, positive associations were found between height and 2,3,7,8-TetraCDD, PCDDs-TEQ, and PCDDs/PCDFs-TEQ, and for weight and PCDDs-TEQ and PCDDs/PCDFs-TEQ at 3 years of age. In this study, sex-specific differences were observed in children, in whom dioxin exposure decreased growth in boys but increased growth in girls during the first 3 years of life.

Do concentrations of perfluoroalkylated acids (PFAAs) in isopods reflect concentrations in soil and songbirds? A study using a distance gradient from a fluorochemical plant

Perfluoroalkylated acids (PFAAs) are persistent chemicals that have been detected globally in the environment and in wildlife. Although it is known that PFAAs sorb to solid matrices, little is known on PFAA concentrations in soils. PFAA pollution has often been studied in aquatic invertebrates. However, this has rarely been done on terrestrial species. In the present study, we examined whether the concentrations of 15 PFAAs in isopods (Oniscidae), collected at a fluorochemical plant and in four other areas, representing a gradient in distance from the pollution source (1 km to 11 km), were related to those in the soil and in eggs of a songbird, the great tit (Parus major), collected in the same areas. Additionally, we examined the effect of physicochemical properties such as total organic carbon (TOC) and clay content on the relationship between the concentrations in soil and isopods. Finally, we examined the composition profile in the soil and isopods. Mean PFOS and PFOA concentrations of 1700 ng/g dw and 24 ng/g dw were detected in the soil at the plant. PFOS and PFPeA were the dominant PFAAs in isopods and were detected at mean concentrations of 253 and 108 ng/g ww, respectively. The great tit eggs showed elevated mean PFOS concentrations of 55,970 ng/g ww. In most cases, PFAA concentrations decreased with increasing distance from the plant. As PFAA concentrations in isopods were correlated with concentrations in the soils, isopods could serve as a bioindicator for PFAA concentrations in soils. Additionally, there were indications that isopods could also serve as a bioindicator for PFAA concentrations in eggs of great tits. However, these indications were only the case at two locations, showing the need to further monitor the possibilities of using isopods as a bioindicator for PFAA concentrations in song bird eggs. CAPSULE: Elevated PFAA concentrations in isopods reflected concentrations in songbird eggs and in soil, indicating that trophic transfer of PFAAs from soil, via isopods, to songbirds might play a role in the PFAA exposure of terrestrial songbirds.

Environmental and health implications of trace metal concentrations in street dusts around some electronic repair workshops in Owerri, Southeastern Nigeria

Assessment of trace metal concentrations in street-deposited sediments around some selected electronic repair workshops in Owerri, Imo State, Nigeria, was carried out. The objective of the study was to determine the concentrations of trace metals, namely nickel (Ni), chromium (Cr), lead (Pb), copper (Cu), cadmium (Cd), and zinc (Zn), in surface dusts from streets within some electronic repair workshops in Owerri, Imo State, Nigeria. Dust samples were collected from seven locations within the month of January 2014 during the dry season when the onset of dust was high in the area. The samples were air-dried, sieved, and digested in aqua regia, with the concentrations of trace metals determined with atomic absorption spectroscopy, Agilant FS 240AA model (USA). Results of the study revealed all the trace metals assessed except Cr in dust sample from Aladinma (ALA). Though elevated concentrations of Zn and Cu were observed in all the sampled locations, the concentrations did not exceed the Dutch intervention values. Risk assessment of the heavy metals showed high average daily dose (ADD) of the heavy metals for children and adults at New Market 2 (NMK2), New Market 1 (NMK1), and Tetlow (TEL), which could be attributed to the presence of electronic repair workshops and activities of electronic scrap dealers within these areas. It was observed that the values of hazard quotient (HQ) were less than 1, while that of hazard index (HI) were all below 1-5, indicating that the heavy metals pose no health risk to adults and children in the environment. However, there may be potential danger if the waste generated from the electronic repair workshops and electronic scrap dealers are not properly disposed and managed.

Characterization of PBDD/F emissions from simulated polystyrene insulation foam via lab-scale programmed thermal treatment testing

Accidental fires and open combustion are regarded as major potential contributors to the environmental release of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs). The characterization of PBDD/Fs emitted from thermal treatment of simulated polystyrene (PS) foam is reported in this study. PS, hexabromocyclododecane (HBCDD) and metals (or metallic compounds) composed the test samples, which imitated real extruded (XPS) and expanded (EPS) polystyrene thermal insulation foams. Test samples were subjected to thermal treatments under different experimental conditions. This study shows that the temperature, metal (metallic compound) content, and type of atmosphere are the key factors in the formation of congeners and PBDD/Fs during thermal processes. The total yield of polybrominated dibenzofurans (PBDFs) was greater than that of the polybrominated dibenzo-p-dioxins (PBDDs) during the test, and 1,2,3,7,8-PeBDF and 2,3,7,8-TBDF were the predominant congeners emitted during the thermal treatment experiments.

Formation of 1,3,8-tribromodibenzo-p-dioxin and 2,4,6,8-tetrabromodibenzofuran in the oxidation of synthetic hydroxylated polybrominated diphenyl ethers by iron and manganese oxides under dry conditions

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are ubiquitous and highly toxic emerging endocrine disruptors found in surface and subsurface soils and clay deposits. Seriously, they could be easily transformed to the more toxic dioxins (PBDD/Fs) in photochemical processes and incineration, but the spontaneous formation of PBDD/Fs has rarely been reported. This study focused on the formation of 1,3,8-tribromodibenzo-p-dioxin (1,3,8-TrBDD) and 2,4,6,8-tetrabromodibenzofuran (2,4,6,8-TeBDF) from 2'-OH-BDE-68 and 2,2'-diOH-BB-80 under the oxidization of iron and manganese oxides (goethite and MnO_x). Approximately 0.09 μmol/kg (2.33%) and 0.17 μmol/kg (4.15%) were transformed to 1,3,8-TrBDD and 2,4,6,8-TeBDF by goethite in 8 days and a higher conversion 0.15 μmol/kg (3.77%) and 0.23 μmol/kg (5.74%) were observed for MnO_x in 4 days. However, the formation of PBDD/Fs, probably proceeding via Smiles rearrangements and bromine elimination processes, was greatly inhibited by the presence of water. Transformation of OH-PBDEs by goethite and MnO_x was accompanied by release of Fe and Mn ions and the possible pathways for the formation of reaction products were proposed. In view of the ubiquity of OH-PBDEs and metal oxides in the environment, oxidation of OH-PBDEs mediated by goethite and MnO_x is likely an abiotic route for the formation of PBDD/Fs.

Has the question of e-waste opened a Pandora's box? An overview of unpredictable issues and challenges

Despite regulatory efforts and position papers, electrical and electronic waste (e-waste) remains ill-managed as evidenced by the extremely low rates of proper e-waste recycling (e-recycling) worldwide, ongoing illegal shipments to developing countries and constantly reported human health issues and environmental pollution. The objectives of this review are, first, to expose the complexity of e-waste problems, and then to suggest possible upstream and downstream solutions. Exploring e-waste issues is akin to opening a Pandora's box. Thus, a review of prevailing e-waste management practices reveals complex and often intertwined gaps, issues and challenges. These include the absence of any consistent definition of e-waste to date, a prevalent toxic potential still involving already banned or restricted hazardous components such as heavy metals and persistent and bioaccumulative organic compounds, a relentless growth in e-waste volume fueled by planned obsolescence and unsustainable consumption, problematic e-recycling processes, a fragile formal e-recycling sector, sustained and more harmful informal e-recycling practices, and more convoluted and unpredictable patterns of illegal e-waste trade. A close examination of the e-waste legacy contamination reveals critical human health concerns, including significant occupational exposure during both formal and informal e-recycling, and persistent environmental contamination, particularly in some developing countries. However, newly detected e-waste contaminants as well as unexpected sources and environmental fates of contaminants are among the emerging issues that raise concerns. Moreover, scientific knowledge gaps remain regarding the complexity and magnitude of the e-waste legacy contamination, specifically, a comprehensive characterization of e-waste contaminants, information on the scale of legacy contamination in developing countries and on the potential environmental damage in developed countries, and a stronger body of evidence of adverse health effects specifically ascribed to e-waste contaminants. However, the knowledge accumulated to date is sufficient to raise awareness and concern among all stakeholders. Potential solutions to curb e-waste issues should be addressed comprehensively, by focusing on two fronts: upstream and downstream. Potential upstream solutions should focus on more rational and eco-oriented consumer habits in order to decrease e-waste quantities while fostering ethical and sustained commitments from manufacturers, which include a limited usage of hazardous compounds and an optimal increase in e-waste recyclability. At the downstream level, solutions should include suitable and pragmatic actions to progressively reduce the illegal e-waste trade particularly through international cooperation and coordination, better enforcement of domestic laws, and monitoring in both exporting and receiving countries, along with the supervised integration of the informal sector into the recycling system of developing countries and global expansion of formal e-waste collection and recycling activities. Downstream solutions should also introduce stronger reverse logistics, together with upgraded, more affordable, and eco-friendly and worker-friendly e-recycling technologies to ensure that benefits are derived fully and safely from the great economic potential of e-waste.

Theoretical study on the formation mechanism of pre-intermediates for PXDD/Fs from 2-Bromophenol and 2-Chlorophenol precursors via radical/molecule reactions

This study investigates reaction pathways for the formation of pre-PXDD/F intermediates via a radical/molecule mechanism. Thermodynamic and kinetic parameters for the combination reactions of 2-bromophenol (2-BP) and 2-chlorophenol (2-CP) precursors with key radical species including the phenoxy radicals, the phenyl radicals and the phenoxyl diradicals were calculated in detail. The couplings of phenoxy radicals with 2-B(C)P tend to produce pre-PXDD intermediates of halogenated o-phenoxyphenol. The combinations of phenyl and phenoxyl diradicals with 2-B(C)P produce two types of structures, i.e., dihydroxybiphenyl and o-phenoxyphenyl, which exclusively act as prestructures of PXDFs. These condensation reactions, especially those involving the phenyl C atom sites in phenyl and phenoxyl diradicals, are proven to be both thermodynamically and kinetically favorable and are nearly comparable with the corresponding steps involved in the radical/radical reactions. Most importantly, reactions of phenyl and phenoxyl diradicals with halogenated phenols solely lead to the formation of PXDFs, which to some extent provides a plausible explanation for the high PXDF-to-PXDD ratios in the real environment. Therefore, our study reveals the pivotal role of the radical/molecule mechanism in homogeneous gas-phase PXDD/F formation, especially in PXDF formation. The present results fill in a knowledge gap that has hitherto existed regarding dioxin formation and improve our understanding of PXDD/F formation characteristics in the environment.

Separate screening of brominated and chlorinated dioxins in field samples using in vitro reporter gene assays with rat and mouse hepatoma cell lines

In 2011, a joint World Health Organization (WHO) and United Nations Environment Programme expert panel recommended the use of the WHO toxicity equivalency factor (TEF) scheme for assessment of the human health risks of brominated dioxins which have different sources from chlorinated dioxins. Therefore, WHO toxic equivalents (TEQs) should be determined for both chlorinated and brominated dioxins. As alternative to the conventional but time-consuming dioxin analysis using gas chromatography high-resolution mass spectrometry, we have developed a screening method involving cleanup and separation of brominated dioxins from chlorinated dioxins in field samples and subsequent analysis by CALUX (chemically activated luciferase expression) assays which are in vitro reporter gene assays detecting dioxin-like compounds. Cleanup and separation were accomplished with silica gel columns impregnated with 55% sulfuric acid and with 10% silver nitrate, respectively, and the average recoveries of the major contributors to the WHO-TEQs were approximately 90%. The CALUX 2,3,7,8-TCDD equivalents (CALUX-TEQs) derived from all the dioxin-like compounds in the cleanup fractions of the field samples (n = 24) were measured by means of the CALUX assays, indicating significant positive correlations between the WHO-TEQs and CALUX-TEQs (r ≥ 0.969, P < 0.001). We found that the ratios of the chlorinated dioxin-derived WHO-TEQs to the brominated dioxin-derived WHO-TEQs were strongly positively correlated with the ratios of the CALUX-TEQs derived from the chlorinated dioxin fractions to the CALUX-TEQs derived from the brominated dioxin fractions (r ≥ 0.833, P < 0.001). These results suggest that our method will be useful for estimating the contributions of chlorinated and brominated dioxins to WHO-TEQs.

Characterization and inventory of PBDD/F emissions from deca-BDE, polyethylene (PE) and metal blends during the pyrolysis process

The thermal treatment of waste electrical and electronic equipment (WEEE) is regarded as the largest potential contributor to the environmental release of polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs). Herein, the pyrolysis of decabromodiphenyl ether (deca-BDE), polyethylene (PE) and metal blends was conducted to investigate the emission characteristics of PBDD/Fs at different thermal treatment conditions. The total yield of polybrominated dibenzo-p-dioxins (PBDDs) was less than that of polybrominated dibenzofurans (PBDFs) during the pyrolysis of the PE matrix and metal blends. 2,3,7,8-TBDF and 1,2,3,7,8-PBDF were the dominant congeners emitted from the pyrolysis. Temperature, presence of oxygen and type of added metal were the critical influencing factors for the PBDD/F formation rates and speciation in the pyrolysis process.