Tracking the Global Distribution of Persistent Organic Pollutants Accounting for E-Waste Exports to Developing Regions

Soil's Hidden Power: The Stable Soil Organic Carbon Pool Controls the Burden of Persistent Organic Pollutants in Background Soils

Persistent organic pollutants (POPs) tend to accumulate in cold regions by cold condensation and global distillation. Soil organic matter is the main storage compartment for POPs in terrestrial ecosystems due to deposition and repeated air-surface exchange processes. Here, physicochemical properties and environmental factors were investigated for their role in influencing POPs accumulation in soils of the Tibetan Plateau and Antarctic and Arctic regions. The results showed that the soil burden of most POPs was closely coupled to stable mineral-associated organic carbon (MAOC). Combining the proportion of MAOC and physicochemical properties can explain much of the soil distribution characteristics of the POPs. The background levels of POPs were estimated in conjunction with the global soil database. It led to the proposition that the stable soil carbon pools are key controlling factors affecting the ultimate global distribution of POPs, so that the dynamic cycling of soil carbon acts to counteract the cold-trapping effects. In the future, soil carbon pool composition should be fully considered in a multimedia environmental model of POPs, and the risk of secondary release of POPs in soils under conditions such as climate change can be further assessed with soil organic carbon models.

Health risk assessment and development of human health ambient water quality criteria for PCBs in Taihu Basin, China

Polychlorinated biphenyls (PCBs) are a class of typical persistent organic pollutants (POPs) with carcinogenicity and extensively found in diverse environmental mediums. The Taihu Basin is one of the most economically developed regions in China, and it has also caused a lot of historical legacy and unconscious emissions of PCBs, posing a threat to the health of people in the region. This study counted the concentrations of PCBs in five environmental media (water, soil, air, dust, and food) in the Taihu Basin from 2000 to 2020 and used Monte Carlo simulation to simulate the multi-channel exposure of PCBs in people of different ages (children, teenagers, and adults), and evaluated their noncarcinogenic and carcinogenic health risks. Finally, the human health ambient water quality standards (AWQC) for PCBs were obtained using regional exposure parameters and bioaccumulation factors. The results showed that the pollution of PCBs in the Taihu Basin was relatively serious in China. The concentration of PCBs in dust is higher than other environmental media. And exposure to water and food is the main exposure pathway for PCBs in the population of the region. Besides, PCBs pose no noncarcinogenic risk to people in this region, but their carcinogenic risk to residents exceeds the safety threshold. Among the three population groups, adults have the highest risk of cancer, and prevention measures need to be taken by controlling the intake of related foods and the concentration of PCBs in water. The following human health AWQC values of the PCBs in Taihu Basin is 3.2 × 10-9 mg/L.

Analysis and modelling of profiles to understand fractionation processes for contaminations with polychlorinated biphenyls observed in fish

Polychlorinated biphenyls (PCB) both continue to spread into the environment and to bioaccumulate from primary urban and industrial sources as well as from secondary sources such as soils and the oceans. Fractions of congeners in PCB mixtures, i.e. PCB profiles, can be used as fingerprints to trace contamination pathways from sources to sinks because PCB mixtures fractionate during transport due to congener specific phase changes and degradation. Using a statistical analysis of a total of 8584 PCB profiles with seven congeners (CB28, CB52, CB101, CB118, CB138, CB153, CB180) for contaminated fish from two international datasets as well as a modelling of profiles, two major fractionation processes related to distinct contamination pathways were identified: (1) A relative enrichment of lighter congeners (CB28, CB52, CB101) in seawater fish due to a predominantly atmospheric transport, whereas freshwater and some coastal fish had higher fractions of heavier congeners (CB138, CB153) because those were mainly contaminated by particle-sorbed PCB from surface runoff. (2) A temperature driven fractionation tended to affect congeners with a medium molecular weight (CB118) as well as the heaviest congeners (CB180), a fractionation process which was conceptually associated with transport of PCB from secondary sources. Specifically, medium chlorinated PCB is sufficiently volatile and persistent for a preferred transport into cooler waters. In warmer climates, only the highest chlorinated congeners are persistent enough to ultimately accumulate in fish. Our analysis and modelling provide a starting point for the development of systems to trace - better than before - sources of PCB contaminations observed in fish.

Modelling PCB-153 in northern ecosystems across time, space, and species using the nested exposure model

There is concern over possible effects on ecosystems and humans from exposure to persistent organic pollutants (POPs) and chemicals with similar properties. The main objective of this study was to develop, evaluate, and apply the Nested Exposure Model (NEM) designed to simulate the link between global emissions and resulting ecosystem exposure while accounting for variation in time and space. NEM, using environmental and biological data, global emissions, and physicochemical properties as input, was used to estimate PCB-153 concentrations in seawater and biota of the Norwegian marine environment from 1930 to 2020. These concentrations were compared to measured concentrations in (i) seawater, (ii) an Arctic marine food web comprising zooplankton, fish and marine mammals, and (iii) Atlantic herring (Clupea harengus) and Atlantic cod (Gadus morhua) from large baseline studies and monitoring programs. NEM reproduced PCB-153 concentrations in seawater, the Arctic food web, and Norwegian fish within a factor of 0.1-31, 0.14-3.1, and 0.09-21, respectively. The model also successfully reproduced measured trophic magnification factors for PCB-153 at Svalbard as well as geographical variations in PCB-153 burden in Atlantic cod between the Skagerrak, North Sea, Norwegian Sea, and Barents Sea, but estimated a steeper decline in PCB-153 concentration in herring and cod during the last decades than observed. Using the evaluated model with various emission scenarios showed the important contribution of European and global primary emissions for the PCB-153 load in fish from Norwegian marine offshore areas.

Sources of polychlorinated biphenyls (PCBs) in sediments of the East China marginal seas: Role of unintentionally-produced PCBs

The production and use of intentionally-produced polychlorinated biphenyls (PCBs) in China have a short history compared with countries of North America and Europe, where technical PCB mixtures were manufactured in large amounts for decades before being banned. Unintentionally-produced PCB emissions increased dramatically in China, leading to unique profiles of PCB burdens. This study first time evaluated 208 individual PCB congeners at 94 sites from surface sediments of the East China Marginal Seas (ECMSs) and explored their sources. Non-technical PCBs transported from atmospheric transport and river discharge played a dominant role in most areas of the ECMSs, while historical residuals of technical PCBs occupied the fine-grained sediments in muddy areas of the central Yellow Sea (YS), regarding to the low sedimentation rate in the central YS. Furthermore, emissions from Taizhou located on the coast of the East China Sea (ECS), which is an important electronic waste dismantling site in East China, contributed additional technical PCBs to the inner shelf of the ECS. Our results indicate that non-technical PCBs have become the dominant PCB species in the ECMSs, and emphasize the synergistic effects of large riverine input, long-range atmospheric transport, and muddy shelf deposition on PCB source and sink of in marginal seas.

Review of Endocrine Disrupting Compounds (EDCs) in China's water environments: Implications for environmental fate, transport and health risks

Endocrine Disrupting Compounds (EDCs) are ubiquitous in soil and water system and have become a great issue of environmental and public health concern since the 1990s. However, the occurrence and mechanism(s) of EDCs' migration and transformation at the watershed scale are poorly understood. A review of EDCs pollution in China's major watersheds (and comparison to other countries) has been carried out to better assess these issues and associated ecological risks, compiling a large amount of data. Comparing the distribution characteristics of EDCs in water environments around the world and analyzing various measures and systems for managing EDCs internationally, the significant insights of the review are: 1) There are significant spatial differences and concentration variations of EDCs in surface water and groundwater in China, yet all regions present non-negligible ecological risks. 2) The hyporheic zone, as a transitional zone of surface water and groundwater interaction, can effectively adsorb and degrade EDCs and prevent the migration of high concentrations of EDCs from surface water to groundwater. This suggests that more attention needs to be paid to the role played by critical zones in water environments, when considering the removal of EDCs in water environments. 3) In China, there is a lack of comprehensive and effective regulations to limit and reduce EDCs generated during human activities and their discharge into the water environment. 4) To prevent the deterioration of surface water and groundwater quality, the monitoring and management of EDCs in water environments should be strengthened in China. This review provides a thorough survey of scientifically valid data and recommendations for the development of policies for the management of EDCs in China's water environment.

Distribution, sources, and ecological risk assessment of polychlorinated biphenyls (PCBs) in the estuary of Dagu River, China

Four different types of 0-30 cm soil/sediment samples were collected from aquaculture land, farmland, industrial land and river bottom sediment in the estuary area of Dagu River, and the pollution status and sources of 7 PCB congeners were analyzed. The results showed that the mean values of Σ7PCBs in soil/sediments of different land use types were 5.01 ng g-1 dw for industrial land, 3.6 ng g-1 dw for estuarine sediments, 2.09 ng g-1 dw for farmland soil and 1.78 ng g-1 dw for farming land. All samples were at low pollution levels and pose little ecological risks. PCBs in the samples are mainly comprised of highly chlorinated biphenyls, and their content decreases gradually with increasing sampling depth. Based on the principal component analysis, it is concluded that the main source of PCBs in the study area is shipping activities, in addition to atmospheric transport and sedimentation sources.

Sea turtle egg yolk and albumen as biomonitoring matrices for maternal burdens of organic pollutants

To establish the use of eggs as biomonitoring tools for maternal body burdens, we investigated the mother-to-egg ratio of 56 PCB, 12 OCP and 34 PBDE unique compounds from maternal plasma into replicate egg yolk and albumen samples in the loggerhead turtle (Caretta caretta) as a case study of a threatened migratory marine species. We applied robust Regression on Order Statistics to fully account for the information in both censored and uncensored data. Our results added new insights into the use of yolk as a suitable biomonitoring matrix; the difference between yolk and albumen which were previously analysed as a homogeneous mixture; and the value of accounting for censored data. Overall, compound-specific mother-to-egg ratios need to be considered when translating yolk levels back to maternal pollution burdens, and when assessing the risk to the subsequent generations of turtle embryos.

Chlorinated paraffins and dechloranes in free-range chicken eggs and soil around waste disposal sites in Tanzania

Electronic waste is a source of both legacy and emerging flame retardants to the environment, especially in regions where sufficient waste handling systems are lacking. In the present study, we quantified the occurrence of short- and medium chain chlorinated paraffins (SCCPs and MCCPs) and dechloranes in household chicken (Gallus domesticus) eggs and soil collected near waste disposal sites on Zanzibar and the Tanzanian mainland. Sampling locations included an e-waste facility and the active dumpsite of Dar es Salaam, a historical dumpsite in Dar es Salaam, and an informal dumpsite on Zanzibar. We compared concentrations and contaminant profiles between soil and eggs, as free-range chickens ingest a considerable amount of soil during foraging, with potential for maternal transfer to the eggs. We found no correlation between soil and egg concentrations or patterns of dechloranes or CPs. CPs with shorter chain lengths and higher chlorination degree were associated with soil, while longer chain lengths and lower chlorination degree were associated with eggs. MCCPs dominated the CP profile in eggs, with median concentrations ranging from 500 to 900 ng/g lipid weight (lw) among locations. SCCP concentrations in eggs ranged from below the detection limit (LOD) to 370 ng/g lw. Dechlorane Plus was the dominating dechlorane compound in all egg samples, with median concentrations ranging from 0.5 to 2.8 ng/g lw. SCCPs dominated in the soil samples (400-21300 ng/g soil organic matter, SOM), except at the official dumpsite where MCCPs were highest (65000 ng/g SOM). Concentrations of dechloranes in soil ranged from below LOD to 240 ng/g SOM, and the dominating compounds were Dechlorane Plus and Dechlorane 603. Risk assessment of CP levels gave margins of exposure (MOE) close to or below 1000 for SCCPs at one location.

Accounting of the Use and Emissions of Polychlorinated Biphenyl Compounds (PCBs) in India, 1951-2100

Polychlorinated biphenyl compounds (PCBs) are highly toxic organic chemicals still prevalent in the environment. While global inventories of the use and emissions of PCBs have been developed, estimates for individual countries determined using bottom-up approaches are few and often show different trends from the global inventory. Here, we determine the past, present, and future consumption and emissions of PCBs in India. A mass balance model was used to estimate middle (low-high) emissions in the period 1950-2100. Up to 7296 tonnes of PCBs have been used in transformers. PCBs imported as wastes are estimated to be approximately 5000 (2400-9100) tonnes. Total emissions from the use and disposal of transformers, industrial processes, and imported waste disposal are estimated to become 13 (0.1-537) tonnes, 89.26 (0.5-178) tonnes, 63 (3-910) tonnes, respectively, in the period 1950-2100. Congener-specific emissions are relatively high for low-chlorinated PCBs (-8, 18, 28, 31, 52, 101, 110, 118, 153, range: 0.1-118 tonnes). We find that industrial emissions are becoming important sources of PCBs and may become predominant, depending on emission scenarios.

New emission inventory reveals termination of global dioxin declining trend

Accurate estimates of spatiotemporally resolved Polychlorinated dibenzo-p-dioxins (PCDD/Fs, or dioxins) emissions are critical for understanding their environmental fate and associated health risks. In this study, by utilizing an empirical regression model for PCDD/Fs emissions, we developed a global emission inventory for 17 toxic PCDD/Fs congeners from 8 source sectors with a spatial resolution of 1° × 1° from 2002 to 2018. The results show that PCDD/Fs emissions decreased by 25.7 % (12.5 kg TEQ) between 2002 and 2018, mostly occurring in upper- and lower-middle income countries. Globally, open-burning processes, waste incineration, ferrous and nonferrous metal production sectors and heat and power generation were the major source sectors of PCDD/Fs. Spatially, high PCDD/Fs emissions were mainly identified in East and South Asia, Southeast Asia, and part of Sub-Saharan Africa. We find that the declining trend of dioxin emissions over the past decades terminated from the early 2010s due to increasing significance of wildfire induced emissions in the total emission. The PCDD/Fs emission inventory developed in the present study was verified by inputting the inventory as initial conditions into an atmospheric transport model, the Canadian Model for Environmental Transport of Organochlorine Pesticides (CanMETOP), to simulate PCDD/Fs concentrations in air and soil. The predicted concentrations were compared to field sampling data. The good agreement between the modeled and measured concentrations demonstrates the reliability of the inventory.

Unlocking India's Potential in Managing Endocrine-Disrupting Chemicals (EDCs): Importance, Challenges, and Opportunities

Endocrine-disrupting chemicals (EDCs) are a prime concern for the environment and health globally. Research shows that in developing countries such as India both the environment and human populations are severely exposed to EDCs and consequently experience rising incidents of adverse health effects such as diabetes and cancers. In this paper, we discuss the current EDC management approach in India, critically assess its limitations, and describe opportunities for potential improvements. Foremost, current EDC management actions and interventions in India are fragmented and outdated, and far behind the modern and comprehensive approaches adopted in the European Union and other developed countries. Strong and well-planned actions are required on various fronts of science, policy, commerce, and public engagement. These actions include the adoption of a dedicated and modern regulatory framework for managing EDCs, enhancing capacity and infrastructure for EDC monitoring in the environment and human population, employing public-private partnership programs for not only managing EDCs but also in the sectors that indirectly contribute toward the mismanagement of EDCs in the country, and raising awareness on EDCs and promoting health-preserving consumption habits among the public. As India hosts a large proportion of the global human population and biodiversity, the success or failure of its actions will substantially affect the direction of global efforts to manage EDCs and set an example for other developing countries.

Polybrominated diphenyl ether quinone exposure leads to ROS-driven lysosomal damage, mitochondrial dysfunction and NLRP3 inflammasome activation

Polybrominated diphenyl ethers (PBDEs) are aromatic compounds that containing bromine atoms, which possess high efficiency, good thermal stability. However, PBDEs had various known toxic effects and were characterized as persistent environmental pollutants. Exposure to a quinone-type metabolite of PBDEs (PBDEQ) is linked with excess production of intracellular reactive oxygen species (ROS) in our previous studies. Here, we observed that PBDEQ exposure led to ROS and mitochondrial dysfunction, which promoted canonical and non-canonical Nod-like receptor protein 3 (NLRP3) inflammasome activation. Further experiments demonstrated that PBDEQ exposure activated Toll-like receptors (TLRs), subsequently regulating nuclear factor kappa B (NF-κB) signaling. Moreover, lysosomal damage and K⁺ efflux were involved in PBDEQ-driven NLRP3 inflammasome activation. Our in vivo study also illustrated that PBDEQ administration induced liver inflammation in male C57BL/6J mice. Cumulatively, our current finding provided novel insights into PBDEQ-induced pro-inflammatory responses.

Evidence of stockpile contamination for legacy polychlorinated biphenyls and organochlorine pesticides in the urban environment of Cyprus (Eastern Mediterranean): Influence of meteorology on air level variability and gas/particle partitioning based on equilibrium and steady-state models

The present study investigated comprehensively the atmospheric occurrence and fate of an extensive range of polychlorinated biphenyls (PCBs; forty-two congeners), organochlorine pesticides (OCPs; twenty-seven emerging and legacy agrochemicals) and polycyclic aromatic hydrocarbons (PAHs; fifty parent and alkylated members, including the non USEPA-16 listed toxic ones), in both gas and particulate phase of the scarcely monitored atmosphere over Cyprus for the first time. Parent-metabolite concentration ratios suggested fresh application for dichlorodiphenyl-trichloroethanes (DDTs), dicofol, hexachlorocyclohexanes, endosulfan and chlorothalonil, particularly during spring (April-May). Regressions of logarithms of partial pressure against ambient temperature revealed that secondary recycling from contaminated terrestrial surfaces regulates the atmospheric level variability of PCBs, DDTs, aldrin, chlordane, dicofol, heptachlor and endosulfan. Enthalpies of surface-air exchange (∆H_SA) calculated from Clausius-Clapeyron equations were significantly correlated to vaporization enthalpies (∆H_V) determined by chromatographic techniques, corroborating presence of potential stockpile-contaminated sites around the study area. The Harner-Bidleman equilibrium model simulating urban areas, and the Li-Jia empirical model, predicted better the partitioning behavior of PAHs (<four-ring parent and alkylated members), PCBs (<hexa-chlorobiphenyls), and OCPs, respectively. For heavier PAHs and PCBs, partitioning coefficients (K_P) were inadequately predicted by the Li-Ma-Yang steady-state model, probably due to local human activities and regional transport in the study area.

Gas-particle partitioning of polycyclic aromatic hydrocarbons from oil combustion involving condensate, diesel and heavy oil

This study focuses on the gas-particle (G-P) partitioning of 16 polycyclic aromatic hydrocarbons (PAHs) from oil combustion, which is one of the important contributors of anthropogenic PAHs but has been rarely studied. The combustions of different types of oils involving ultra-light to heavy oils were investigated, and the PAH partitioning mechanism was determined by the widely used Junge-Pankow adsorption model, K_oa absorption model, and dual sorption model, respectively. The results show that the source-specific diagnostic ratios of Ant/(Ant+Phe) are between 0.09 and 0.24, the estimated regression slopes of G-P partition coefficients (K_P) of the total PAHs on their sub-cooled liquid vapor pressures (P_L^O) are in the range of - 0.34 to - 0.25, and the predicted fractions of PAHs in the particle phase (φ) by K_oa absorption model are close to the measured values, while the log K_Pvalues of the LMW PAHs from the combustions of diesel and heavy oil are better represented by the dual sorption model. Our findings indicate that PAHs are derived from mixed sources that include the unburned original oil and combustion products, and the PAH partitioning mechanism is governed by the process of absorption into organic matter because of the unburned oil, but both adsorption and absorption exist simultaneously in the lighter PAHs from the combustions of heavier oils (i.e., diesel and heavy oil). Based on these findings, the understanding of the fate and transport of PAH emissions and the optimization of the emergency responses to accidents such as marine oil spills would be potentially improved.

Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyls Catalyzed by a Reductive Dehalogenase in Dehalococcoides mccartyi Strain MB

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) are notorious persistent organic pollutants. However, few organohalide-respiring bacteria that harbor reductive dehalogenases (RDases) capable of dehalogenating these pollutants have been identified. Here, we report reductive dehalogenation of penta-BDEs and PCBs byDehalococcoides mccartyi strain MB. The PCE-pregrown cultures of strain MB debrominated 86.6 ± 7.4% penta-BDEs to di- to tetra-BDEs within 5 days. Similarly, extensive dechlorination of Aroclor1260 and Aroclor1254 was observed in the PCE-pregrown cultures of strain MB, with the average chlorine per PCB decreasing from 6.40 ± 0.02 and 5.40 ± 0.03 to 5.98 ± 0.11 and 5.19 ± 0.07 within 14 days, respectively; para-substituents were preferentially dechlorinated from PCBs. Moreover, strain MB showed distinct enantioselective dechlorination of different chiral PCB congeners. Dehalogenation activity and cell growth were maintained during the successive transfer of cultures when amended with penta-BDEs as the sole electron acceptors but not when amended with only PCBs, suggesting metabolic and co-metabolic dehalogenation of these compounds, respectively. Transcriptional analysis, proteomic profiling, and in vitro activity assays indicated that MbrA was involved in dehalogenating PCE, PCBs, and PBDEs. Interestingly, resequencing of mbrA in strain MB identified three nonsynonymous mutations within the nucleotide sequence, although the consequences of which remain unknown. The substrate versatility of MbrA enabled strain MB to dechlorinate PCBs in the presence of either penta-BDEs or PCE, suggesting that co-metabolic dehalogenation initiated by multifunctional RDases may contribute to PCB attenuation at sites contaminated with multiple organohalide pollutants.

Semi-volatile organic compounds in fine particulate matter on a tropical island in the South China Sea

Measurements of hazardous semi-volatile organic compounds (SVOCs) in remote tropical regions are rare. In this study, polycyclic aromatic compounds (PACs) [including polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (NPAHs), and oxygenated PAHs (OPAHs)], organophosphate esters (OPEs), and phthalic acid esters (PAEs) were measured in fine particulate matter (PM_2.5) at Yongxing Island in the South China Sea (SCS). The concentrations of PACs (median = 53.5 pg/m³) were substantially low compared with previous measurements. The concentration weighted trajectory (CWT) model showed that the eastern and southern China was the main source region of PAC, occurring largely during the northeast (NE) monsoon. The PM_2.5 showed remarkably high concentrations of OPEs (median = 3231 pg/m³) and moderate concentrations of PAEs (13,013 pg/m³). Some Southeast Asian countries were largely responsible for their higher concentrations, driven by the tropical SCS monsoons. We found significant atmospheric loss of the SVOCs, which is an explanation for the low concentrations of PACs. Enhanced formation of N/OPAHs originated from tropical regions was also observed. The positive matrix factorization model was applied to apportion the SVOC sources. The results, as well as correlation analyses of the SVOC concentrations, further indicate insignificant local sources and enhanced atmospheric reactions on this island.

Atmospheric concentrations of polychlorinated biphenyls, brominated flame retardants, and novel flame retardants in Lagos, Nigeria indicate substantial local sources

Polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) like polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), and novel flame retardants (NFRs) like decabromodiphenyl ethane (DBDPE) are ubiquitous environmental pollutants. Despite this, little is known about their concentrations in outdoor air in the African continent. To address this knowledge gap, concentrations of BFRs, NFRs, and PCBs were measured in outdoor air at 8 sites located within the metropolitan area of Lagos, Nigeria. Concentrations of ∑₈BDEs, ∑HBCDD, ∑₇NFRs and ∑₈PCBs were: 21-750 (median = 100) pg/m³, <12-180 (median = < 12) pg/m³, 34-900 (median = 300) pg/m³ and 85-460 (median = 300) pg/m³, respectively. Decabromodiphenyl ether (BDE-209, range: <16-620 pg/m³, median = 71 pg/m³) and DBDPE (range: <37-890 pg/m³, median = 280 pg/m³) were the dominant BFRs detected, while the non-Arochlor PCB 11 (range: 49-220 pg/m³, median = 100 pg/m³) was the dominant PCB. To the authors' knowledge, these are the first data on the non-Arochlor PCB 11 in outdoor air in Africa. In general, concentrations of all target contaminants in this study were within the range reported elsewhere in Africa and worldwide. Likely due to the tropical climate of Lagos, no seasonal variation in concentrations was discernible for any of the target contaminants. While concentrations of PBDEs and some NFRs were correlated with population density, concentrations of PCBs appear more impacted by leaks from electrical transformers and for PCB 11 to proximity to activities like textile factories that produce and use dyes.

Spatial Variation in Contaminant Occurrence in Marine Fishes and Prawns from Coastal Tanzania

There are limited data on organic contaminants in marine biota from coastal Tanzania, especially on the occurrence of industrial-use contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). The present study, performed in 2018-2019 in coastal Tanzania and Zanzibar Island, aimed at assessing spatial variation in the occurrence of PCBs; brominated flame retardants (BFRs), including PBDEs; and organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), among three locations that differ in degree of anthropogenic activity. Analyzed samples included edible tissues of marine fishes and prawns representing different trophic levels and habitats. The results indicate a mainland-island difference, with fishes and prawns collected on Zanzibar having significantly lower PCB and DDT concentrations but higher concentrations of hexachlorobenzene compared to the two mainland locations. The highest contaminant concentrations were found in fishes and prawns collected around central Dar es Salaam harbor, with median ΣPCBs ranging from 22.3 to 577 ng/g lipid weight and ΣDDTs from 22.7 to 501 ng/g lipid weight, suggesting local sources. Concentrations of PBDEs were similar among locations, suggesting more diffuse sources. None of the "newer-type" BFRs, including compounds introduced as replacements for PBDEs, were detected in the present study. Stable isotope values of carbon (δ¹³ C) and nitrogen (δ¹⁵ N) varied among locations, and the relationship between contaminants and δ¹⁵ N varied among locations and habitat (pelagic/demersal). Concentrations measured in the present study are below European guidelines for human consumption of fishes and prawns. However, industrial-use contaminants should be monitored in developing countries because they are contaminants of emerging concern as a result of increasing industrialization and global trade of used products and wastes. Environ Toxicol Chem 2022;41:321-333. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Environmental contamination and human exposure of polychlorinated biphenyls (PCBs) in China: A review

Polychlorinated biphenyls (PCBs), together with 11 other organic compounds, were initially listed as persistent organic pollutants (POPs) by the Stockholm Convention because of their potential threat to ecosystems and humans. In China, many monitoring studies have been undertaken to reveal the level of PCBs in environment since 2005 due to the introduced stricter environmental regulations. However, there are still significant gaps in understanding the overall spatial and temporal distributions of PCBs in China. This review systematically discusses the occurrence and distribution of PCBs in environmental matrices, organisms, and humans in China. Results showed that PCB contamination in northern and southern China was not significantly different, but the PCB levels in East China were commonly higher than those in West China, which might have been due to the widespread consumption of PCBs and intensive human activities in East China. Serious PCB contamination was found in e-waste disassembling areas (e.g., Taizhou of Zhejiang Province and Qingyuan and Guiyu of Guangdong Province). Higher PCB concentrations were also chronicled in megalopolises and industrial clusters. The unintentionally produced PCBs (UP-PCBs) formed during industrial thermal processes may play an increasingly significant role in PCB pollution in China. Low PCB levels were recorded in rural and underdeveloped districts, particularly in remote and high-altitude localities such as the Tibetan Plateau and the South China Sea. However, these data are limited. Human exposure to PCBs is closely related to the characteristics of environmental pollution. This review also discusses existing issues and future research prospects on PCBs in China. For instance, the accumulation characteristics and migration regularities of PCBs in food webs should be further studied. More investigations should be undertaken to assess the quantitative relationship between external and internal exposure to PCBs. For example, bioaccessibility and bioavailability studies should be supplemented to evaluate human health risks more accurately.

Influences of humic acid on the release of polybrominated diphenyl ethers from plastic waste in landfills under different environmental conditions

Landfill-formed humic acid are an important substance in landfill leachate. The effect of landfill-formed humic acid in different environments (temperature and surfactant concentrations) on the release of chemicals from plastic waste remains unknown. In order to explore the pollution release rates of polybrominated diphenyl ethers (PBDEs) in different plastic waste, humic acid were used as the extractant to conduct leaching simulation tests to study the effects of time, temperature, and surfactant (sodium dodecyl benzene sulfonate (SDBS)) concentrations on the release of PBDEs in waste. This waste includes polypropylene random pipes (PPRP), polyethylene of raised temperature resistance pipes (PERTP), polyvinyl chloride pipes (PVCP), polypropylene plastic benches (PPB), polypropylene washing machines (PPWM), polystyrene television (PSTV), and flame-retardant acrylonitrile butadiene styrene (FRABS). The leaching amounts of PBDEs had significant linear growth over time. Among them, the leaching amount of PBDEs in daily plastics is lower than dismantling plastics. The rate of leaching of BDE-209 was greater than the other congeners, with a leaching amount of up to 93.10%. Different types of waste exhibited different changes with temperature and surfactants concentrations. Among all the waste types, the leaching amounts of PBDEs in PPRP and PERTP gradually increased with increasing temperature. Surfactants within a certain concentration range can promote the release of PBDEs. The purpose of the research is to explore the dissolution law of PBDEs of different plastic products and the same product in different environment, provides a theoretical basis for the management and risk control of landfills.

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.

Contaminants of emerging concern: sources, soil burden, human exposure, and toxicities.

Targeted and Nontargeted Detection and Characterization of Trace Organic Chemicals in Human Serum and Plasma Using QuEChERS Extraction

Humans are exposed to a broad range of organic chemicals. Although targeted gas chromatography mass spectrometry techniques are used to quantify a limited number of persistent organic pollutants and trace organic contaminants in biological samples, nontargeted, high-resolution mass spectrometry (HRMS) methods assess the human exposome more extensively. We present a QuEChERS extraction for targeted and nontargeted analysis of trace organic contaminants using HRMS and compare this method to a traditional, cartridge-based solid-phase extraction (SPE). Following validation using reference and spiked serum samples, the method was applied to plasma samples (n = 75) from the Prospective investigation of Obesity, Energy, and Metabolism (POEM) study. We quantified 44 analytes using targeted analysis and 6247 peaks were detected using the nontargeted approach. Over 90% of targeted analytes were at least 90% recovered using the QuEChERS method in spiked serum samples. In nontargeted analysis, 84% of the peaks were above the method detection limit with area counts up to 3.0 × 105 times greater using the QuEChERS method. Of the targeted compounds, 88% were also identified in the nontargeted analysis. We categorized the 4212 chemicals assigned an identity in using EPA's CompTox Dashboard and 1076 chemicals were found in at least one list. The category with the highest number of chemicals was "androgen or estrogen receptor activity." The findings demonstrate that a QuEChERS technique is suitable for both targeted and nontargeted analysis of trace organic contaminants in biological samples.

Impact of sociodemographic profile, generation and bioaccumulation on lifetime dietary and internal exposures to PCBs

Polychlorinated biphenyls (PCBs) are persistent organic pollutants triggering numerous adverse effects. Because they are present in various food, dietary exposure of the population to these contaminants must be estimated to assess the related health risk. However, the classical risk assessment approach allows only short-term estimates of exposure and does not account for dietary changes, evolution of food contaminations and bioaccumulation of PCBs through life. The approach presented here assesses lifetime PCB exposure trajectories according to birth year and individual sociodemographic profiles. Moreover, a physiologically based toxicokinetic model was developed to simulate lifetime PCB plasma concentrations, while considering physiological changes with age. A focus on the long-term impact of breastfeeding is also presented in order to consider the risk related to PCBs and due to the mother-to-child transfer. For example, the exposure of an individual born in 1972 exceeds the critical value of 20 ng PCB/kg bw/day half as often as an individual born in 1932 throughout their lifetime but 13 times more often than an individual born in 2012, according to our simulations. In addition, even if breastfeeding clearly leads to much higher dietary exposures than formula feeding, the long-term impact on PCB body burden remains negligible. Risk assessment related to PCB lifetime trajectories is described and discussed.

Release, transformation, and risk factors of polybrominated diphenyl ethers from landfills to the surrounding environments: A review

Polybrominated diphenyl ethers (PBDEs) serve as brominated flame retardants when added to various products. When these products reach their end of life, a large amount of domestic waste containing PBDEs enters the landfills. Given their weak chemical bonds, they are easily affected by physical, chemical, and biological processes. These processes result in their release and the subsequent contamination of the surrounding soil, groundwater, and atmosphere, causing harm to humans and ecosystems. However, despite the progress made in the research of PBDEs over the years, understanding of the environmental behavior and fate of pollutants is still limited. With the development of cities, the release of PBDEs in old landfills will gradually increase the risk to the surrounding environment. Here we review the biological and nonbiological transformation of PBDEs and their derivatives in landfills and surrounding areas, as well as their distribution in soil, groundwater, and atmosphere. Specifically, this review aims to provide insights into the following aspects: 1) the biological (plant, animal, and microbial) and nonbiological (metal catalysis and photodegradation) conversion of PBDEs and their derivatives in landfills and surrounding areas; 2) the distribution of landfill-sourced PBDEs in the soil, groundwater, atmosphere and cross-media migration; and 3) suggestions and future research directions for the management and control of PBDEs in landfills.

Concentrations of halogenated flame retardants and polychlorinated biphenyls in house dust from Lagos, Nigeria

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCDD) are regulated under the Stockholm Convention of the United Nations' Environment Programme; with similar concerns emerging about alternative halogenated flame retardants (alt-HFRs), the use of which is increasing as replacements for PBDEs and HBCDD. While the presence in indoor dust of PCBs, PBDEs, and HBCDDs has been reported previously in a few African locations including Lagos, Nigeria, we are unaware of similar data for alt-HFRs. The present study thus aimed to provide the first information on alt-HFRs in indoor dust in sub-Saharan Africa, and to evaluate the impact of restrictions on the use of PBDEs, HBCDD, and PCBs on their concentrations in house dust in Lagos, Nigeria. Concentrations of ∑₈PBDEs, ∑HBCDDs, ∑₇alt-HFRs, and ∑₈PCBs in 15 samples of dust from homes in Lagos, Nigeria were found to be: 43-810 (median = 300) ng g^-1, <dl - 66 (median = <dl) ng g^-1, 32-2600 (median = 320) ng g^-1 and 3.8-61 (median = 18) ng g^-1 respectively. The dominant PBDE was BDE-209, its replacement decabromodiphenyl ethane (DBDPE) was the predominant alt-HFR, while PCB-138 displayed the highest concentration of the 8 PCBs targeted. Likely due to their higher vapour pressures, concentrations of the non-arochlor PCB 11, as well as those of PCB 28, and PBDE 28 were below detection limits. Concentrations of PBDEs and PCBs reported are generally below those reported previously for Lagos, Nigeria; suggesting restrictions on their manufacture and use have been effective. In contrast, while concentrations of BDE-209 in this study were lower than in one previous study in Lagos, they exceeded those in another; implying that the more recent restrictions on the deca-BDE product have yet to be fully effective. The evidence presented here of concentrations of alt-HFRs in Nigerian house dust provide a valuable benchmark against which future trends in their concentrations may be evaluated.

Characterization of top 100 researches on e-waste based on bibliometric analysis

With rapid development of energy, information, and communication technology, e-waste problem has become one of the global issues to be settled urgently. The main features on publication years, journals, countries and institutions, authors, keywords, and content types of the 100 most-cited articles on e-waste had been unfolded in this research. The direction and way forward were illustrated, the trends to date were demonstrated, and the terrain and pathways were evaluated on the research of e-waste. Bibliometric analysis method was applied to analyze various attributes on the 100 most-cited articles which were retrieved from WoSCC on May 25, 2021, by utilizing the software tools Microsoft Excel 2016 and VOS viewer 1.6.9. The publication year and citation number of the 100 articles ranged between 2003 and 2017 and from 83 to 925, respectively. Environmental Science & Technology (n=17) published the maximum articles. Waste Management, Journal of Hazardous Materials, and Environmental Science & Technology were the core journals on e-waste. One hundred twenty-three institutions and 25 countries were involved in publishing the 100 articles. Three hundred seventy authors contributed to the 100 articles in total. A total of 267 keywords occurred in the 100 articles. The keywords "e-waste" and "recycling" held the highest occurrences. The study content of the 100 articles could be classified into four types including the characteristic-and-property type, the environment-and-health type, the management-and-economic type, and the technique-and-processing type. Overall completeness and applicability of the evidence found in this study were verified sufficiently; the potential biases in the review process were also considered. The innovations of the research from the past bibliometric analysis work on e-waste were stated, and the implication for practice and research of this study were explained as well. 2007, 2008, and 2009 were a peak of the researches on e-waste, while the recent years were experiencing a valley. China and its institutions were most influential in this field on e-waste. India was becoming more and more influential on e-waste research in the world. Nigeria was the research center in Africa, and Brazil was the research center in Latin America. Wong Minghung was the most important expert on e-waste. The impact on environment and human being's health was the hot topic of researches on e-waste; the characteristic and property of e-waste were studied not enough. The researches of technique and processing would be the direction and way forward in the study field on e-waste. The characteristic and property on e-waste would need more attention to be researched. The researchers could develop new pathways based on and beyond the four types of content evaluated in this research.

Introducing a nested multimedia fate and transport model for organic contaminants (NEM)

Some organic contaminants, including the persistent organic pollutants (POPs), have achieved global distribution through long range atmospheric transport (LRAT). Regulatory efforts, monitoring programs and modelling studies address the LRAT of POPs on national, continental (e.g. Europe) and/or global scales. Whereas national and continental-scale models require estimates of the input of globally dispersed chemicals from outside of the model domain, existing global-scale models either have relatively coarse spatial resolution or are so computationally demanding that it limits their usefulness. Here we introduce the Nested Exposure Model (NEM), which is a multimedia fate and transport model that is global in scale yet can achieve high spatial resolution of a user-defined target region without huge computational demands. Evaluating NEM by comparing model predictions for PCB-153 in air with measurements at nine long-term monitoring sites of the European Monitoring and Evaluation Programme (EMEP) reveals that nested simulations at a resolution of 1°× 1° yield results within a factor of 1.5 of observations at sites in northern Europe. At this resolution, the model attributes more than 90% of the atmospheric burden within any of the grid cells containing an EMEP site to advective atmospheric transport from elsewhere. Deteriorating model performance with decreasing resolution (15°× 15°, 5°× 5° and 1°× 1°), manifested by overestimation of concentrations across most of northern Europe by more than a factor of 3, illustrates the effect of numerical diffusion. Finally, we apply the model to demonstrate how the choice of spatial resolution affect predictions of atmospheric deposition to the Baltic Sea. While we envisage that NEM may be used for a wide range of applications in the future, further evaluation will be required to delineate the boundaries of applicability towards chemicals with divergent fate properties as well as in environmental media other than air.

Passive Air Sampling of PCDD/Fs, PCBs, PAEs, DEHA, and PAHs from Informal Electronic Waste Recycling and Allied Sectors in Indian Megacities

Xenobiotic chemical emissions from the informal electronic waste recycling (EW) sector are emerging problem for developing countries, with scale and impacts that are yet to be evaluated. We report an intensive polyurethane foam disk passive air sampling study in four megacities in India to investigate atmospheric organic pollutants along five transects viz., EW, information technology (IT), industrial, residential, and dumpsites. Intraurban emission sources were estimated and attributed by trajectory modeling and positive matrix factorization (PMF). ∑₁₇PCDD/Fs, ∑₂₅PCBs, ∑₇plasticizers, and ∑₁₅PAHs concentrations ranged from 3.1 to 26 pg/m³ (14 ± 7; Avg ± SD), 0.5-52 ng/m³ (9 ± 12); 7.5-520 ng/m³, (63 ± 107) and 6-33 ng/m³ (17 ± 6), respectively. EW contributed 45% of total PCB concentrations in this study and was evidenced as a major factor by PMF. The dominance of dioxin-like PCBs (dl-PCBs), particularly PCB-126, reflects combustion as the possible primary emission source. PCDD/Fs, PCBs and plasticizers were consistently highest at EW transect, while PAHs were maximum in industrial transect followed by EW. Concentrations of marker plasticizers (DnBP and DEHP) released during EW activities were significantly higher (p < 0.05) in Bangalore than in other cities. Toxic equivalents (TEQs) due to dl-PCBs was maximum in the EW transect and PCB-126 was the major contributor. For both youth and adult, the highest estimated inhalation risks for dl-PCBs and plasticizers were seen at the EW transect in Bangalore, followed by Chennai and New Delhi.

Temporal Trends of Persistent Organic Pollutants across Africa after a Decade of MONET Passive Air Sampling

The Global Monitoring Plan of the Stockholm Convention on Persistent Organic Pollutants (POPs) was established to generate long-term data necessary for evaluating the effectiveness of regulatory measures at a global scale. After a decade of passive air monitoring (2008-2019), MONET is the first network to produce sufficient data for the analysis of long-term temporal trends of POPs in the African atmosphere. This study reports concentrations of 20 POPs (aldrin, chlordane, chlordecone, DDT, dieldrin, endrin, endosulfan, HBCDD, HCB, HCHs, heptachlor, hexabromobiphenyl, mirex, PBDEs, PCBs, PCDDs, PCDFs, PeCB, PFOA, and PFOS) monitored in 9 countries (Congo, Ghana, Ethiopia, Kenya, Mali, Mauritius, Morocco, Nigeria, and Sudan). As of January 1, 2019, concentrations were in the following ranges (pg/m³): 0.5-37.7 (∑₆PCB), 0.006-0.724 (∑₁₇PCDD/F), 0.05-5.5 (∑₉PBDE), 0.6-11.3 (BDE 209), 0.1-1.8 (∑₃HBCDD), 1.8-138 (∑₆DDT), 0.1-24.3 (∑₃endosulfan), 0.6-14.6 (∑₄HCH), 9.1-26.4 (HCB), 13.8-18.2 (PeCB). Temporal trends indicate that concentrations of many POPs (PCBs, DDT, HCHs, endosulfan) have declined significantly over the past 10 years, though the rate was slow at some sites. Concentrations of other POPs such as PCDD/Fs and PBDEs have not changed significantly over the past decade and are in fact increasing at some sites, attributed to the prevalence of open burning of waste (particularly e-waste) across Africa. Modeled airflow back-trajectories suggest that the elevated concentrations at some sites are primarily due to sustained local emissions, while the low concentrations measured at Mt. Kenya represent the continental background level and are primarily influenced by long-range transport.

Persistent Organic Pollutants (POPs) and Related Chemicals in the Global Environment: Some Personal Reflections

Persistent organic pollutants (POPs) and related chemicals are fascinating because of their combination of physical-chemical properties and complex effects. Most are man-made, but some also have natural origins. They are persistent in the environment, but they can be broken down variously by biodegradation, atmospheric reactions, and abiotic transformations. They can exist in the gas or particle phases, or both, in the atmosphere and in the dissolved or particulate phases, or both, in water. These combinations mean that they may undergo long-range transport in the atmosphere or oceans, or they may stay close to sources. Hence, emissions from one country are frequently a source of contamination to another country. They are also usually lipophilic, so-combined with persistence-this means they can accumulate in organisms and biomagnify through food chains. We all have a baseline of POPs residues in our tissues, even the unborn fetus via placental transfer and the newly born baby via mother's milk. POPs in biological systems occur in mixtures, so confirming effects caused by POPs on humans and other top predators is never straightforward. Depending on which papers you read, POPs may be relatively benign, or they could be responsible for key subchronic and chronic effects on reproductive potential, on immune response, as carcinogens, and on a range of behavioral and cognitive end points. They could be a factor behind diseases and conditions which have been increasingly reported and studied in modern societies. In short, they are endlessly fascinating to scientists and a nightmare to regulators and policy makers.

Role of low-latitude forests in modulating forest filter effect on a continental scale: Long-term simulation on PCB-153 in Chinese forests

Forests are important compartments influencing the environmental fate of persistent organic pollutants (POPs). To illustrate the effect of forests on the regional cycle of POPs, a level IV fugacity fate and transport model coupled with a detailed dynamic-forest module was applied to simulate the long-term variations of PCB-153 in China, where forest coverage accounts for approximately one fifth of land area. In the scenarios with forests, atmospheric outflow from China was 69% of that in the scenario without forests due to the enhanced storage in soil, degradation, and leaching. Previous studies regarded high-latitude areas, such as the polar region and boreal forests, as environments capable of reducing mobility of PCB-153, and they act as sinks of POPs. This modeling result suggests that tropical and subtropical forests may also play a similar role despite high temperatures favoring volatilization. Unlike boreal forest, the low-latitude forests may reduce the overall lifetime of PCB-153 in China due to enhanced degradation in warmer and moist soils of the tropical and subtropical area. Given that approximately half of the global forests are located in tropical and subtropical regions, they can be important environments influencing the global geochemical cycle and distribution of POPs, hence deserving more scientific attention by modeling and empirical studies.

Main sources controlling atmospheric burdens of persistent organic pollutants on a national scale

National long-term monitoring programs on persistent organic pollutants (POPs) in background air have traditionally relied on active air sampling techniques. Due to limited spatial coverage of active air samplers, questions remain (i) whether active air sampler monitoring sites are representative for atmospheric burdens within the larger geographical area targeted by the monitoring programs, and thus (ii) if the main sources affecting POPs in background air across a nation are understood. The main objective of this study was to explore the utility of spatial and temporal trends in concert with multiple modelling approaches to understand the main sources affecting polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in background air across a nation. For this purpose, a comprehensive campaign was carried out in summer 2016, measuring POPs in background air across Norway using passive air sampling. Results were compared to a similar campaign in 2006 to assess possible changes over one decade. We furthermore used the Global EMEP Multi-media Modeling System (GLEMOS) and the Flexible Particle dispersion model (FLEXPART) to predict and evaluate the relative importance of primary emissions, secondary emissions, long-range atmospheric transport (LRAT) and national emissions in controlling atmospheric burdens of PCB-153 on a national scale. The concentrations in air of both PCBs and most of the targeted OCPs were generally low, with the exception of hexachlorobenzene (HCB). A limited spatial variability for all POPs in this study, together with predictions by both models, suggest that LRAT dominates atmospheric burdens across Norway. Model predictions by the GLEMOS model, as well as measured isomeric ratios, further suggest that LRAT of some POPs are dictated by secondary emissions. Our results illustrate the utility of combining observations and mechanistic modelling approaches to help identify the main factors affecting atmospheric burdens of POPs across a nation, which, in turn, may be used to inform both national monitoring and control strategies.

Seasonal rainfall affects occurrence of organohalogen contaminants in tropical marine fishes and prawns from Zanzibar, Tanzania

Seasonal differences in precipitation may affect contaminant dynamics in tropical coastal regions due to terrestrial runoff of contaminants to the marine environment after the rainy seasons. To assess the effect of seasonal rainfall on occurrence of organohalogen contaminants in a coastal ecosystem, marine fishes and prawns were collected off the coast of Zanzibar, Tanzania in January and August 2018, representing pre- and post-rainy season, respectively. Samples were analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) and emerging BFRs, as well as the dietary descriptors stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N). Across all species and seasons, mean contaminant concentrations ranged from below limit of detection (LOD) to 129 ng/g lipid weight (lw) ΣPCBs; 5.6-336 ng/g lw ΣOCPs; and < LOD -22.1 ng/g lw ΣPBDEs. Most of the emerging BFRs were below LOD. Contaminant concentrations generally increased with higher pelagic carbon signal (δ¹³C) and higher relative trophic position (δ¹⁵N). The ratio of DDE/ΣDDTs in fishes and prawns was lower in August than in January, suggesting runoff of non-degraded DDT into the marine system during or after the seasonal rainfall. Contaminant patterns of OCPs and PCBs, and concentrations of BFRs, differed between seasons in all species. A higher relative concentration-increase in lower halogenated, more mobile PCB and PBDE congeners, compared to higher halogenated congeners with lower mobility, between January and August aligns with a signal and effect of terrestrial runoff following the rainy season.

Investigating the spatial distribution of polychlorinated biphenyls in sediment in the Pearl River Delta, South China

One hundred forty-three surface sediment (0-5 cm depth) samples were collected from locations representing industrialized areas, less-industrialized areas, and e-waste recycling areas in the Pearl River Delta (PRD). The spatial distribution of polychlorinated biphenyls (PCBs) and their potential adverse effects on aquatic organisms were investigated. The average PCB concentration in the less-industrialized areas (background) in the PRD was approximately 10 ng/g dry weight (dw), which was generally half that found in the industrialized areas (approximately 22 ng/g dw). Severe PCB contamination, with concentrations ranging from 1000 to 26500 ng/g dw, was found in pond sediments collected from e-waste recycling areas. It is very likely that such contamination would have had adverse effects on the aquatic biota there. PCBs in the e-waste recycling areas were dominated by penta- and hex-PCB congeners, which made them significantly different from those found in other regions, where tri- and tetra-PCB congeners were predominant. Higher abundances of less chlorinated congeners were seen in the less-industrialized areas compared to the industrialized areas. Differences in the transport abilities of different congeners, together with dechlorination of higher chlorinated congeners, is the most likely reasons for this.

Combined action of gamma radiation and exposure to copper ions on Lemna minor L

PURPOSE

Under natural conditions, the reaction of living organisms to the action of acute gamma radiation depends on other stressors, including heavy metals. The aim of this work was to study changes in morphometric parameters, the content of photoassimilation pigments and the level of oxidative stress in irradiated duckweed at various copper concentrations in the culture medium.

MATERIALS AND METHODS

As a model organism, we used Lemna minor L. Duckweed was exposed to acute γ-radiation at doses of 18, 42, 63 Gy. After irradiation, the plants were transferred into a medium containing 3, 5, 6.3 μmol/L Cu. On the 4th day of exposure, the levels of chlorophyll, carotenoids, malondialdehyde (MDA) were measured; after 7 days, the specific growth rate, the level of damage, the change in the frond area, copper concentration in plant tissues were determined.

RESULTS

The action of γ-radiation (18, 42, 63 Gy) and copper ions (3, 5, 6.3 μmol/L) reduced the growth rate, increased the membrane lipid peroxidation, reduced the area of the fronds more significantly than under the separate action of the factors. The factors acted antagonistically on the specific growth rate. The content of copper in the tissues of irradiated plants (42, 63 Gy) increased.

CONCLUSION

Irradiation of duckweed with acute doses of gamma radiation reduced the resistance of plants to excess copper in the environment.

GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m³, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2-5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a 'reference city' for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.

Global emissions of Dechlorane Plus

Dechlorane Plus (DP) is a chlorinated flame retardant applied in parallel to or as a replacement product for regulated flame retardants. Detection of DP in environmental media all over the world in recent years necessitates the development of detailed global emission estimates for environmental model studies. Based on production, usage and disposal data two global atmospheric emission scenarios were made with a detailed geographical distribution. The total DP emission is estimated to be 0.02 t/year and 3.2 t/year in a low and high emission scenario, respectively, reflecting the uncertainties in production volumes and emission factors. The emission estimates are tested by implementation in the Danish Eulerian Hemispheric Model, an advanced chemistry-transport model. An evaluation against measurements in the Arctic from the early 2010s, considered to represent background concentrations, shows that the predicted concentration range for the high emission scenario is in line with the measured range, whereas the predicted concentrations for the low emission estimate are more than a factor of 100 lower than the measurements, rendering the high emission estimate most probable.

Inevitable human exposure to emissions of polybrominated diphenyl ethers: A perspective on potential health risks

Polybrominated diphenyl ethers (PBDEs) serve as flame retardants in many household materials such as electrical and electronic devices, furniture, textiles, plastics, and baby products. Though the use of PBDEs like penta-, octa- and deca-BDE greatly reduces the fire damage, indoor pollution by these toxic emissions is ever-growing. In fact, a boom in the global market projections of PBDEs threatens human health security. Therefore, efforts are made to minimize PBDEs pollution in USA and Europe by encouraging voluntary phasing out of the production or imposing compelled regulations through Stockholm Convention, but >500 kilotons of PBDEs still exist globally. Both 'environmental persistence' and 'bioaccumulation tendencies' are the hallmarks of PBDE toxicities; however, both these issues concerning household emissions of PBDEs have been least addressed theoretically or practically. Critical physiological functions, lipophilicity and toxicity, trophic transfer and tissue specificities are of utmost importance in the benefit/risk assessments of PBDEs. Since indoor debromination of deca-BDE often yields many products, a better understanding on their sorption propensity, environmental fate and human toxicities is critical in taking rigorous measures on the ever-growing global deca-BDE market. The data available in the literature on human toxicities of PBDEs have been validated following meta-analysis. In this direction, the intent of the present review was to provide a critical evaluation of the key aspects like compositional patterns/isomer ratios of PBDEs implicated in bioaccumulation, indoor PBDE emissions versus human exposure, secured technologies to deal with the toxic emissions, and human toxicity of PBDEs in relation to the number of bromine atoms. Finally, an emphasis has been made on the knowledge gaps and future research directions related to endurable flame retardants which could fit well into the benefit/risk strategy.

Characterizing the Variation of Dissolvable PAHs in Receiving Water in a Reclaimed Water Irrigation Region

Long-term wastewater and reclaimed water irrigation systems constitute the major processes in local water circulation, which concomitantly introduce plenty of undesirable substances that can threaten water quality, ecosystem functions and human health. At the Southeast Reclaimed Water Irrigation Region (SRWIR) of Beijing, wastewater irrigation was adopted from 1969 to 2002, and second-treated effluents (reclaimed water) has been used thereafter. Polycyclic aromatic hydrocarbons (PAHs) were the most ubiquitously detected contaminant in wastewater and reclaimed water and are reported to be carcinogenic. Hence, we measured the concentrations of dissolved sixteen United States Environmental Protection Agency (USEPA) priority PAHs in surface water and groundwater at the SRWIR to characterize their spatial and temporal variations, and to clarify the role of reclaimed water to natural water. The concentration of 16 individual PAHs in reclaimed water, rivers and groundwater varied from 339.4 to 636.2 ng/L, 359.1 to 3,435.0 ng/L and 216.5 to 488,205.2 ng/L, respectively. The lower aromatic rings of PAHs prevailed in aquatic environments rather than the higher ones. Thereinto, naphthalene was the predominant isomer within the highest concentration reached to 486,600 µg/L. The groundwater samples had higher PAHs concentrations at Tongzhou district which attributed to the higher vulnerability of aquifer. Additionally, strong correlations between PAHs and total nitrogen, nitrate, dissolved oxygen and electrical conductivity suggested those potential factors affecting the photo degradation and/or biodegradation of PAHs. The relationship identified between PAHs concentrations and physical and chemical indices would help us to enhance the understanding migration and transformation of PAHs spatially and temporally, enable us to assess the potential risks of the environmental pollutants to aquatic organisms and human water supplies.

A Global, Cross-System Meta-Analysis of Polychlorinated Biphenyl Biomagnification

Studies evaluating the mechanisms underpinning the biomagnification of polychlorinated biphenyls (PCBs), a globally prevalent group of regulated persistent organic pollutants, commonly couple chemical and stable isotope analyses to identify bioaccumulation pathways. Due to analytical costs constraining the scope, sample size, and range of congeners analyzed, and variation in methodologies preventing cross-study syntheses, how PCBs biomagnify at food web, regional, and global scales remains uncertain. To overcome these constraints, we compiled diet (stable isotopes) data and lipid-normalized concentrations of sum total PCB (PCB_ST), seven indicator PCB congeners, and their sum (PCB_∑7). Our analyses revealed that the number of congeners analyzed, region, and class most strongly predicted PCB_ST, while similarly, region, class, and feeding location best predicted PCB_∑7 and all seven congeners. We also discovered that PCB_ST, PCB_∑7, and the seven indicator congeners all occur in higher concentrations in freshwater than marine ecosystems but are more likely to biomagnify in the latter. Moreover, although the seven congeners vary in their propensity to biomagnify, their trophic magnification factors are all generally greater in the Atlantic than the Pacific. Thus, novel insights regarding PCB biomagnification across taxonomic, food webs, regional, and global scales can be gleaned by leveraging existing data to overcome analytical constraints.

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.

Chemical fate of persistent organic pollutants in the arctic: Evaluation of simplebox

Persistent organic pollutants (POPs) are of great concern for decades due to their persistence, bioaccumulation and long-range transport potential. Multimedia fate models are useful scientific and decision-support tools for predicting the chemical fate in the environment. The SimpleBox multimedia fate model (v4.0) was used in this study to estimate the impact of POP emissions from the European and North American mainland on POP contamination in the Arctic. The purpose of the study was to evaluate the performance of SimpleBox by comparing estimations to measurements. Model performance for the air compartment was reasonable as estimated concentrations were generally within a factor of five of measured concentrations. SimpleBox suggested higher POP concentrations in Arctic oceans than in temperate oceans, contrary to the few measured data. Discrepancies between estimations and measurements may be attributed to the variability in emission estimates and degradation rates of POPs, representativeness of monitoring data, and a missing snow and ice environmental compartment in SimpleBox. Emission rates and degradation rate constants were the most influential input parameters in SimpleBox based on sensitivity analysis. Suggestions for improvements of SimpleBox refining POP risk assessment are provided.

Removal of persistent organic pollutants (POPs) from waters and wastewaters by the use of ionizing radiation

The most important advantages of the use of ionizing radiation over other AOPs are exceptionally efficient in situ generation of very reactive oxidizing free radicals ^•OH from water radiolysis and very unique simultaneous generation of strongly reducing hydrated electrons. They allow to carry out Advanced Oxidation and Reduction Processes (AO/RPs) simultaneously. Carrying out only oxidative or reductive processes is also possible by the use of appropriate scavengers of free radicals in irradiated solutions. For the application of these processes for environmental protection purposes gamma-rays from radioisotope sources or beams of accelerated electrons are most commonly used. In the case of particularly resistant POPs some chemical additives to the irradiated solutions may enhance the yield of decomposition. This review based on 125 references reported so far presents the applications of the discussed technology in removing POPs from waters and wastewaters, including pesticides listed among POPs, dioxins, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and selected perfluorinated surfactants.

The presence, emission and partitioning behavior of polychlorinated biphenyls in waste, leachate and aerosols from Norwegian waste-handling facilities

Even though production and open use of polychlorinated biphenyls (PCBs) have been phased out in Western industrialised countries since the 1980s, PCBs were still present in waste collected from different waste handling facilities in Norway in 2013. Sums of seven indicator-PCBs (I-PCB₇: PCB-28, -52, -101, -118, -138, -153 and -180) were highest in plastic waste (3700 ±1800 μg/kg, n=15), waste electrical and electronic equipment (WEEE) (1300 ± 400 μg/kg, n=12) and fine vehicle fluff (1800 ± 1400 μg/kg, n=4) and lowest in glass waste, combustibles, bottom ash and fly ash (0.3 to 65 μg/kg). Concentrations in leachate water varied from 1.7 to 2900 ng/L, with higher concentrations found at vehicle and WEEE handling facilities. Particles in leachate water exhibited similar PCB sorption properties as solid waste collected on site, with waste-water partitioning coefficients ranging from 10⁵ to 10⁷. I-PCB₇ in air samples collected at the sites were mostly in the gas phase (100-24000 pg/m³), compared to those associated with particles (9-1900 pg/m³). In contrast, brominated flame retardants (BFRs) in the same samples were predominantly found associated with particles (e.g. sum of 10 brominated diethyl ethers, ΣBDE₁₀, associated with particles 77-194,000 pg/m³) compared to the gas phase (ΣBDE₁₀ 6-473 pg/m³). Measured gas-phase I-PCB₇ concentrations are less than predicted, assuming waste-air partitioning in equilibrium with predominant waste on site. However, the gas-particle partitioning behavior of PCBs and BFRs could be predicted using an established partitioning model for ambient aerosols. PCB emissions from Norwegian waste handling facilities occurred primarily in the form of atmospheric vapor or leachate particles.

Toxicity evaluation of E-waste plastics and potential repercussions for human health

At present, waste mobile phone is considered to be one of the fastest-growing obsolete items in the stream of electronic waste (e-waste). Toxic substances such as heavy metals and brominated flame retardants (BFRs) have been widely added to plastics used in electrical and electronic equipment (EEE). The recent technological revolution in electronic appliances combined with high and growing consumption has caused a huge generation of waste electrical and electronic equipment (WEEE). Therefore, e-waste plastics are considered to be one of the fastest-growing waste streams globally. In this study, we examined the hazardous substances in the plastic components of waste mobile phones and then applied the USEtox life cycle impact assessment (LCIA) model to determine the impacts on human health. Specifically, various plastic parts separated from waste mobile phones (n = 20) were collected and then, we used standard tests to characterize the heavy metals and brominated flame retardants. The mean and range of the results are 2207.7 μg/kg (503.9-11569.9 μg/kg) for Pb, 91.6 μg/kg (8.8-464.4 μg/kg) for Cd, 13.7 μg/kg (1.6-58.9 μg/kg) for Be, 7203.3 μg/kg (117-69813 μg/kg) for Sb, 471.3 μg/kg (143.4-2351.3 μg/kg) for As, 1.5 mg/kg (2.1-12.5 mg/kg) for Hg and 523.7 mg/kg (27.1-3859 mg/kg) for Cr. The BFRs - a sum Polybrominated Biphenyls, Polybrominated Diphenyl Ethers and Hexabromocyclododecane - were not detected except for two samples, which was an average of 234.5 μg/kg for nona-BDE and deca-BDE. The total bromine (Br) concentration varied from 0 to 471 mg/kg (average value of 87.9 mg/kg) , while Tetrabromobisphenol A (TBBP-A) showed an average concentration of 214.3 μg/kg. In the case of potential human health risks, Hg contributed the major risk for carcinogens and non-cancer disease in the plastics, but the contribution of Pb was also significant. In the case of eco-toxicity, Cr posed the most significant risks in the plastics. Overall, the results show that the toxic substances are below the limit values of substances regulated in the RoHS Directive in China and Europe. However, the results of LCIA highlight the growing importance to avoid the open burning practices of e-waste plastics that contain Hg, Pb, Cr ad Sb. Additionally, the results set a new database for the e-waste plastics recycling industry and provide information for ecodesign in EEE production.

Solid-Phase Extraction, Preservation, Storage, Transport, and Analysis of Trace Contaminants for Water Quality Monitoring of Heavy Metals

Accurate quantification of trace contaminants currently requires collection, preservation, and transportation of large volumes (250-1000 mL) of water to centralized laboratories, which impedes monitoring of trace-level pollutants in many resource-limited environments. To overcome this logistical challenge, we propose a new paradigm for trace contaminant monitoring based on dry preservation: solid-phase extraction, preservation, storage, transport, and analysis of trace contaminants (SEPSTAT). We show that a few grams of low-cost, commercially available cation exchange resin can be repurposed to extract heavy metal cations from water samples even in the presence of background ions, dryly preserve these cations for at least 24 months, and release them by acid elution for accurate quantification. A compact, human-powered device incorporating the sorbent removes spiked contaminants from real water samples in a few minutes. The device can be stored and transported easily and produces a sample suitable for measurement by standard methods, predicting the original sample heavy metal concentration generally within an error of 15%. These results suggest that, by facilitating the collection, storage, handling, and transportation of water samples and by enabling cost-effective use of high-throughput capital-intensive instruments, SEPSTAT has the potential to increase the ease and reach of water quality monitoring of trace contaminants.

Historical sedimentary deposition and flux of PAHs, PCBs and DDTs in sediment cores from the western Adriatic Sea

The sources and depositional history of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) over the last century were investigated in sediment cores from the North Adriatic Sea (Po River prodelta) and the South-Western Adriatic Margin (SWAM). Contaminant concentrations were higher in the Po River prodelta. ∑₁₆PAHs ranged from 193 to 533 ng g^-1, ∑₅PCBs ranged from 0.9 to 5.2 ng g^-1 and ∑DDTs (p,p'-DDD + p,p'-DDE) ranged from 0.1 to 2.5 ng g^-1. In the SWAM, ∑PAHs ranged from 11 to 74 ng g^-1 while ∑PCB and ∑DDT concentrations were close to the MQL. Accordingly, contaminant fluxes were much higher in the northern (mean values of 152 ± 31 ng cm² y^-1 and 0.70 ± 0.35 ng cm² y^-1 for PAHs and OCs, respectively) than in the southern Adriatic (2.62 ± 0.9 ng cm² y^-1 and 0.03 ± 0.02 ng cm² y^-1 for PAHs and OCs, respectively). The historical deposition of PAHs seemed to be influenced by the historical socioeconomic development and by changes in the composition of fossil fuel consumption (from petroleum derivatives to natural gas) in Italy from the end of the 19th century to the present. Similarly, vertical variations in DDT concentrations matched its historical use and consumption in Italy, which started around in the mid-late 1940s to fight typhus during the II World War. Contaminant concentrations detected in sediments does not seem to pose ecotoxicological risk for marine organisms in the Adriatic Sea.