Modeling the Time-Variant Dietary Exposure of PCBs in China over the Period 1930 to 2100

Kelp as a biomonitor of persistent organic pollutants in coastal areas of China: Contamination levels and human health risk

Kelp, the brown alga distributed in coastal areas all over the world, is also an important medicine food homology product in China. However, the levels and profiles of persistent organic pollutants (POPs) in kelp have not been thoroughly investigated to date. Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and emerging bromine flame retardants (eBFRs) were evaluated in 41 kelp samples from the main kelp producing areas in China. The concentrations of total PCBs, PBDEs and eBFRs were in the range of 0.321-4.24 ng/g dry weight (dw), 0.255-25.5 ng/g dw and 3.00 × 10-3-47.2 ng/g dw in kelp, respectively. The pollutant pattern was dominated by decabromodiphenyl ethane (DBDPE, 13.0 ± 11.7 ng/g dw) followed in decreasing order by BDE-209 (2.74 ± 4.09 ng/g dw), CB-11 (1.32 ± 1.06 ng/g dw). The tested results showed that kelp could reflect the pollution status of PCBs, PBDEs and eBFRs, indicating the suitability of kelp as a biomonitor of these harmful substances. Finally, the data obtained was used to evaluate human non-cancer and cancer risks of PCBs and PBDEs via kelp consumption for Chinese. Though the calculated risk indices were considered acceptable according to the international standards even in the worst scenarios, the POPs levels in kelp should be monitored continuously as a good environmental indicator.

Simulating behavior of perfluorooctane sulfonate (PFOS) in the mainstream of a river system with sluice regulations

Perfluorooctane sulfonate (PFOS) is a persistent, anionic and ubiquitous contaminant that undergoes long-range transport within the environment. Its behavior has attracted wide-range academic and regulatory attention. In this article, a mass balance model was employed to simulate PFOS concentrations in the mainstream of Haihe River water system, encompassing sluices and artificial rivers. The dynamic simulation of PFOS concentrations in both sediment and freshwater took into account fluctuations in PFOS emissions, water levels and water discharge. Furthermore, the study delved into exploring the impacts of sluices and artificial rivers on the behavior of PFOS. The simulated concentrations of PFOS in steady state agreed with the measured concentrations in surveys carried out in Nov. 2019, July 2020, Oct. 2020, and June 2021. Every year, approximately 24 kg PFOS was discharged into the Bohai Sea with Chaobai New River being the largest contributor for 44 %. Moreover, the transport of PFOS in the original rivers is likely to be restricted by sluices and replaced by artificial rivers. Monte Carlo analysis showed that model predictions of PFOS concentrations in sediment were subject to greater uncertainty than those in freshwater as the former is impacted by more parameters, such as density of sediment. This study provides a scientific basis for the local government to manage and control PFOS.

Modeling the long-term fate of polycyclic aromatic hydrocarbons (PAHs) and public health risk in Bohai Bay Sea Area, China

The target of this study was to reconstruct the historical concentration, distribution, variation, and exposure risk evaluation for EPA PAHs to the whole sea of Bohai Bay and the coastal population, by employing a specific dynamic multimedia model during 1950-2050. The unsteady-state model, driven by temporal energy activities from 1950 and sustainable scenarios based on socioeconomic development, indicated the annual emission increased by 4.6 times (from 84.8 tons to 391 tons) until 2020 and resulted in concentrations up to 5.2 times in the atmospheric compartment, and 4.9 times in seawater. Two peak concentrations in 1997 and 2014, consistent with total PAHs input revealed significant regional anthropogenic input in northern Bohai Bay (Tianjin) and southern Bohai Bay (Hebei). The peak-to-peak values of the timing concentration revealed a notably alternative increase in the south (+109.4 %-128.6 %), instead of the rapid decline in the north (-21.5 %-44.5 %). The dominant processes at air-seawater interfaces were air-seawater molecular transfer (from 38.4 % to 51.8 %), and wet deposition (from 60.5 % to 47.5 %). Under 5 shared socioeconomic pathways, the optimal scenario (SSP1) achieved a 24.7 % emission decline, an atmospheric decrease of 15.1 %-31.1 %, and 24.8 %-41.2 % mitigation in seawater during 2020-2050, and each pathway exhibited a general lessening concave in the northern developed municipality, compared with convex in the southern developing regions. The inhalation risk assessment evaluated 10 generations living on Bohai Bay coasts, with an acceptable result, while the current sustainable conceive was with meager fruition in reducing risk.

Health Effects of Exposure to Indoor Semi-Volatile Organic Compounds in Chinese Building Environment: A Systematic Review

People spend a considerable portion of their lives indoors; thus, the quality of the indoor environment is crucial. Semi-volatile organic compounds (SVOCs) are among the primary indoor pollutants responsible for various health risks. This paper systematically reviews the impact of SVOC exposure on human health in Chinese built environments. Based on a set of criteria, we judged 12 publications as providing sufficient information on both SVOC exposure and health effects to inform the relationship. Out of six studies on polycyclic aromatic hydrocarbons (PAHs), three observed a positive association between PAH exposure and lung cancer. Out of six studies of phthalate exposure, two studies reported a significant positive association between DEP and DiBP and asthma, between DEP and DEHP and dry cough among children, and between DBP and rhinitis among younger adults. The results of this review suggest that there might be a link between phthalate exposure and asthma and allergies, as well as a link between PAH exposure and lung cancer. However, due to the limited number of studies conducted, more evidence is necessary to definitively guide the establishment of standards for SVOC control in China.

The influence of anaerobic dechlorination on the aerobic degradation of PCBs in e-waste-contaminated soils in an anaerobic-aerobic two-stage treatment

The combination of microbial reductive dechlorination and aerobic oxidation (RD-AO) process was proposed to be a promising strategy for extensive bioremediation of highly chlorinated polychlorinated biphenyls (PCBs). Nonetheless, experimental evidence on the impact of the RD on subsequent AO in anaerobic-aerobic two-stage treatment remains scarce. The present study applied stable-isotope probing (SIP) to explore the RD-AO mediated degradation of PCBs in an e-waste-contaminated soil. The RD-AO treatment resulted in 37.1 % and 48.2 % degradation of PCB180 and PCB9, respectively, while the PCB9 degradation efficiency decreased compared to the sole AO (81.2 %). The inhibition of PCB aerobic degradation might be caused by the alteration of aerobic bacterial community, which was proved by a higher abundance of anaerobic bacteria and a lower abundance of aerobic bacteria being observed in the aerobic stage of RD-AO. Further evidence was obtained using DNA-SIP that the anaerobic stage altered the PCB degraders' community structures and changed three of the five degraders. There were four lineages (Arenimonas, Steroidobacter, Sulfurifustis, and Thermoanaerobacterales) identified as PCB degraders for the first time. Interestingly, three of them were found in RD-AO microcosm, suggesting that anaerobic-aerobic two-stage treatment can recruit novel bacteria involved in PCBs aerobic degradation. The present study provided novel insight into the synergistic integration of anaerobic and aerobic processes for extensive degradation of highly chlorinated PCBs.

Temporal Trends of Alternative Halogenated Flame Retardants in Humpback Dolphins from the South China Sea

Increasing human activities are altering marine ecosystems, which may have ramifications for predator feeding ecology and, thus, the degree of contaminant exposure. We conducted the first investigation of spatiotemporal trends for nine alternative halogenated flame retardants (AHFRs) and their relations with dietary variations in 128 humpback dolphins that were stranded along the northern South China Sea during 2003-2020. We detected the highest levels of seven major AHFRs in humpback dolphins compared with the results reported in cetaceans globally, indicating high AHFR contamination in coastal regions of South China. Dolphins that were stranded near urban regions generally contained higher AHFR concentrations than those that were stranded near rural areas, mirroring the environmental trends of AHFRs occurring in this area. Model-generated diet estimates suggested that humpback dolphins have reduced their consumption of high trophic-level prey in recent years, likely attributable to overfishing-induced prey decline in this region. After adjusting AHFR concentrations due to diet changes, the temporal trends of AHFR contamination in humpback dolphins were only slightly altered. Our results suggest that increasing discharges of AHFRs into the South China Sea during the 2000s and 2010s may have had a greater influence on AHFR trends in humpback dolphins than dietary shifts.

Ecosystem impact and dietary exposure of polychlorinated biphenyls (PCBs) and heavy metals in Chinese mitten crabs (Eriocheir sinensis) and their farming areas in Jiangsu, China

This study investigated the presence of 18 dioxin-like and non-dioxin-like polychlorinated biphenyls (dl- and ndl-PCBs), heavy metals (Cd, Hg, Pb, and As) in Chinese mitten crabs (Eriocheir sinensis) and their distribution in Jiangsu, China. Risk assessment and source apportionment were employed for evaluating the eco-toxicological impact and human exposure. It was found that the compositions of PCBs varied spatially, suggesting different sources of pollutants, whilst PCB 28, 105, 114, and 126 were consistently found in all sample types, suggesting a common pollution source remained, and the bio-accumulation process was in effect. The total PCBs in sediment were found much higher than in water, and brown meat had the highest and most diverse PCB congeners among all tissues. The presence of heavy metals was found in all samples in descending order of As>Cd>Pb>Hg and in the order of shell>brown meat>white meat>gill for crabs. The results of risk assessment indicated that the potential carcinogenic and non-carcinogenic risks were within the acceptable range for long-term consumption of the crabs overall. However, the highest toxic equivalent (TEQ), carcinogenic, and non-carcinogenic risks were all recorded in Location C, where dl-PCB 126, 169, and As contributed to the majority of the risks. The ecological risk posed by all HMs was low, but cases of serious point source pollution have been found in the investigated regions, and risks caused by Cd individually should raise concerns. Source apportionment study revealed that the contaminants mostly originated from anthropogenic activities. Natural deposition and transportation played an important role as well.

Pilot study on long-term simulation of PCB-153 human body burden in the Tibetan Plateau

The historical body burden of 2,2',4,4',5,5'-Hexachlorobiphenyl (PCB-153) in the Tibet Autonomous Region (TAR) population was simulated on the basis of localized exposure factors and dietary data, which present a preliminary attempt to quantify the influence of high lipid dietary patterns, grain transported from inland China, and atmospheric transport on human exposure to polychlorinated biphenyls (PCBs). Herdsman with large animal-based food consumption exhibited the highest body burden that was comparable with that in inland China. The body burden of other residents was within the range of low-to-moderate level. High-lipid diet of urban residents caused their body burden being 1.5--2.5 times higher than that of rural residents. The consumption of grain transported from higher polluted areas can also result in 50%-115% increase in the body burden of Tibetan rural residents compared with when local produced grain is consumed, suggesting that the influence of grain logistic can be as important as dietary patterns. The exposure risk for rural residents associated with grain logistic should not be ignored even if they consumed less high-lipid food. By splitting the inventory, over 80% of the PCB-153 pollution in the TAR was identified to be induced by atmospheric transport from foreign countries. However, the grain logistic contributed approximately half of the overall human body burden of Tibetan residents recently if assuming that the grain shortage was supplied by adjacent Sichuan Province. The combined influence of high-lipid diet, atmospheric transport and food logistic highlights the difficulties of risk control in remote regions that accumulate POPs, such as TAR.

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.

High inter-species differences of 12378-polychlorinated dibenzo-p-dioxin between humans and mice

Although huge interspecies differences in the response to dioxins have been acknowledged, toxic equivalency factors derived from rodent studies are often used to assess human health risk. To determine interspecies differences, we first developed a toxicokinetic model in humans by measuring dioxin concentrations in environmental and biomonitoring samples from Southern China. Significant positive correlations between dioxin concentrations in blood and age were observed for seven dioxin congeners, indicating an age-dependent elimination rate. Based on toxicokinetic models in humans, the half-lives of 15 dioxin congeners were estimated to be 1.60-28.55 years. In consideration that the highest contribution to total toxic equivalency in blood samples was by 12378-polychlorinated dibenzo-p-dioxin (P₅CDD), this study developed a physiologically based pharmacokinetic (PBPK) model of 12378-P₅CDD levels in the liver, kidney, and fat of C57/6J mice exposed to a single oral dose, and the half-life was estimated to be 26.1 days. Based on estimated half-lives in humans and mice, we determined that the interspecies difference of 12378-P₅CDD was 71, much higher than the default usually used in risk assessment. These results could reduce the uncertainty human risk assessment of 12378-P₅CDD, and our approach could be used to estimate the interspecies differences of other dioxin congeners.

Lactational exposure to dioxin-like polychlorinated biphenyl 169 and nondioxin-like polychlorinated biphenyl 155: Effects on rat femur growth, biomechanics and mineral composition

Exposure to polychlorinated biphenyls (PCBs), which are persistent lipophilic environmental pollutants, has a variety of adverse effects on wildlife and human health, including bone mineralization, growth and mechanical strength. The present study evaluated the effects of lactational exposure to nondioxin-like PCB-155 and dioxin-like PCB-169, individually and in combination, on pubertal rat femur development and its biomechanics. After offspring delivery, Wistar rat mothers were divided into four groups, i.e., PCB-169, PCB-155, PCB-155+169 and control, and were administered PCBs intraperitoneally. Data on bone geometry, biomechanics and mineral composition were obtained by analysis of femurs from 42-day-old offspring by microCT scanning, three-point bending test and inductively coupled plasma mass spectrometry. Decreased somatic mass and femur size, i.e., mass, periosteal circumference and cross sectional area, were observed in the PCB-169 and PCB-155 groups. Additionally, lactational exposure to planar PCB-169 resulted in harder and more brittle bones containing higher amounts of minerals. Combined exposure to structurally and functionally different PCBs demonstrated only mild alterations in bone width and mineralization. To conclude, our results demonstrated that alterations, observed on postnatal day 42, were primarily induced by PCB-169, while toxicity from both of the individual congeners may have been reduced in the combined group.