Changes of polybrominated diphenyl ether concentrations in ducks with background exposure level and time

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

A Pilot Study on the Concentration, Distribution and Bioaccumulation of Polybrominated Diphenyl Ethers (PBDEs) in Tissues and Organs of Grassland Sheep

Polybrominated diphenyl ether (PBDE) concentrations in various tissues and organs of grassland sheep from Inner Mongolia, China, were determined. The abilities of PBDEs binding to ovine serum albumin (OSA) and Cytochrome P450 enzyme (CYP3A24) were assessed by fluorescence spectroscopy and molecular docking simulations. The PBDE concentrations in the sheep tissue and organ samples were 33.4-167 pg/g dw. The distribution of PBDEs in sheep organs and tissues is affected not only by the function of organs and tissues, but also by the characteristics of PBDEs. Adipose tissue tends to bioaccumulate more-brominated BDEs (BDE-154, -153, and -183), but muscle tissues and visceral organs mainly bioaccumulate less-brominated BDEs. The distribution of PBDEs in visceral organs is mainly affected by the transport of ovine serum albumin (OSA) and the metabolism of CYP3A24 enzyme. The distribution of PBDEs in adipose tissue and brain is mainly affected by their logK_OW.

Exploring the environmental fate of novel brominated flame retardants in a sediment-water-mudsnail system: Enrichment, removal, metabolism and structural damage

Novel brominated flame retardants (NBFRs) are now ubiquitous in the environment with the extensive production and application. In the present study, pentabromotoluene (PBT), hexabromobenzene (HBB) and decabromodiphenyl ethane (DBDPE) were spiked into the sediments where mudsnails (Bellamya aeruginosa) were cultivated. In the 35-day enrichment process, the highest concentration of the three NBFRs measured in mudsnail is 2.0 mg/kg, 22 mg/kg and 5.2 mg/kg dry weight (dw), respectively. The average enrichment of NBFRs in viscera was about 3 times of pleopod with the same mass. Meanwhile, the parent mudsnails can transfer NBFRs to their offspring. The removal half-life of the three NBFRs was in the range of 2.6 and 5.7 days according to the first-order kinetic equation. Several degradation products of the NBFRs were detected in mudsnail samples, which were exposed to single substance. 2,4,6-tribromotoluene was identified as degradation product of PBT; 1,2,4,5-tetrabromobenzene and 1,2,4-tribromobenzene were identified as debromination products of HBB. Possible degradation pathways were further proposed. Additionally, mudsnails after exposed to 50 mg/kg of NBFRs were observed under a scanning electron microscope, indicating that shrinkage, tissue hyperplasia and perforation occurred on the visceral surface. Such damage might be related to the accumulation of more pollutants in mudsnails viscera. As one of the few studies to explore the biological process of NBFRs, our observation could provide a scientific basis for evaluating the environmental risks of NBFRs to benthic organisms.

Bioaccumulation of short-chain chlorinated paraffins in chicken (Gallus domesticus): Comparison to fish

Short chain chlorinated paraffins (SCCPs) are a complex group of chlorinated organic pollutants that have raised an increasing public attention. However, limited information is currently available on the bioaccumulation of SCCPs in terrestrial birds which are abundant and widely distributed around the world. In the present study, chicken (Gallus domesticus) was used as a model organism to provide significant implications for other avian species. We investigated the transfer of SCCPs from dietary sources (feed and topsoil) to chicken and their tissue distribution behavior. SCCPs were detected in chicken feed (54-170 ng/g, dry weight), topsoil (170-860 ng/g, dry weight), and adult chicken tissues (460-13000 ng/g, lipid weight). Adult chicken tended to accumulate SCCP congeners with lower n-octanol-water partition coefficients (K_OW) and octanol-air partition coefficients (K_OA). The accumulation ratio values for SCCPs of the chicken were more influenced by K_OA than by K_OW, which was contrary to those for aquatic fish. Levels and homologue profiles of SCCPs varied among chicken tissues. SCCP levels in the livers were significantly lower than those in the other tissues (p < 0.05). The accumulation potential for SCCP congeners with higher K_OW increased in the order of muscle < liver < fat.

Polybrominated Diphenyl Ethers (PBDEs) in a Large, Highly Polluted Freshwater Lake, China: Occurrence, Fate, and Risk Assessment

Polybrominated diphenyl ethers (PBDEs) were extensively investigated in water, sediment, and biota samples collected from Chaohu Lake basin in China. The total concentrations of eight PBDEs (Σ₈PBDEs) were in the ranges of 0.11–4.48 ng/L, 0.06–5.41 ng/g, and 0.02–1.50 ng/g dry weight (dw) in the water, sediment, and biota samples, respectively. The concentrations showed wide variations in the monitoring area, while the congener profiles in all the water, sediment, and biota samples were generally characterized by only a few compounds, such as BDE-47, BDE-99, and/or BDE-209. The spatial analysis depicted a decreasing trend of PBDEs from west to east Chaohu Lake, consistent with regional industrialization degree. The distributions of PBDE congeners in the biota samples were similar to the compositional profiles in the water, which were dominated by BDE-47 and/or BDE-99. Nevertheless, BDE-47 and BDE-153 in the brain tissue showed a higher accumulative potential than PBDEs in other tissues as well as the whole body, with 96% relative contribution of Σ₈PBDEs. The noncarcinogenic risk values estimated for BDE-47, BDE-99, and BDE-153 indicated that the specific risk associated with the studied water and foodstuffs is limited. However, there is a potential mixture ecotoxicity at three trophic levels at some sampling points in the water, which should draw considerable attention.

Accumulation of polybrominated diphenyl ethers in the brain compared with the levels in other tissues among different vertebrates from an e-waste recycling site

This study aimed to investigate the accumulation of polybrominated diphenyl ethers (PBDEs) in the brain compared with that in other tissues among different vertebrates. We collected mice, chickens, ducks, frogs, and fish from an e-waste recycling region in Taizhou, China, and measured PBDE concentrations in brain, liver and muscle tissues. The levels of PBDE in the tissues of mice, chickens, ducks, frogs and fish ranged 0.45-206, 0.06-18.8, 1.83-112, 2.75-108, and 0.02-32.0 ng/g wet weight, respectively. Preferential distribution in the liver and muscle relative to the brain was observed for PBDEs in mice, chickens, ducks and frogs. However, a high retention in the brain compared to the liver and muscle was observed in fish. Comparison of the brain/liver concentration (B/L) ratios revealed differences in PBDEs accumulation in the brain among these vertebrates. PBDEs accumulation in the brain was greatest in fish, followed by frogs, while the lowest accumulation occurred in the brains of mammals and birds. The findings apparently coincided with the evolution of the blood-brain barrier (BBB) across vertebrates, i.e. the BBB of fish might be less efficient than those of mammals, birds and amphibian. Low brominated congeners (such as BDE-28, BDE-47 and BDE-99) were predominant in the brains of investigated vertebrates, whereas BDE-209 was most abundant in liver and muscle tissues of mice, chickens and ducks. Significant differences in B/L ratios among PBDE congeners were found in both mice and chickens (p < 0.05). Particularly in mice, the B/L ratios of PBDE congeners presented a declining trend with increased bromine number. Our findings suggested that low brominated congeners might have a higher capacity to penetrate the BBB and accumulate in the brain, whereas high brominated congeners such as BDE-209 might have less potency to pass through the barrier. Further experimental studies are needed to confirm our findings.

Brominated flame retardants (BFRs): A review on environmental contamination in China

Brominated flame retardants (BFRs) which were detected extensively in environmental and biota samples worldwide, have raised significant concerns during past decades for their persistence, bioaccumulation and potential toxicity to ecological environment and human health. In this paper, we have compiled and reviewed existing literature on the contamination status of BFRs in abiotic and biotic environments in China, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane, tetrabromobisphenol A and new BFRs. Temporal trends were also summarized and evaluated. Based on this review, it has been concluded that (1) high concentrations of PBDEs were generally related to the e-waste disposal processing, while the spatial distribution pattern of other BFRs was not necessarily in accordance with this; (2) extremely high concentrations of BFRs in indoor dust emphasized the importance of indoor contamination to human body burdens, while more work need to be done to confirm its contribution; (3) PBDEs in electronics dismantling workers were higher compared to the general population, indicating the occupational exposure should be of particular concern; (4) more data are now becoming available for BFRs in aquatic and terrestrial organisms not previously studied, while studies that consider the occurrence of BFRs in organisms of different trophic levels are still of urgent need for evaluating the fate of BFRs in the food web; and (5) limited data showed a decreasing trend for PBDEs, while more data on time trends of BFR contamination in various matrices and locations are still needed before the impact of regulation of BFRs can be assessed.

Assessment of the Polychlorinated Biphenyl (PCB) Occurrence in Copper Sulfates and the Influential Role of PCB Levels on Grapes

Copper sulfates (CuSO₄) are widely used as the primary component of fungicides in the grape industry. The agricultural-grade CuSO₄ that we collected from Chinese nationwide markets were found to be contaminated by polychlorinated dibenzo-p-dioxins and dibenzofurans and high levels of polychlorinated biphenyls (Σ₁₉PCBs: 0.32~9.51 ng/g). In the following research, we studied the impact of CuSO₄ application on PCB levels in grape products through a field experiment, and conducted a national survey to speculate the role that CuSO₄ played on the occurrence of PCB in grapes. In the field experiment, an obvious increase of PCBs in grape leaves (from 174 to 250 pg/g fw) was observed after Bordeaux mixture (the main component of which is CuSO₄) application. As to the main PCB congener in CuSO₄, the most toxic CB 126 (toxic equivalency factor = 0.1) also increased in grape peels (from 1.66 to 2.93 pg/g fw) after pesticide spray. Both the correlation study and the principal component analysis indicated that environmental factors were dominant PCB contributors to grapes, and grapes from e-waste dismantling area containing the highest PCBs also proved the notion. It is worth noting that this report describes the first research examining PCBs in CuSO₄ and its influence on agricultural products to date.

Evaluation of chlorpyrifos transferred from contaminated feed to duck commodities and dietary risks to Chinese consumers

The present study describes chlorpyrifos residues in duck commodities through the duck food chain, transfer factors, and dietary risks to Chinese consumers. After duck feeding experiments with pellet feed that lasted for 42 days, chlorpyrifos residues found in all samples collected from the ducks on maximum estimated dose group (3.20 mg/kg level) were from <0.0005 to 0.019 mg/kg. The residue levels of the fat, intestine, and tongue were obviously higher than those of the meat and other edible tissues. The transfer factors of all duck commodities were from 0.0001 to 0.0049 among different contamination levels, which indicated that chlorpyrifos had a low persistency in duck meat and metabolism organs. The chronic exposure assessment revealed that only 0.034-0.150% of the acceptable daily intake (ADI; 0-0.01 mg/kg/bw/day) of chlorpyrifos was consumed via the duck commodities for different age and gender groups in China. The acute exposure assessments of different age and gender groups were only 0.019-0.082% of the acute reference dose (ARfD; 0-0.1 mg/kg/bw). The results show that the single dietary exposure risk of chlorpyrifos raised by the intake of duck commodities was quite low in China.