Bioaccumulation characteristics of PBDEs and alternative brominated flame retardants in a wild frog-eating snake.

While a large body of studies have examined polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants (ABFRs) in wildlife, information on the bioaccumulation of these contaminants in reptiles in general, and snakes in particular, are scarce. We investigated the bioaccumulation characteristics of PBDEs and several ABFRs including decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB) and pentabromotoluene (PBT) in a frog-eating snake, the striped keelback snake (Amphiesma stolata), from an e-waste recycling site in South China. The concentrations of ∑PBDEs and ∑ABFRs in the snakes ranged 53-5200 and 3.1-87 ng/g lipid weight, respectively; with higher levels in males than females. Additionally, the concentrations of BDE-28, -47, and -66 were positively correlated with snake size (snout-vent length and body mass), while negative correlations were found for most of the higher brominated PBDE congeners and HBB, PBT and BTBPE. The biomagnification factors (BMFs) estimated in the snake/frog relationship indicated a mild to moderate biomagnification of BDE-28, -47, -66, -100, -153 and -154 (with mean BMFs of 1.1-5.3), while a lack of magnification for the other PBDE congeners and all the ABFRs. This is the first report on the sex- and size-related accumulation and biomagnification potentials of PBDEs and ABFRs in snakes.

Polychlorinated biphenyls in apple snails from an abandoned e-waste recycling site, 2010-2016: A temporal snapshot after the regulatory efforts and the bioaccumulation characteristics.

The rudimentary recycling of electronic waste (e-waste) has been banned in China since the late 2000s, leaving many abandoned e-waste sites. However, knowledge is limited on the concentrations and fates of the e-waste derived contaminants such as polychlorinated biphenyls (PCBs) in these abandoned sites. In this work, we assessed the temporal trend of PCB concentrations in the year 2010, 2012, and 2016 at an abandoned e-waste site in South China, using apple snail as a bioindicator. The mean ∑PCBs concentrations in apple snails sampled in 2016 (53.2 ng/g dry weight) was approximately 11-fold higher than that (4.68 ng/g dry weight) in apple snails from a reference site. The result suggested that the abandoned e-waste recycling site was still heavily polluted by PCBs, despite of the fact that crude e-waste recycling processes have been prohibited for nearly 10 years. The concentrations of ∑PCBs were significantly decreased in 2016 compared to those in 2010 (mean: 115 ng/g dry weight) and 2012 (mean: 92.3 ng/g dry weight), but there were no significant differences in the concentrations between 2010 and 2012. Regarding the congener profiles, the contributions of lower chlorinated congeners (tri- and tetra-PCBs) in the snails tended to be higher over the years. The ∑PCBs in snails were significantly correlated with those in soils. Additionally, PCB profiles in snails resembled those in soils. These results suggested that apple snails can be used as an ideal bioindicator for PCBs in the paddy soils. Field determined biota-soil accumulation factors (BSAFs) for PCBs ranged from 0.31 to 1.9, with most of the values being 1-2; indicating that theoretical BSAFs can be used to predict the bioaccumulation of PCBs in the snails with a reasonable degree of certainty.

Sex-dependent accumulation and maternal transfer of Dechlorane Plus flame retardant in fish from an electronic waste recycling site in South China.

Knowledge is limited on sex-related accumulation and maternal transfer of Dechlorane Plus (DP) flame retardant in wildlife. In the present study, DP isomers were examined in liver and eggs of two fish species, northern snakehead and crucian carp, from an electronic waste recycling site in China. Hepatic ∑DP (sum of syn- and anti-DP) concentrations ranged 260-1920 ng/g lipid in northern snakehead and 340-1670 ng/g in crucian carp, with significantly higher levels in males relative to females. ∑DP concentrations ranged 4.6-310 ng/g lipid in the eggs, demonstrating their maternal transfer in the female fish. The mean eggs to liver concentration ratios (E/L ratios) were 0.03 and 0.03 in northern snakehead, and 0.26 and 0.25 in crucian carp, for syn- and anti-DP, respectively. A significantly negative correlation between the E/L ratios and the hepatic DP concentrations was observed, indicating a dose-dependent maternal transfer of DP isomers in the fish.

Bioaccumulation of polybrominated diphenyl ethers and several alternative halogenated flame retardants in a small herbivorous food chain.

Little is known about the bioaccumulation behavior of polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) in plants and in herbivores. In the present study, PBDEs and several alternative HFRs (AHFRs) were examined in a small herbivorous food chain (paddy soils-rice plant-apple snails) from an electronic waste recycling site in South China. Mean concentrations of total PBDEs were 40.5, 1.81, and 5.54 ng/g dry weight in the soils, rice plant, and apple snails, respectively. Levels of total AHFRs in the samples were comparable to or even higher than those of PBDEs. The calculated plant to soil concentration ratios for most AHFRs (0.05-3.40) were higher than those for PBDEs (0.02-0.23), indicating the greater bioavailability of the AHFRs in the rice plant. All PBDE congeners and Dechlorane Plus (DP) isomers were biomagnified from the rice plant to apple snails, with mean biomagnification factors (BMFs) of 1.1-5.0.

Methylsulfonyl polychlorinated biphenyls in fish from an electronic waste-recycling site in South China: levels, congener profiles, and chiral signatures.

Great concerns have been raised about the fate and effects of polychlorinated biphenyls (PCBs) and other organic contaminants contained in electronic waste (e-waste) exported from industrialized countries at midlatitudes to subtropical and tropical regions. Information on the metabolites of these chemicals, for example, methylsulfonyl-PCBs (MeSO(2)-PCBs) in wildlife from the later regions is scarce. In the present study, 17 MeSO(2)-PCBs, including five chiral congeners, were detected in the muscle, liver, and brain tissues of two benthic fish species--northern snakehead and mud carp--from a small pond near an electronic waste recycling site in South China. The mean concentrations of the sum of the MeSO(2)-PCBs ranged from 80 to 340 ng/g lipid weight in the tissues, with relative higher levels in the liver than the muscle and brain tissues. These levels were one order of magnitude greater than the highest levels of MeSO(2)-PCBs previously reported in fish. The 3'-MeSO(2)-CB 87, 3'- and 4'-MeSO(2)-CB 101, 4-MeSO(2)-CB 110, and 4-MeSO(2)-CB 149 were dominant, collectively comprising more than 55% of the total MeSO(2)-PCBs. Except for 4-MeSO(2)-CB149, all of the investigated chiral MeSO(2)-PCBs displayed a clear, congener-specific enantiomeric enrichment in the tissues. No tissue-specific enantioselective retention of the enantiomers was observed in the investigated fish. This is the first report on chiral signatures of MeSO(2)-PCBs in fish tissues.

A review of polybrominated diphenyl ethers and alternative brominated flame retardants in wildlife from China: levels, trends, and bioaccumulation characteristics.

Accelerated industrialization and urbanization, and unregulated disposal of waste of electric and electronic equipment (e-waste) in China have caused environmental pollution of brominated flame retardants (BFRs). This review summarized the levels, trends, and bioaccumulation characteristics of polybrominated diphenyl ethers (PBDEs) and other potential alternative BFRs including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-dibromophenoxy) ethane (BTBPE) and decabromodiphenylethane (DBDPE) in wildlife from China. PBDE levels in wildlife from China were generally higher than those from other parts in Asia, and were comparable to those from Europe but were lower than those from North America. However, wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world, suggesting the heavy contamination of PBDEs in these regions. The alternative BFRs were also detected in wildlife, revealing that the animals are exposed to these chemicals, in addition to PBDEs. Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s, but decreased from the middle of 2000s, followed by relatively steady levels. In contrast, HBCDs were found to be continuously increasing from 1997 to 2007, indicating the increasing usage of HBCDs in China in recent years. Compared to PBDE profiles found in other parts, aquatic species and birds from China contained relatively higher contributions of BDE-28 and 209, respectively, suggesting the possible different usage pattern of PBDEs. Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed. Additionally, focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination, and incorporation of sentinel species in monitoring efforts are recommended.

Halogenated flame retardants in home-produced eggs from an electronic waste recycling region in South China: levels, composition profiles, and human dietary exposure assessment.

Three regulated halogenated flame retardants (HFRs), i.e., polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and hexabromocyclododecanes (HBCDs), and several alternative HFRs (AHFRs) including Dechlorane Plus (DP), decabromodiphenyl ethane (DBDPE), and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), were investigated in the home-produced eggs from three recycling sites and a reference site in an electronic waste (e-waste) recycling region, South China. Mean levels of HFRs in eggs from the recycling sites ranged 2640-14100, 700-1620, 44-350, and 720-3920 ng/g lipid weight for ∑PBDEs, ∑PBBs, ∑HBCDs, and ∑AHFRs, respectively, which were one to two orders of magnitude higher than those examined in the reference site. PBDEs were the predominant HFR in those eggs, with contributions >50% to the total HFRs; followed by PBBs and the AHFRs (contributing 14-22% in average). The α-HBCD was the predominant diastereoisomers of HBCDs, with preferential enrichment of the (-)-enantiomer in most of the eggs; but no significant stereoselective enrichment of the DP isomers was observed in these eggs. The average estimated daily intakes (EDIs) of PBDEs, PBBs, HBCDs, and the AHFRs via eggs from the recycling sites ranged 4200-20000, 1120-2440, 80-490, and 970-4530 ng/day, respectively, which were one to two orders of magnitude higher than those reported from other parts of the world. The potential adverse effects of these HFRs to human health in the e-waste sites should be further investigated. This is the first report on the isomer compositions of DP and the chiral signatures of HBCDs in hen eggs.