Trophic Transfer of Halogenated Organic Pollutants in a Wetland Food Web: Insights from Compound-Specific Nitrogen Isotope of Amino Acids and Food Source Analysis.

A trophic position (TP) model (TPmix model) that simultaneously considered trophic discrimination factor and ßGlu/Phe variations was developed in this study and was first applied to investigate the trophic transfer of halogenated organic pollutants (HOPs) in wetland food webs. The TPmix model characterized the structure of the wetland food web more accurately and significantly improved the reliability of TMF compared to the TPbulk, TPAAs, and TPsimmr models, which were calculated based on the methods of stable nitrogen isotope analysis of bulk, traditional AAs-N-CSIA, and weighted ßGlu/Phe, respectively. Food source analysis revealed three interlocking food webs (kingfisher, crab, and frogs) in this wetland. The highest HOP biomagnification capacities (TMFmix) were found in the kingfisher food web (0.24-82.0), followed by the frog (0.08-34.0) and crab (0.56-11.7) food webs. The parabolic trends of TMFmix across combinations of log KOW in the frog food web were distinct from those of aquatic food webs (kingfisher and crab), which may be related to differences in food web composition and HOP bioaccumulation behaviors between aquatic and terrestrial organisms. This study provides a new tool to accurately study the trophic transfer of contaminants in wetlands and terrestrial food webs with diverse species and complex feeding relationships.

Sex-Specific Bioamplification of Halogenated Organic Pollutants during Silkworm (Bombyx mori) Metamorphosis and Their Adverse Effects on Silkworm Development.

A partial life cycle test was performed with silkworms (Bombyx mori) exposed to different levels of halogenated organic pollutants (HOPs). The aims were to investigate the fate of HOPs during metamorphosis and the adverse effects of HOP exposures on silkworm development. Contaminant exposures resulted in decreased body weights, increased development times, and reductions of fecundity in silkworms. Assimilation efficiencies of HOPs decreased with an increasing octanol-water partition coefficient (log KOW). From the larvae to the pupae stage, bioamplification factors (BAmFs) exhibited concentration-dependent results, in which there was a positive correlation with the log KOW at the high concentrations but no correlation at the low concentrations. From the pupae to the moth stage, BAmFs were linearly negatively correlated with the log KOW for males, but a parabolic correlation with the log KOW was more suitable for females. Regarding reproductive activities, female moths selectively transferred low log KOW HOPs to eggs by the oviposition except for highly halogenated lipophilic pollutants. However, BAmFs of male moths during mating showed no correlation with the log KOW, although highly halogenated lipophilic pollutants had the highest BAmF values. The sex-specific bioamplification processes and special behaviors of highly halogenated lipophilic pollutants deserve further research.

A comprehensive assessment of external exposure to persistent halogenated organic pollutants for residents in an e-waste recycling site, South China.

Human skin wipes from 30 participants, air, dust, and food items were collected from a former electronic waste site in South China to provide a comprehensive understanding of residents' exposure to halogenated flame retardants (HFRs) and polychlorinated biphenyls (PCBs). The total concentration of halogenated organic pollutants (HOPs) in the dust, air, food and skin wipes ranged 240-25000 ng/g, 130-2500 pg/m3, 0.08-590 ng/g wet weight, and 69-28000 ng/m2, respectively. Wild fish, vegetables, and air were dominated by PCBs, whereas dust, livestock, and poultry were dominated by HFRs. The HOP concentrations were several orders of magnitude higher in local foodstuffs than in market foodstuffs. The chemical composition on the forehead was remarkably different from that on the hand. The importance of different exposure routes depends on the residents' food choices, except decabromodiphenyl ethane (DBDPE). For residents who consumed a 100-foot diet (mainly egg) and local wild fish, diet ingestion overwhelmed other exposure routes, and PCBs were mainly contributed by fish and HFRs by egg. For residents who consumed market food, the dermal absorption of most PCB congeners and dust ingestion of highly brominated flame retardants were relatively prominent. Inhalation was found to be a crucial route for pentabromoethylbenzene (PBEB).

Occurrence, spatial distribution, and risk assessment of short- and medium-chain chlorinated paraffins in sediment from black-odorous rivers across China.

Chlorinated paraffins (CPs) were massively produced for varied industrial purposes, of which improper handling and consequent environmental release resulted in worldwide contamination. The present study investigated the occurrence and spatial distribution of short- and medium-chain chlorinated paraffins (SCCP/MCCPs) in 171 sediment samples from black-odorous urban rivers across China. Total SCCP and MCCP concentrations ranged from 8.3 to 9.4 × 104 (median: 1.1 × 103) ng/g dw, and from not-detected-value to 1.0 × 106 (median: 1.3 × 104) ng/g dw, respectively. No clear spatial distribution of SCCPs and MCCPs was observed since black-odorous urban rivers were polluted by point-sources of the SCCP/MCCPs. Significant positive correlations were identified between SCCP/MCCPs and total organic carbon, and between SCCP/MCCPs and other persistent organic matter, including polybrominated diethyl ethers, polychlorinated biphenyls, antibiotics, and plasticizers. The average ratios of MCCPs to SCCPs in most samples were divided into 11 and 16, implying the manufacturing and use of at least two types of CP technical mixtures in China. The composition of SCCP/MCCPs were similar to that in their commercial products. Ecological risk assessments by two approaches, including the Federal Environmental Quality Guidelines and Risk Quotient, both revealed that SCCP/MCCP in surface sediments confer an ecological risk. ENVIRONMENTAL IMPLICATION: SCCPs and MCCPs can be considered "hazardous materials" because of their massive production and their potential persistence, long-distance transfer, bioaccumulation potential, and toxicity. This research conducted a comprehensive study on SCCP/MCCP in black-odorous urban river sediments across China and revealed their environmental risk, which may improve understanding of SCCP/MCCP contamination characteristics.

Bioamplification and Biomagnification of Polycyclic Aromatic Hydrocarbons and Halogenated Organic Pollutants in Moths from an Electronic Waste Recycling Site.

Samples of Asota caricae (larvae, pupae, and adults) and its host plant leaf (Ficus hispida), larvae of Aloa lactinea, and mixed adult moths were collected from an electronic waste (e-waste) recycling site in south China. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers were found to exhibit concentrations of 420-1300, 100-860, and 7.6-49 ng/g dry weight, respectively. The different chemical compositions among the samples of the three groups indicated that at least two exposure scenarios occurred among the moths in the study area. A complex relationship between bioamplification factors and the octanol-water partition coefficient (log KOW ) was observed during metamorphosis, in which a positive relationship was evident for 5 < log KOW < 7, whereas an inverse relationship occurred for log KOW values outside of this range. The biomagnification factors (BMFs) calculated from the larvae of Asota caricae to the host plant were negatively correlated with log KOW for all chemicals, differing completely from those obtained in previous studies. However, after metamorphosis, the correlation between BMF and log KOW was found to coincide with that in previous studies. These results indicate that the biotransformation of pollutants in organisms played a key role in determining whether or not biomagnification occurred in organisms and highlight the potential application of the metabolic rate of chemicals in screening-level risk assessments of new chemicals. Environ Toxicol Chem 2022;41:2395-2403. © 2022 SETAC.

Tissue-Specific Distribution of Legacy and Emerging Organophosphorus Flame Retardants and Plasticizers in Frogs.

Five types of tissues, including the liver, kidney, intestine, lung, and heart, were collected from black-spotted frogs and bullfrogs to study the tissue-specific accumulation of organophosphorus flame retardants (PFRs) and plasticizers. Thirteen PFRs and nine plasticizers were detected, with average total concentrations of 1.4-13 ng/g ww and 858-5503 ng/g ww in black-spotted frogs, 3.6-46 ng/g ww and 355-3504 ng/g ww in bullfrogs. Significant differences in pollutant concentrations among different tissues in the two frog species were found, indicating the specific selectivity distribution of PFRs and plasticizers. Overall, liver tissues exhibited significantly higher pollutant concentrations. The pollutant concentration ratios of other tissue to the sum of liver tissue and other tissues (OLR, Cother/(Cother + Cliver)) corresponding to male frogs were significantly greater than those of females, suggesting that male frogs could have higher metabolic potentials for PFRs and plasticizers. No obvious correlations between OLR and log KOW were found, indicating that the other factors (e.g., bioaccumulation pathway and metabolism) besides lipophicity could influence the deposition of PFRs and plasticizers in frog livers. Different parental transfer patterns for PFRs and plasticizers were observed in frogs when using different tissues as parental tissues. Moreover, the liver tissues had similar parental transfer mechanism with muscle tissues.

Legacy and emerging organophosphorus flame retardants and plasticizers in frogs: Sex difference and parental transfer.

Black-spotted frogs and bullfrogs from an e-waste polluted area were collected and examined for legacy and emerging organophosphorus flame retardants (PFRs) and plasticizers. Total concentrations of PFRs and plasticizers were 0.62-15 ng/g wet weight (ww) and 316-4904 ng/g ww in muscles, 2.2-59 ng/g ww and 127-5757 ng/g ww in eggs and gonads, and 1.2-15 ng/g ww and 51-1510 ng/g ww in oviducts, respectively. For muscle tissues, concentrations of ∑PFRs, triethyl phosphate, tris-(2-chloroethyl) phosphate, and tris-(chloro-2-propyl) phosphate were significantly higher in the males than females (p < 0.05). However, for reproductive tissues, eggs exhibited higher levels of those contaminants than gonads (p < 0.05). No significant sex difference in levels of plasticizers was observed in muscles. In contrast, levels for (2-ethylhexyl) phthalate, di-n-butyl phthalate, and di-iso-butyl phthalate in gonads were significantly higher than those in eggs (p < 0.05). Significantly negative linear correlations between maternal transfer ratios and log KOW were found in female frogs. Paternal transfer potentials were first significantly and positively correlated to log KOW (<6) and then decreased afterward in the males. These results indicated that parental transfer was answer for the sex-specific accumulation of PFRs and plasticizers in frogs.