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Characterizing the detailed compositions of chlorinated paraffins (CPs) commercial mixtures is crucial to understand their environmental sources, fates, and potential risks. In this study, dichloromethane (DCM)-enhanced UPLC-ESI-QTOFMS analysis combined with characteristic isotope chlorine peaks is applied to screen all CPs and their structural analogues in the three most commonly produced CP commercial mixtures (CP-42, CP-52, and CP-70). Mass fractions of total short-chain CPs (SCCPs), medium-chain CPs (MCCPs) and long-chain CPs (LCCPs) ranged from 0.64 to 31.9%, 0.64 to 21.8%, and 0.04 to 43.9%, respectively, in the three commercial mixtures. 113 unsaturated SCCPs, MCCPs, and LCCPs were identified in the commercial mixtures. The detailed mass percentages of saturated and unsaturated CPs with carbon numbers of 10-30, chlorine numbers of 5-28, and unsaturated degrees of 0-7 were characterized in all commercial mixtures. Occurrences of the predominant saturated and unsaturated CPs were further confirmed in air samples collected in Guangdong Province, one of the major CP production areas in China, over one year. The profiles of the detected compounds indicated that LCCPs in air samples might come mainly from the production and usage of CP-52, and unsaturated C-LCCPs were specifically originated from CP-70 used in the area.

a b s t r a c tWe measured Dechlorane Plus (DP) and its dechlorinated analogs in the blood and milk from women living in e-waste recycling sites in Wenling of Taizhou region, China (n ¼ 49). Both syn-DP and anti-DP were detected in all samples. Another compound, Cl 11 -DP, was detected in 45% and 84% of milk and serum samples, respectively. DP levels in blood and milk from residents living in the local environment >20 yrs (R 20 group) were significantly higher than those living in Taizhou <3 yrs (R 3 group) (p < 0.05). The milk/serum partition coefficient from the same women was approximately 0.43 and 0.47 for syn-DP and anti-DP, respectively. A similar value in milk compared with anti-DP/ P DPs (f anti ) in serum suggested that stereoselective DP bio-accumulation did not occur during the DP transport from blood to milk. This result indicate that DP can bio-accumulate in blood and milk with the low milk/serum partition coefficient and similar blood and milk stereoselective bio-accumulation profiles.

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It has been reported that breastfeeding can expose newborns to dechlorane plus (DP), but transplacental transfer of DP has not been documented. We measured DP and its dechlorinated analogs in matched maternal blood− placenta−cord blood samples from 72 residents of the e-waste recycling area of Wenling, China. DP was detected in cord sera, indicating the occurrence of prenatal DP exposure and the transfer of DP across the placenta. The concentration ratio in the cord serum and maternal serum was estimated to be 0.45 for syn-DP and 0.35 for anti-DP, indicating the placenta partially limited DP transfer with a greater extent for anti-DP. The DP concentrations in the maternal serum, placenta, and cord serum strongly correlated, indicating that DP could transfer between the tissues. The DP concentrations in the matched samples could be predicted from each other. The anti-DP/ total DP concentration ratios in the placentas and cord sera were significantly different from those in the maternal sera, suggesting that DP stereoselectively bioaccumulates in human tissues. When the congener concentrations of polybrominated diphenyl ethers (PBDEs) were used as control variables, DP and total triiodothyronine concentrations were associated in the sera from mothers who had lived in Wenling for over 20 years.

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a b s t r a c tDechlorane Plus (DP), a flame retardant used as an alternative to decabromodiphenylether, has been frequently detected in organisms, indicating its bioaccumulation and biomagnification potential in aquatic and terrestrial species. However, little data is available on the bioaccumulation of DP in amphibians. Dechlorane Plus and its analogs (DPs) were detected in the liver, muscle and brain tissues of wild frogs (Rana limnocharis), which were collected from an e-waste recycling site, Southeast China. DP, Mirex, Dec 602 and a dechlorinated compound of DP (anti-Cl 11 -DP) varied in the range of 2.01-291, 0.650-179, 0.260-12.4, and not detected (nd)-8.67 ng/g lipid weight, respectively. No difference of tissue distribution was found for syn-DP, Mirex and Dec 602 between the liver and muscle tissue (liver/muscle concentration ratio close to 1, p > 0.05). However, higher retention was observed for anti-DP and anti-Cl 11 -DP in the frog muscle relative to the liver tissue (liver/muscle concentration ratio < 1, p < 0.05). Additionally, the blood-brain barrier was found to work efficiently to suppress these compounds entering brain tissues in this species (liver/brain concentration ratio > 1, p < 0.05), and the molecular weight was a key factor impacting the extent of the blood-brain barrier. Compared to levels in the muscle and brain tissue, a preferential enrichment of syn-DP was observed in the liver tissue, suggesting the occurrence of stereo-selective bioaccumulation in the wild frog.