| The global production of halogenated flame retardants is still increasing rapidly,and the human health risks associated with the release of halogenated flame retardants from products cannot be ignored.China is one of the major countries producing and using halogenated flame retardants,and the human health problems caused by halogenated flame retardants are particularly prominent Current research on halogenated flame retardants in humans is mainly focused on high-exposure risk areas such as electronic waste dismantling sites,while less attention has been paid to low-exposure risk areas.Wuxi is a typical city in the Yangtze River Delta region,and there are no pollution sources such as halogenated flame retardant production factories and electronic waste dismantling plants in the city.However,the city has a large number of new industrial enterprises such as new materials,new energy,electronics and information,which are potential pollution sources of halogenated flame retardants,so it is representative to set Wuxi as the study area.It is of great practical importance to study the pollution status of halogenated flame retardants in the serum of the local general population.In this study,serum samples of the general population in Wuxi were collected for five consecutive years from 2012 to 2016,and the concentrations of two Dechlorane Plus(DPs)isomers and 35 polybrominated biphenyls(PBBs)congeners in the samples were determined by GC-MS and GC-MS/MS.levels,the current pollution status,temporal trends and differences among different populations of these two types of halogenated flame retardants were discussed by comparing historical literature and statistical analysis.The binding mechanism of DPs to human serum albumin(HSA)and the effect of PBBs to the binding of 3,5,3’-triiodo-L-thyronine(T3)and thyroid hormone receptors(TR)were analyzed by fluorescence spectroscopy and molecular docking simulations.The results of the study showed that:The total serum concentrations of syn-DP and anti-DP in the general population of Wuxi from 2012 to 2016 averaged 4.67 ng-g-1 lw.The serum concentrations of DPs in the population studied in this paper were lower than those in the population in highly exposed areas such as DPs manufacturing plants and e-waste dismantling sites,but higher than those in the general population in other areas,indicating that the population in this area may be at risk of exposure.In addition,there was no significant temporal trend in serum DPs concentrations over five years,indicating that the exposure to DPs in this region is stable,but still requires continuous attention.Serum DPs concentrations in the study population were significantly higher in males than in females,and higher in the overweight population than in the normal weight population,and lower in the drinking population than in the non-drinking population,while there were no significant differences in serum DPs concentrations in the young and middle-aged populations,and in the smoking and non-smoking populations.The affinities of the two isomers of DPs with HSA were determined by fluorescence spectroscopy experiments.syn-DP and anti-DP had binding constants K of(2.19±1.32)×104 and(2.70±0.42)×105 L·mol-1 with HSA,respectively.the higher values of serum fanti in the general population in this study may be due to the fact that the affinity of anti-DP with HSA.The binding site of DPs on HSA was determined to be between domain IIA and domain IIB by binding site competition substitution experiments.At the microscopic level,it was explained that the affinity of anti-DP to HSA was significantly greater than that of syn-DP.Finally,it was demonstrated experimentally that fatty acids increase the affinity of DPs for HSA,while ethanol decreases the affinity of DPs for HSA.This may be one of the reasons why the serum concentration of DPs in the overweight population in this study was higher than that in the normal weight population,while the serum concentration of DPs in the drinking population was lower than that in the non-drinking population.The main PBBs congeners detected in the serum of general population in Wuxi from 2012 to 2016 were BB-1,BB-2,BB-10,BB-4,and BB-209.The detection rate of BB-153,a PBBs contaminant that has been controlled by various countries,was less than 10%and the concentration was much lower,indicating that the population in this region is less affected by BB-153.In contrast,high concentrations of lower brominated PBBs and BB-209 were detected in this study.levels of BB-1,BB-10 and BB-209 increased significantly from 2014 to 2015.In addition,serum PBBs concentrations in the study population were lower in males than in females,higher in young adults than in middle-aged adults,and the differences in the concentrations of PBBs in the serum of overweight and normal weight people,smoking and non-smoking people,and drinking and non-drinking people were not significant.We confirmed by fluorescence spectroscopy experiments that BB-1,BB-10 and BB-153 all interfered with the binding of T3 and TRβ1.BB-153 has a stronger interfering effect than BB-10 but weaker than BB-1,while BB-209 had less effect on the binding of T3 and TRβ1.This suggests that we should pay more attention to the interference of lower brominated PBBs such as BB-1 and BB-10 on human thyroid function in the future. |
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