| People have paid great attention to the threat posed by brominated flame retardants(BFRs)to the environmental ecological system and human health,and the recent restrictions to the production and consumption of BFRs have resulted in the extensive use of organophosphate esters(OPEs)in products.As an important production area of BFRs in China,Weifang City in Shandong Province has suffered great pollution caused by BFRs due to its mass production of BFRs.Thus,we collected pooled serum samples from residents in Weifang City,Shandong Province,and analyzed 8 congeners of polybrominated diphenyl ethers(PBDEs),7 kinds of novel brominated flame retardants(NBFRs),2 isomers of dechlorane plus(DPs)and 6 kinds of OPEs in human serum.OPEs were found to be the dominant pollutants in our samples,with the 6 OPEs detected in all the serum samples.Mean concentrations of ?6OPEs in serum samples collected in 2011 and 2015 were 6801±191 ng/g lipid and 709± 154 ng/g lipid,respectively.Tris(2-chloroethyl)phosphate(TCEP)and tributyl phosphate(TNBP)were the first and second dominant OPEs,which represented 82%and 11%of the total OPE concentrations,respectively.Mean concentrations of ?8PBDEs in serum samples collected in 2014 and 2015 were 41 ± 15 ng/g lipid and 32 ±36 ng/g lipid,respectively,with BDE-209 being the dominant congener.Of the 7 kind of NBFRs analyzed in this research,only pentabromobenzene(PBBz),pentabromotoluene(PBT)and hexabromobenzene(HBB)were detected,with mean concentrations of ?3NBFRs in serum samples collected in 2014 and 2015 being 2.2 ± 0.28 ng/g lipid and 3.5 ± 0.72 ng/g lipid,respectively,and mean concentrations of ?ZDPs were 2.1 ±0.61 ng/g lipid and 3.1 ±0.97 ng/g lipid in serum samples collected in 2014 and 2015,respectively.Furthermore,temporal changes of the concentrations of those flame retardants in serum were determined in this research.We observed a slight increase in mean total concentrations of OPEs in serum.More specifically,TCEP concentrations in pooled serum samples increased by 13%from 2011 to 2015,while the 5 kinds of non-chlorinated OPE concentrations dropped by 5-61%during the same period.BDE-209 concentrations in pooled serum samples decreased significantly between 2007 and 2015,which might result from the rapid elimination of BDE-209 in human body and the declined production and consumption volume of BDE-209 in China.Meanwhile,?7PBDE(except BDE-209)concentrations in pooled serum samples declined sharply from 2007 to 2011,but this decrease was not statistically significant between 2011 and 2015.No clear uptrend or downtrend in PBBz,PBT and DPs concentrations were observed in this study,indicating that residents in Weifang City,Shandong Province have been continuously and steadily exposed to those pollutants in recent years.Moreover,?6OPE concentrations in drinking water from Weifang City,Shandong Province were also determined.Mean total OPE concentration in drinking water was 215 ±30 ng/L,and TCEP was the dominant OPE,accounting for 95%of the total OPEs.Similar distribution of the 6 OPEs in pooled serum samples and in drinking water was observed,and has reached statistical significance(r=0.829,p=0.042).This could indicate the significant contribution of OPEs in drinking water to OPEs in human serum.We also estimated human daily intake of OPEs via drinking water,with the daily intake being 2.9-11 ng/(kg bw d).It is notable that the daily intake estimated for young children was 2 to 5 times higher than adults,thus OPEs would pose more risks to young children that adults.The daily intake of OPEs estimated in this research was far lower that the reference doses(RfDs)suggested in a previous study,which might indicate that human intake of OPEs via drinking water would not pose any threats to human health.However,given human intake of OPEs via food,air,indoor dust and dermal absorption,and given the possible synergistic toxic effects among various kinds of OPEs,it is still of great importance to extensively pay attention to human exposure to OPEs. |
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