Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of the...Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is needed.We have previously proved that density functional theory（DFT） is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis（2,4,6-tribromophenoxy）ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis（2,4,6-tribromophenoxy）ethanol, which may undergo hydrolysis yielding2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.展开更多
The presence of brominated flame retardants(BFRs)in foodstuffs of African origin is poorly understood.To fill this gap,animal-derived food samples comprising 13 different items originally from Nigeria were obtained in...The presence of brominated flame retardants(BFRs)in foodstuffs of African origin is poorly understood.To fill this gap,animal-derived food samples comprising 13 different items originally from Nigeria were obtained in 2021,and concentrations of novel brominated flame retardants(NBFRs),polybrominated diphenyl ethers(PBDEs),and hexabromocyclododecane(HBCDD)were measured.Arithmetic mean concentrations of NBFRs,PBDEs,and HBCDD in Nigerian foodstuffs were 2.1 ng/g(18 ng/g lipid weight(lw)),1.3 ng/g(9.2 ng/g lw),and 0.42 ng/g(2.8 ng/g lw),with median concentrations of 1.7 ng/g(14 ng/g lw),1.1 ng/g(8.2 ng/g lw),and<0.34 ng/g(<3.3 ng/g lw),respectively.Higher concentrations of NBFRs than of PBDEs and HBCDDs in Nigerian foodstuffs likely reflect use of NBFRs as substitutes for legacy BFRs in Nigeria.Comparison with previous dietary studies reveals rising concentrations of PBDEs in Nigerian foodstuffs in recent years with associated rises in dietary exposure,possibly due to active domestic use of PBDEs in Nigeria.Reassuringly,comparison of our exposure estimates with health-based limit values suggests adverse health effects of dietary intake of BFRs by Nigerians are unlikely to occur.展开更多
基金supported by the National Basic Research Program(No.2013CB430403)the National Natural Science Foundation(Nos.21137001,21325729,and 21173211)of Chinasupported by Supercomputing Center of Dalian University of Technology
文摘Alternative brominated flame retardants（BFRs） have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers（PBDEs）. For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is needed.We have previously proved that density functional theory（DFT） is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis（2,4,6-tribromophenoxy）ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis（2,4,6-tribromophenoxy）ethanol, which may undergo hydrolysis yielding2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.
文摘The presence of brominated flame retardants(BFRs)in foodstuffs of African origin is poorly understood.To fill this gap,animal-derived food samples comprising 13 different items originally from Nigeria were obtained in 2021,and concentrations of novel brominated flame retardants(NBFRs),polybrominated diphenyl ethers(PBDEs),and hexabromocyclododecane(HBCDD)were measured.Arithmetic mean concentrations of NBFRs,PBDEs,and HBCDD in Nigerian foodstuffs were 2.1 ng/g(18 ng/g lipid weight(lw)),1.3 ng/g(9.2 ng/g lw),and 0.42 ng/g(2.8 ng/g lw),with median concentrations of 1.7 ng/g(14 ng/g lw),1.1 ng/g(8.2 ng/g lw),and<0.34 ng/g(<3.3 ng/g lw),respectively.Higher concentrations of NBFRs than of PBDEs and HBCDDs in Nigerian foodstuffs likely reflect use of NBFRs as substitutes for legacy BFRs in Nigeria.Comparison with previous dietary studies reveals rising concentrations of PBDEs in Nigerian foodstuffs in recent years with associated rises in dietary exposure,possibly due to active domestic use of PBDEs in Nigeria.Reassuringly,comparison of our exposure estimates with health-based limit values suggests adverse health effects of dietary intake of BFRs by Nigerians are unlikely to occur.
