Human exposure to organophosphate esters (OPEs): A comparison between home and school microenvironments and inter-individual variations

Indoors human exposure to organophosphate esters (OPEs) remains unclear when considering the microenvironment and inter-individual differences. This study compares children's exposure to OPEs at school with at home using silicone wristbands and elucidates the internal exposure difference in OPEs between children and adults living in the same household. Silicone wristbands worn by 24 children and one of their parents (24 adults) for 5 consecutive days were collected for analyzing12 tri-OPEs. Early morning-void urine samples on the 3rd, 4th, 5th day over the five-day study were also collected for analyzing 6 di-OPEs. The results show that children have higher exposure to tri-OPEs at school than at home, with the geomeans of tri-OPEs being 55 and 12 ng/g/h in wristbands, respectively. The tri-OPE profile in wristbands is dominated by TCIPP and TPHP for both children and adults. While BCEP is the most abundant urinary metabolites in all urine samples. No significant differences in OPE external and internal exposures between children and adults are apparent for most OPE congeners, reflected by the comparable tri-OPEs in wristbands and urinary di-OPEs metabolites concentrations between children and adults. Wristband-OPEs are generally not significantly associated with their specific metabolites in urine samples. Our findings further the understanding on OPE exposures in indoor environments and OPE internal exposures between individuals under the same exposure scenario.