Oral bioaccessibility of SVOCs in indoor settled dust: a simplified in vitro method for polybrominated diphenyl ethers (PBDEs) and pyrethroids

摘要

Dust ingestion is a pathway of human exposure to many indoor chemical pollutants including several semi-volatile organic compounds (SVOCs), such as polybrominated diphenyl ethers (PBDEs) and pyrethroid insecticides. Children are particularly concerned because their specific behavior (crawling on the floor, hand to mouth contact, object to mouth contact) may contribute to a higher ingestion of dust. To assess human exposure to SVOCs, their oral bioaccessibility, i.e. the fraction of the pollutant released from the dust matrix into the digestive fluid following dust ingestion, should be considered. Here, a simple method for the extraction of the bioaccessible fraction of SVOCs is proposed, consisting of 200 mg of dust incubated continuously for 20 hours at 37°C in 40 mL of neutral pH water containing bile and pancreatin. An insert made of 500 mg of sorptive material (XAD®-2) is added, acting as an adsorption sink trapping the SVOCs released into the gut solution. Method performance was assessed using SRM 2585, producing comparable results to those acquired with physiologically base extraction tests (PBET). The new method was then used to measure the bioaccessibility of PBDE flame retardants (BDE 47, 85, 99, and 100) and pyrethroids insecticides (cyfluthrin, cypermethrin, permethrin, and tetramethrin) in 30 settled dust samples collected in French schools. Permethrin and BDE congeners 47 and 99 were the most frequently detected compounds in dust samples and their median bioaccessibilities ranged from 37 to 48%. Our data show that doses considered for human exposure could be potentially lowered by a minimum of 50%, thus emphasizing the importance of considering oral bioaccessibility when assessing human exposure to organic pollutants via dust ingestion.