Characterization and human exposure assessment of organophosphate flame retardants in indoor dust from several microenvironments of Beijing, China

Ten target organophosphate flame retardants (PFRs) were measured from floor dust samples collected from homes (n = 21), offices (n = 23) and daycare centers (room n = 16) located in Beijing, China, and paired elevated surface dust and floor dust from the same daycare centers (room n = 9) were analyzed in this study. Most PFRs were detected in analyzed dust samples, and detection frequency up to 100% was observed on tris (2-chloroethyl) phosphate (TCEP), tris (2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPHP) and tris (2-butoxyethyl) phosphate (TBOEP). Among studied microenvironments, office samples showed significantly (p < 0.05) higher PFRs contamination level (1687-200,489 ng/g), followed by homes (4571-67,450 ng/g), and daycare centers (1489-33,316 ng/g). TCEP was the predominant PFR in both home and daycare center samples, while TCIPP was dominant in floor dust from offices. TCEP, TCIPP and TBOEP showed positive correlations (p < 0.05) between their levels in elevated surface dust and corresponding floor dust, and the mean concentrations of TPHP (1116 ng/g) and tricresyl phosphate (TMPP) (336 ng/g) were significantly higher (p < 0.05) in floor dust than those in elevated surface dust (269 and 93 ng/g, respectively). Estimated exposures of toddlers, average adults and the elderly to PFRs via dust ingestion were 38, 6 and 5 ng/kg bw/day, respectively (assuming the average daily time spent are 62.5% home and 37.5% daycare center for toddlers, 62.5% home and 37.5% office for average adults, and 100% home for the elderly; assuming median concentrations and average dust ingestion rate).