Children's exposure risk toward brominated flame retardants and organophosphate esters during preschool attendance and potential contamination sources

Brominated flame retardants (BFRs) and organophosphate esters (OPEs) are added to various products to gain specific properties such as reduced flammability and increased flexibility, which has resulted in constant, but usually slow, emission of these compounds to indoor environments. Many BFRs and OPEs are persistent, bioaccumulative and toxic, and have often been detected in indoor dust. This has raised concerns because indoor dust has been identified as one of the major non-dietary exposure pathways for children. In this study, 26 BFRs and OPEs were measured in indoor dust samples collected from 26 preschools in Sweden to identify potential indoor contamination sources and estimate the exposure risk of the detected levels. Among the targeted OPEs, tris(2-butoxyethyl) phosphate (TBOEP) was detected in all the preschools, with a mean concentration of 610 μg/g. Among the BFRs, decabromodiphenyl ether (BDE-209) was the predominant compound, with a mean concentration of 130 ng/g, even though it is globally regulated. Triphenyl phosphate (TPHP) was significant higher in preschools built before 2014. Also, 2-ethylhexyl diphenyl phosphate (EHDP) and BDE-209 were significant higher in preschools with sound boards on the walls and without wallpaper, respectively. Furthermore, in three of the participating preschools, an increase in total OPEs was observed between the years 2015 and 2023, possibly due to constant release of the targeted compounds and introduction of new and recycled products. Although the detected indoor dust levels showed a low exposure risk, levels of TBOEP were found to significantly contribute to the chemical burden of children attending the preschools.