Perfluoroalkyl substances (PFASs), flame retardants and cyclic volatile methylsiloxanes in indoor air in Uppsala, Sweden : occurrence and human exposure assessment

Abstract: Indoor air samples were collected from three buildings located at the Swedish University of Agricultural Science (SLU) campus in Ultuna, Uppsala, Sweden and from residences of nine volunteers working in the three buildings. Sorbent-impregnated polyurethane foam (SIP) disk passive air samplers were deployed in different types of rooms in the three buildings including computer room (n = 1), labs (n = 3), lecture rooms (n = 3), offices (n = 8) and dining areas (n = 3) and homes (n = 9) of the volunteers between September and November in 2016. In addition, fingernail samples were collected from the nine volunteers. The samples were analyzed for three fluorotelomer alcohols (FTOHs), eight brominated flame retardants (BFRs), five organophosphorus flame retardants (OPFRs) and three cyclic volatile methyl siloxanes (cVMSs) to investigate their concentrations in indoor air, the influence of building and room types on the concentration level and human daily exposure dose (DED) via inhalation. Average concentrations of ΣFTOHs, ΣBFRs, ΣOPFRs and ΣcVMSs in in-door air were 5100 pg m-3, 110 pg m-3, 430 pg m-3 and 1700 ng m-3, respectively, and varied greatly both within each building and across buildings. The most abundant compounds were 8:2 FTOH for the FTOHs, decamethyl cyclopentasiloxane (D5) for the cVMSs, and 2,4,6-tribromophenol (2,4,6-TBP) for the FRs. Variations in the OPFRs composition were observed among different types of rooms. Home samples had a higher average concentration of Tris(2-chloroethyl) phosphate (TCEP), while office samples had higher average concentration of Tris(2-ethylhexyl) phosphate (TEHP) and tributyl phosphate (TNBP). Distribution of cVMSs and FTOHs followed a similar pattern in the three buildings that concentration in offices and dining areas was higher than in lecture rooms and labs, and significant correlation was found between the two compound groups in all air samples (R = 0.51, p<0.05). BFRs were found significantly correlated with the age of the buildings (R = 0.60, p<0.05) and with the number of electronic equipment (R = 0.50, p<0.05) at the sampling sites. Average inhalation DED of ΣFTOHs, ΣBFRs, ΣOPFRs and ΣcVMSs were 1200, 17, 94 and 340000 pg day-1 kg body weight (BW)-1, respectively. Generally, the higher average concentration of the analytes in samples from the homes of the volunteers and longer exposure duration time at home resulted in 5 times on average higher DED at homes compared to offices. No correlation was observed between 2,4,6-TBP in fingernail samples and its DEDs, suggesting inhalation may be a less important pathway of human exposure to this compound. DEDs of all the four compound groups were much lower than the reference dose values.