The concentrations of 9 organophosphate flame retardants (OPFRs) were determined in 56 indoor and 9 outdoor air samples in the Rhine/Main area in Germany. The indoor samples were collected from seven different indoor microenvironments including private cars, private homes, floor/carpet stores, building material markets, schools, offices, and day care centers, while outdoor samples were simultaneously collected close to the indoor sampling locations. The total OPFR concentrations (∑OPFRs) in indoor air ranged from 3.30 to 751.0 ng/m with a median of 40.23 ng/m, which was approximately eight times higher than those in outdoor air (median 5.38 ng/m), indicating that sources of OPFRs predominate in the indoor environment. Tris(2-chloroisopropyl)phosphate (TCPP), tris(isobutyl)phosphate (TiBP), and tributyl phosphate (TnBP) were the dominating compounds both in indoor and outdoor air. The median concentration of ∑OPFRs in private cars (180.3 ng/m) was significantly higher than that in private homes (12.51 ng/m), schools (36.23 ng/m), day care centers (31.80 ng/m), and building material markets (31.17 ng/m) (p < 0.05). Distribution profiles of OPFRs varied among different indoor microenvironments, which are evidenced by dominating indoor air concentrations of non-Cl-OPFRs in day care centers, floor/carpet stores, schools, and of Cl-OPFRs in other indoor microenvironments. Multivariate analyses revealed three distinct groups for OPFRs, i.e., TiBP/TnBP, TEP/TCEP/TDCPP, and TCPP, whose concentrations were closely associated with the distribution profiles and pollution characteristics of materials predominating in different indoor microenvironments.

We analyzed organophosphate flame retardants (OPFRs) in 74 indoor dust samples collected from seven microenvironments (building material markets, private cars, daycare centers, private homes, floor/carpet stores, offices, and schools) in the Rhine/Main region of Germany. Ten of 11 target OPFRs were ubiquitously detected, some with more than 97% detection frequency, including tris(1,3-dichloroisopropyl)phosphate (TCIPP), tris(2-butoxyethyl)phosphate (TBOEP), triphenyl phosphate (TPHP), and tris(isobutyl) phosphate (TIBP). Total concentrations (∑OPFRs) ranged from 5.9 to 4800 μg/g, with TBOEP and TCIPP being the most abundant congeners. The ∑OPFRs in schools, private cars, offices, and daycare centers were significantly (P<.05) higher than in private homes. The ∑OPFRs for building material markets (19 μg/g) and floor/carpet stores (20 μg/g) showed no significant difference to the other microenvironments, likely because of forced ventilation. The profiles of OPFRs in dust samples from offices and private homes were highly similar, while profiles from the other five microenvironments were substantially different. Comparison of our results with previous studies indicates a significant global variation in OPFR concentrations and their profiles, reflecting distinct fire safety regulations in different countries and/or different sampling strategies. Dust ingestion constitutes the major exposure pathway to OPFRs for toddlers, while air inhalation is the major pathway for adults.