National Urinary Metabolites of Organophosphate Flame Retardants in Urban Chinese Residents

Organophosphate flame retardants (OPFRs) are extensively added to household products for fire safety. However, little is understood about the national scale of human exposure levels and the factors influencing OPFRs in developing countries. In this study, five metabolites of OPFRs (mOPFRs) were determined for the first time in the urine of 1184 general population in 26 provincial capitals of mainland China. The detection frequency and median concentration of ∑mOPFRs were 86.0% and 61 μg/L, respectively, with bis(1-chloro-2-propyl) phosphate, bis(2-chloroethyl) phosphate (BCEP), and diphenyl phosphate predominantly accounting for 75.9% of the total. Human exposure to OPFRs is higher in western China than in other Chinese regions. Gender, age, bottled water, and takeout consumption significantly influenced the urinary mOPFRs. Monte Carlo simulations showed that 3.6% of participants had hazard indices values higher than one, indicating that a small proportion of the Chinese population exposed to OPFRs had potential non-carcinogenic risks. Here, BCEP was the primary contributor, making up 81.5% of the total risk. This study indicated that investigating human exposure to OPFRs is imperative, especially the safety of these substances as a substitute for polybrominated diphenyl ethers.