Organophosphate Esters in Breast Milk from Beijing, China

Organophosphate esters (OPEs) are employed as flame retardants. Although human and environmental exposure to legacy OPEs is well characterized, data on novel OPEs remain limited. This study examined legacy and novel organophosphate triesters (tri-OPEs) and their metabolites (m-OPEs) in breast milk samples from Beijing, China. Notably, 4-hydroxy triphenyl phosphate (4-OH-TPHP) and butyl diphenyl phosphate (BDPP) were detected in breast milk for the first time. Among the nine most frequently detected tri-OPEs, tris(1-chloro-2-propyl) phosphate (TCIPP), tri-<i>n</i>-butyl phosphate (TNBP), and triethyl phosphate (TEP) dominated (median: 1.45, 0.50, and 0.31 ng/mL), contributing 42%, 18%, and 14%, respectively. The metabolites bis(1-chloro-2-propyl) phosphate (BCIPP) and bis(2-ethylhexyl) phosphate (BEHP) both exhibited the highest median concentration (1.09 ng/mL). The median concentration of six metabolites reached 5.69 ng/mL, which was significantly higher than that of the nine highly detected tri-OPEs (3.34 ng/mL). Although the risk of tri-OPEs is low, elevated m-OPE levels need further studies for risk assessment.