Emerging and traditional organophosphate esters in office air from Hangzhou, East China: Seasonal variations, influencing factors and human exposure assessment.

Eight emerging and six traditional organophosphate esters (OPEs) were investigated in office air from Hangzhou China with all the traditional OPEs and 5 out of 8 emerging OPEs detected. The median concentrations of ∑ OPEs and ∑ OPEs were 61,200 and 5.81 pg/m, respectively. Butylphenyl diphenyl phosphate (BPDPP) and trisisopropyltrisphenyl phosphate (TIPPP) were observed for the first time in indoor air and Chinese office, respectively. The levels of ∑ OPEs decreased in the following order: summer > autumn > spring > winter. Conversely, no obvious trends were observed for emerging OPEs. ∑ OPEs (p < 0.001) and tri(chloroisopropyl) phosphate (TCIPP) (p < 0.01) concentrations were positively correlated with temperature. Interestingly, ∑ OPEs and the individual emerging OPEs analytes had no significant correlations with temperature (p > 0.05). ∑ OPEs, tris(2-chloroethyl) phosphate (TCEP) and TCIPP levels were significantly positively correlated with relative humidity (p < 0.05), while ∑ OPEs levels were negatively correlated with relative humidity (p < 0.05). Median intakes of traditional OPEs were estimated to be several orders of magnitude lower than the corresponding Reference Dose (RfD) values. The distinct environmental behaviors of emerging OPEs compared to traditional OPEs, coupled with the lack of established RfD values for them, underscore the need for their risk evaluations in future.