In China, organophosphate esters (OPEs) are widely used in indoor environments. However, there is little information regarding the internal and external exposure of university students to OPEs. Therefore, in this study, nine OPEs and eight OPE metabolites (mOPEs) were measured in indoor dust and atmospheric PM2.5 samples from a university campus in Shanghai, as well as in urine samples collected from the university students. The total concentration of OPEs in the indoor dust in female dormitories (1420 ng/g) was approximately twice that in male dormitories (645 ng/g). In terms of indoor PM2.5, the highest OPE concentration was found in meeting rooms (105 ng/m3, on average), followed by chemical laboratories (51.2 ng/m3), dormitories (44.9 ng/m3), and offices (34.9 ng/m3). The total concentrations of the eight mOPEs ranged from 279 pg/mL to 14,000 pg/mL, with a geometric mean value of 1590 pg/mL. The estimated daily intake values based on the indoor dust and PM2.5 OPE samples (external exposure) were 1-2 orders of magnitude lower than that deduced from the concentration of urinary mOPEs (internal exposure), indicating that dermal contact, dust ingestion, and inhalation do not contribute significantly to OPE exposure in the general population. Moreover, additional exposure routes lead to the accumulation of OPEs in the human body.
Keywords: external exposure; indoor exposure; internal exposure; organophosphate ester metabolites; organophosphate esters; urine.