Herein, 16 traditional and 13 novel organophosphate esters (OPEs) in skin wipes, personal PM2.5, sputum, and nails (fingernails and toenails) and 7 OPE metabolites in urine synchronously obtained from 64 college students were analyzed. Similar compositional profiles of the OPEs were found in skin wipes and nails and in personal PM2.5 and induced sputum. Significant correlations were observed between the concentrations of high-lipophilicity low-volatility OPEs in skin wipes and nails and between the concentrations of high-volatility low-lipophilicity OPEs in personal PM2.5 and sputum. These results imply that OPEs in fingernails and toenails may mainly come from external sources rather than internal exposure, and human nails and sputum can be used as indicators of human exposure to OPEs. A comparison between the daily exposure doses of the OPEs in personal PM2.5 and sputum shows that more volatile compounds may have higher inhalation bioavailability, which should be considered to improve the accuracy of inhalation exposure assessments. According to comprehensive external and internal exposure assessment, dermal absorption may be a more dominant pathway than inhalation, and skin wipes may be the best representative environmental matrix of human exposure to OPEs.
Keywords: PM2.5; nail; organophosphate esters; skin wipe; sputum; urine.