Geographical distributions and human exposure of organophosphate esters in college library dust from Chinese cities

Organophosphate esters (OPEs) in indoor dust were closely related to human health. However, OPE contamination in college library dust remained unknown at present. In this study, OPEs were first investigated in 78 indoor dust samples and 26 field blanks of 26 college libraries from 13 prefecture-level cities across China between October and December 2017. The total OPEs fell in the range of 8706-34872 ng/g, and were dominated by tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP). OPEs exhibited geography-specific distributions, with high levels in Beijing, Shanghai and Guangzhou. OPEs significantly correlated with population density and gross domestic product (p < 0.01), indicating the distinct effect of these two indicators on OPE pollution. Analysis of pollution source indicated volatilization and abrasion as main emission pathways of OPEs from OPEs-added products to dust. The daily exposure doses (DEDs) of OPEs via dust ingestion, inhalation and dermal contact were similar for male and female students, ranging from 135 to 5.92 ng/kg-bw/day during study time in libraries (25% of day). High DEDs were found in Beijing, shanghai and Guangzhou, indicating high exposure risk of OPEs to college students in large cities. The non-carcinogenic and carcinogenic risks of OPEs to college students were quantitatively evaluated based on the oral reference dose and cancer slope factor of OPEs recently updated by USEPA, and all much lower than the threshold risk values. However, the potential risk may occur if exposure to OPEs is high in other microenvironments over remaining hours of the day. (C) 2019 Elsevier Ltd. All rights reserved.