Assessing the threats of organophosphate esters (flame retardants and plasticizers) to drinking water safety based on USEPA oral reference dose (RfD) and oral cancer slope factor (SFO)

As one group of emerging pollutants, the threat of organophosphate esters (flame retardants and plasticizers, OPEs) to drinking water safety is not well recognized. Now, the oral reference dose (RfD) and oral cancer slope factor (SFO) of OPEs have been updated by USPEA, therefore the threat of OPEs to drinking water safety could be assessed. In this study, occurrence, health risk and key impact factor of OPEs in drinking water of China were analyzed covering 79 cities, whose population and gross domestic product (GDP) accounted for 28.8% and 44.1% of them in China, respectively. Total concentration of 14 common OPEs in drinking water was 13.42-265.48 ng/L. The exposure level of OPEs via ingestion of drinking water was much lower than that of food ingestion but was comparable with dust ingestion, inhalation and dermal absorption. A health assessment for OPEs via ingestion of drinking water suggested that the potential cancer risk occurred (>1.00E-6) but no obvious non-carcinogenic effects occurred (<1). Tris-(2,3-dibromopropyl) phosphate (TDBPP) contributed to about 72.4% of carcinogenic risk, which should be treated as "prior monitoring OPEs" in further studies. The occurrence and distribution of OPEs in drinking water of China have a good corresponding relationship with the Aihui-Tengchong Line, and drinking water treatment technology (DWTT) was found to be a key factor. Total OPEs, halogeno-OPEs and alkyl-OPEs in drinking water from advanced DWTT cities were much lower than those of conventional DWTT cities. Compared with conventional DWTT, advanced DWTT could reduce about 65.6% and 36.5% of carcinogenic risk and non-carcinogenic risk of OPEs, respectively. Considering the annual growth of OPEs consumption in China and world, further studies regarding the environmental threat of OPEs are required.