Organophosphate esters (OPEs) in Chinese foodstuffs: Dietary intake estimation via a market basket method, and suspect screening using high-resolution mass spectrometry

Despite of the ubiquity of organophosphate esters (OPEs) in various environmental matrices, information regarding the dietary intakes of OPEs is currently limited. To better understand dietary exposure and intake, the present study investigated 11 OPE flame retardants (FRs) in 105 composite food samples divided into 9 food categories, collected in 2018 and based on the contents of a typical Chinese food market basket. Nine OPEs, including triethyl phosphate (TEP), tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPHP), 2-ethylhexyl-diphenyl phosphate (EHDPP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-ethylhexyl) phosphate (TEHP) and tris(methyl-phenyl) phosphate (TMPP), were measurable above the method limits of quantifications (MLOQs) in at least one of the analyzed samples. Among the 9 food categories, sweets were contaminated most severely with a mean sum (Σ) OPE concentration of 10.34 ng/g wet weight (ww). Regardless the food categories, EHDPP and TEP were the predominant OPEs with mean concentrations of 1.12 and 0.95 ng/g ww, respectively. In addition, the levels of OPEs in "processed foods" were significantly (unpaired t-test, p < 0.01) higher than those in "non-processed foods". Based on the measured OPE concentrations, we estimated daily per capita dietary intakes of ΣOPEs for Chinese adult population to be 44.3 ng/kg bw/day, that was mainly contributed by TCEP (14.3 ng/kg bw/day), TEP (12.7 ng/kg bw/day) and EHDPP (8.4 ng/kg bw/day). In addition to these 9 detected OPEs, further suspect screening in the combined extracts of foodstuffs by use of high-resolution spectrometry revealed a novel OP-FR, triphenyl phosphine oxide (TPPO). The highlight findings in this study were: 1) the amount of OPE via dietary intakes for the Chinese population is generally in the same order of magnitude as for other countries, i.e. the Swedish, Belgian and Australian adult population, and far less than the reference dosage value of each OPE (hazard index ≪ 1); 2) the total dietary intakes of OPEs were dominated by cereals, approximately accounting for 52.2%; and 3) the first reported detection of the novel OP-FR, TPPO, in foodstuff samples.