Synthetic Phenolic Antioxidants in Personal Care Products in Toronto, Canada: Occurrence, Human Exposure, and Discharge via Greywater

Although synthetic phenolic antioxidants (SPAs) are widely used in various personal care products (PCPs), little is known about their levels, composition profiles, human exposure, or environmental emissions. In this study, the occurrence of SPAs was evaluated in 15 categories of 214 PCPs collected in Toronto, Canada. Nine SPAs were detected in the PCPs, of which only 2,6-di-tert-butyl-4-methylphenol (BHT, < method quantification limit (MQL)-827 900 ng/g, mean: 35 602 ng/g, median: 249 ng/g) was observed with a detection frequency of >50%. When the 214 PCPs were separated into products labeled as containing BHT and those labeled as not containing BHT, the BHT-labeled PCPs (mean: 369 253 ng//g, median: 382 560 ng/g) contained significantly higher concen- trations of BHT than the BHT-unlabeled PCPs (mean: 4960 ng/g, median: 199 ng/g) did (p < 0.01). Five transformation products (TPs) of BHT were also detected in the PCPs at low concentrations (Sigma TPs: < MQL to 19 014 ng/g, mean: 730 ng/g, median: < MQL) and detection frequencies (12.6-37.4%). Preliminary calculations found that dermal absorption via PCP use may be an important exposure pathway for BHT (mean: 565 879 ng/day median: 2988 ng/day), although this is a negligible exposure pathway for other SPAs. In addition, the estimated discharges of BHT (mean: 7852 g/day, median: 88 g/day) via greywater after PCP use were calculated, which represents a nonignorable source of BHT loading into wastewater treatment plants in Toronto (contributing 10%). To our knowledge, this is the first evaluation of human exposure to and discharge of SPAs via PCP use.