Novel High Molecular Weight Synthetic Phenolic Antioxidants in Indoor Dust in Toronto, Canada

Synthetic phenolic antioxidants (SPAs) are additives that are used to retard oxidative degradation in polymers, extending their lifespans. Previous studies have mainly focused on the pollution and toxicity risk of low molecular weight SPAs such as 2,6-di-tert-butyl-4-methylphenol (BHT, C15H24O). In this study, 10 novel high molecular weight SPAs were investigated, along with BHT. Surprisingly, all 10 high molecular weight SPAs, as well as BHT, were detected in indoor dust collected in Toronto, with ∑SPAs of 239–2.13 × 105 ng/g (geometric mean (GM): 1.77 × 103 ng/g). Although BHT (GM: 749 ng/g) was the primary congener in the indoor dust, contributing 55.2% to ∑SPAs, the 10 newly identified high molecular weight SPAs, such as pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (AO1010, C73H108O12, GM: 146 ng/g), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (AO1076, C35H62O3, GM: 76.4 ng/g), and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (AO245, C34H50O8, GM: 28.8 ng/g), also contributed substantially to ∑SPAs (44.8%). The newly identified high molecular weight SPAs were predicted to have intermediate to high toxicity risks by Toxtree. The high molecular weight SPAs are likely hydrolytically stable in indoor environments, as their hydrolysis product was detected seldomly and only at low concentrations. To our knowledge, this is the first study reporting the occurrence of eight high molecular weight SPAs in indoor environments, among which seven congeners were detected for the first time in any environmental samples. Further studies on SPAs should include these newly identified high molecular weight SPAs, particularly AO1010, AO1076, and AO245.