Synthetic Phenolic Antioxidants and Transformation Products in Human Sera from United States Donors

Synthetic phenolic antioxidants (SPAs) make up a group of widely used anthropogenic additives, whose potential for toxicity has received more attention in recent years. Although SPAs can reach humans through many exposure pathways, few data on the concentrations of SPAs in humans are available. In this study, five SPAs were quantified, at significant concentrations, in 50 individual serum samples collected from donors in the United States. The measured total SPA concentrations [0.46–34.7 ng/mL, geometric mean (GM) of 7.77 ng/mL] were dominated by 2,6-di- tert -butyl-4-methylphenol (BHT) and 2,4-di- tert -butylphenol (DBP), which contributed 42 and 57% on average to the total concentrations, respectively. Four putative biotransformation products (TPs) of BHT [2,6-di- tert -butyl-4-(hydroxymethyl)phenol (BHT-OH), 3,5-di- tert -butyl-4-hydroxybenzaldehyde (BHT-CHO), 2,6-di- tert -butyl-1,4-benzoquinone (BHT-Q), and 2,6-di- tert -butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-quinol)] were also detected, with total concentrations ranging from below the method quantification limits to 3.66 ng/mL (GM of 0.77 ng/mL). Five pooled serum samples, each containing sera from at least 1000 donors, were also included in this study. The concentrations of the SPAs (GM of 24.5 ng/mL) and TPs (GM of 10.4 ng/mL) were even higher in pooled sera than in individual samples, indicating the prevalent human burdens of SPAs in a large population. To the best of our knowledge, this is the first analysis of a wide range of SPAs and TPs in human sera.