Multi-target analysis of synthetic phenolic compounds in human blood

Synthetic phenolic compounds are widely used in plastics and personal care products, leading to potential high human exposure. This study aimed to develop two multi-target analytical methods to quantify phenolic compounds in human serum, including free and conjugated synthetic phenolic antioxidants (SPAs), bisphenols, parabens, and UV filters. The two methods were applied to 30 human serum samples from young adults (15 females and 15 males) living in Stockholm, Sweden. An average recovery of 73 % (range 36-125 %) and good reproducibility (RSD <30 %) were established for 37 target analytes, and another four analytes were semi-quantified. Twenty-one target analytes were found above quantification levels. Notable, five SPAs, namely 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (AO2246), 4,4'-methylenebis(2,6-di-tert-butylphenol) (AO4426), 4-tert octylphenol (4-tOP), butylade hydroxyanisole (BHA), butylated hydroxytoluene (BHT) were quantified in >93 % of samples, and with median concentrations between 1.4 (BHA) and 520 ng/g (AO2246). Other compounds quantified in the samples were bisphenol B (quantification frequency 57 %) and methylparaben (quantification frequency 87 %), with median concentrations of 0.38 and 1.6 ng/g respectively. Additionally, two features were semi-quantified using suspect screening: Fenozan (an SPA metabolite, 3-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionic acid) and benzophenone-4 (a UV filter, 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid). To the best of our knowledge, this is the first time AO4426, 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH), 2-tert-butylbenzene-1,4-diol (TBHQ), bisphenol B, and Fenozan have been found in human blood. The finding of SPAs in human blood indicates high human exposure and needs further investigation.