Quantitative identification of and exposure to synthetic phenolic antioxidants, including butylated hydroxytoluene, in urine.

Synthetic phenolic antioxidants (SPAs) such as 2,6-di-tert-butyl-4-hydroxytoluene (butylated hydroxytoluene, BHT), are used in a wide variety of consumer products, including certain foodstuffs (e.g. fats and oils) and cosmetics. Although BHT is considered generally safe as a food preservative when used at approved concentrations, there is debate whether BHT exposure is linked to cancer, asthma, and behavioral issues in children. Little is known with regard to human exposure to SPAs and the methods to measure these chemicals in urine. In this study, six SPAs and the metabolites were analyzed in 145 urine samples collected from four Asian countries (China, India, Japan, and Saudi Arabia) and the United States. BHT was found in 88% of the urine samples at median and maximum concentrations of 1.26 and 15 ng/mL, respectively. BHT metabolites and butylated hydroxyanisole (BHA) were found in 39% to 89% of the urine samples at a concentration range of <LOQ-46 ng/mL. 3,5-Di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH), the major metabolite of BHT, is suggested as a potential urinary biomarker of exposure to BHT. The estimated median daily intakes (EDIs) of BHT, calculated from urinary concentrations, in children and adults were 0.38-56.6 and 0.21-31.3 μg/kg bw/day, respectively. BHT levels were high in urine samples from Japan, India, and the United States.