Characteristic Profiles of Benzonphenone-3 and its Derivatives in Urine of Children and Adults from the United States and China

Widespread exposure of humans to benzophenone-3 (BP-3) is a concern due to this compound's potential to disrupt endocrine function. BP-3 can be metabolized by phase I and phase II reactions of the human cytochrome P450 system. Urinary measurements of BP-3 have been used as a biomarker of exposure. Nevertheless, metabolic transformation pathway and the transformation products of BP-3 in humans are still less known. In this study, 166 urine samples collected from children and adults in the U.S. and China were analyzed for free and total forms (free plus conjugated) of BP-3 as well as four of its metabolic derivatives, 4-OH-BP, 2,4-diOH-BP, 2,2',4,4'-tetraOH-BP, and 2,2'-diOH-4-MeO-BP, using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BP-3 was found in almost all urine samples from the U.S. and China. Concentrations of BP-3 in urine from children (GM: 9.97 ng/mL) and adults (15.7 ng/mL) in the U.S. were significantly higher than those in children (0.622 ng/mL) and adults (0.977) from China. A significant positive relationship was found between the concentrations of urinary BP-3 and its derivatives. The profiles of BP derivatives in urine suggested that demethylation was a major route of BP-3 metabolism. The percentage of the free form of BP-3 in urine was used in the determination of efficacy of phase II metabolism among the different population groups studied. A significantly lower percentage of the free form of BP-3 was found in urine from the U.S. population than in the Chinese population.