Toxicokinetics of benzotriazole UV stabilizer UV-P in humans after single oral administration

UV-P (2-(2H-Benzotriazol-2-yl)-p-cresol) is used as an ultraviolet (UV) light absorber in coating products, paints, adhesives, and sealants. Due to its widespread industrial and consumer uses, human exposure to UV-P is conceivable. In the study presented herein, initial data on its human in vivo metabolism were obtained for three study participants after single oral administration of 0.3 mg of UV-P/kg body weight. Urine and blood samples of two volunteers were collected up to 48 h after exposure. The third study participant donated urine and blood samples up to 72 h. Maximum levels of UV-P in blood of 184 ± 36 µg/l (85 ± 3% as conjugates) were reached 2.4 ± 1.2 h post-exposure. Maximum excretion rates of UV-P in urine of 2896 ± 884 µg/h (completely conjugated) were reached 3.5 ± 1.1 h post-exposure. 37.2 ± 5.4% of the orally administered dose of UV-P was recovered in urine within 48 h post-exposure. The present study provides insight into the complex absorption, distribution, metabolism, and elimination (ADME) processes of benzotriazole UV stabilizers (BUVS). The study also demonstrates differences in the ADME between sterically hindered BUVS, such as UV-327 and UV-328, and sterically unhindered BUVS, such as UV-P, in which the phenolic hydroxyl group is readily accessible for conjugation with glucuronic acid or sulfate.