Benzotriazoles and Benzothiazoles in Human Urine: Method Development, Occurrence, Human Exposures, and Biotransformation

Benzotriazole (BTR) and benzothiazole (BTH) derivatives are used in a wide variety of industrial and consumer products and have been reported to occur in the environment. Owing to a lack of analytical methods, human exposure to BTRs and BTHs is still unknown. Therefore, a liquid chromatography-electrospray ionization tandem mass spectrometry (LC–ESI(+)MS/MS) method was developed for simultaneous determination of six 1,2,3-benzotriazoles and six 1,3-benzothiazoles in human urine. The target BTRs were 1H-benzotriazole, 1-hydroxy-benzotriazole, 4and 5-hydroxy-benzotriazole (mixture), tolyltriazole, xylyltriazole (or 5,6-dimethyl-1H-benzotriazole), and 5-chlorobenzotriazole. The target BTHs were benzothiazole, 2-morpholin-4-yl-benzothiazole, 2hydroxy-benzothiazole, 2-methylthio-benzothiazole, 2-amino-benzothiazole, and 2thiocyanomethylthio-benzothiazole. Urine specimens were enzymatically deconjugated with β-glucuronidase and extracted by a solid-phase extraction (SPE) procedure for the measurement of total concentrations (i.e., free + conjugated forms) of BTRs and BTHs. Additionally, a liquid liquid extraction (LLE) method was developed for comparison of extraction efficiencies between SPE and LLE. A total of 332 urine specimens collected from the general populations in seven countries (the U.S., Greece, Vietnam, Korea, Japan, China, and India), were analyzed by enzymatic deconjugation and SPE. Benzothiazole, tolyltriazole and xylyltriazole were found frequently, and their concentrations were on the order of a few ng/mL. The median concentration of sum of five BTRs (Σ5BTRs; 4and 5-hydroxy-benzotriazole were not included) ranged from 0.2 ng/mL (Korea) to 2.8 (India) ng/mL among the countries studied, with the highest Σ5BTRs concentration of 24.5 ng/mL found in a urine sample from China. Xylyltriazole was found more frequently in urine from all five Asian countries than in urine from the U.S. and Greece. The median concentration of sum of six BTHs (Σ6BTHs) ranged from 3.6 (U.S.) to 10.9 (Japan) ng/mL among the countries studied, with a maximum detection rate of 100 % in urine samples from Vietnam; BTH was the predominant derivative accounting for, on average 43 % of the Σ6BTH concentration in urine from all the countries. Based on the concentrations and detection rates of several BTR and BTH derivatives in urine, possible metabolic transformation pathways of these compounds were discussed and human exposure doses calculated. The estimated daily intake doses of BTRs and BTHs were on the order of a few to few tens of micrograms per day.