Metabolism of 1H-benzotriazolecarboxylic acids in vitro and in vivo

Photochemical degradation of benzotriazole

Benzotriazole is a commonly used additive in aircraft de-icing fluids. As a result of extensive de-icing activities the compound is detected in the groundwater below de-icing platforms at several international airports. The compound is toxic, and not biodegradable. Laboratory tests have been performed to study if UV irradiation can degrade the compound and reduce the aquatic toxicity. Benzotriazole can be degraded by UV irradiation at pH values below 7. Approximately 65% reduction in the benzotriazole concentration was achieved at a dose of 320 mWs/cm2, and almost 90% reduction was achieved at 1070 mWs/cm2, with an apparent first order relation between the logarithm to the UV dose and the reduction. Benzotriazole is not significantly mineralised by UV irradiation, but transformed into other compounds, of which aniline and phenazine were identified. The metabolites show toxic effects, but they are not as toxic as benzotriazole, resulting in a general decrease in toxicity as a result of UV irradiation.

Hydrolysis and oxidation of 1H-benzotriazole-carboxylic acid esters by rat liver microsomes

The 1H-benzotriazole-carboxylic acid esters under investigation were almost - with the exception of the tert.-butylester - completely hydrolyzed by rat liver microsomes. Some substrates were metabolically oxidized to a very small extent (less than 1%) yielding small amounts of possibly toxic metabolites after inhibition of the esterases with paraoxone.