Acute and chronic toxicity of benzotriazoles to aquatic organisms

Resulting from their intensive use as corrosion inhibitors in aircraft deicing and anti-icing fluids (ADAF) and for silver protection in dishwasher detergents benzotriazoles (BTs) are widespread in European surface waters. The current study aimed on an ecotoxicological characterization of 1H-benzotriazole (1H-BT) and 5-methyl-1H-benzotriazole (5MBT).

Acute and chronic OECD guideline tests were conducted with primary producers (Desmodesmus subspicatus, Lemna minor) and two daphnia species (Daphnia magna, Daphnia galeata) to characterize the hazard of these chemicals. Additionally, the estrogenic activity of both BTs was analyzed in vitro using a recombinant yeast estrogen screen (YES).

Both BTs revealed significant effects in acute and chronic experiments, but exhibited no estrogenic activity in the YES. The algal growth test displayed an inhibited cell number increase with effect concentration (EC) values of EC(10) 1.18 and 2.86 mg l(-1) for 1H-BT and 5MBT, respectively. In the Lemna test, EC(10) values were 3.94 mg l(-1) (1H-BT) and 2.11 mg l(-1) (5MBT). D. magna was also affected with EC(50) (48 h) values of 107 mg l(-1) for 1H-BT and 51.6 mg l(-1) for 5MBT. D. galeata was more sensitive with an EC(50) (48 h) of 14.7 mg 1H-BT l(-1) and 8.13 mg 5MBT l(-1). In the 21-day reproduction tests with D. magna, the EC(10) for 5MBT was 5.93 mg l(-1) while 1H-BT showed no adverse effects. D. galeata turned out to be more sensitive in the chronic study with EC(10) values of 0.97 mg l(-1) for 1H-BT and 0.40 mg l(-1) for 5 MBT.

Because BTs are regularly found in the aquatic environment at lower μg l(-1) concentrations reflecting their persistence and poor elimination during wastewater treatment processes, a preliminary risk assessment was conducted. There is little indication that BTs pose a risk for aquatic ecosystems at current exposure levels during most of the year. However, it cannot be excluded that in winter with a higher usage of ADAFs environmental concentrations may well exceed the level that is considered safe for aquatic organisms.