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Ecotoxicological information

Endpoint summary

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Tests on all three trophic levels (fish, daphnia, algae) were performed to examine the aquatic toxicity of the test substance.

Acute effects towards fish (Danio rerio) and algae (Desmodesmus subspicatus) were found in the same range providing a LC50 (96h) of 70.7 mg/L for fish and an EC50 (72h) of 97 mg/L for algae. Based on the low water solubility of the test item, saturated stock solutions were prepared and all reported effect values belong on nominal test substance concentrations. Pretests (for both acute and the chronic tests) were conducted to determine the minimum stirring time to reach a maximum loading rate. However, all measured concentrations in the media were below the LOQ of 0.02 mg/L. Therefore, the start concentration for exposure could not be maximized. In consequence, a standard stirring time for sparingly soluble substances of 24 hours was chosen for all subsequent ecotoxicological tests. Since undissolved test item particles were available throughout the stirring period, losses from hydrolysation during stirring were compensated.

Thus it can be reasonably assumed that the filtrates prepared from the suspension after 24 hours of stirring represent a worst case situation with a maximum of soluble test item and of potential hydrolysation products in the filtrate. Therefore, the results of the acute toxicity to fish and algae and the chronic toxicity to daphnids are based on nominal loadings and include effects of the test item and its potential hydrolisation products formed during the 24 hour stirring period.

Long-term effects on the reproduction of the waterflea Daphnia magna were investigated in a semi-static test, which resulted in an NOEC of 0.1 mg/L. Therefore aquatic invertebrates turned out to be more sensitive than algae, where a EC10 (72h) of 15.4 mg/L on growth was determined. No long-term data on fish are available. However, the chemical safety assessment indicates no need to investigate further the effects on fish.