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Ecotoxicological information

Toxicity to terrestrial arthropods

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Based on the results of the OECD 309 study, 2-mercaptoethanol degrades in the aquatic environment to a level of >70% within a 28 day period and therefore, the substance is considered to be rapidly biodegradable. Also, as the logKoc and LogPow are below 3 and no cationic and surface active properties are given, a low adsorption potential is indicated. Therefore, transfer to the soil compartment is not expected. However, aquatic ecotoxicity tests showed Daphnia magna were the most sensitive species revealing a 48 hour EC50 of 0.4 mg/L and a 21 day NOEC of 0.0632 mg/L and thus, 2-mercaptoethanol is considered acutely and chronically very toxic for aquatic organisms.

On the basis of the available data, 2-mercaptoethanol would meet the criteria for soil hazard category 2 and, as such, confirmatory short-term soil toxicity tests were conducted on terrestrial invertebrates (earthworms) and terrestrial micro-organisms. As the initial risk assessment using equilibrium partitioning for the soil compartment and the updated risk assessment using the terrestrial toxicity data did not indicate risk, no further toxicity testing on soil organisms is considered necessary and the Annex IX and X higher tier tests on soil organisms have been waived.