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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

There are no reliable data for short-term toxicity to aquatic invertebrates. However, the requirement to test is waived in accordance with Column 2 specific rules for adaptation from Column 1 of REACH Annex VII.

Key value for chemical safety assessment

Additional information

A water-accommodated fraction of the test substance prepared at a loading rate of 1000 mg/L was not toxic to mobility of Daphnia magna over 48 hours when tested at a concentration of 9 parts water-accommodated fraction in 10 parts total volume of test medium. The test medium contained approximately 11 mg/L of silicon. The results indicate that the substance is unlikely to be toxic at its solubility limit of approximately 0.9 mg/L. However this result is disregarded because the concentrations tested are well above the solubility limit of the test substance. The results of two other tests, for which there was insufficient information to assess reliability, also indicated that effects were only observed at nominal loadings that significantly exceeded the solubility of the substance. Using a reliable, validated QSAR method, a worst case EC50 of 0.2 mg/l is estimated; however for substances with a log Kow greater than 5.0, the validation process has indicated that the EC50 would not be reached at the limit of solubility. The log Kow of HMDS (5.06) places this substance on the threshold for quantitative or qualitative application of the ECOSAR predictive method, but it is notable that the qualitative conclusion (EC50 > limit of solubility) appears to be in keeping with the indicative evidence from the available low-reliability experimental studies.