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Long-term toxicity to fish

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Key value for chemical safety assessment

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Testing for long-term toxicity to fish is not considered necessary because:

In accordance with Column 2 of REACH Annex IX, there is no need to further investigate the effects of this substance in a long-term aquatic toxicity to fish study because, as indicated in guidance R. (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is well below 1, and therefore the risk is already adequately controlled and further testing is not justifiable.

Long-term invertebrate toxicity data are available with the registered substance and have been read across from the structural analoguetrichloro(2,4,4-trimethylpentyl)silane (CAS 18379-25-4). The results from the test withtrichloro(2,4,4-trimethylpentyl)silanehave been used to derive PNECs for the hydrolysis product. Due to uncertainties with the test with the registered substance, a long-term toxicity to invertebrate test proposal has been read-across from the structural analoguetriethoxyoctylsilane (CAS 2943-75-1). Results from this test will be used to derive reliable aquatic PNECs for the registered parent substance because there is no indication that fish would be significantly more sensitive than invertebrates, as indicated by the short-term data.

A PNEC has been derived for the purpose of chemical safety assessment. An assessment factor of 50 was applied to derive the freshwater PNEC, based on long-term invertebrate data. For a narcotic chemical without a specific mode of toxic action, it is unlikely that the aquatic PNEC would be significantly over-estimated using this method.

Overall it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further in vivo testing is not considered necessary or justified on ethical grounds.

Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 and Chapters 9 and 10 of the Chemical Safety Report, respectively.