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Long-term toxicity to fish

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Description of key information

No long-term test for toxicity to fish is available, nevertheless no effects of long-term toxicity to fish are expected up to the limit of water solubility (<0.24 mg/L)

Key value for chemical safety assessment

Additional information

Isooctadecanoic acid (CAS No. 30399-84-9) is readily biodegradable. The substance is therefore not foreseen to pose a risk to aquatic organisms on the long-term. However, due to the poor water solubility of the test substance and as long term toxicity to aquatic organisms is a mandatory endpoint in accordance to Regulation (EC) No 1907/2006, annex IX 9.1 Aquatic toxicity. According to the “Guidance on information requirements and chemical safety assessment Chapter R.7b: Endpoint specific guidance, R.7.8.5.3” (ECHA, 2012), long-term testing of fish should only be conducted if it represents the most sensitive taxonomic group. The Guidance states that if invertebrates are likely to be more sensitive than fish and algae or the relative sensitivity of invertebrates cannot be predicted, long-term testing on Daphnia sp. should be preferred instead of fish. Therefore a long-term toxicity study with Daphnia magna was conducted with the read-across substance Fatty acids, C16-18 and C18-unsaturated, branched and linear, “Monomer acid” (CAS No. 68955-98-6) to confirm that no toxicity to aquatic organisms occurs. As no effects on the reproduction of the daphnids was observed in this study, and there is no sign that fish are more sensitive than aquatic invertebrates, it cannot be expected that a long-term test with fish would show significant effects. 

Additionally, with Sub-category 2 (predominantly oligomers) of the Dimerised Fatty acid and its derivatives for the hydrogenated Dimer (CAS 68783-41-5), no long-term toxicity was observed with the fresh water fish Danio rerio up to the water solubility of the tested substance (Marshall, 1994). Hence in accordance to Regulation (EC) No. 1907/2006, 9.1.5., Column 2 the chemical safety assessment according to Annex I has found no need to investigate further the effects on fish, thus a long-term study on fish is not required.