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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Description of key information

No long-term toxicity test with aquatic invertebrates is available, but no long-term effects can be expected.

Key value for chemical safety assessment

Additional information

There is no long-term test on aquatic invertebrates available for Fatty acids, C16-18 and C18-unsaturated, dimerized (CAS No 71808-39-4). However, data on the chronic toxicity to fish does exist for the category member Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5). During the 28-day long-term toxicity study with the freshwater fish Danio rerio, according to ISO/DIS 10229-1, no effects were observed and a NOEC of ≥ 0.85 mg/L (mean measured) was determined (Marshall, 1994). As the water solubility of the test substance was determined to be < 0.52 mg/L no effect within the water solubility was observed.


Thus, in accordance with Article 13(1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met". Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 states that substances may be considered as a category provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern. Fatty acids, C16-18 and C18-unsaturated, dimerized (CAS No 71808-39-4), also referred to as “Crude dimer”, is composed of approximately 20-45 % Monomer C16-18 Acids, 45-60 % Dimeric C36 Acids and < 20 % Trimeric acids. Therefore all read across substances are structurally and compositionally related to crude dimer and have similar properties. Derived from the same starting substance, all substances in this category have a homologous composition of fatty acids with a C16 - C18 carbon chain in diverse forms. All sub-category 2 members of the Dimerized Fatty Acids and Its Derivatives category have a low water solubility (< 0.52 mg/L, limit of detection) and are not readily biodegradable. As a result of structural similarity, common origin, similar metabolic pathways, similar physico-chemical properties, common environmental fate & eco-toxicologcial profile of the two substances, and since there was no sign that aquatic invertebrates are more sensitive than fish in the short term tests, it cannot be expected that a long-term test with aquatic invertebrates will generate different results than the existing long-term test with fish. Therefore, a long-term study on aquatic invertebrates is not required.