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Long-term toxicity to fish

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Description of key information

Fatty acids, C16-C18 and C18-unsaturated, dimerized (CAS No. 71808-39-4) is expected to show no chronic effects up to the limit of the water solubility (<0.41 mg/L). The NOEC (28 d) was determined to be > 0.850 mg/L.

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Additional information

One study investigating the long-term toxicity of Fatty acids, C18-unsaturated, dimers, hydrogenated (CAS No. 68783-41-5) to freshwater fish was used as read across to Fatty acids, C16-18 and C18-unsaturated, dimerized (CAS No 71808-39-4) in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5, grouping of substance and read across approach. No study is available for the test substance itself.

The long-term toxicity test conducted in accordance with GLP and to ISO/DIS 10229-1 with the fresh water fish Danio rerio resulted in a NOEC (28 d) of ≥ 0.850 mg/L, and it is concluded that no effects up to the limit of the water solubility of the tested substance occurred (Marshall, 1994). Due to the low water solubility of the test substance a vehicle (DMSO) was used. Continuously flowing test solutions were generated from a constant-head tank containing dilution water and from a series of stocks which were dosed into the test vessels via a peristaltic pump.


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, it can be concluded that as no effects for long term toxicity to fish will be observed up to the water solubility limit (< 0.41 mg/L).