Fatty acids, C16-18 and C18-unsatd., dimerized

Short-term toxicity to fish

Description of key information

Fatty acids, C16-18, C18-unsaturated, dimerized (CAS No. 71808-39-4) is expected to show no effects up to the limit of the water solubility (<0.41 mg/L).

Additional information

No studies on the short-term toxicity of Fatty acids, C16-18 and C18-unsaturated, dimerized (CAS No 71808-39-4), “Crude dimer” are available. However, three studies investigating the short-term toxicity to freshwater fish were conducted. Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4), Fatty acids, C16-18 and C18-unsaturated, branched and linear (CAS-No. 68955-98-6), and Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6), were used for read across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5, grouping of substance and read across approach.

An OECD 203 guideline study with Fatty acids, C18-unsaturated, dimers (CAS No. 61788-89-4) was conducted under static test conditions and with Danio rerio (Benjits, 2002). No mortality was observed up to the highest tested concentration (350 mg/L nominal) during 96 h exposure under the conditions tested. Details on preparation of test solutions were not provided. A second study (Sewell, 1994) conducted with Fatty acids, C16-18 and C18 unsaturated, branched and linear (CAS 68955-98-6) under semi-static conditions with the freshwater fish (Leuciscus idus) according to OECD guideline 203 also reported no mortality within the tested concentration range. Due to the low water solubility of Fatty acids, C16-18 and C18-unsaturated, branched and linear (CAS 68955-98-6) the test solutions were prepared as water accommodated fractions (WAF). No mortality up to the limit of the water solubility of the test substance was observed. The LL50 (96 h) is > 1000 mg/L and the NOELR ≥ 1000 mg/L. In addition, in a third semi-static short-term study with Fatty acids, C18-unsaturated, trimers (CAS No. 68937-90-6) with the marine fish Scophthalmus maximus, conducted according to OECD 203 and modified to the marine conditions (OSPAR 1995), a LL50 (96 h) > 1800 mg/L is reported (Sacker, 2005). Due to the low water solubility of the test substance, the test solutions were prepared as WAF, too. No mortality up to the limit of the water solubility of the test substance 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 Dimerised Fatty Acids and Its Derivatives category have a low water solubility (all <0.52 mg/L, limit of detection), and are not readily biodegradable. As a result of structural similarity, the common origin, similar metabolic pathways, similar physico-chemical properties, common environmental fate & eco-toxicologcial profile of the category members, it can be concluded that no toxicological effects on freshwater fish are expected for Fatty acids, C16-18 and C18-unsaturated, dimerized (CAS No 71808-39-4), “Crude dimer” up to the water solubility for the substance (< 0.41 mg/L, detection limit).