Fatty acids, C18 unsaturated, trimers, hydrogenated

Short-term toxicity to fish

Description of key information

LC50 (96h) > 350 mg/L (OECD 203, Brachydanio rerio); read-across

Additional information

Since no studies investigating the short-term toxicity to fish of Fatty acids, C18 unsaturated, trimers, hydrogenated are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5, a read across to the structurally similar substances Fatty acids, C18-unsatd., dimers (CAS No. 61788-89-4), Isooctadecanoic acid (CAS No. 30399-84-9) and Fatty acids, C16-18 and C18-unsatd., branched and linear (CAS No. 68955-98-6) was conducted. Further justification is given within the endpoint summary 6.1 and within the analogue justification in Section 13.

The key study conducted with Fatty acids, C18-unsatd., dimers (CAS No. 61788-89-4) was performed, according to OECD Guideline 203, in a static system, using Brachydanio rerio as test organism (Benijts, 2002). The fish were exposed to the nominal test concentrations of 0.02, 0.04, 0.07, 0.10, 0.15, 0.25, 0.30 and 0.35 g/L for 96 hours. As no mortality occurred during the study, the LC50 was determined to be > 350 mg/L.

The key study conducted with Fatty acids, C16-18 and C18-unsatd., branched and linear (CAS No. 68955-98-6) was performed as a limit test according to OECD Guideline 203, in a semi-static system, using Leuciscus idus as test organism (Sewell, 1994). The fish were exposed to the nominal test concentration of 1000 mg/L, prepared as water accommodated fractions (WAF), for 96 hours. As no mortality occurred during the study, the LL50 was determined to be > 1000 mg/L.

The supporting study conducted with Isooctadecanoic acid (CAS No. 30399-84-9) was performed, according to the guideline “Bewertung wassergefährdender Stoffe, Bestimmung der akuten Fischtoxozität, Ad-hoc Arbeitsgruppe 1, LTwS, Nr. 10, Sept 1979” with some modifications (not specified in the report) (Bogers, 1988). The test organism Cyprinus carpio was exposed to the test substance in a static system, at nominal concentrations of 1, 1.8, 3.2, 5.6, 10, 18, 32, 56 and 100 mg/L. Tween 80 was used as solubiliser in order to obtain a homogenous dispersion of the test substance in water. Furthermore the test duration was only 48 instead of 96 hours. An LC50 of 13.4 mg/L and a NOEC of 5.6 mg/L were determined after 48 hours. One might expect that the LC50 after 96 hours will be lower, however, as the water solubility of the test substance is only 0.24 mg/L, it can be assumed that the LC50 (96 h) will be above the water solubility limit of isooctadecanoic acid, without solubiliser.

Thus, based on the above mentioned results, and due to the structural and profile similarities of the substances, as are explained with in the overall endpoint summary 6.1, it can be concluded that no short-term toxicological effects on fish are expected up to the limit of water solubility (0.001 mg/L) for Fatty acids, C18 unsaturated, trimers, hydrogenated.