Fatty acids, C18 unsaturated, ethyl & methyl esters

Toxicity to soil microorganisms

Additional information

The chemical safety assessment according to Annex I of Regulation (EC) No 1907/2006 indicates no need for further studies on terrestrial organisms. Thus in accordance with Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.4 further studies on the effects on terrestrial organisms do not have to be conducted. The substance is readily biodegradable and furthermore characterised by a low water solubility and high log Koc. Due to the expected environmental fate of the substance an exposure of terrestrial organisms is considered unlikely. Read-across data on the terrestrial toxicity of the analogue substance isopropyl myristate (CAS 110-27-0) to the earth worm Eisenia fetida determined no toxicity up to a test concentration of 20,000 mg/kg (LC50 (14 d) >20,000mg/kg) . Based on the available information toxicity of Fatty acids, C18 unsaturated, ethyl & methyl esters (EC 941-981-3) to terrestrial organisms is not expected.

This is supported by further evidence from literature data. This data showed that soil microorganism communities are well capable of degrading fatty acid esters (Hita et al., 1996 and Cecutti et al., 2002) and use them as energy source (Banchio & Gramajo, 1997). Hita et al. investigated the degradation of the model molecule tristearin which is a triglyceride containing of glycerin tri-esterified with stearic acid in three different soils for 4 weeks. The amount of stearic acid increased in considerable amounts during the experiment showing the hydrolytic activity of lipases breaking the ester bonds. The investigation of ester fractions moreover showed the generation of new alkanoic acids (methyl stearate, ethyl stearate and propyl stearate) which were not determined in the controls. Nevertheless the amounts were no longer present after 4 weeks, which leads to the assumption that degradation by soil microorganisms had occurred. The same was shown by Cecutti et al. One soil sample was chosen and incubated with methyl oleate (plant oil) for 120 d. Methyl oleate and its metabolites were completely degraded after 60 d. Streptomyces coelicolor, a common gram-positive soil bacterium uses fatty acids (C4-C18) as sole carbon end energy source indicating that fatty acids are not-toxic and can be used for catabolism (Banchio and Gramajo, 1997). The available literature data shows that soil microorganisms are capable to break-up ester bonds and degrade fatty acids in significant amounts. Moreover, the data indicated the non-toxic properties of fatty acids since they can be used as energy source.

Taking all the available information into account in a Weight of Evidence approach in accordance with Annex XI, 1.2, effects on soil microorganisms are thus not expected to be of concern, and consequently, no further testing is required.

 

A detailed reference list can be found in the CSR and in section 13 of the dossier.