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Toxicity to soil macroorganisms except arthropods

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Description of key information

NOEC (14 d) ≥ 1000 mg/kg dw for Eisenia fetida (OECD 207)

Key value for chemical safety assessment

Additional information

No experimental data evaluating the toxicity of isooctadecanoic acid, mono- and diester with glycerol (CAS No. 97358-80-0) to soil macroorganisms are available. Therefore, toxicity data from a structurally related category member (Glycerides, C14-18 and C16-18 unsatd. mono-, di- and tri- (CAS No. 91052-28-7) are used as read-across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Both are UVCB substances, formed from the esterification of long-chain fatty acids (C14-18 and C16-18 unsaturated and C18 iso for CAS No. 91052-28-7 and CAS No. 97358-80-0, respectively) and glycerol. The log Kow values of these substances (> 4 for both) indicate a high adsorption potential to soil particles. Based on their structural similarity and comparable physico-chemical properties, it is justified to use the available read-across data to cover this endpoint.

 

The toxicity of Glycerides, C14-18 and C16-18 unsaturated, mono-, di- and tri- (CAS No. 91052-28-7) to earthworms was evaluated by Moser (2012). Eisenia fetida was exposed to the test substance for 14 days at a concentration of 1000 mg/kg dw (limit test). Due to the poor solubility of the substance in water, test solutions were prepared using a solvent. No effects on survival or biomass during the exposure period were reported, leading to a NOEC (14 d) ≥ 1000 mg/kg dw.

 

Isooctadecanoic acid, mono- and diester with glycerol is readily biodegradable. Therefore, rapid and ultimate degradation in the environment, including soil, can be expected. Chronic exposure of terrestrial organisms is thus very unlikely. Furthermore, this substance shows only low toxicity, if at all, to aquatic organisms. Due to the metabolization via enzymatic hydrolysis of the Glycerides category members, a relevant uptake and bioaccumulation in biota is not expected. Enzymatic breakdown will initially lead to the free fatty acid and glycerol. Glycerides are naturally stored by organisms as long-term energy reserves. Especially in periods in which the energy demand is high (reproduction, migration, etc.), glycerides are mobilized from the storage sites as source of fatty acids. Fatty acid catabolism is the most important energy source in many species, resulting in the release of acetyl CoA and NADH (throughβ-oxidation) and eventually, via the tricarboxylic cycle, the production of metabolic energy in the form of ATP. Please refer to IUCLID Section 5.3.1 for a detailed overview on bioaccumulation of the Glycerides category members.

Based on the results obtained for the structurally related analogue (in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5) and the characteristics of isooctadecanoic acid, mono- and diester with glycerol (CAS No. 97358-80-0), this substance is not expected to show toxicity to soil macroorganisms.