Glycerides, mixed coco, decanoyl and octanoyl

Toxicity to soil macroorganisms except arthropods

Description of key information

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

Additional information

No experimental data evaluating the toxicity of Glycerides, mixed coco, decanoyl and octanoyl (CAS No. 68606-18-8) to soil macroorganisms are available. Therefore, toxicity data from analogue category members, propane-1,2,3-triyl trisheptanoate (CAS No. 620-67-7) and Glycerides,C14-18 and C16-18 unsaturated, 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. Glycerides, mixed coco, decanoyl and octanoyl is mainly a triglyceride formed by the combination of fatty acids of different C-chain lengths (C6 to C18 unsaturated) and glycerol. Propane-1,2,3-triyl trisheptanoate (CAS No. 620-67-7) is also a triglyceride with fatty acid chain length of C7. For Glycerides,C14-18 and C16-18 unsaturated, mono-, di- and tri- (CAS No. 91052-28-7) the triester content is lower than for the other two substances (up to 15%), with a predominant monoester content. The lower degree of esterification might have an effect in the bioavailability to terrestrial organisms, due to a reduced size of the molecules, the potential to cross biological membranes is expected to increase. Therefore, Glycerides,C14-18 and C16-18 unsaturated, mono-, di- and tri- can be regarded as a worst-case read-across substance.The log Pow values of these three substances are > 4, indicating a high adsorption potential to soil particles. The water solubilities (< 0.05 mg/L) and aquatic toxicity profiles are also comparable (see Aquatic toxicity section). The two read-across substances cover the whole fatty acid C-chain range present in Glycerides, mixed coco, decanoyl and octanoyl. Therefore, they are considered to give a reliable indication of the toxicity of this substance to soil macroorganisms, and the read-across is justified.

Both tests were performed according to OECD 207, under GLP conditions (Muckle, 2012; Moser, 2012). In both studies, the test organism Eisenia fetida was exposed to the test substance for 14 days at a concentration of 1000 mg/kg dw (limit test). No effects on survival or biomass were reported during the exposure period, leading to NOEC values (14 d) ≥ 1000 mg/kg dw.

 

Glycerides, mixed coco, decanoyl and octanoyl 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 category members (in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5) and the characteristics of Glycerides, mixed coco, decanoyl and octanoyl (CAS No. 68606-18-8), this substance is not expected to show toxicity to soil macroorganisms.