Soybean oil, epoxidized, ether with ethylene glycol

Endpoint summary

Description of key information

A theoretical assessment of toxicokinetic behaviour is presented

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Soybean oil, epoxidised, ether with ethylene glycol is a UVCB substance. Based on its structure and physicochemical properties, it is considered related to epoxidised soybean oil which is also derived by epoxidation of soya bean oil.

No experimental data are available for either substance. OECD QSAR Toolbox (v3.1) predicts no oral bioavailability (Lipinski’s Rules; OASIS) for both substances, consistent with the high molecular weight and large molecular weight.  A lack of dermal absorption is also predicted. Inhalation exposure is not relevant based on the physicochemical properties of the substances.

In its evaluation of epoxidised oils and derivatives, the OECD SIDS conclusion indicates that epoxidised fatty acid esters can be assumed to follow similar metabolic pathways to those of other vegetable oils since the primary constituents of the metabolic products are similar.

Based on structural, functional and metabolic similarities, primary epoxidised oils can be considered within one functional category. While the intact substances are not predicted to be absorbed, the 2006 OECD SIDS for Epoxidised Oils and Derivatives notes that epoxidised soybean oil is likely to be subject to degradation by intestinal lipase enzymes. This will therefore result in the liberation of epoxidised fatty acids and glycerol. Similar enzymic activity with the consequent liberation of fatty acid ethylene glycol esters is predicted for the submission substance. I t is therefore concluded that, although absorption of the intact substances is unlikely, oral administration to experimental animals may result in systemic exposure to the products of enzymic digestion.  One potential difference between the substances is the possible liberation of small amounts of ethylene glycol from resulting from hydrolysis of the ether group present in the submission substance.  However this is not considered likely to significantly influence the toxicity of the reference substance and, in any case, is only relevant to the oral route of exposure.  Following metabolism, the alcohol metabolites are a minor constituent of metabolism and are not produced in sufficient quantity to influence the toxicity profile.

Absorption

The intact substance is not predicted to be absorbed by any route of exposure; however the action of lipase enzymes is likely to result in the liberation of epoxidised fatty acids (linked to ethylene glycol) and glycerol, which are likely to be systemically absorbed.

Distribution

Consideration of distribution following dermal and inhalation exposure is not relevant in the absence of predicted absorption. Following oral exposure, the products of enzymic hydrolysis will be distributed systemically, at least as far as the liver prior to further metabolism.

Metabolism

The hydrolysis product glycerol is likely to be incorporated into normal fat metabolism in the liver or adipose tissues. The ether linkage may be subject to enzymic hydrolysis, resulting in the liberation of ethylene glycol and esterified fatty acids. The metabolism of ethylene glycol is well chcracterised. Liberated esterified fatty acids may be incorporated into normal metabolism.

Excretion

Bearing in mind the likely metabolism of the substance, it is likely that the majority of its hydrolysis or metabolic products will be incorporated into normal metabolism and not excreted. The metabolites of ethylene glycol are likely to be subject to urinary excretion.

OECD SIDS (2006), Epoxidized Oils and Derivatives CAS No: 61789-01-3: Fatty acids, tall-oil, epoxidized, 2-ethylhexyl esters (ETP) 68609-92-7: 9-Octadecanoic acid (Z)-, epoxidized, ester W/propylene glycol (EODA) 8013-07-8: Epoxidized soybean oil (ESBO) 8016-11-3: Epoxidized linseed oil (ELSO or ELO), UNEP Publications