Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated

Endpoint summary

Additional information

In accordance with Regulation (EC) No 1907/2006 (REACH) Annex IX 9.3.2 Column 2, a bioaccumulation study does not need to be conducted, since Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) has a low potential for bioaccumulation and/or a low potential to cross biological membranes.

As Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) is poorly soluble in water (< 0.1 mg/L), only low concentrations in the aquatic environment and thus low concentrations in aquatic organisms can be expected at all. The U.S. EPA HPV report (2009) on the Fatty Acid Dimers and Trimer Category also judged an expected low bioaccumulation potential based on the negligible solubility and the anionic nature (low absorption potential) of the substances.

Due to the potential of Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) to adsorb, one may assume that the uptake may occur through the ingestion of soil or sediment. However, uptake is expected to be low based on the fact that the constituents of the substance are relatively large molecules with high molecular weights (ca. 536 g/mol). Thus, according to Lipinski’s rule of five, they have a low potential to cross biological membranes (Lipinski, 2001).

From the toxicokinetic behaviour of mono- and oligomeric fatty acids in mammals it can be assumed that the absorption ofFatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) is low. Very low absorption is reported for dimeric and trimeric fatty acids via the gastro intestinal tract and thus, most of the ingested fatty acids will be excreted with the faeces (≥ 80% for dimeric acid methyl esters (Hsieh and Perkins, 1976; Paschke et al. 1964)). In case of absorption fatty acids will undergo rapid metabolisation and excretion (either in the expired CO2 or as hydroxylated or conjugated metabolite in the urine in the case of cyclic fatty acids) as they feed into physiological pathways like the citric acid cycle, sugar synthesis, and lipid synthesis.

Fatty acids are naturally stored in the form of triacylglycerols primarily within fat tissue until they are used for energy production. It is therefore concluded that there will be no risk to organisms from bioconcentration/biomagnification of fatty acids within the food chain.

QSAR calculations performed for the main constituent using the regression based method yielded a BCF value of 3.16. The Arnot-Gobas method, including biotransformation, resulted in an even lower BCF value (0.893) and a BAF value of 3.29. The QSAR estimations may not be fully reliable as the log Kow range of the constituents is not covered by the training set of these models. However, they do support the assumption of low bioaccumulation potential.

Finally, as Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) has a low water solubility (< 0.1 mg/L), only a very low substance concentration in water can be expected and consequently, exposure to the aquatic environment would be extremely low, if at all. This would automatically reduce, if not eliminate, the uptake of the chemical through the aquatic environment. Hence, Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) does not pose a risk to organisms with regard to bioaccumulation/biomagnification.

References:

Hsieh, A. and Perkins, E.G. (1976). Nutrition and Metabolic Studies of Methyl Ester of Dimer Fatty Acids in the Rat. Lipids, 11(10):763-768.

Lipinski et al. (2001) Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings, Adv. Drug Del. Rev., 2001, 46, 3-26.

Paschke, R.F. et al. (1964). Dimer acid structures. The dehydro-dimer from methyl oleate and Di-t-butyl peroxide. Journal of the American Oil Chemists' Society 41(1):56-60.

U.S.Environmental Protection Agency (2009). Risk-Based Prioritization Document. Initial Risk-Based Prioritization of High Production Volume (HPV) Chemicals – Fatty Acid Dimers and Trimer Category. pp 1-19. Report date: April 2009.