2-(1-(3',3'-dimethyl-1'-cyclohexyl)ethoxy)-2-methyl propyl propanoate

Endpoint summary

Description of key information

The registered substance was found to undergo hydrolysis at pH 9 only (of the three pHs tested, 4, 7 and 9), with a half-life (at 25°C) of 224 hours (method similar to OECD Guideline 111).

The registered substance is not readily biodegradable. However, the key biodegradation study (similar to OECD Guideline 301 C) performed on the C6 isomers of the registered substance with analytical support, demonstrated that this substance disappears in a ready test and therefore is not considered persistent (non-P). Indeed, total primary biodegradation of the C6 isomers of the registered substance was demonstrated, to form a transformation product (C6 isomers) at 79% and initially Propionic acid at ca. 20%, which was then mineralised. The primary biodegradation was also observed for the C7 isomer of the registered substance, based on QSAR prediction (Catalogic 301C v.08.12).

To conclude on the persistence of the transformation product, a screening non-GLP readily biodegradation study (OECD 301F) was performed on the transformation product (C6 and C7 isomers) and in this study only 0% to 4% biodegradation was observed after 28 days and then prolongation to 60 days, respectively. Therefore, the transformation product can be considered as potentially persistent (potential P) or very persistent (potential vP), in the absence of simulation testing.

The bioconcentration factor (BCF) of the registered substance was estimated with a QSAR model (BCFBAF model v3.01 from EPI Suite v4.1, using experimental log Kow value at 4.68) at 382 L/kg wet-wt and 435 L/kg wet-wt, for C6 and C7 isomers, respectively. This can be expected as the substance is an ester which will be rapidly metabolised upon entry into organisms. Therefore, the registered substance (parent compound) should not be considered Bioaccumulable for aquatic organisms. For the major transformation product (a shorter chain alcohol), an experimental study was performed in water at two sub-lethal concentrations of the C6 isomers of the transformation product for a period of 28 days. In both concentrations extremely low BCFs were determined with a mean of 15 at the highest water concentration and <35 [LOD] at the lowest water concentration of approximately 0.007 mg/L. In addition, the BCF values of the C6 and C7 isomers of the transformation product were determined with the same QSAR model as above, at 374 L/kg wet-wt and 490 L/kg wet-wt, for C6 and C7 isomers, respectively. The QSAR model can therefore be considered as slightly conservative in its results compared to experimental values. These data conclusively demonstrated that the breakdown product of the registered substance will not bioaccumulate to any significant degree in aquatic organisms. The second breakdown product, propionic acid is not considered to be of regulatory concern (non-toxic short chain molecule that will undergo rapid mineralisation).

A summary of the environmental fate of the registered substance is provided in the attached document.

Finally, the adsorption coefficient (log Koc) of the registered substance was determined to be 4.3 (OECD Guideline 121 and EU Method C.19). This result indicates that the substance is immobile in soils (according to McCall et al., 1980*).

*McCall PJ,Swann RL,Laskowski DA,Unger SM,Vrona SA,Dishburger HJ

Estimation of chemical mobility in soil from liquid chromatographic retention times.

Bull Environ Contam Toxicol.1980 Feb;24(2):190-5.