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

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Introduction:

The registered substance is a reaction mass of three constituents. Two diastereomers with a cyclohexyl group (here called C6 diastereomers) and one structural isomer with a cycloheptyl group (here called C7 isomer). The C6 constituents represent ca. 78% of the substance, and the C7 constituent ca. 10%.

The environmental data available lead to the use of the constituent approach for the PBT assessment.

The registered substance disappears completely, as primarily biodegraded following STP treatment as demonstrated in a ready biodegradation test with analytical monitoring. Hence, the PBT assessment is performed in two parts, first, for the registered substance and then for the transformation product.

The transformation product is composed of the same ratios of isomers as the parent but in the alcohol form.

PBT Assessment:

The registered substance is not considered readily biodegradable. However, the key experimental biodegradation study, performed on the C6 isomers of the registered substance, demonstrates 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 is demonstrated (to form the C6 isomers of the transformation product at 79% and Propionic acid at ca. 20% but mineralised). The same primary biodegradation is observed for the C7 isomer of the registered substance, based on QSAR predictions (Catalogic 301C v.08.12).

To conclude on the persistence of the transformation product, a screening non-GLP ready biodegradation study (OECD 301F) was performed on the transformation product (C6 and C7 isomers) and only 0 to 4% biodegradation was observed after 28 and 60 days. This result is also confirmed based on QSAR prediction (Catalogic 301C v.08.12). Therefore, the transformation product of the registered substance can be considered as potentially persistent (potential P) or potentially very persistent (potential vP), in the absence of simulation studies.

The BCF values are much lower than 2000 L/kg for the registered substance and the transformation product, based on estimated and experimental/estimated BCFs, respectively. Therefore, the registered substance and it's transformation product are not considered bioaccumulable (non-B) or very bioaccumulable (non-vB).

The registered substance is not considered Toxic (non-T) based on the lowest NOEC value at 0.20 mg/L (aquatic invertebrates) and the absence of evidence of chronic toxicity.

The transformation product is not considered Toxic (non-T) based on the estimated acute and chronic toxicity. The estimated L(E)C50 values and chronic values are well greater than 0.1 and 0.01 mg/L, respectively. In addition, one experimental acute fish study is available on the C6 isomers of the transformation product (but considered not assignable due to lack of information). The experimental 96h-LC50 (Danio rerio) was 10.7 mg/L (far higher than 0.1 mg/L). All these data demonstrate that the transformation products of the registered substance is not Toxic (non-T).

In conclusion, the registered substance and it's transformation product should not be considered as PBT or vPvB substances.

Likely routes of exposure:

None