Phenethyl pivalate

Short-term toxicity to aquatic invertebrates

Description of key information

 A closely structurally-related compound, Phenethyl isovalerate , was found in a guideline and GLP study to have an EC50 (48 hr) of 6.2 mg/L. It was considered justifiable to use this measured data for Phenethyl isovalerate  to read-across to Pivarose on the basis that both substances are expected to have similar ecotoxicological properties as a result of structural similarity, the same expected aquatic toxicity mode of action and similar physicochemical properties. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.2 mg/L

Additional information

A valid study is available for the analogue substance, Phenylethyl Isovalerate. It is a GLP compliant study conducted in compliance with agreed protocols, with no deviations from the standard test. Important considerations for the use of read-across are:

1) There are close structural similarities between the two chemicals

2) Both substances are expected to act via the same mode of action for aquatic toxicity

3) There are no impurities that are expected to affect the ecotoxicological properties of the source and target substance

4) Both substances have similar physico-chemical properties relevant for fate and behaviour of the substance under aquatic toxicity test conditions (e.g. water solubility and log Kow)

5) The measured log Kow value for the target-substance, Phenethyl pivalate is 3.86 (OECD 117). The Kow for the source-substance, Phenethyl isovalerate has not been measured. The KOWWIN (v1.68) module of EPISuite (v4.11) with default phys-chem values only, predicts a log Kow of 3.97 and 3.93, respectively, for the source-substance and the target-substance and therefore the strength of aquatic toxicity for the two substances is expected to be similar.

6) Both chemicals have been tested for ready biodegradability and have demonstrated to both be readily biodegradable under screening method test conditions.

7) In the absence of directly comparable experimental data obtained with the source and target sub-stances for aquatic toxicity endpoints, i.e. no inter-substances studies performed on the same aquatic trophic level, QSAR modelling (ECOSAR (v1.11) has been employed to predict the comparative aquatic toxicity. The simulations have been predicted based on default input values in order to compare like-with-like. ECOSAR (v1.11) predicts the Phenethyl isovalerate (source-substance) to be slightly more toxic to all three aquatic trophic levels than Phenethyl pivalate. In both cases, the relevant predicted EC50 and LC50 values are all above 1 mg/L. Algae are predicted as being the most sensitive species, and, Daphnia least sensitive.

Based on the above, the read-across is considered adequate for the purpose of classification and labelling and/or risk assessment.