2-(3,3-dimethylcyclohex-1-enyl)-2,5,5-trimethyl-1,3-dioxane

Ecotoxicological Summary

Additional information

Aquatic toxicity:

Three acute experimental studies and two QSAR predictions are available to assess the aquatic toxicity of the registered substance.

For algae, the experimental study performed on Desmodesmus subspicatus was not considered reliable due to insufficient information provided on the methodology used. Therefore, QSAR prediction for this endpoint was performed using iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship (KREATIS, 2019). Toxic effect was predicted in acute conditions, with a 72h-ErC50 value calculated at 1.2 mg/L.

For aquatic invertebrates, the experimental study performed on Daphnia magna was considered reliable with restrictions due to the use of acetone as solvent in quantity 20 times higher than the acceptable quantity (2 mL/L instead of max. 0.1 mL/L) but 5 times lower than the EC50 of acetone. In this study, the 48h-EC50 value was determined at 2.2 mg/L based on analytically confirmed nominal concentrations. This result supports the more conservative QSAR prediction using iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship (KREATIS, 2019). Toxic effect was predicted in acute conditions, with a 48h-ErC50 value calculated at 1.5 mg/L. Due to the vulnerability of the experimental study, the QSAR prediction was considered as the key data.

For fish, the experimental study performed on Danio rerio was considered reliable with restrictions due to the use of acetone as solvent but in acceptable quantity (0.125 mL/L). The 96h-LC50 value was determined to be greater than the maximum tested concentration, measured at 5.4 mg/L (geometric mean measured concentrations).

Environmental fate and pathways:

Based on the key biodegradation study (OECD Guideline 301D, GLP), the registered substance is not readily biodegradable but ultimately (completely) biodegradable (45% biodegradation after 28 days and 72% biodegradation after 60 days). Therefore, the registered substance is not persistent in the environment. In addition, with a log Kow value determined experimentally at 4.37, the substance is considered to be bioaccumulative according to CLP (>4.0) but not bioaccumulative according to PBT criteria (<4.5).

Conclusion on classification

No harmonised classification is available.

Data available:

- Lowest E(L)C50 value comprised between 1 and 10 mg/L (M-factor not applicable);

- Not rapidly degradable;

- log Kow > 4.

Classification according to the Annex VI of the Regulation (EC) No 1272/2008 (CLP): The registered substance is classified as Aquatic Chronic 2 for the environment.