(E)-4-Ethoxy-1,1,1-trifluoro-3-buten-2-one (stabilized with BHT)

Ecotoxicological Summary

Conclusion on classification

Environmental fate information: With 49% biodegradation after 28 days (OECD 301D), ETFBO is not readily biodegradable. As a result, ready biodegradability cannot be used as an evidence of rapid degradation for a classification purpose. An hydrolysis study (OECD 111) is available and demonstrated a half-life time at 7°C shorter than 30 minutes at pH = 4, 7 and 9; therefore, the half-life time at 20°C for pH = 4, 7 and 9 was also reported as shorter than 30 min. This quick hydrolysis was supported by the water solubility study. Hydrolysis can be used as an evidence of rapid degradation only when the longest half-life time determined within the pH range 4-9 is shorter than 16 days and it can be satisfactorily demonstrated that the hydrolysis products formed do not fulfil the criteria for classification as hazardous for the aquatic environment (ECHA Guidance on the Application of the CLP Criteria, v.5.0, July 2017, Section II.2.3.8). The results obtained during the ecotoxicity study on algae are not in adequation with this last criterion because adverse effects were observed while algae were exposed to the hydrolysis products (indeed, the study period of 72 hours allowed hydrolysis to occur). As a whole, this pool of information leads to conclude that ETFBO has to be regarded as not rapidly degradable from a classification standpoint.

 

Ecotoxicity information: Acute ecotoxicity data are available on fish (OECD 203) and daphnids (OECD 202). In both species, no adverse effects were observed in organisms exposed to the highest concentration of 100 mg/L and the L/EC50 were set superior to this concentration. It can be thus concluded that initial exposure to ETFBO and then to its hydrolysis product did not cause any adverse acute effect on fish and aquatic invertebrates under the experimental conditions tested. An algal growth inhibition study (OECD 201) is also available. Initial exposure to ETFBO and then to its hydrolysis product triggered a 72h-EC50 of 20 mg/L in Selenastrum capricornutum based on growth rate; leading to apply the conclusion as harmful to aquatic plants. No NOEC value was available for growth rate. In the absence of details on the statistical results, it was difficult to determine the highest concentration without significant effect on growth rate. Considering growth rate inhibition percentages, the fact that the other available ecotoxicological value (i.e. EC50) is significantly higher when based on growth rate than on biomass and the fact that the available 72h-NOEC value based on biomass is equal to 1 mg/L, it does not seem aberrant to conclude that the NOEC value based on growth rate should be superior to 1 mg/L. As a matter of precaution and in the absence of a precise numerical NOEC value based on growth rate, it was nevertheless decided to apply the conclusion as harmful to aquatic plants with long-lasting effects based on the acute EC50 value (growth rate) together with environmental fate information (i.e. not rapidly degradable).

 

Conclusion on environmental classification: According to the pool of evidence above described, ETFBO has to be considered harmful to aquatic life with long-lasting effects and has to be classified in category 3 for chronic aquatic hazard under CLP. The same classification applies under UN-GHS and a classification in category 3 for acute aquatic hazard has also to be added under this system.