Trifluoro(trifluoromethoxy)ethylene

Endpoint summary

Additional information

Aquatic toxicity studies are not proposed by the registrant because direct or indirect exposure of the aquatic compartment is unlikely to occur as the substance is a volatile gas with a boiling point of -26 °C (Yaws, Carl L. ©2010 Knovel) which primarily and rapidly partition to the atmosphere where it remains.

The above considerations have been deducted on the following basis:

The Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance, Appendix R.7.1-4 indicates that substances with a Henry's Law constant of around 1 hPa m3/mole will rapidly volatilise from water. On the basis of its boiling point of -26 °C (Yaws, Carl L. ©2010 Knovel) that entails a not measurable vapour pressure (i. e. 10^5 Pa) and a limited solubility in water PMVE is expected to primarily and rapidly partition to the atmosphere. The value of water solubility of 31.5 mg/l was experimental determined in a completely sealed system with an atmosphere saturated with PMVE. Althoughthe value of 31.5 mg/l itself reveals a slight water solubility, it represents an overestimation of the actual water solubility of PMVE in the natural system since the experimental conditions did not represent the natural conditions.

The EQC Fugacity III Model confirms that the whole amount of PMVE released to air remains in this compartment. The model was run assuming emission only to air. In case of an accidental emission, PMVE is only released to air, because PMVE is a volatile gas at ambient conditions with a boiling point of -26 °C. Therefore, PMVE would not be expected to partition into water.

The specific physico-chemical properties of the substance, cited above, indicates the difficulty to properly test PMVE and provide meaningful results of its aquatic toxicity. For this reason any experimental aquatic toxicity data are available. However, in order to evaluate the aquatic hazard profile of PMVE despite the fact, that it is expected to rapidly partition to the atmospheric compartment, the ECOSAR model may be applied.

All ECOSAR results are reported in the specific endpoints of this section however, the ECOSAR model cannot be considered reliable for the ECOSAR class of chemicals which PMVE is assigned to, since the results are based on a very limited dataset of substances which identity is often not further specified or, as for the most sensitive and critical group of the food chain the fish, the coefficient of determination R^2 is low.