Trifluoro(trifluoromethoxy)ethylene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING

In accordance with column 2 of REACH (REGULATION (EC) No 1907/2006) Annex VII the study on toxicity to aquatic algae and cynobacteria (required in section 9.1.2) does not need to be conducted because there are mitigating factors indicating that aquatic toxicity is unlikely to occur. Specifically, due to its physic-chemical properties, PMVE is not expected to distribute significantly to the aquatic compartment.

PMVE is in fact a gas with a limited water solubility (31.5 mg/L) resulting in a very high Henry’s Law Constant (HLC) (32000 Pa m3/mol). The HLC of PMVE indicates that, in a system water-atmosphere, PMVE would tend to rapidly leave the water phase distributing to the atmosphere, therefore, even in the hypothesis that PMVE is emitted to water, it would be expected to not remain in the aqueous compartment the time sufficient to exert toxic effects on aquatic organisms.
The reported water solubility value of 31.5 mg/L is itself not representative of the actual solubility of the substance is the natural environment as it was obtained with the application of laboratory conditions much more stringent (completely closed system with the atmosphere completely saturated of PMVE) than the environmental ones. The actual solubility of PMVE in natural waters under environmental conditions is expected to be significantly lower resulting in a even more limited potential of exposure for aquatic organisms.

The EQC Fugacity III Model confirms that the whole amount of PMVE eventually released to air would tend to remain into this compartment. The model was run assuming emission only to air as no significant emissions to water are expected and considering that in case of an accidental emissions, due to its gaseous nature, PMVE is expected to be released to air only.

In addition, because of its high tendency to leave the water phase, the feasibility of aquatic toxicity experimental studies is doubtful as they would be expected to be very challenging due to the technical difficulty of generating a stable concentration in water, making the possibility to finally obtain meaningful results unlikely.

Description of key information

In accordance with column 2 of REACH (REGULATION (EC) No 1907/2006) Annex VII the study on toxicity to aquatic algae and cynobacteria (required in section 9.1.2) does not need to be conducted because there are mitigating factors indicating that aquatic toxicity is unlikely to occur. Specifically, due to its physic-chemical properties, PMVE is not expected to distribute significantly to the aquatic compartment.

A quantitative estimate of the acute toxicity to aquatic invertebrates was tried to be performed by ECOSAR QSAR models but the prediction was found to be unreliable and therefore it is not considered for the risk assessment.