Chlorotrifluoroethylene

Short-term toxicity to aquatic invertebrates

Description of key information

In accordance with column 2 of REACH (REGULATION (EC) No 1907/2006) Annex VII the study on short term toxicity to aquatic invertebrates (required in section 9.1.1) does not need to be conducted as there are mitigating factors indicating that aquatic toxicity is unlikely to occur:
1. CTFE is expected to rapidly partition to atmosphere.
2. CTFE is not expected to partition to water. 
The explanations supporting the above mitigating factors are the following:
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 rapidly volatilise from water. On the basis of a Henry’s Law constant of 31,500 Pa m3/mol (HENRYWIN v3.20, EPISUITE v1.00), a vapour pressure of 612 kPa at 25°C  (ISCS No. 0685, NIOSH) and a moderate water solubility, CTFE isexpected to primarily and rapidly partition to the atmosphere.
The value of water solubility of 380 mg/l was experimentally determined in a completely sealed system with an atmosphere saturated with CTFE. Although the value of 380 mg/l itself reveals a slight water solubility, it represents an overestimation of the actual water solubility of CTFE in the natural system since the experimental conditions did not represent the natural conditions.
The EQC Fugacity III Model (Version 2.02, The Canadian Centre for Environmental Modelling and Chemistry, May 2003) confirms that all the CTFE released to atmosphere remains in this compartment. The model was run assuming emission only to air. In case of an accidental emission, CTFE is only released to air, because CTFE is a volatile gas at ambient conditions with a boiling point in the range of -26.2°C (The Beilstein database. Reference: Miller - 1951 ) to -26.8°C (The Beilstein database. Reference: Henne - 1948). Therefore, CTFE would not be expected to partition into water. 

Additional information

CTFE is a volatile gas at ambient conditions with a boiling point in the range of -26.2°C (The Beilstein database. Reference: Miller - 1951 ) to -26.8°C (The Beilstein database. Reference: Henne - 1948), and a moderate water solubility. limited water solubility. The value of water solubility of 380 mg/l was experimentally determined in a completely sealed system with an atmosphere saturated with CTFE. Although the value of 380 mg/l itself reveals a slight water solubility, it represents an overestimation of the actual water solubility of CTFE in the natural system since the experimental conditions did not represent the natural conditions.

The Henry’s Law constant of CTFE was calculated to be 31.500 Pa m3/mol (HENRYWIN v3.20, EPI Suite v4.0), suggesting that the substance is expected to rapidly volatilise from water to the air in fact 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 the properties of CTFE it is expected that the substance primarily and rapidly partition to the atmosphere.

Hence, due to the gaseous nature of the substance and its partition to the atmosphere, as well as the consequent difficulty to appropriately test CTFE and provide meaningful results, no experimental aquatic toxicity data are reported. However, in order to evaluate theaquatic hazard profile of CTFE despite the fact that it is expected to rapidly partition to the atmospheric compartment, the results of the ECOSAR model ( v.1.00, EPI Suite v 4.0) may be applied.

The ECOSAR estimation for acute toxicity for daphnia is: 48h LC50 = 219.758 mg/L, however due to the limited dataset of substances for the ECOSAR class of chemicals which CTFE is assigned to, the result is not considered reliable.