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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

No experimental data on CTFE biodegradation in water and sediment are available. In fact, on the grounds of the physico-chemical properties and environmental fate assessments of the substance, no release to the aquatic environment is expected. Moreover the substance profile itself indicates the difficulty to properly test CTFE and provide meaningful results of its biodegradation  in aqueous systems as well as in sediment. Nevertheless, in order to evaluate  the biodegradation  hazard profile of CTFE, the BIOWIN v. 4.10 model has been applied. The prediction obtained from the model  suggests that CTFE is not ready biodegradable. However, no adverse effects on aquatic organisms are expected because of no partitioning
of CTFE into water.

Key value for chemical safety assessment

Additional information

The biodegradation studies in surface water and in sediment (required in sections 9.2.1.2 and 9.2.1.4, respectively) of REACH (Regulation (EC) No 1907/2006) Annex IX, are not proposed by the registrant as CTFE is a gas at ambient condition with a limited water solubility and an high tendency to rapidly volatilise from water to the air.

The value of water solubility of 380 mg/l was experimentally determined in a completely sealed system with an atmosphere saturated with CTFEE. Althoughthe value of 380 mg/l itself reveals a moderate 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.

On the basis of its physico-chemical properties, CTFE is expected to primarily and rapidly partition to the atmosphere. This tendency is also confirmed by the results from the EQC Fugacity III Model (Version 2.02, The Canadian Centre for Environmental Modelling and Chemistry, May 2003) which makes absolutely remote the possibility of a CTFE partitioning into water and sediments.

Moreover the substance profile itself indicates the difficulty to properly test CTFE and provide meaningful results of its biodegradation in aqueous systems as well as in sediment.

Nevertheless an assessment based on Quantitative Structure Activity Relationships (QSARs) has been however applied as far as biodegradation is concerned.

The prediction of the BIOWIN model (BIOWIN v.4.10, EPI Suite v.4.0) suggests that CTFE is not ready biodegradable. In fact the CTFE molecule is characterized by carbon-fluorine bonds, which are the strongest bonds in organic chemistry (O'Hagan, 2008). Nevertheless no adverse effects

on water and sediment organism are expected because of no partitioning of CTFE into water.