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Environmental fate & pathways

Biodegradation in soil

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No experimental data on CTFE biodegradation in soil 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 indicate the difficulty to properly test CTFE and provide meaningful results of its biodegradation  in aqueous systems as well as in soil. 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 terrestrial organisms are expected because of no partitioning of CTFE into soil. 

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In accordance with section 2 of REACH (Regulation (EC) No 1907/2006) Annex IX, the biodegradation in soil study (required in section 9.2.1.3) is not proposed by the registrant because direct or indirect exposure of soil is unlikely to occur as the substance 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) a vapour pressure of 612 kPa at 25°C (ISCS No. 0685, NIOSH) . CTFE is also characterized by a moderate water solubility of 380 mg/L. The value of water solubility of 380 mg/l was experimentally determined in a completely sealed system with an atmosphere saturated with CTFE. 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.

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 soil.

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 molecule is characterized by carbon-fluorine bonds, which are the strongest bond in organic chemistry (O'Hagan, 2008). Nevertheless no adverse effects on soil organisms are expected because of no partitioning of CTFE into soil.