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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

(2E)-1,1,1,4,4,4-hexafluoro-2-butene (the registered substance) was found to be not readily and not inherently biodegradable in guideline aquatic biodegradation screening studies. Based on these results, the registered substance is considered to fulfill the P/vP criterion. Nonetheless, the registered substance is a gas at room temperature and is expected to partition primarily into the atmosphere upon release into the environment. In the atmosphere, breakdown through reaction with OH radicals will lead to CF2O and CF3CHO as breakdown products. These will further degrade through reaction with radicals and/or photolytic cleavage to yield HF and CO2. Breakdown/transformation of CF3CHO can also lead to some formation of trifluoroacetic acid (TFA), with a molar yield of TFA that is expected not to exceed 4%. Given the natural background concentrations of TFA, the registered substance is considered to be a negligible source of TFA.

Based on an experimental log Kow of < 4.5 and an estimated log Koa << 5, it is concluded that the registered substance does not fulfil the B or vB criterion.

The lowest long term environmental effect concentration for the registered substance was obtained in an early life stage test (FELS) with the fish Gobiocypris rarus that resulted in a 32-day NOEC of 0.131mg/L (measured concentration). This is more than 1 order of magnitude higher than the cut-off value of 0.01 mg/L for the T criterion. The substance is furthermore not classified for carcinogenicity, mutagenicity, reproductive toxicity, or specific target organ toxicity. Based on this it is concluded that the substance does not fulfil the T criterion.

Based on the assessment described in the subsections above the submission substance is not a PBT / vPvB substance.