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Environmental fate & pathways

Phototransformation in air

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Description of key information

The atmospheric half-life of FC-72 is 2200 years.

Key value for chemical safety assessment

Additional information

The 4th Assessment Report of the Intergovernmental Panel on Climate Change lists an atmopheric lifetime (1/rate constant) of 3200 years for perfluorohexane. As this is the standard reference work for evaluation of this type of compound, the half-life was calculated directly from the lifetime. In the second key study, perfluorohexane showed no detectable degradation under mercury vapor lamp irradiation, contact with single oxygen atoms, or contact with hydroxyl radicals. This second key study demonstrates that indirect photolysis and direct photolysis in the lower atmosphere do not contribute to FC-72 degradation. The expected fate is therefore direct photolysis in the upper atmosphere.