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Environmental fate & pathways

Phototransformation in water

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Description of key information

Under the experimental conditions, 4,4'-MDA exhibits an environmental direct photolysis half-life of 190 days.

Key value for chemical safety assessment

Additional information

A mean quantum yield of 0.006 was obtained from two photodegradation experiments. This value was used in two computer programs to provide so-called environmental half-lives for the direct photodegradation of 4,4'-MDA in water. The longest half-life of 190 days (December, 50th degree of latitude and no contribution from other mono- or bimolecular elimination processes) was obtained with the Frank and Klopffer program.

Considering the total water body it is likely that the real environmental half-life is at least one order of magnitude higher than that calculated. Therefore a half-life of 1900 days may be considered to be more appropriate.