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Environmental fate & pathways

Phototransformation in water

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Description of key information

1) Supporting: phototransformation study in water with one of the main constituents of DAPD (R-898; CAS 15017-02-4), K1, GLP, according to USEPA guideline

Key value for chemical safety assessment

Half-life in water:
1.78 d

Additional information

There is one study available evaluating photodegradation potential of DAPD (McLaughlin, 2004). This test was performed on N,N'-bis(2 -methylphenyl)benzene-1,4 -diamine (R-898; 20 to 30% of DAPD) as a surrogate for the entire test material. The substance was radiolabeled with 14C, making accurate quantification of the degradation kinetics possible with HPLC/beta counting. The substance was tested in two aqueous buffers (pH 6 and 8) at a concentration of 0.1 mg/L. Samples were exposed to xenon arc illumination with a radiation distribution which is similar to natural sunlight (photoperiod 12/12 light/dark). The experimental half-lives determined were 2.5 and 4.7 days at pH 6 and 8 respectively. These were then adjusted to compensate for actual external environments (natural sunshine) resulting in estimated half -lives of 0.94 and 1.78 days at pH 6 and 8 respectively. The value at pH 8 was used for further assessment.