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Environmental fate & pathways

Phototransformation in air

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Tests on phototransformation in the air are not required to be performed under Annexes VII to X of REACH.

Photooxidation of tributyl phosphate was estimated using a computer model accepted by the US EPA. The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) is a programme for estimation of indirect photo-oxidation which estimates the rate constant for the atmospheric, gasphase reaction between photochemically produced hydroxyl radicals and organic chemicals and calculates atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone. Therefore, this model is reliable, adequate and relevant to tributyl phosphate. Thus, a half life of 1.628 hours is estimated for reaction of tributyl phosphate with hydroxyl radicals in the atmosphere at 25oC [AOPWIN Program, v.1.92].

Overall QSARs estimated half-life for degradation of tributyl phosphate in air based upon AOPWIN Model is 3.257 hours.

Based on the data on photochemical degradation of tributyl phosphate in the air, it is considered to rapidly degrade in the atmosphere via photooxidation process.