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Environmental fate & pathways

Phototransformation in air

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Description of key information

The calculated half-lives for two representative structures of the substance by photodegradation in air were 0.21 and 0.33 days with Overall OH rate constants of 49.1678*10-12 and 76.8026*10-12 cm³/molecule-sec. The estimation rules applied for the substance appears appropriate. The predicted results for the substance can be considered reliable yielding a useful result for further assessment. (Currenta, 2017).

Key value for chemical safety assessment

Half-life in air:
0.326 d
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information

As no data on phototransfromation in air are available, the rate constant for the atmospheric gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals is estimated with the Atmospheric Oxidation Program (AOPWIN) of US Environmental Protection Agency. The rate constant is then used to calculate the atmospheric half-life. A 24-hour day and an OH radical conc. of 500,000 OH/cm³are assumed for calculation.As the substance is an UVCB two generic structures were used as representative of the substances for the calculation of the phototransformation in air and therefore two results were obtained: 2-[2-(2-hydroxypropoxy) ethoxy]ethyl 2-hydroxypropyl phthalate (Structure A) and 1-O-{2-[(2-hydroxypropoxy) carbonyl]benzoyl}-6-O-(2-hydroxypropyl) hexitol (Structure B). The higher value was chosen as a worst-case.