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Environmental fate & pathways

Phototransformation in air

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Description of key information

Conclusion (indirect photodegradation): DTDP has the potential to degrade rapidly by OH- attack.  However multimedia distribution modeling indicates DTDP is predicted to partition negligibly (0.1%) to the air compartment because it has a low vapor pressure (0.000000036 Pa) and a relatively short atmospheric oxidation half-life (4 hours). Therefore, this process is unlikely to contribute significantly to the loss of DTDP from the environment.

Key value for chemical safety assessment

Additional information

Indirect photochemical degradation of DTDP as mediated by OH- attack is estimated to have a half-life of 0.33 days or 4 hours based on a 12 -hour sunlight day, a rate of 3.27E-11 cm3/molecule*sec, and an average OH- concentration of 1.5E6 OH-/cm3 (USEPA, 2000). A 12-hour day half-life value normalizes degradation to a standard day light period during which hydroxyl radicals needed for photolysis are generated in the atmosphere.