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Environmental fate & pathways

Phototransformation in air

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Description of key information

Phototransformation in air is no requirement under REACH.

Key value for chemical safety assessment

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

Additional information

Generally, both HEDTA and its surrogate (EDTA) are used in aqueous solutions. For both substances, there is expected to be no emission into the atmosphere when the very low vapour pressure is considered. Emission to the atmosphere of EDTA (and, by analogy, HEDTA) could appear in dust form during production [EU Risk Assessment, 2004].

Based on a calculation according to AOPWIN v1.92, both HEDTA and its surrogate EDTA is expected to be indirectly photodegraded by reaction with hydroxyl radicals in the atmosphere with a half-life (t1/2) of approximetaly 2 hours taking into account a 24-h day and a mean OH radical concentration of 0.5E06 radicals per cm³.