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Environmental fate & pathways

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Additional information

Sodium 2,4-dichlorophenoxyacetate is a non-volatile substance (calculated Henry’s Law Constant = 9.37 x 10-4Pa m3/mol), expected degrade in air with a half-life of 106.97 hours. This substance dissociates in the water phase into 2,4-dichlorophenoxyacetic acid, which is hydrolytically stable but susceptible of photodegradation in water (half-life due to indirect photolysis 23.1 up to 541 days due to direct photolysis). As demonstrated in a test according to OECD 301D sodium 2,4-dichlorophenoxyacetate is not readily biodegradable.

Once released into the environment it will be mainly distributed into the aquatic environment (100%, Mckay Level I calculation). The dissociation product, 2,4-dichlorophenoxyacetic acid is considered to be easily eliminated from water as indicated by a biodegradation value of 99% after 28 days in a Zahn-Wellens test and the short dissipation half-life in water/sediment systems of 29 days. Furthermore, this substance shows no adsorption potential to soil and sediment particles (Koc =56). Therefore, persistence in the environment is not expected. Bioaccumulation of sodium 2,4-dichlorophenoxyacetate in biota is unlikely in view of its low log Kow value (-1.19).