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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

The sodium salt has a relatively low level of biodegradation in seawater, based on a degradation rate of 23% (relative to COD) and 18% (relative to ThOD) in 56d 

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Additional information

This conclusion is based upon a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

This substance is a member of a category of various ionised forms of the acid ATMP (CAS 6419-19-8). The main assumption is that ammonium is not significant in respect of all the properties under consideration. In dilute aqueous conditions of defined pH a phosphonate ion will behave no differently to the parent acid, at identical concentration of the particular speciated form present and will be fully dissociated. Hence some properties (measured or expressed in aqueous media, e.g. ecotoxicity) for a salt can be directly read across (with suitable mass correction) to the parent acid and vice versa. Exposure of the soil would only be expected to occur via some form of aqueous processing (e.g. from spreading of WWTP sewage sludge). Thus it is acceptable to additionally read across between the parent acid and salts for the soil compartment. In the present context the effect of the counter-ion (potassium) will not be significant. In biological systems and the environment, polyvalent metal ions will be present, and the phosphonate ions show very strong affinity to them.

The ammonium ion upon release into the environment would enter natural nitrogen cycles in air, soil and water.