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Environmental fate & pathways

Biodegradation in soil

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Description of key information

A reliable study, measured with the parent acid (DTPMP, CAS 15827 -60 -8), indicates a soil biodegradation rate of 64% over 148d in river bank soil and 62.6% in silt loam soil was determined (Saeger 1978). 

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Additional information

This substance is a member of a category of various ionised forms of the acid DTPMP (CAS 15827 -60 -8). The main assumption is that sodium is not significant in respect of all the properties under consideration. In dilute aqueous conditions of defined pH a salt 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 (sodium) 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.