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Sediment toxicity

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Description of key information

A 10-day LC50 value of >2,910 mg active acid/kg dw has been determined for the effects of DTPMPxNa on mortality of the marine sediment-dwelling invertebrate Corophium sp (read-across, reliability 2, TNO 1997).

Key value for chemical safety assessment

Additional information

No data are available with the registered substance. However data are avaiable with the closely related substance DTPMPxNa. A 10-day LC50 value of >2,910 mg active acid/kg dw has been determined for the effects of DTPMPxNa on mortality of the marine sediment-dwelling invertebrate Corophium sp.

DTPMP-xNH4will dissociate when it is released into aqueous environments, including sediments, 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 to yield DTPMP and ammonia. Binding behaviour is not affected by acid or alkali metal salt form. Hence some properties (measured or expressed in aqueous media) for a salt can be directly read across (with suitable mass correction) to the parent acid andvice versa (see CSR for mass correction values). In the present context the effect of the alkaline metal counter-ion (sodium/potassium/calcium) will not be significant and has been extensively discussed in the public literature. In biological systems and the environment, polyvalent metal ions will be present, and the phosphonate ions show very strong affinity to them.

Ammonia is highly soluble in water and does not accumulate in sediments or in organisms. Test data for the derivation of PNECs for ammonia for the protection of sediment-dwelling organisms are therefore not required.

DTPMP and ammonia will be treated separately for the purposes of deriving PNECs for the sediment compartment.