Registration Dossier

Environmental fate & pathways

Biodegradation in soil

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Description of key information

No study of biodegradation in soil is available for the registration substance. A reliable study of biodegradation in soil conducted with the parent acid form of the structurally analogous aminomethylenephosphonate substance HMDTMP is read-across. This study shows extensive degradation during the study in two soil types, indicating a conclusion that a significant degree of removal is possible in the wider environment. The half-life has not been quantified.

Key value for chemical safety assessment

Additional information

The registration substance is part of a category family (super-category; see CSR for more details) which consists of several phosphonates that share a common chemistry incorporating alkyl backbones with one or more tertiary amine centres and multiple methylphosphonate groups present.

 

HMDTMP-H (CAS 23605-74-5) has two aminobismethylphosphonate groups, connected by a hexyl chain. BHMT acid (CAS 34690-00-1) has three amine centres (five methylphosphonate groups), connected by hexyl chains.

 

As well as being structural analogues, both phosphonates have consistent chemical properties including high MW (492 and 685 respectively), very low log Kow(≤-4 for both substances) and are highly soluble in water. The substances generally posses similar physico-chemical properties and are not readily biodegradable.

 

Therefore, for the purpose of this assessment, read-across is considered valid. Further information on the super-category and the validity of read-across are presented in the CSR Chapter 1.