Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

HEBMP-H is not susceptible to hydrolytic degradation due to lack of hydrolyzable groups.

HEBMP-H is not biodegradable. Simulation tests for biodegradation in water/sediment and biodegradation in soil are waived.

Bioaccumulation aquatic/sediment for HEBMP-H is waived based on its low potential of bioaccumulation (log Kow ≤ 3)

No data are available regarding Absorption/Desorption of HEBMP-H so Kd for the substance is derived from Kd of its sodium salts (cyclic form and linear form): average Kd for linear structure is 1500 l/kg and for cyclic structure sodium salt is 110 l/kg.

Additional information

HEBMP-H is not susceptible to hydrolytic degradation due to lack of hydrolyzable groups.

 

HEBMP-H is not biodegradable but simulation tests for biodegradation in water/sediment and biodegradation in soil are waived. The waiving for biodegradation in water/sediment is possible due to the chemical safety assessment according to Annex I indicates that these are not necessary. The chemical safety assessment also indicates that identification of degradation products is not necessary. Moreover simulation tests (soil) are not considered necessary because the risk characterisation ratios (RCRs) for the terrestrial compartment, even with the realistic assumption that the parent substance is not biodegradable, are <1.

Bioaccumulation: aquatic/sediment for HEBMP-H is waived according to REACH regulation (EC n.1907/2006), annex IX, column 2 : the substance has a low potential for bioaccumulation (for instance a log Kow ≤ 3) and/or a low potential to cross biological membranes.

Adsorption coefficients have been derived in a reliable OECD 106 test in soil-water systems under a range of conditions. At low concentrations of the range predicted to occur in the environment, the average Kd has been extrapolated to 1500 l/kg (for the linear constituent structure). There is some evidence that binding in high-clay substrates is likely to be higher still and in hard waters (calcium concentration equivalent to 40 mg/l or higher) the Kd would be significantly higher. For the cyclic constituent, the equivalent value was 110 l/kg based on a preliminary test at higher concentration. Adsorption and desorption behaviour of the cyclic constituent is not yet fully understood and until/unless definitively proven otherwise, the chemical safety assessment assumes at this stage that some desorption of cyclic constituent from the substrate is possible. This is a conservative interpretation and is not the case for the linear constituent (and other aminomethylenephosphonates) which show negligible desorption and effectively irreversible binding. Under the negatively-charged, alkaline conditions at the surface of mineral substrate, it would be thermodynamically favourable for the ring structure present in the cyclic constituent molecule to open, and behaviour like the linear constituent is then to be expected.