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Environmental fate & pathways

Adsorption / desorption

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Description of key information

A key study for the endpoint 'adsorption/desorption' has not been performed for disodium dihydrogenpyrophosphate. An adaptation from the standard testing regime is justified on the following basis: In accordance with Section 2 of Annex XI of Regulation (EC) No 1907/2006 (REACH), testing is technically not possible as the relevant guideline for a screening study (OECD 121) is not validated for this type of substance and the batch equilibrium method (OECD 106) is not considered to be applicable (see 'discussion'). The literature data provided are not sufficient to determine a Kd value for risk assessment and are therefore provided as supporting information only. 

Key value for chemical safety assessment

Additional information

According to Annex XI, Section 2 of Regulation (EC) No 1907/2006 (REACH) testing for a specific endpoint may be omitted if it is technically not possible to conduct the study as a consequence of the properties of the substance itself. A study to investigate the adsorption / desorption characteristics of disodium dihydrogenpyrophosphate has not been conducted. The justifications for not providing these data are as follows:

- A screening study according to OECD Guideline 121, is not technically possible as the test method is not validated for inorganic substances.

- A batch equilibrium study according to OECD Guideline 106 was deemed to be not applicable to disodium dihydrogenpyrophosphate for the following reasons:

 

Firstly, analysis of the test material may not be possible due to interference from the soil extracts that may leach into the aqueous media during the test. This would prevent quantification of the test material.

In addition, the mobility of the test item would be dependent on the anion exchange capacity of the soils as the main component of the test material is an anion. This absorption relationship would not be anticipated to correlate with the organic carbon content of the soils and is considered to be beyond the scope of the OECD 106 method.