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Diss Factsheets

Environmental fate & pathways

Hydrolysis

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Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Data waiving:
other justification
Justification for data waiving:
other:

Description of key information

In accordance with REACH Annex VIII column 2, the study does not need to be conducted if the substance is highly insoluble in water. Water solubility of Ash is <1 mg/L.

Key value for chemical safety assessment

Additional information

The OECD 111 test guideline (Ref 1) describes a method for the determination of (1) the rate of hydrolysis of a test substance as a function of pH and (2) the identification and rates of formation of hydrolysis products to which organisms may be exposed. It is applicable to substances which can enter surface waters either by direct application or via spray drift, run off, drainage, waste disposal or industrial, domestic or agricultural effluents.

 

The method is applicable to chemicals for which an analytical method of sufficient accuracy and sensitivity is available, which are non-volatile, and which can be kept in solution under the experimental conditions of the test.

 

The Ash is a mixture of many compounds, many of which are inorganic materials, and is of low solubility. The main components of the Ash sample are calcium (24%), silicon (15%) and aluminium (7%), with the remainder of the material being a variety of other chemical identities. The guideline states that the purity of the test substance should be at least 95%, which is not the case for this substance. Similarly, Tier 3 of the test requires identification of hydrolysis products which represent more than 10% of the applied dose. This would not be applicable for the Ash, as the majority of components constitute less than 10% of the test substance, before any reaction takes place.

 

The mineral components which are not in solution would not be subject to hydrolysis, so the test is not applicable to this fraction. Of the components which are soluble, there are many, each one representing only a small fraction of the total test material. Testing of each of these components for hydrolysis would not give useful information about the total mixture.

 

For these reasons it is not considered appropriate to test ash for hydrolysis.

REFERENCES

OECD Guidelines for the Testing of Chemicals. Test Guideline 111, Hydrolysis as a Function of pH. Adopted 13 April 2004.