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Environmental fate & pathways

Hydrolysis

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Description of key information

In accordance with column 2 of REACH Annex VIII, a study on hydrolytical properties does not need to be conducted as the substance is highly insoluble in water.

Key value for chemical safety assessment

Additional information

In a fully valid study on water solubility, conducted according to OECD 120, two test item concentrations were assessed (100 mg/L and 1000 mg/L). The test item is a mixture and the water solubility was calculated based on TOC with a limit of quantification (LoQ) of 2 mg/L. The solubility for both concentrations was below the LoQ and, therefore, the test item water solubility was calculated as < 0.0051 mg/L. As the water solubility was equal for both test item concentrations the constituents of the mixture seem to have an equal solubility. Different solubilities of constituents would be expected to result in varying solubilities at the two test concentrations, which was not the case here. Thus, the water solubility of the test item (i.e. mixture constituents) was determined to be < 0.0051 mg/L which is a very low water solubility and should be understood as a proof for high insolubility.

In accordance with REACH regulation, Annex VIII, column 2, studies on hydrolysis need not to be conducted if the test item is highly insoluble. Neither the REACH regulation nor the REACH guidance document define a threshold water solubility for highly insoluble substances. However, in the past the experience was that ECHA considered substances with water solubilities in the range of 1 mg/L or below as highly insoluble. The water solubility reported in the current case was < 0.0051 mg/L (= LoQ) and will very likely be even lower than 1 mg/L which is supported by the high partition coefficient (log Kow) of 4.8. It is, therefore, considered to be appropriate to treat the substance as if the water solubility of the substance had been determined at a distinct concentration at or below 1 mg/L. The conclusion that the substance is highly insoluble is, therefore, appropriate and valid.

Concluding, a study on hydrolytical properties does not need to be conducted due to high insolubility of the test item. The date requirement can be waived.