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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
The substance is only manufactured in situ in a generic inert carrier, typically the carrier is base oil as the main use of the substance is as thickener for greases. In realistic use scenarios, the thickeners will be contained in a base oil matrix, with the formulated greases specifically designed to minimise the leaching of the thickener. Data read across from lithium and calcium salts of fatty acids have shown no leaching of the thickeners from base oil into water and, given the very low solubility of the substance in water, the concentrations of the substance which would be available for adsorption to soil or sediment are limited.
The dissociation and degradation in the environment of the substance would result in fatty acids and hydrated aluminium oxide species. The fatty acid components biodegrade rapidly to carbon dioxide and water. At environmental pH (ca 7.0), aluminium will mainly be in the form of insoluble hydrated oxide species which, although likely to absorb onto soil, are not expected to be scientifically relevant as they are naturally abundant in the environment.

Description of key information

The adsorption/desorption study was not conducted as the substance decomposes rapidly to carbon dioxide, water and inorganic aluminium species. At environmental pH (ca 7.0) aluminium will mainly be in the form of insoluble hydrated oxide species which, although likely to absorb onto soil, are not expected to be scientifically relevant as they are naturally abundant in the environment. In realistic use scenarios, the thickeners will be contained in a base oil matrix, with the formulated greases specifically designed to minimise the leaching of the thickener and, given the very low solubility of the substance in water, the concentrations of the substance which would be available for adsorption are limited. 

Key value for chemical safety assessment

Additional information

It was not possible to determine an octanol partition coefficient as the substance in the form used for hazard testing (50% w.w. concentration in pharmaceutical white oil) is not sufficiently soluble in octanol, water or suitable HPLC solvents. Therefore, it is not possible to estimate the adsorption of the substance. However, in n most cases the reactions to form the grease thickener occur in situ during the grease manufacturing process and consequently grease thickeners normally only exist in the base oil matrix. In realistic use scenarios, the thickeners will be contained in base oil, with the formulated greases specifically designed to minimise the leaching of the thickener. Data read across from lithium and calcium salts of fatty acids have shown no leaching of the thickeners from base oil into water and, given the very low solubility of the substances in water, the concentrations of the substance which would be available for adsorption to soil or sediment are limited.

The dissociation and degradation in the environment of the substance would result in carbon dioxide, water and hydrated aluminium oxide species. No data for adsorption/desorption were included in the REACH dossiers for aluminium oxide or aluminium hydroxide. No data are available on the partition coefficient of purely inorganic aluminium compounds as, in accordance with column 2 of REACH Annex VII, the partition coefficient studies do not need to be conducted as the substances are inorganic. Aluminium is the most abundant metal to be found on earth making up 8.1% of the Earth’s crust (Lide, 2008). However, it is never found in the pure form but always in the form of minerals, for example bauxite, which is an impure form of hydrated oxide ore. At environmental pH (ca 7.0), aluminium will mainly be in the form of insoluble hydrated oxide species which, although likely to absorb onto soil, are not expected to be scientifically relevant as they are naturally abundant in the environment.