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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Both aluminium and benzoic acid are expected to have a low potential for bioaccumulation, with a BCF for aluminium of around 36 at pH 7.2 and, for benzoic acid, a calculated BCF of 7.9 based on a log partition coefficient of 1.88. Considering that (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium is readily biodegradable and that fatty acids are natural substances with a long history of safe use in food, (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium is not expected to bioaccumulate in the aquatic environment.

Key value for chemical safety assessment

Additional information

No data are available for the bioconcentration of (benzoato-O,O')hydroxy(octadecanoato-O,O')aluminium in aquatic species. This endpoint can be waived if the substance has a low potential for bioaccumulation (indicated by a log Kow <3). However, due to the very low solubility of this substance in water and octanol, the octanol-water partition coefficient could not be measured. Also, the HPLC method (OECD 121) could not be used because the substance was not soluble in typical reverse phase HPLC solvents (MeOH, MeCN and THF) thus invalidating this method as well.

 

The fatty acids used for the formation of the substance are either natural substances or chemically indistinguishable from natural substances. The fatty acid component of the substance is considered to be non-hazardous and readily biodegradable. Fatty acids of natural origin have a long history of safe use in foods and, under the REACH regulation Annex V, natural C6 to C24 fatty acids are exempt from registration (with certain caveats). Fatty acids are organic materials ubiquitous in living organisms. These fatty acids are biotransformed via ß-oxidation and thus have a very low potential for bioaccumulation. Benzoic acid has a reported partition coefficient (log Kow) of 1.88 (Lide 2008) and will therefore, in accordance with REACH Annex IX column 2, have a very low potential to bioaccumulate (log Kow <3). Therefore, bioaccumulation data are presented here for the aluminium component only.

Cleveland et al (1991) determined the steady state bioaccumulation factor of aluminium in brook trout Salvenlinus fontinalis. The flow-through experimental procedure followed sound scientific principles and is considered reliable and suitable for use for this endpoint.The fish were exposed to a steady state nominal aluminium concentration of 200 µg/L for 56 days followed by a 28-day depuration period. Duplicate studies were run at nominal pH of 5.3, 6.1 and 7.2. The whole fish estimated steady state BCF, which were inversely related to pH, was 215 at pH 5.3, 123 at pH 6.1 and 36 at pH 7.2. The estimated time to 90% steady state was 1.5 days at pH 5.3, 4.2 days at pH 6.1 and 1.7 days at pH 7.2. The fish eliminated aluminium rapidly with biological half-life of 0.46 days at pH 5.3, 1.26 days at pH 6.1 and 0.52 days at pH 7.2.

The availability of aluminium in the aqueous environment is very dependent on pH. Soluble aluminium species are only readily available to aquatic species at pH < 4. At neutral pH, aluminium will be in the form of essentially insoluble hydrated oxide species, which reduces their bioavailability by direct uptake from water. Since

(benzoato-O,O')hydroxy(octadecanoato-O,O')aluminiumis readilybiodegradable and the fatty acid and benzoic acid components are considered not to bioaccumulate in theaquatic environment the substance isnot expected to pose a risk of secondary poisoning.Furthermore, in realistic use scenarios, the aluminium thickener will be contained in base oil, with the formulated greases specifically designed to minimise the leaching of the thickener. Therefore, during use, the concentrations of the substance which would be bioavailable are further limited.