Aluminum, benzoate C16-18 fatty acids complexes - high aluminium

Endpoint summary

Description of key information

There is no evidence from the experimental studies to indicate that aluminum, benzoate C16-18 fatty acid complexes are absorbed systemically.  No information on distribution, metabolism or excretion can be derived from the experimental data.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Experimental data for the mammalian toxicity Annex VII and VIII endpoints have been generated on this substance.

The following conclusions can be drawn on the basis of a review of available key experimental data from physico-chemical and toxicological studies on aluminum, benzoate C16-18-fatty acids complexes performed according to international technical guidelines and in compliance with GLP in internationally recognised contract research organisations:

· Aluminum, benzoate C16-18 fatty acid complexes do not appear to be absorbed via the gastrointestinal tract, though the lack of toxicity via the oral route may also be indicative of high-threshold toxicity for the substance over the relatively short-term exposures examined.

A lack of any systemic toxicity was observed in the acute oral toxicity study, which was conducted on aluminium, benzoate, C16-18 fatty acid complexes isolated from an oil base and re-dissolved in arachis oil, at doses up to 2000 mg/kg bw. An OECD 422 study was conducted in rats by daily oral gavage administration of the substance manufactured in situ in a medicinal grade white oil base and there were no effects on any of the reproductive or developmental parameters measured. As the maximum dose that could be administered was limited by the physico-chemical characteristics of the dosing preparation, the limit dose of actual aluminium, benzoate C16-18 fatty acid complexes could not be attained and the maximum dose was below the limit dose of 1500 mg/kg/day (actual maximum dose achieved was 225 mg/kg bw/day, which was considered to be the NOAEL).

Aluminium, benzoate, C16-18 fatty acids is used specifically as a thickener in industrial greases and lubricants and as such is manufactured and used solely in situ in base oil. Thickener chemistry is complex and interactions between the thickener and base oil do not strictly fall under the definitions of a reaction product nor do they act as a simple mixture of components due to changes which occur in the manufacturing/ blending process. Matrix effects should be taken into account when assessing whether adverse effects would be seen in grease products because entrainment of grease thickeners during the manufacturing process as part of the grease matrix severely limits exposure and will have a significant impact on the outcome of any risk assessments. The fact that matrix effects do occur is a point recognised in the OECD Lubricant Emission Scenario document (2004) and it is therefore reasonable to assess the influence the process of manufacturing the thickener in an inert base oil has on factors such as availability, which are critical to assessing the potential risks posed by the grease thickeners when in the grease.

Leaching tests have been undertaken to assess whether the metallic components of the metal-soap and metal-complex-soap grease thickeners remain in base grease(s) and hence determine the degree of availability of the thickeners (see section 4.5 and Appendix 2 of the CSR). The results of the study show no leaching of the thickener from the base oil and a lack of bioavailability of the substance in aqueous media. The same lack of bioavailability is expected in GI fluids as well and as a further demonstration of this lack of availability, it is proposed to conduct an ex vivo study to investigate the translocation of the substance across the gastrointestinal wall using the everted gastric sac method developed by CXR Biosciences Ltd, Dundee. This evaluates the potential of the test material to cross the rat small intestine by measuring the resultant concentration of aluminium ions in fed state simulated intestinal fluid - FeSSIF).

· Aluminum, benzoate C16-18 fatty acid complexes do not appear to be absorbed via the skin.

This is supported by the lack of any systemic toxicity in an acute dermal toxicity study at doses up to 2000 mg/kg bw in male and female Wistar rats and, also due to the absence of any change in stimulation index following topical application of the test substance in a propylene glycol suspension in a local lymph node assay. Although lack of dermal absorption is the likely scenario for the absence of systemic effects via this route of exposure, the alternative explanation of high threshold toxicity over the short-term exposure examined cannot be ruled out.

No available data from these studies allows conclusions to be drawn regarding distribution, metabolism or excretion of aluminum, benzoate C16-18-fatty acids complexes.