Oxoaluminium, C16-C18-alkyl esters

Endpoint summary

Description of key information

Since the substance has low volatility, aerial deposition is unlikely, and the substance is not applied directly to soil and is not expected to enter sewage treatment works at significant concentrations which could lead to agricultural exposure via application of sewage sludge to land. Thus, terrestrial exposure of the substance is considered unlikely and as the terrestrial toxicity would not be environmentally relevant, these tests have not been conducted.

Additional information

No data are available for the toxicity to terrestrial organisms. The substance is expected to exhibit no measurable aquatic toxicity, is not bioavailable and direct and indirect emissions are unlikely. Therefore, no testing has been proposed for toxicity to terrestrial organisms and the endpoints have been waived on the basis that there is expected to be no exposure of the terrestrial environment.

Equilibrium partitioning

The ECHA guidance document Chapter R.10 – Dose [Concentration]-Response Regarding Environment guidance document (ECHA 2008) states that “when no toxicity data are available for soil organisms, the equilibrium partitioning method is applied to identify a potential risk to soil organisms”. Equilibrium partitioning is based on estimation of the toxicity to terrestrial organisms from the aquatic toxicity and the physico-chemical and environmental fate properties of the substance.

The water solubility of the substance (measured using a 50% w. w. concentration in pharmaceutical white oil) was determined as <0.00015 g/L (Harlan 2013) at 21°C and the vapour pressure was determined to be 0.00015 Pa at 25°C (Harlan 2013), therefore it is possible to make an estimation of Henry’s Law Constant. However, no determination of the partition coefficient was possible by the shake-flask method due to the insolubility of the substance in both n-octanol and water. Further to this, determination of the partition coefficient by the HPLC estimation method was also not possible due to the insolubility of the substance in suitable reverse phase HPLC solvents. As the partition coefficient and adsorption/desorption coefficient could not be determined, it is not possible to use the equilibrium partitioning method to estimate the toxicity to terrestrial organisms.

Exposure

The terrestrial toxicity endpoints may be waived if it can be demonstrated that direct and indirect exposure of soil is unlikely to occur. ECHA guidance document REACH Chapter R.10 – Dose [Concentration]-Response Regarding Environment (2008) states that chemicals can reach the soil via several routes: application of sewage sludge in agriculture, direct application of chemicals and deposition from the atmosphere.

The substance only occursin situin an inert carrier, typically base oil. The matrix effect, as recognised by the OECD Lubricant Emission Scenario document (OECD 2004), needs to be taken into account as the process of manufacturing the thickener in an inert base oil is likely to influence factors such as availability of the thickeners. In the grease manufacturing process, unique interactions, more appropriately defined as physical bonding effects, occur between the base oils and the thickeners. The 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. In realistic use scenarios, the 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 limited.

The isolated form (i.e. outside base oil) of the substance is considered readily biodegradable based on proprietary data read across from aluminum, benzoate C16-18-fatty acids complexes (Harlan 2013). Aluminum, benzoate C16-18-fatty acids complexes is considered suitable for read-across as it contains a fatty acid moiety coordinated to an aluminium atom, although it also contains a coordinated benzoate ion. However, proprietary data are available (Harlan 2013) showing the substance at 50% w. w. concentration in pharmaceutical white oil (representative of the form in which it is marketed and used) only reached 31% degradation after 28 days and therefore cannot be considered readily biodegradable. The white oil, which constituted 50% by weight of the substance tested, is known not to be readily biodegradable (31% biodegradation after 28 days) (ECHA Dissemination Portal CAS 8042-47-5). It can therefore be concluded that the test results are significantly determined by the properties of the pharmaceutical white oil. Although the substance itself in isolated form (i.e. extracted from base oil) can be considered readily biodegradable, the substance in the form in which it is marketed and used cannot be considered readily biodegradable. However, the substance has no identified uses in which it would enter the sewage treatment system in significant quantities and therefore there is not expected be significant exposure to agriculture from the spreading of sewage sludge.

The substance is used as a thickener in lubricants and greases in open and closed systems and thus there is no direct application to soil. The majority of greased parts are designed to keep the grease within the contact zone. A large proportion of light to medium duty grease-lubricated parts are sealed for life and the user will not interact with the grease during any time of the part’s use from purchase to disposal. Due to the nature of the grease as a semi-solid, it will remain within the part and not be released, even in catastrophic failure. Some applications require a grease to be used as a total loss lubricant, such as on rail tracks, heavy duty trucks, spindles on agricultural crop pickers and marine applications. In these applications, there are voluntary/ compulsory schemes in place that limit the type of product used based on its toxicity, ecotoxicity and biodegradability (e.g. Nordic Swan, Ecolabel, Blaue Engel, VGP).

The vapour pressure of the substance as a 50% w. w. concentration in pharmaceutical white oil was determined to be 0.00015 Pa at 25°C (Harlan 2013). As the substance has very low volatility, it is not expected to enter the atmosphere. Thus, aerial deposition of the substance will be negligible and deposition is not expected to be a relevant route of exposure.

No testing has been proposed for terrestrial endpoints and the endpoints have been waived on the basis that there is expected to be no exposure of the terrestrial environment. The isolated thickener is considered readily biodegradable and the thickenerin situin an inert carrier, such as base oil, is unlikely to come in contact with the terrestrial environment, so the derivation of terrestrial data on the isolated thickener is not considered to be relevant. The substance is used as a thickener in lubricants and greases in open and closed systems so there is no direct application to soil. The substance also has no identified uses in which it would enter the sewage treatment system in significant quantities which would lead to exposure to agriculture from the spreading of sewage sludge. As the thickener in base oil has very low volatility, it is not expected to enter the atmosphere and aerial deposition of the substance will be negligible.The substance is only manufacturedin situin a generic inert carrier, typically base oil, and therefore is not bioavailable. Thus, the isolated thickener is unlikely to come in contact with the terrestrial environment and the derivation of terrestrial toxicity data on the isolated thickener is not considered to be relevant to the potential exposure of the substance in the environment.

This substance has been registered by a Member of the European REACH Grease Thickeners Consortium (ERGTC). A number of decisions have been made in the dossier with regard to the approach taken for registering the substance including the testing strategy and the justification for waiving certain endpoints. Several of the decisions reflect the technical difficulties of testing the substance and the relevance of data with regard to the potential for exposure, given that the substance typically occurs in situ in base oil. A face to face meeting between the ERGTC and ECHA was held in Helsinki on 8th September 2016 which discussed many of these topics and a copy of the minutes from the meeting are attached to the dossier (See section 13 of IUCLID). Therefore, if there are any queries or concerns which arise when the dossier is reviewed, it is requested that the reviewer discuss these with the ERGTC ([e-mail]) as there may be background information and previous discussions between the ERGTC and ECHA which are relevant.

Conclusion for terrestrial toxicity

Since the substance has low volatility, aerial deposition is unlikely, and the substance is not applied directly to soil and is not expected to enter sewage treatment works at significant concentrations which could lead to agricultural exposure via application of sewage sludge to land. Thus, terrestrial exposure of the substance is considered unlikely and as the terrestrial toxicity would not be environmentally relevant, these tests have not been conducted.

Furthermore, in the environment, the substance will dissociate and degrade into inorganic aluminium species and fatty acids.The fatty acid components biodegrade rapidly to carbon dioxide and water and are natural substances with a long history of safe use in foods. Aluminium is expected to have a low potential for bioaccumulation, with BCF of around 36 at pH 7.2 and, at environmental pH (ca 7.0), aluminium will mainly be in the form of essentially insoluble hydrated oxide species which, although likely to absorb onto soil, are not expected to be scientifically relevant.Hydrated aluminium oxides occur naturally in the environment and are not considered hazardous.