Naphthenic acids, lithium salts

Endpoint summary

Description of key information

The data indicate that the substance would degrade in the environment and QSAR results for representative structures indicate that the substance would not meet the criteria for P or vP in the PBT assessment. The hydrolysis endpoint has been waived as the substance is insoluble in water. The test item, representative of the chemical class of anionic surfactants, shows significant surface-active properties in an aqueous environment, forming colloidal suspension (i.e. containing micelles < 0.2 µm) in water which contained dispersed, excess, undissolved material that could not be satisfactorily removed by either centrifugation of filtration techniques. The BCF values of the representative constituents of lithium naphthenate are estimated by QSAR to be in the range of 3.162 to 207.7 L/kg ww. The adsorption coefficients of the representative constituents of lithium naphthenate are estimated by QSAR to be in the range of 0.42 to 4.75 E+09 (log Koc -0.08 to 9.68).

Additional information

In most cases, the reactions to form the grease thickener occur in situ during the grease manufacturing process and consequently these grease thickeners normally only exist in the base oil matrix. 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 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. 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. Therefore, during use, the concentrations of the substances which would be bioavailable are limited.

 

Studies have been conducted to assess the potential for grease thickener, similar to lithium naphthenate, to leach from base oil. There is negligible leaching of the thickeners from base oils into water in the samples tested. The SPME-GC data confirm that the total peak area counts are all extremely low and equivalent to background readings associated with a control sample. All of the results for calcium and lithium analysis were below the limit of detection for the method, hence all results are reported as <0.1 mg/L.

 

Reference

OECD (2004) OECD Series on emission scenario documents, Number 10: Emission scenario document on lubricants and lubricant additives. Environment directorate: Joint meeting of the chemicals