report no. 12/12

17 Dec 2012

Existing data demonstrate that residual aromatic extracts (RAEs) can be eithercarcinogenic or non-carcinogenic. CONCAWE had previously concluded that“Although limited data available indicate that some RAEs are weakly carcinogenic, itis not possible to provide a general recommendation. Classify on a case-by-casebasis” (CONCAWE 2005) [11]. Therefore CONCAWE’s Health/Toxicology Subgroup(H/TSG) has developed a proposal for the use of the modified Ames test as a shorttermpredictive screening tool for decisions on the classification of RAEs forcarcinogenicity. The relationship between RAE chemistry and carcinogenic potential is not as wellunderstood as it is for some other categories of substances, e.g. Other LubricantBase Oils (OLBO). However, a correlation has been found between the results ofthe skin carcinogenicity bioassay and the mutagenicity index (MI) obtained from themodified Ames test. Data supporting this correlation are summarised in this report.The H/TSG confirmed that the modified Ames test can be used as a predictivescreening tool and that a cut-off value can be established to make a distinctionbetween carcinogenic and non-carcinogenic products. RAEs with a MI > 0.4demonstrated carcinogenic potential upon dermal application to mouse skin withchronic exposure. RAEs with a MI < 0.4 did not demonstrate a carcinogenicpotential. To justify the use of the modified Ames test with RAEs, additional analysis of therepeatability of the test with RAEs was required. With this objective, CONCAWEsponsored a round robin study with different samples of RAEs from membercompanies, at three different laboratories. The repeatability demonstrated in theround robin study with RAEs support the proposed use of the modified Ames test. As part of the tools available for use by member companies, the H/TSG proposed astandard operating procedure (SOP) (included as an Appendix to this report) on theconduct of the modified Ames test with RAEs. The H/TSG also prepared two specialOil Industry Notes (OINs) for use in cancer hazard classification. One OIN based onDangerous Substances Directive (DSD) (OIN 9) and one based on Classification,Labelling and Packaging (CLP) regulation (OIN 10) have been adopted.