The test method is based on a modification of the Ames Salmonella mutagenesis assay. As modified, there is good correlation with mouse skin-painting bioassay results for samples of raw and refined lubricating oil process streams.

Mutagenic potency in this modified assay and carcinogenicity in the skin-painting bioassay also correlate with the content of 3 to 7 ring PACs, which include polycyclic aromatic hydrocarbons and their heterocyclic analogs. The strength of these correlations implies that PACs are the principal mutagenic and carcinogenic species in these oils. Some of the methods that have provided evidence supporting this view are referenced in Appendix X1.

1.1 This test method covers a microbiological test procedure based upon the Salmonella mutagenesis assay of Ames et al (1) (see also Maron et al (2)). It can be used as a screening technique to detect the presence of potential dermal carcinogens in virgin base oils used in the formulation of metalworking oils. Persons who perform this test should be well-versed in the conduct of the Ames test and conversant with the physical and chemical properties of petroleum products.

1.2 The test method is not recommended as the sole testing procedure for oils which have viscosities less than 18 cSt (90 SUS) at 40°C, or for formulated metalworking fluids.

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information only.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Section 7 provides general guidelines for safe conduct of this test method.