The ASTM E1687 guideline describes a modified Ames test that is used to screen for the potential mutagenic and carcinogenic risks associated with exposure to virgin base oils used in formulating metalworking fluids. This approach was developed for heavy and complex petroleum-based oil matrices, which include polycyclic aromatic compounds (PACs) that have been historically linked to dermal carcinogenicity.

The assay uses specific strains of Salmonella typhimurium that are unable to synthesize the amino acid histidine, and thus cannot grow under histidine-deficient conditions unless a reverse mutation restores this function. Mutagenic activity after treatment with the test material is, therefore, indicated by the number of revertant colonies growing on histidine-deficient agar.

For heavy petroleum fractions, the complex oil matrix limits bacterial exposure or may interfere with the assay's performance. The modified method using ASTM E1687 includes a solvent-extraction step with dimethyl sulfoxide (DMSO) to concentrate fractions containing potentially mutagenic PACs and increase their availability in the bacterial assay system.

The Modified Ames Test under ASTM E1687 is therefore well-suited for screening the mutagenic and carcinogenic potential of virgin base oils used in metalworking-fluid applications.

Vipragen Biosciences offers ASTM E1687-based Modified Ames Testing as part of its in vitro genetic toxicology and petroleum-product safety assessment services.