Ames mutagenicity tests of repeatedly heated edible oils.

Six cooking oils with different levels of unsaturation were each heated at 180 +/- 3 degrees C for 6 hr on each of four consecutive days and cut potatoes were fried in the oils at hourly intervals. Samples of the heated and unheated oils were tested in the Ames mutagenicity assay. None of the oil samples (taken before or after 24 hr heating) showed any mutagenicity in the Ames test with or without metabolic activation.