Strength and weaknesses of microbial test results for predicting human response

Concern over the mutagenic activity of environmental chemicals is widespread as a result of exploratory work during the past ten years. Mutagens seem to exist in just about every category of chemicals in our environment, and many of these chemicals have been shown to have widespread human exposure. Probably the best example in recent times is the food additive AF-2, (2-[2-furyl]-3-[5-nitro-2-furyl]acrylamide) which was used as a food preservative in Japan for about ten years starting in the mid-60's. It was used to preserve soybean curd, fish, and meat sausage and many other foods which were considered staples in the diet of every person living in Japan during that period. In 1973, AF-2 was found by Japanese scientists to be mutagenic in newly developed microbial tests for mutagenicity as well as in mammalian cells in culture (de Serres, 1974, 1976). Subsequently, AF-2 was found to be mutagenic in numerous other assay systems by scientists in other parts of the world. There was great concern over potential mutagenic effects of AF-2 on the Japanese population early in 1974 as a result of the test data on mutagenicity from experiments on these laboratory organisms. However, it was not until AF-2 was found to produce cancer in the fore-stomach in mice (Sano et al., 1977) in August of 1974 that the use of AF-2 was finally banned by the Japanese Ministry of Health.