He invented the Ames test, as a system of easily and affordably testing the mutagenicity of compounds. This system is used for determining if a chemical is a mutagen or not. The Ames test is a biological assay to assess the mutagenic potential of chemical compounds. The use of the Ames test is based on the assumption that any substance that is mutagenic for the bacteria used in his test may also turn out to be a carcinogen; that is, to cause cancer. When the test was developed, it was thought that most of the chemicals that produce results in the Ames test could also cause cancer.
It was hoped that this simple test would be an easy way to find cancer-causing chemicals. Over time, the test was found to be a less reliable predictor of carcino-genesis than had been hoped. Some chemicals that are known to cause cancer do not test positive in the Ames test and some chemicals that test positive do not cause cancer. Although, in fact, some substances that cause cancer in laboratory animals such as dioxin, do not give a positive Ames test result. The screening still helps to identify chemicals that affect the structure of DNA.
The test exposes Salmonella bacteria to chemicals and looks for changes in the way bacteria grow. These changes result from mutations that occur when the structure of DNA is altered in certain places. Its seems that even though the Ames test has it flaws this test is still very useful as a screening tool for setting priorities because it is an inexpensive and quick way to help single out chemicals that should be targeted for further testing. It is also used in industry as a primary preventive approach to eliminate potential carcinogens early in the process of developing new commercial chemicals.