There's too many to list:

In 1987, Ames and Gold ranked natural and synthetic pesticides and found that cancer risks from traces of pesticide residues on fruits and vegetables are minuscule compared with the cancer-causing potential of some natural chemicals in plants. “We wrote a review pointing out that every plant has a hundred or so toxic chemicals—nature’s pesticides—to kill off insects, animals, and other predators, and that we were getting 10,000 times more of them than [of] man-made pesticides. Still, everybody is buying expensive organic food,” says Ames. “It’s the new religion. We won the scientific battle but we lost the public-relations battle.” For that work and more, arguing that traces of synthetic chemicals are not a cancer risk, Ames and Gold have been criticized as being in the pocket of the pesticide industry, despite never accepting money, consulting with industry companies, or testifying in trials.
http://www.the-scientist.com/?articles.view/articleNo/40054/title/Mutagens-and-Multivitamins/

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The Ames test is a widely employed method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism. More formally, it is a biological assay to assess the mutagenic potential of chemical compounds.[1] A positive test indicates that the chemical is mutagenic and therefore may act as a carcinogen, because cancer is often linked to mutation. The test serves as a quick and convenient assay to estimate the carcinogenic potential of a compound because standard carcinogen assays on mice and rats are time-consuming (taking two to three years to complete) and expensive. However, false-positives and false-negatives are known.[2]

The procedure was described in a series of papers in the early 1970s by Bruce Ames and his group at the University of California, Berkeley.[3][4][5][6]
https://en.wikipedia.org/wiki/Ames_test