BOB2, your mention of the basil reminded of a Prof. Bruce Ames of UC Berkeley. He is most well known for his 1970's era creation of the Ames test (still in use today), which could quickly assess chemicals and their ability to alter DNA. He was a hero of environmentalist until 1987, the point in time he released his comparative risk studies, which is when I first read about his work.

Quote:

In 1987, Ames and his collaborator Lois 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.
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Brief history of Ames

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