EDITOR: Recent articles about organic food overlook important points. The Sept. 9 article "Making sense of organic food label" said the Stanford study "found that organic foods have 31 percent lower levels of pesticide, and more phenols, a substance believed to help fight cancer." The pesticides referred to are understood to be synthetic chemicals (and as such automatically assumed to be bad for health) while the naturally occurring substances (phenols) are usually, and unfairly, assumed to be good for health.
What is not widely known is that all plants, organic or otherwise, contain toxic chemicals that developed naturally to ward off attacks by disease or insects. More important, work by Berkeley biochemistry professor Bruce Ames showed that about half of these natural pesticides tested positive for carcinogenicity, the same proportion as found for synthetic chemicals.
Furthermore, he found that the amounts of these naturally occurring carcinogens remaining on fruits and vegetables exceed the traces of synthetic pesticides by about 10,000 times. Ames argued that it doesn't necessarily follow that the large amount of natural pesticides cause cancer any more than the traces of synthetic pesticides do because of the uncertainty of testing methods.