Naturally Deadly: The Scientific Attack on Natural Foods

Raw peach pits and moldy peanuts contain toxic chemicals. But does that mean pesticides are safe?

By the 1970s, Americans were bombarded by reports of toxic substances in their food. The bug killer DDT could bioaccumulate in body fat. Dioxin-contaminated 2,4,5-T herbicide could cause miscarriages. The synthetic hormone diethylstilbestrol, implanted in steers to make them gain weight faster, was linked to breast cancer. Even cyclamate, a commonly used artificial sweetener, was banned by the FDA after it caused cancer in lab rats.

Not surprisingly, the chemical industry launched a propaganda campaign trying to prove that these chemicals were safe. One way they tried to do this was by launching an attack on “natural” foods. “Toxicants occur naturally in foods such as mushrooms, almonds, and spinach,” University of Minnesota nutritionist Mary Darling warned in a 1975 article for Science Teacher. “Peach pits can be poisonous if consumed in large quantities.” The “immature shoots of bracken fern,” Thomas Jukes pointed out in a 1979 article for Food Technology, contain a substance that “produces cancer of the colon in rats.” Too much sassafras tea could cause liver cancer.

Even normally nutritious foods like grain and nuts could be contaminated by another type of natural toxins—mycotoxins. These toxic substances are produced by molds like Aspergillus that can infect improperly stored foods. As the Council for Agricultural Science and Technology pointed out in their 1979 report “Aflatoxin and Other Mycotoxins: An Agricultural Perspective,” aflatoxin is “the most potent, naturally occurring, cancer-producing substance known.”

If untreated human excrement is used for fertilizer, there’s always the danger of fecally transmitted diseases and parasites. Foods can also be contaminated with dangerous pathogens like Salmonella, and eating raw pork can infect people with the nasty trichinosis parasite. And don’t even thinking about drinking raw milk, Jean Mayer warned in a 1979 article for Family Health. “Pasteurization, which apparently does not even cause any nutrient loss, is a small price to pay for avoiding the danger of tuberculosis or brucellosis.”

What did any of this have to do with pesticide safety? Nothing. Proving that some natural substances could be toxic didn't prove that pesticides weren’t. And none of the natural toxins that the anti-organic writers chose to focus on are any more likely to occur in organic than conventional foods. The pits from pesticide-sprayed peaches are still toxic—and conventionally raised pork can still have trichinosis. So why even bring up natural toxins?

The reality is that the scientists knew that pesticides were toxic. They always acknowledged that ingesting large quantities of pesticides could be deadly. The emphasis on naturally occurring toxins seems to have been their way of illustrating the classic toxicology concept that “the dose makes the poison.” Everything is poisonous in too large of quantities, even “natural” foods. So if eating a little bit of natural poison doesn’t hurt you, a little synthetic poison on top won’t make a bit of difference, right?

From another perspective, this emphasis on natural toxins was rather disingenuous. Eating too many raw peach pits or too much aflatoxin-contaminated grain really can kill you. And if natural chemicals that humans have been exposed to for thousands of years can be deadly, synthetic pesticides we have no natural resistance to are even worse. Highlighting natural toxins doesn’t make pesticides seem safe. It might make them even scarier.