We've been swallowing the storks-bring-babies kind of logic for years. (My favorite version: I see fat people drinking diet soda; therefore diet soda must make people fat.) For instance, stories about pesticides making food carcinogenic would fill several pages of a Google search. To the scientifically illiterate, the stories are logical. After all, farmers keep using new pesticides, we consume them in the food we eat, and we keep hearing more people are getting cancer. It must be cause and effect! Get the shovel.
MYTH: Pesticide residues in food cause cancer and other diseases.
TRUTH: The residues are largely harmless.
Ames laughs at the claims of chemically induced cancers, and he should know-he's the one who invented the test that first frightened people about a lot of those chemicals. It's called the Ames Test, and its first use in the 1970s raised alarms by revealing there were carcinogens in hair dye, and in the flame retardants in children's pajamas. Ames helped get the chemicals banned.
Before the Ames Test, the traditional way to test a substance was to feed big doses of it to animals and wait to see if they got cancer or had babies with birth defects. But those tests took two to three years and cost $100,000. So Dr. Ames said, "Instead of testing animals, why not test bacteria? You can study a billion of them on just one Petri dish and you don't have to wait long for the next generation. Bacteria reproduce every twenty minutes."
The test proved successful. It was hailed as a major scientific breakthrough, and today, the Ames Test is one of the standards used to discover if a substance is carcinogenic.
But after getting the hair dye and the flame retardants banned, Dr. Ames and other scientists continued testing chemicals. "People started using our test," he told me, "and finding mutagens everywhere-in cups of coffee, on the outside of bread, and when you fry your hamburger!"
This made him wonder if his tests were too sensitive, and led him to question the very bans he'd advocated. A few years later, when I went to a supermarket with him, he certainly didn't send out any danger signals.
DR. AMES Practically everything in the supermarket, if you really looked at it at the parts per billion level, would have carcinogens. Vegetables are good for you, yet vegetables make toxic chemicals to keep off insects, so every vegetable is 5 percent of its weight in toxic chemicals. These are Nature's pesticides. Celery, alfalfa sprouts, and mushrooms are just chock-full of carcinogens.
STOSSEL Over there it says "Organic Produce." Is that better?
DR. AMES No, absolutely not, because the amount of pesticide residues-man-made pesticide residues-people are eating are actually trivial and very, very tiny amounts! We get more carcinogens in a cup of coffee than we do in all the pesticide residues you eat in a day.
In a cup of coffee? To put the risks in perspective, Ames and his staff analyzed the results of every cancer test done on rats and mice. By comparing the dose that gave the rodents cancer to the typical exposure people get, they came up with a ranking of the danger. Pesticides such as DDT and EDB came out much lower than herb tea, peanut butter, alcohol, and mushrooms. We moved over to the mushrooms as the cameras continued to roll, and Dr. Ames put his mouth where his convictions were.
DR. AMES One raw mushroom gives you much more carcinogens than any polluted water you're going to drink in a day.