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Scientists, physicians, and other technically informed people will also be shocked by Silent Spring—but for a different reason. They recognize Miss Carson's skill in building her frightening case; but they consider that case unfair, one-sided, and hysterically overemphatic. Many of the scary generalizations—and there are lots of them—are patently unsound. "It is not possible," says Miss Carson, "to add pesticides to water anywhere without threatening the purity of water everywhere." It takes only a moment of reflection to show that this is nonsense. Again she says: "Each insecticide is used for the simple reason that it is a deadly poison. It therefore poisons all life with which it comes in contact." Any housewife who has sprayed flies with a bug bomb and managed to survive without poisoning should spot at least part of the error in that statement.
But Author Carson's oversimplifications and downright errors only serve to highlight a question that has bothered many Americans: Just how dangerous are insecticides? Experts of the Department of Agriculture and the U.S. Public Health Service readily admit that some of them are extremely poisonous to humans as well as to insects and other pests. Parathion. an organic phosphate used against mites and other highly resistant insects, is so deadly that men who spray it must wear respirators and protective clothing.
A few related chemicals are almost as dangerous, but luckily they break down quickly into harmless substances and so leave no poisonous residue on fruits and vegetables or in the soil. Their disadvantage is that they can poison farm workers who handle them carelessly. Miss Carson describes these very rare accidents and gets shock effect out of them, but they are comparable to accidents caused by careless handling of such violent industrial chemicals as sulfuric acid. The highly toxic phosphates are no menace to the general public, which seldom comes in contact with them.
DDT in Every Meal. The chlorinated hydrocarbons, on the other hand (including the familiar DDT), are used in enormous quantities by almost everyone. Much of Miss Carson's case against spraying depends on her contention that DDT and its near chemical relatives are poisonous to humans, especially since they tend to accumulate in fatty tissues. Experts do not agree. A mere trace of DDT kills insects, but humans and other mammals can absorb large doses without damage. Dr. Wayland J. Hayes, chief of the toxicology section of the U.S. Public Health Service in Atlanta says that every meal served in the U.S. probably contains a trace of DDT, but that this is nothing to worry about. He and his co-workers fed 200 times the normal amount to 51 convict volunteers. The insecticide accumulated in their bodies for about one year and then was excreted as fast as it arrived. The human guinea pigs felt no ill effects, and doctors pronounced them as healthy as a control group that got the same diet without extra DDT.