Cancer Hysteria Gets Old

A major new European cancer study has reported that 20 to 40 percent of human cancers are hereditary. This is good news for both people and the environment. It means that people can live without being terrified that their food and furnishings are creating a cancer epidemic. They also won't have to plow down the Earth's forests and subsist on low-yield organic crops.

A team of Scandinavian researchers combed detailed government records in Sweden, Denmark, and Finland to study cancer rates in nearly ninety thousand twins. Identical twins possess identical DNA, whereas fraternal twins share only half. The researchers used this differential to obtain an indication of how much cancer is truly hereditary. The most "inherited" cancers, they found, were prostate cancer (42 percent), colon and rectal cancers (35 percent), and breast cancer (27 percent). Scientists already know that 30 percent of our cancers are from smoking and many more result from eating too few fruits and vegetables. (The one-fourth of the public that eats the most fruits and vegetables has just half the total cancer risk of the one-fourth that eats the least. Only about 10 percent of the population eat the recommended five-a-day servings of fruits and vegetables.) Very few occupational cancers exist; most are among asbestos workers and some from hard-rock miners exposed to radon. Adding a few cases of cancer from drinking alcohol (a well-known carcinogen) pretty much completes the catalogue of "environmental" cancers that afflict humans.

This is not to say that a cancer epidemic doesn't exist in the world's wealthier countries. The culprit, however, is not an environmental menace but something that is a fact of life: old age. With a few rare exceptions, cancer is a disease of old age. In 1900, average life expectancy in the United States was only about forty-five years, and cancer rates were much lower. Today, the average life expectancy is rapidly closing in on eighty years. As life spans lengthen, cancer diagnoses will undoubtedly increase.

Cancer rates, then, are indeed becoming more prevalent, but that is certainly the lesser of two evils. Doctors are diagnosing more cancers, but that's also good news. In George Washington's day, cancer victims died of "wasting disease" or some such homegrown label, with no hope of a cure or even much relief. They'd be dosed with morphine and bled with leeches, but they certainly wouldn't be cured. My Aunt Virginia, by contrast, was diagnosed with breast cancer in 1983 while in her late seventies but was cured and lived another decade. Cancer mortality (other than lung cancer) has fallen more than 16 percent in the United States since 1950. Lung cancer mortality is up overall because more women smoke.

Food is really not a key source of cancer. Some analysts blame pesticides, but there is no evidence whatever that any pesticide causes cancer in humans. The myth derives from Rachel Carson's erroneous claim, in her wildly popular book Silent Spring (1962), that six or seven of the pesticides then in use caused human cancer. Both Carson and her followers, moreover, totally missed the biggest food-cancer danger in history: lead arsenate. Every year from 1900 to 1950, farmers used millions of pounds of lead arsenate, a lethal, sky-blue powder made of—you guessed it—lead and arsenic. They sprayed it on apples and dusted it on cabbages and kohlrabi. Scientists didn't know that it was carcinogenic, of course, thinking it was just severely poisonous. As a precaution, consumers simply washed their food carefully. I used to dust it on our garden from a burlap bag, wearing my usual T-shirt and jeans. To this day, lead arsenate is the only pest-control substance we have ever put on food crops that we now know can truly cause human cancer. (I'm sixty-three and fortunately have not developed cancer yet.)

Farmers haven't used lead arsenate since 1950 because modern pesticides are far safer. Yes, some of the new pesticides cause tumors in rats at high doses, but so do half of nature's compounds. In fact, half of everything ever tested on rats causes tumors at high doses. At lower doses (ten to one hundred times expected human exposures), almost none of the chemicals now being used in agriculture cause rat tumors.

Bruce Ames, the famed toxicologist who was awarded last year's National Science Medal, says that plants contain thousands of natural pesticides. The plants manufacture them for self-protection. These make up 99.9 percent of the pesticides we ingest. Coffee contains more than one thousand natural chemicals. Twenty-eight of them have been tested, and nineteen of those cause tumors in rats at high doses. No one has scientifically linked either coffee or today's food supply to a cancer epidemic.