Cancer is terrible enough--still resisting cure 25 years after President Richard Nixon declared war on it, often intractably painful, and lamentably frequent. In 1994 the United States recorded 538,000 deaths from cancer, more than a fifth of the nation’s total. Yet bad as it is clinically, the fear it inspires magnifies its agony. We can’t trace cancer to any single agent or fateful event. It claws its way into existence out of the billions of complex interactions that make up our cellular biochemistry; its causes, as a decades-old drumbeat of research demonstrates, are myriad. Some are inherited--like the gene called BRCA-1, whose malfunction appears to be a component in many cases of breast cancer. But many are environmental and hence presumably avoidable: asbestos, infamously; tobacco; air pollution; a diet low in vegetables and fruits; alcohol; the ultraviolet radiation in sunlight.
If we could count out the dangers on the fingers of one or two or even a dozen hands, we might consider ourselves forearmed. But as researchers screen more and more substances, a dizzying number emerge from the lab festooned with skull and crossbones. Peanut butter, mustard, mushrooms, all-natural root beer--they’ve all been found to contain at least trace amounts of known carcinogens. So long has the list of possible carcinogens become that a certain cynicism has set in. Are you really courting malignancy every time you crunch a slice of bacon or take in a deep draft of your mobile home’s formaldehyde-laden air? Is life itself the ur-carcinogen?
On the face of it, there’s no good reason to flout the warnings. The animal experiments traditionally used to measure toxicity are eminently sensible. Researchers dose a population of laboratory-bred rats or mice with a suspect substance for an extended period of time, then measure the number of tumors that appear against a control population of genetically similar rodents that haven’t been given the test chemical. If the exposed animals show a significant rise in malignancies, the implication seems clear: you’ve found a carcinogen.
