Manufacturing Scientific Uncertainty

For decades, the tobacco industry manufactured more than just cigarettes. While aggressively marketing tobacco products, they also waged a successful public relations campaign designed to create uncertainty about the destructive and lethal characteristics of their products. Though discovery of these efforts has come too late for many tobacco smokers, documents unearthed in lawsuits have revealed concerted efforts to avoid the imposition of government regulation by attacking public health science and scientists.

There are few scientific challenges more complex than understanding the causes of disease in humans. Scientists cannot feed toxic chemicals to people, for example, to see what doses cause cancer. Instead, scientists must harness the “natural experiments” in which exposures have already occurred.

To be sure, in the laboratory, scientists use animals in controlled experimental conditions to investigate the workings of toxic agents. But, like epidemiological evidence, laboratory studies have many uncertainties, and scientists must extrapolate from study-specific evidence to make judgments about causation and recommend protective measures. Absolute certainty is rarely an option.