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.

Nevertheless, much scientific “uncertainty” about the causes of disease is not real, but manufactured. Years ago, a tobacco executive unwisely committed to paper the perfect slogan for his industry’s disinformation campaign: “Doubt is our product.” For 50 years, tobacco companies employed a stable of scientists to assert (sometimes under oath) that they did not believe there was conclusive evidence that smoking cigarettes causes lung cancer.

Less well known, but following the same pattern, are efforts being mounted to question studies documenting the adverse health effects of exposure to lead, mercury, vinyl chloride, chromium, beryllium, benzene, and a long list of pesticides and other toxic chemicals. Polluters and manufacturers of dangerous products hire experts in what they call “product defense” to dissect every study whose findings they oppose, highlighting flaws and inconsistencies. In many cases, they won’t deny that a relationship exists between the exposure and the disease, but are quick to proclaim that “the evidence is inconclusive.”

These industries have learned that by focusing the debate on uncertainties in the science (and the need for more research), it is possible to avoid a debate on public policy. This can delay for years the expenditures required to protect people’s health and the environment.

Nowadays, the most well known (and probably best financed) campaign to manufacture scientific doubt is being waged by the fossil fuel industry in an effort to impugn scientists’ work on issues related to climate change. When confronted by an overwhelming worldwide scientific consensus on the contribution of human activity to global warming over the past century, the industry and its political allies follow the tobacco road.

Evidence of this surfaced when Frank Luntz, a leading Republican political consultant, sent a strategy memo to his clients in 2002. Luntz asserted that “ The scientific debate remains open. Voters believe that there is no consensus about global warming in the scientific community. Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly.”

In parallel to their attempts to delay or prevent regulation through assertions of scientific uncertainty, polluters and manufacturers of hazardous products have promoted the “junk science” movement, which attempts to influence public opinion by ridiculing scientists whose research threatens powerful interests, irrespective of the quality of that scientist’s research. “Junk science” advocates allege that many scientific studies (and even scientific methods) used in the regulatory and legal arenas are fundamentally flawed, contradictory, or incomplete.

Every first-year public health student is taught how John Snow stopped a cholera epidemic in London. During a ten-day period in September 1854, during which more than 500 Londoners died from the disease, Snow used a city map to mark the location of each household with a case of cholera. He determined that Londoners who drank from one particular water source were at the highest risk for the disease, and he recommended removal of the handle from the pump supplying drinking water from that source.

By using the best evidence available at the time, hundreds of additional deaths were avoided. If government officials in London had demanded absolute certainty, the epidemic might have continued for another 30 years until the cholera bacterium was identified.

The manufacturing of scientific uncertainty endangers the public’s health, as well as programs to protect public health and to compensate victims. It is time to return to first principles: use the best science available, but do not demand certainty where it does not exist.