We Should Celebrate, Not Censor, Learning From Epidemiologic History.

The controversy over whether repeated head impact (RHI)-a feature of occupations including professional contact sports, military service, firefighting, and logging-can cause the neurodegenerative disease now known as CTE (chronic traumatic encephalopathy) has thrust many positive epidemiologic studies into the spotlight. Various skeptics who dispute that the relationship is strong and causal continue to raise objections to these studies and their interpretation. The arguments these skeptics use remind other observers of many past sagas of "manufactured doubt," particularly the history of attempts to cast doubt on the propensity of tobacco products to cause lung cancer. A recent article in the Journal of Science and Medicine in Sport3 complained that drawing the parallel between RHI and cigarettes is unhelpful, concluding that "the time for politically motivated analogies has now passed." This author disagrees, and explains in detail 2 scientific aspects of risk assessment and management that make the analogy apt and instructive for the future. In particular, I argue that the problem of "manufactured doubt" here is two-fold: it relies on various fallacies of reasoning discussed herein, but more importantly, it seeks to divert and delay the utilitarian imperative-while we grope toward the ever-elusive certainty, there are many low-regret actions we can and should take on the basis of persuasive signals of harm.