A quantitative risk assessment for chronic traumatic encephalopathy (CTE) in football: How public health science evaluates evidence

How should science and policy interpret the recent finding that 110 of 111 former National Football League (NFL) players had brain pathology known as chronic traumatic encephalopathy (CTE) at autopsy? Some physicians view this (and related epidemiologic and mechanistic evidence) skeptically, emphasizing that the association between repeated head trauma (RHT) and CTE may be artifactual, that this “incidence” is biased by self-selection of players with cognitive or emotional symptoms, and that even if RHT causes CTE, the lesions themselves may be inconsequential. Public health scientists look at this emerging evidence quite differently; in particular, they tend not to fall prey to certain illogical arguments justifying inaction. We present a quantitative risk assessment showing that even accounting for the non-representativeness of the 110 cases, the risk of CTE in the NFL workforce amply meets both parts of the test for “a significant risk of material impairment of health” that would permit the U.S. Occupational Safety and Health Administration to intervene to reduce RHT exposure. We further conclude that according to available evidence, CTE is a public health problem, and that lawyers and physicians need to understand that this conclusion is based on standards of evidence at least as long-standing and robust as their own.