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On this day in 1964, U.S. Surgeon General Luther Terry issued a definitive report that linked smoking cigarettes with lung cancer. The 150,000-word report was assembled by 10 scientists (half of them were smokers) and released on a Saturday, partly out of fear that the findings might disrupt the stock market. Decades later, the national battle to curb smoking still smolders.

What Americans knew about the hazards of cigarettes in 1964 was largely unsettled, thanks to a publicity offensive waged by tobacco companies. Since the early 1950s, studies had asserted that smoking led to fatal illnesses, but cigarette manufacturers didn't go gently, calling the claims inconclusive and citing the development of filters as a means to keep toxins from reaching smokers. Aficionados of the AMC show Mad Men might recall the pilot episode's key tension revolves around the development of a (pre-1964) strategy to combat the claims that cigarettes were poisonous. "It's toasted!" becomes the chosen maxim of obfuscation.

But the Terry Report changed all of that. "In comparison with non-smokers, average male smokers of cigarettes have approximately a 9-to-10-fold risk of developing lung cancer and heavy smokers at least a 20-fold risk," the report read. At that point, over 42 percent of American adults were smokers.