The history of the discovery of the cigarette-lung cancer link: evidentiary traditions, corporate denial, global toll.

Lung cancer was once a very rare disease, so rare that doctors took special notice when confronted with a case, thinking it a once-in-a-lifetime oddity. Mechanisation and mass marketing towards the end of the 19th century popularised the cigarette habit, however, causing a global lung cancer epidemic. Cigarettes were recognised as the cause of the epidemic in the 1940s and 1950s, with the confluence of studies from epidemiology, animal experiments, cellular pathology and chemical analytics. Cigarette manufacturers disputed this evidence, as part of an orchestrated conspiracy to salvage cigarette sales. Propagandising the public proved successful, judging from secret tobacco industry measurements of the impact of denialist propaganda. As late as 1960 only one-third of all US doctors believed that the case against cigarettes had been established. The cigarette is the deadliest artefact in the history of human civilisation. Cigarettes cause about 1 lung cancer death per 3 or 4 million smoked, which explains why the scale of the epidemic is so large today. Cigarettes cause about 1.5 million deaths from lung cancer per year, a number that will rise to nearly 2 million per year by the 2020s or 2030s, even if consumption rates decline in the interim. Part of the ease of cigarette manufacturing stems from the ubiquity of high-speed cigarette making machines, which crank out 20,000 cigarettes per min. Cigarette makers make about a penny in profit for every cigarette sold, which means that the value of a life to a cigarette maker is about US$10,000.