Newly analyzed historical documents reveal that tobacco companies have known for decades that cigarettes contain polonium-210, a radioactive material, and covered up its own studies that found their products caused cancerous growths in smokers’ lungs.

ABC News reports University of Southern California researchers reviewed the documents and found that, over 25 years, the radiation in their products caused 138 deaths for every 1,000 smokers.

Polonium-210, which is also found in low levels in nature, is still in cigarettes today. Scientists have found that the radioactive substance damages lung tissue and work in concert with other carcinogens in cigarettes to put smokers at risk of cancer.

Tobacco Companies Knew of Radiation in Cigarettes, Covered It Up [ABC News]

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