Cigarette smoke radioactivity and lung cancer risk.

Introduction: To determine the tobacco industry's policy and action with respect to radioactive polonium 210 ((210)Po) in cigarette smoke and to assess the long-term risk of lung cancer caused by alpha particle deposits in the lungs of regular smokers.

Methods: Analysis of major tobacco industries' internal secret documents on cigarette radioactivity made available online by the Master Settlement Agreement in 1998.

Results: The documents show that the industry was well aware of the presence of a radioactive substance in tobacco as early as 1959.