Tobacco companies knew of the presence of cancer causing particles (radioactive alpha particles) in cigarette smoke for more than four decades but they kept their findings from the public, claim UCLA researchers.
They found the secret after analysing dozens of previously unexamined internal tobacco industry documents, made available in 1998 as the result of a legal settlement.
The documents reveal that the industry was aware of cigarette radioactivity some five years earlier than previously thought and that tobacco companies, concerned about the potential lung cancer risk, began in-depth investigations into the possible effects of radioactivity on smokers as early as the 1960s.
"The documents show that the industry was well aware of the presence of a radioactive substance in tobacco as early as 1959," the researchers said.
"They knew that the cigarette smoke was radioactive way back then and that it could potentially result in cancer, and they deliberately kept that information under wraps," said the study's first author, Hrayr S. Karagueuzian, a professor of cardiology.
"Specifically, we show here that the industry used misleading statements to obfuscate the hazard of ionizing alpha particles to the lungs of smokers and, more importantly, banned any and all publication on tobacco smoke radioactivity," he added.
The study has been published online Sept. 27 in Nicotine and Tobacco Research.