Source: USA Today Tobacco companies knew for decades that cigarette smoke was radioactive and potentially carcinogenic but kept that information from the public, according to a new study. The tobacco industry began investigations into the possible effects of these radioactive particles, identified as polonium-210, on smokers as early as the 1960s, says the study by UCLA researchers who analyzed dozens of previously unexamined industry documents. "I've not seen a document before that's specifically cited the industry's own internal research finding that sufficient levels of polonium-210 can cause cancer," says Matt Myers of the Campaign for Tobacco-Free Kids. He says the study reinforces the need for the U.S. Food and Drug Administration to scrutinize tobacco products. This week, the FDA began requiring tobacco companies to disclose detailed information about new products and changes to existing ones. The study, published in the peer-reviewed journal Nicotine & Tobacco Research, suggests the FDA make removal of the radioative particles from tobacco products a top priority. "We used to think that only the chemicals in the cigarettes were causing lung cancer," said Hrayr S. Karagueuzian, lead author of the study. Now, Karagueuzian said, the industry's own research shows that polonium-210, absorbed by tobacco leaves and inhaled by smokers, is dangerous. He said UCLA researchers found that the radioactivity could cause 120 to 138 deaths for every 1,000 regular smokers over a 25-year period. Karagueuzian said tobacco companies have declined techniques that could help eliminate polonium-210 from tobacco because of concern that smokers might lose the "instant [...]