Tobacco companies knew that cigarettes contained a radioactive substance called polonium-210, but hid that knowledge from the public for over four decades, a new study of historical documents revealed. Scientists from the University of California, Los Angeles, reviewed 27 previously unanalyzed documents and found that tobacco companies knew about the radioactive content of cigarettes as early as 1959. The companies studied the polonium throughout the 1960s, knew that it caused "cancerous growths" in the lungs of smokers, and even calculated how much radiation a regular smoker would ingest over 20 years. Then, they kept that data secret. Hrayr Karagueuzian, the study's lead author, said the companies' level of deception surprised him...David Sutton, a spokesman for Philip Morris USA [part of Altria], the largest U.S. tobacco manufacturer, said the public health community has known about polonium in tobacco for decades.