Tobacco companies have known for half a century that cigarette smoke contains radioactive alpha-particles that can cause hot-spot tumors in human lungs, and they kept the information secret for half a decade.
The information came to light after unexamined internal documents were made public in 1998 following a legal settlement. Researchers from University of California Los Angeles (UCLA) examined the papers and have just published their findings, noting that "the industry was well aware of the presence of a radioactive substance in tobacco as early as 1959. Furthermore, the industry was not only cognizant of the potential 'cancerous growth' in the lungs of regular smokers, but also did quantitative radiobiological calculations to estimate the long-term lung radiation absorption dose of ionizing alpha particles emitted from cigarette smoke."
Radioactive particles in tobacco smoke
The alpha-particles are emitted by a radioactive isotope, Polonium-210, which is still present in all domestic and foreign cigarette brands today according to the study's authors. The isotope is absorbed by tobacco leaves through radon gas in the atmosphere, and is also taken in from the high-phosphate content fertilizers used to stimulate growth of tobacco plants. The radioactive particles are inhaled by smokers into the lungs, and also by non-smokers who frequent environments where tobacco smoke is in the air.
Lung Cancer and Hot Spots
According to the authors, the radioactive polonium-210 alpha particles bind with resins in the cigarette smoke and when inhaled, accumulate in the junctions where bronchial tubes divide, causing hot spots. These hot spots are areas of malignant growths in lung tissue, which has been observed countless times during autopsies of the lungs of people who have died from lung cancer.
"We used to think that only the chemicals in the cigarettes were causing lung cancer," Karagueuzian said. "But the case of the these hot spots, acknowledged by the industry and academia alike, makes a strong case for an increased probability of long-term development of malignancies caused by the alpha particles. If we're lucky, the alpha particle-irradiated cell [in the lungs] dies. If it doesn't, it could mutate and become cancerous."
The Solution Wasn't Acted On
Tobacco companies were presented with solutions to the Polonium problem in 1959 and again in 1980 when an acid wash treatment was found to be highly effective at removing most of the isotope from the tobacco leaves. Yet the industry chose not to use the technique because it would make the cigarettes less addictive, which would ultimately reduce sales and lower profits.
"The industry was concerned that the acid media would ionize the nicotine, making it more difficult to be absorbed into the brains of smokers and depriving them of that instant nicotine rush that fuels their addiction," Karagueuzian said. "The industry also were well aware that the curing of the tobacco leaves for more than a one-year period also would not eliminate the polonium-210, which has a half-life of 135 days, from the tobacco leaves because it was derived from its parent, lead-210, which has a half-life of 22 years."
If you smoke, realize that tobacco companies are not on your side; they want to provide you with a product that they know sends radioactive particles into your body and can kill you - they've also done their best to keep it secret for close to 50 years.
Ask yourself these questions: Why do you want to give your money to companies that want to hide the fact that their product kills you? What else could you do with the money? What other methods can you use to release stress instead of smoking?
Karagueuzian, H. S., White, C., Sayre, J., & Norman, A. (2011). Cigarette smoke radioactivity and lung cancer risk. Nicotine and Tobacco Research, 10.1093/ntr/ntr145.