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The tobacco leaves used in making cigarettes contain radioactive material, particularly lead-210 and polonium-210. The radionuclide content of tobacco leaves depends heavily on soil conditions and fertilizer use.
Soils that contain elevated radium lead to high radon gas emanations rising into the growing tobacco crop.
Radon rapidly decays into a series of solid, highly radioactive metals (radon decay products). These metals cling to dust particles which in turn are collected by the sticky tobacco leaves.
The sticky compound that seeps from the trichomes is not water soluble, so the particles do not wash off in the rain. There they stay, through curing process, cutting, and manufacture into cigarettes.
Lead-210 and Polonium-210 can be absorbed into tobacco leaves directly from the soil. But more importantly, fine, sticky hairs (called trichomes) on both sides of tobacco leaves grab airborne radioactive particles.
For example, phosphate fertilizers, favored by the tobacco industry, contain radium and its decay products (including lead-210 and polonium-210). When phosphate fertilizer is spread on tobacco fields year after year, the concentration of lead-210 and polonium-210 in the soil rises.
According to the American Lung Association, there are about 48 million adult smokers in the U.S., and 4.8 million adolescent smokers. This means that the U.S., population, directly exposed to radioactivity in cigarette smoke, is approximately 53 million.
According to the Centers for Disease Control and Prevention, 80 percent of adult tobacco users started smoking as teens; 35 percent had become daily smokers by age 18. Thirty nine percent of adult smokers smoke one pack of cigarettes per day, and 20% smoke more than a pack a day.
But what happens when I smoke a cigarette?
Research indicates that lead-210 and polonium-210 are present in tobacco smoke as it passes into the lung. The concentration of lead-210 and polonium-210 in tobacco leaf is relatively low, however, this low concentration can accumulate into very high concentrations in the lungs of smokers.
As it passes into the lungs, the smoke impacts the branches of the lung passages, called bronchioles, where the branches split. Tar from tobacco smoke builds up there, and traps lead-210 and polonium-210 against the sensitive tissues of the bronchioles. Studies show filters on ordinary commercial cigarette remove only a modest amount of radioactivity from the smoke inhaled into the lungs of smokers.
Most of what is deposited is lead-210, but polonium-210 (whose half life is about 138 days) quickly grows in as the lead-210 (half life = 22.3 years) decays and becomes the dominant radionuclide. Over time, the concentration of polonium-210 directly on tissues of the bronchioles grows very high, and intense localized radiation doses can occur at the bronchioles.
There is very little information concerning radioactivity in cigar, pipe, or smokeless tobacco, or on the potential health effects from radioactivity in tobacco products other than cigarettes.
From the
Swiss Federal Office of Public Health
(FOPH) site:
Radon - what is it?
Radon is a rare gas formed in the earth's crust by the radioactive decay of uranium. Since it is a gas, it can readily enter buildings through gaps and become a component part of the ambient air we breathe. The ultimate decay of radon into lead, polonium and bismuth releases radioactivity that is capable of irradiating lung tissues. This irradiation can cause malignant tumours.
In Switzerland, radon is responsible for around 40 % of the annual radiation sustained by the population.
Is radon dangerous?
In Switzerland, 8.5 % of lung cancers are attributable to radon. This gas accounts for 240 deaths a year and is the second biggest cause of lung cancer after smoking.
Radon is the most dangerous carcinogenic substance in a residential environment. However, people can protect themselves through various constructional measures.
For more information
U.S. Environmental Protection Agency - EPA
See also
Drugs Block Deadly Harm from Radiation Exposure (19/07/2012)
Novel biomarkers reveal evidence of radiation exposure (03/07/2012)
(MDN)
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