Smokers inhale a measurable amount of polonium-210 each year, a radioactive element naturally present in tobacco leaves due to environmental contamination and the use of phosphate fertilizers. Polonium-210 is an alpha-emitting radioactive isotope that accumulates in tobacco plants, and when tobacco is burned and smoked, this polonium is released in the smoke and inhaled into the lungs.
The amount of polonium-210 inhaled by a smoker annually depends on several factors, including the number of cigarettes smoked per day, the polonium content per cigarette, and the efficiency of polonium transfer from tobacco to smoke. On average, a single cigarette contains about 0.03 to 0.1 picocuries (pCi) of polonium-210. Given that one picocurie corresponds to a very small amount of radioactive material, this still represents a significant health risk because polonium-210 emits alpha particles, which cause intense localized damage to lung tissue when inhaled.
If a smoker consumes about 20 cigarettes per day, the annual intake of polonium-210 can be roughly estimated as follows:
– Polonium-210 per cigarette: approximately 0.05 pCi (mid-range estimate)
– Cigarettes per day: 20
– Days per year: 365
Annual polonium-210 inhalation = 0.05 pCi × 20 × 365 = 365 pCi per year
This translates to about 365 picocuries of polonium-210 inhaled annually by a typical smoker. In terms of mass, this is on the order of a few nanograms of polonium-210 per year, but because of its intense radioactivity, even these tiny amounts are biologically significant.
The danger of polonium-210 lies in its alpha radiation, which cannot penetrate the skin but causes severe damage when alpha particles are emitted inside the body, particularly in lung tissue. The alpha particles emitted by polonium-210 can break DNA strands and cause mutations, significantly increasing the risk of lung cancer. Studies estimate that polonium-210 in cigarette smoke contributes to thousands of lung cancer cases worldwide each year.
Tobacco plants are natural accumulators of polonium-210 because they absorb it from the soil and from fertilizers containing uranium and radium decay products. This polonium then concentrates in the tobacco leaves. When tobacco is burned, polonium-210 attaches to smoke particles and is inhaled deep into the lungs, where it deposits and irradiates lung cells over time.
The half-life of polonium-210 is about 138 days, meaning it remains radioactive for several months after being deposited in the lungs, continuously emitting alpha particles during this period. This prolonged exposure to alpha radiation in lung tissue is a key factor in the carcinogenicity of smoking.
Efforts to reduce polonium-210 in tobacco have been limited and challenging because the contamination is environmental and linked to the natural decay chains of uranium and radium in phosphate fertilizers and soil. Tobacco companies have researched ways to remove or reduce polonium-210 but have not developed a complete solution.
In summary, a regular smoker inhales several hundred picocuries of polonium-210 annually, a small mass but a potent radioactive dose that contributes significantly to the health risks of smoking, especially lung cancer. This radioactive contamination is a hidden but critical factor in tobacco’s toxicity, adding to the well-known harms of nicotine and tar.
