Polonium -210 is the only component of cigarette smoke that has produced cancer by itself in laboratory animals by inhalation - tumors appeared already at a polonium level five times lower than those of a normal heavy smoker.

Lung cancer rates among men kept climbing from a rarity in 1930 (4/100,000 per year) to the No. 1 cancer killer in 1980 (72/100,000) in spite of an almost 20 percent reduction in smoking. But during the same period, the level of polonium -210 in American tobacco had tripled. This coincided with the increase in the use of phosphate fertilizers by tobacco growers - calcium phosphate ore accumulates uranium and slowly releases radon gas.

Read more: [link to www.lenntech.com]