 In addition to the acute effects, radiation exposure (both internal and external) carries a long-term risk of death from cancer of 5 – 10 % per Sv. The general population is exposed to small amounts of polonium as a radon daughter in indoor air; the isotopes 214Po and 218Po are thought to cause the majority of the estimated 15,000 – 22,000 lung cancer deaths in the US every year that have been attributed to indoor radon. Tobacco smoking causes additional exposure to polonium.
