In general, alpha radiation is of small risk to humans. Compared to its cousins, beta and gamma particles, alpha radiation has an extremely low penetration depth and is often completely blocked by the outer layers of skin or even the surrounding air. Although external exposure poses little to no risk to humans, internal exposure, such as through inhalation or ingestion, can prove to be extremely damaging to the body.
Because of the nature of most alpha particle exposure, which comes from inhaling a naturally occurring gas in soil and rock known as radon, lung cancer is the most common negative result. According to the Environmental Protection Agency, alpha particle exposure attributable to radon inhalation is estimated to cause 21,000 deaths a year in the United States. Lung cancer can also be caused by the alpha-emitting isotope polonium-210, which is present in tobacco smoke.
Drinking water contaminated with alpha radiation can cause kidney damage. The radiation attacks the renal system as it moves through the body. According to the State of Vermont, this risk stems mostly from the presence of uranium in the water supply.
According to a study conducted by German Professor Wolfgang Köhnlein, alpha radiation is 20 times more damaging than gamma particles once inside the body. This potency can cause damage to chromosomes, which results in an increased probability of cancer and other diseases in the affected individual.
Higher levels of exposure to alpha radiation can result in a case of radiation poisoning. Depending on the dose, the body can suffer from minor symptoms, ranging from nausea and headaches during the first few days to almost certain death in extreme cases. In 2006 former Russian spy Alexander Litvinenko was poisoned with a large dose of Po-210 and died of radiation poisoning.