Alpha-particle - Biological Effects

Biological Effects

Because of the short range of absorption, alphas are not, in general, dangerous to life unless the source is ingested or inhaled, in which case they become extremely dangerous. Because of this high mass and strong absorption, if alpha-emitting radionuclides do enter the body (upon being inhaled, ingested, or injected, as with the use of Thorotrast for high-quality X-ray images prior to the 1950s), alpha radiation is the most destructive form of ionizing radiation. It is the most strongly ionizing, and with large enough doses can cause any or all of the symptoms of radiation poisoning. It is estimated that chromosome damage from alpha particles is anywhere from 10 to 1000 times greater than that caused by an equivalent amount of gamma or beta radiation, with the average being set at 20 times. The powerful alpha emitter polonium-210 (a milligram of 210Po emits as many alpha particles per second as 4.215 grams of 226Ra) is suspected of playing a role in lung cancer and bladder cancer related to tobacco smoking. 210Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006.

Not only do alphas themselves cause damage, but approximately equal ionization is caused by the recoiling nucleus after alpha emission, and this energy may in turn be especially damaging to genetic material, since the positive cations of many soluble transuranic elements that emit alphas, are chemically attracted to the net negative charge of DNA, causing the recoiling atomic nucleus to be in close proximation to the DNA.