Editing Alpha decay (section)

== Toxicity ==
Highly charged and heavy, alpha particles lose their several [[MeV]] of energy within a small volume of material, along with a very short [[mean free path]]. This increases the chance of [[double-strand break]]s to the DNA in cases of internal contamination, when ingested, inhaled, injected or introduced through the skin. Otherwise, touching an alpha source is typically not harmful, as alpha particles are effectively shielded by a few centimeters of air, a piece of paper, or the thin layer of dead skin cells that make up the [[epidermis]]; however, many alpha sources are also accompanied by [[beta decay|beta-emitting]] radio daughters, and both are often accompanied by gamma photon emission.

[[Relative biological effectiveness]] (RBE) quantifies the ability of radiation to cause certain biological effects, notably either [[cancer]] or [[necrosis|cell-death]], for equivalent radiation exposure. Alpha radiation has a high [[linear energy transfer]] (LET) coefficient, which is about one ionization of a molecule/atom for every [[angstrom]] of travel by the alpha particle. The RBE has been set at the value of 20 for alpha radiation by various government regulations. The RBE is set at 10 for [[neutron]] irradiation, and at 1 for [[Beta decay|beta radiation]] and ionizing photons.

However, the [[Atomic recoil|recoil]] of the parent nucleus (alpha recoil) gives it a significant amount of energy, which also causes ionization damage (see [[ionizing radiation]]). This energy is roughly the weight of the alpha ({{val|4|ul=Da}}) divided by the weight of the parent (typically about 200&nbsp;Da) times the total energy of the alpha. By some estimates, this might account for most of the internal radiation damage, as the recoil nucleus is part of an atom that is much larger than an alpha particle, and causes a very dense trail of ionization; the atom is typically a [[heavy metal (chemistry)|heavy metal]], which preferentially collect on the [[chromosome]]s. In some studies,<ref>
{{cite journal
 |author=Winters TH, Franza JR
 |year=1982
 |title=Radioactivity in Cigarette Smoke
 |journal=[[New England Journal of Medicine]]
 |volume=306 |issue=6 |pages=364–365
 |doi=10.1056/NEJM198202113060613
 |pmid=7054712
}}</ref> this has resulted in an RBE approaching 1,000 instead of the value used in governmental regulations.

The largest natural contributor to public radiation dose is [[radon]], a naturally occurring, radioactive gas found in soil and rock.<ref>{{Cite web |url=http://www.ans.org/pi/resources/dosechart/ |title=ANS: Public Information: Resources: Radiation Dose Chart<!-- Bot generated title --> |access-date=2007-10-31 |archive-date=2018-07-15 |archive-url=https://web.archive.org/web/20180715152300/http://www.ans.org/pi/resources/dosechart/ |url-status=dead }}</ref> If the gas is inhaled, some of the radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting alpha particles, which can damage cells in the lung tissue.<ref>EPA Radiation Information: Radon. October 6, 2006, [http://www.epa.gov/radiation/radionuclides/radon.htm] {{Webarchive|url=https://web.archive.org/web/20060426072741/http://www.epa.gov/radiation/radionuclides/radon.htm|date=2006-04-26}}, Accessed December 6, 2006,</ref> The death of [[Marie Curie]] at age 66 from [[aplastic anemia]] was probably caused by prolonged exposure to high doses of ionizing radiation, but it is not clear if this was due to alpha radiation or X-rays. Curie worked extensively with radium, which decays into radon,<ref>Health Physics Society, "Did Marie Curie die of a radiation overexposure?" [http://www.hps.org/publicinformation/ate/q535.html] {{Webarchive|url=https://web.archive.org/web/20071019220501/https://hps.org/publicinformation/ate/q535.html|date=2007-10-19}}</ref> along with other radioactive materials that emit [[beta decay|beta]] and [[gamma ray]]s. However, Curie also worked with unshielded X-ray tubes during World War I, and analysis of her skeleton during a reburial showed a relatively low level of radioisotope burden.

The Russian defector [[Alexander Litvinenko]]'s 2006 murder by [[radiation poisoning]] is thought to have been carried out with [[polonium-210]], an alpha emitter.