by What are Alpha Emitters?
They are a category of radioactive isotopes that emit alpha particles as they undergo radioactive decay.
Key Properties of Alpha Particles
Alpha particles consist of two protons and two neutrons bound together, which makes them identical to a helium-4 nucleus. They have a +2 elementary charge and relatively large mass, giving them high energy over a short range. Within tissue or air, alpha particles can only travel a few centimeters at most before losing their energy.
Biological Effects of Alpha Radiation
Despite their low penetration depth, alpha particles are densely ionizing and can cause significant biological damage if alpha-emitting isotopes are inhaled, ingested or absorbed. Close proximity to an alpha source inside or near cells can destroy DNA and kill cells. This makes alpha emitters particularly dangerous when they enter the body, as alpha radiation exposures are associated with higher relative biological effectiveness than extern exposures.
Examples
Some common alpha emitting isotopes used in applications and present in the natural environment include:
– Uranium-238 – A long-lived primordial isotope and major component of uranium found in rocks and soil. It is responsible for most natural alpha radiation exposure through ingestion or inhalation.
– Radium-226 – A daughter product of uranium-238 decay and present at low levels in nature. It was historically used in self-luminous paint and clock dials prior to the biological effects being known.
– Plutonium-239 – A man-made transuranic element produced for nuclear applications. Its various isotopes were major components of nuclear weapons and are of radiological concern from nuclear fuel cycles.
– Thorium-232 – A naturally-occurring actinide present at low levels that mainly decays by alpha emission. It is slightly less abundant than uranium in the Earth’s crust.
– Polonium-210 – A rare, highly radioactive isotope best known from the poisoning of Alexander Litvinenko in 2006. It finds some uses as an antistatic agent.
Radiation Protection against Alpha Emitters
Standard radiation protection principles apply to alpha emitters to reduce exposure and limit intake into the body. As alpha radiation poses little external hazard, protecting against inhalation and ingestion is the priority. Proper handling procedures and containment within sealed sources prevents their dispersal. Personal protective equipment like respiratory protection and special handling tools are employed when working with unsealed alpha-emitting materials. Strict decontamination is required to avoid dispersing any contamination. Due to their high effectiveness at causing biological damage internally, alpha emitters demand meticulous controls to limit internal exposure.
Health Risks from Alpha Particle Exposure
Epidemiological studies have provided significant evidence that exposure to alpha emitting radionuclides increases cancer risks, particularly for leukemia and specific solid organ cancers:
– Inhalation of radon gas and its short-lived decay products in mines and homes is established as a cause of lung cancer. The risk depends strongly on cumulative exposure levels over time.
– Thousands of cases of lung cancer have been associated with exposure to plutonium particles inhaled following nuclear weapons tests and accidents. Risk is linked to particle size affecting deposition in lungs.
– workers exposed to radium luminous compound paints experienced very high incidences of bone cancers decades later due to radium deposition in bone.
– internal contamination incidents involving polonium-210 and americium-241 have led to fatal exposures at extremely low intake levels due to their high alpha energies.
Overall, inhaled or ingested alpha emitting particles are classified as Group 1 carcinogens by the International Agency for Research on Cancer based on consistent epidemiological evidence. Precautions against internal exposure are therefore paramount.
While alpha particles present a high density of ionization over only short tissue ranges, the radionuclides that emit them can be extremely hazardous if introduced into the body through inhalation, ingestion or absorption. Understanding their physical properties and biological effects is key to applying proper safety measures and radiation protection practices against internal exposures to alpha emitters in various applications and environmental settings. With care taken to control and restrict intake, risks from these isotopes can be effectively managed.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
