
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirable (from the
International Atomic Energy Agency
The International Atomic Energy Agency (IAEA) is an intergovernmental organization that seeks to promote the peaceful use of nuclear technology, nuclear energy and to inhibit its use for any military purpose, including nuclear weapons. It was ...
(IAEA) definition).
Such contamination presents a hazard because the
radioactive decay
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
of the contaminants produces
ionizing radiation
Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...
(namely
alpha
Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...
,
beta
Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...
,
gamma ray
A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...
s and
free neutron
The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the f ...
s). The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable.
The sources of radioactive pollution can be classified into two groups: natural and man-made. Following an atmospheric nuclear weapon discharge or a nuclear reactor
containment
Containment was a Geopolitics, geopolitical strategic foreign policy pursued by the United States during the Cold War to prevent the spread of communism after the end of World War II. The name was loosely related to the term ''Cordon sanitaire ...
breach, the air, soil, people, plants, and animals in the
vicinity will become contaminated by
nuclear fuel
Nuclear fuel refers to any substance, typically fissile material, which is used by nuclear power stations or other atomic nucleus, nuclear devices to generate energy.
Oxide fuel
For fission reactors, the fuel (typically based on uranium) is ...
and
fission products. A spilled vial of
radioactive material
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...
like
uranyl nitrate
Uranyl nitrate is a water-soluble yellow uranium salt with the formula . The hexa-, tri-, and dihydrates are known. The compound is mainly of interest because it is an intermediate in the preparation of nuclear fuels. In the nuclear industry, it ...
may contaminate the floor and any rags used to wipe up the spill. Cases of widespread radioactive contamination include the
Bikini Atoll
Bikini Atoll ( or ; Marshallese language, Marshallese: , , ), known as Eschscholtz Atoll between the 19th century and 1946, is a coral reef in the Marshall Islands consisting of 23 islands surrounding a central lagoon. The atoll is at the no ...
, the
Rocky Flats Plant in Colorado, the area near the
Fukushima Daiichi nuclear disaster
The Fukushima nuclear accident was a major nuclear accident at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan, which began on 11 March 2011. The cause of the accident was the 2011 Tōhoku earthquake and tsunami, which r ...
, the area near the
Chernobyl disaster
On 26 April 1986, the no. 4 reactor of the Chernobyl Nuclear Power Plant, located near Pripyat, Ukrainian Soviet Socialist Republic, Ukrainian SSR, Soviet Union (now Ukraine), exploded. With dozens of direct casualties, it is one of only ...
, and the area near the
Mayak disaster.
Sources of contamination
The sources of radioactive pollution can be natural or man-made.
Radioactive contamination can be due to a variety of causes. It may occur due to the release of radioactive gases, liquids or particles. For example, if a radionuclide used in
nuclear medicine
Nuclear medicine (nuclear radiology, nucleology), is a medical specialty involving the application of radioactivity, radioactive substances in the diagnosis and treatment of disease. Nuclear imaging is, in a sense, ''radiology done inside out'', ...
is spilled (accidentally or, as in the case of the
Goiânia accident
The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, in Goiânia, Goiás, Brazil, after an unsecured radiation therapy, radiotherapy source was stolen from an abandoned hospital site in the city. ...
, through ignorance), the material could be spread by people as they walk around.
Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive
xenon
Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
in
nuclear fuel reprocessing
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
* Nuclear physics
* Nuclear power
* Nuclear reactor
* Nuclear weapon
* Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
* Nuclear space
* ...
. In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. For a discussion of environmental contamination by
alpha
Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...
emitters please see
actinides in the environment.
Nuclear fallout
Nuclear fallout is residual radioactive material that is created by the reactions producing a nuclear explosion. It is initially present in the mushroom cloud, radioactive cloud created by the explosion, and "falls out" of the cloud as it is ...
is the distribution of radioactive contamination by the 520 atmospheric
nuclear explosion
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, th ...
s that took place from the 1950s to the 1980s.
In nuclear accidents, a measure of the type and amount of radioactivity released, such as from a reactor containment failure, is known as the source term. The
United States Nuclear Regulatory Commission defines this as "Types and amounts of radioactive or hazardous material released to the environment following an accident."
Contamination does not include residual
radioactive material
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...
remaining at a site after the completion of
decommissioning. Therefore, radioactive material in sealed and designated containers is not properly referred to as contamination, although the units of measurement might be the same.
Containment

Containment is the primary way of preventing contamination from being released into the environment or coming into contact with or being ingested by humans.
Being within the intended Containment differentiates radioactive ''material'' from radioactive ''contamination''. When radioactive materials are concentrated to a detectable level outside a containment, the area affected is generally referred to as "contaminated".
There are a large number of techniques for containing radioactive materials so that it does not spread beyond the containment and become contaminated. In the case of liquids, this is by the use of high integrity tanks or containers, usually with a sump system so that leakage can be detected by radiometric or conventional instrumentation.
Where the material is likely to become airborne, then extensive use is made of the
glovebox
A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects where a separate atmosphere is desired. Built into the sides of the glovebox are gloves arranged in such a way that the user can place their hand ...
, which is a common technique in hazardous laboratory and process operations in many industries. The gloveboxes are kept under slight negative pressure and the vent gas is filtered in high-efficiency filters, which are monitored by radiological instrumentation to ensure they are functioning correctly.
Naturally occurring radioactivity
A variety of
radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...
s occur naturally in the environment. Elements like
uranium
Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...
and
thorium
Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
, and their
decay product
In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...
s, are present in rock and soil.
Potassium-40
Potassium-40 (K) is a long lived and the main naturally occurring radioactive isotope of potassium. Its half-life is 1.25 billion years. It makes up about 0.012% (120 parts-per notation, ppm) of natural potassium.
Potassium-40 undergoes four dif ...
, a
primordial nuclide
In geochemistry, geophysics and nuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed. Primordial nuclides were present in the ...
, makes up a small percentage of all potassium and is present in the human body. Other nuclides, like
carbon-14
Carbon-14, C-14, C or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic matter is the basis of the radiocarbon dating method pioneered by Willard Libby and coll ...
, which is present in all living organisms, are
continuously created by
cosmic ray
Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ...
s.
These levels of radioactivity pose little bit danger but can confuse measurement. A particular problem is encountered with naturally generated
radon
Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to b ...
gas which can affect instruments that are set to detect contamination close to normal background levels and can cause false alarms. Because of this skill is required by the operator of radiological survey equipment to differentiate between
background radiation and the radiation which emanates from contamination.
Naturally occurring radioactive material
Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive materials, radioactive elem ...
s (NORM) can be brought to the surface or concentrated by human activities such as mining, oil and gas extraction, and coal consumption.
Control and monitoring of contamination

Radioactive contamination may exist on surfaces or in volumes of material or air, and specialized techniques are used to measure the levels of contamination by detection of the emitted radiation.
Contamination monitoring
Contamination monitoring depends entirely upon the correct and appropriate deployment and utilisation of radiation monitoring instruments.
Surface contamination
Surface contamination may either be fixed or "free". In the case of fixed contamination, the radioactive material cannot by definition be spread, but its radiation is still measurable. In the case of free contamination, there is the hazard of contamination spread to other surfaces such as skin or clothing, or entrainment in the air. A concrete surface contaminated by radioactivity can be shaved to a specific depth, removing the contaminated material for disposal.
For occupational workers, controlled areas are established where there may be a contamination hazard. Access to such areas is controlled by a variety of barrier techniques, sometimes involving changes of clothing and footwear as required. The contamination within a controlled area is normally regularly monitored. Radiological protection instrumentation (RPI) plays a key role in monitoring and detecting any potential contamination spread, and combinations of
hand held survey instruments and permanently installed area monitors such as
Airborne particulate monitors and area gamma monitors are often installed. Detection and measurement of surface contamination of personnel and plant are normally by
Geiger counter
A Geiger counter (, ; also known as a Geiger–Müller counter or G-M counter) is an electronic instrument for detecting and measuring ionizing radiation with the use of a Geiger–Müller tube. It is widely used in applications such as radiat ...
,
scintillation counter
A scintillation counter is an instrument for detecting and measuring ionizing radiation by using the Electron excitation, excitation effect of incident radiation on a Scintillation (physics), scintillating material, and detecting the resultant li ...
or
proportional counter
The proportional counter is a type of gaseous ionization detector device used to measure Charged particle, particles of ionizing radiation. The key feature is its ability to measure the Electronvolt, energy of incident radiation, by producing a det ...
. Proportional counters and dual phosphor scintillation counters can discriminate between alpha and beta contamination, but the Geiger counter cannot. Scintillation detectors are generally preferred for hand-held monitoring instruments and are designed with a large detection window to make monitoring of large areas faster. Geiger detectors tend to have small windows, which are more suited to small areas of contamination.
Exit monitoring
The spread of contamination by personnel exiting controlled areas in which nuclear material is used or processed is monitored by specialised installed exit control instruments such as frisk probes, hand contamination monitors and whole body exit monitors. These are used to check that persons exiting controlled areas do not carry contamination on their bodies or clothes.
In the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
,
HSE has issued a user guidance note on selecting the correct portable radiation measurement instrument for the application concerned. This covers all radiation instrument technologies and is a useful comparative guide for selecting the correct technology for the contamination type.
The UK
NPL publishes a guide on the alarm levels to be used with instruments for checking personnel exiting controlled areas in which contamination may be encountered.
Surface contamination is usually expressed in units of radioactivity per unit of area for alpha or beta emitters. For
SI, this is
becquerel
The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as an activity of one per second, on average, for aperiodic activity events referred to a radionuclide. For applicatio ...
s per
square meter
The square metre ( international spelling as used by the International Bureau of Weights and Measures) or square meter (American spelling) is the unit of area in the International System of Units (SI) with symbol m2. It is the area of a square w ...
(or Bq/m
2). Other units such as
picoCuries per 100 cm
2 or
disintegrations per minute per square
centimeter
upright=1.35, Different lengths as in respect to the electromagnetic spectrum, measured by the metre and its derived scales. The microwave is in-between 1 meter to 1 millimeter.
A centimetre (International spelling) or centimeter (American ...
(1 dpm/cm
2 = 167 Bq/m
2) may be used.
Airborne contamination
The air can be contaminated with radioactive isotopes in particulate form, which poses a particular inhalation hazard. Respirators with suitable air filters or completely self-contained suits with their own air supply can mitigate these dangers.
Airborne contamination is measured by specialist radiological instruments that continuously pump the sampled air through a filter. Airborne particles accumulate on the filter and can be measured in a number of ways:
# The filter paper is periodically manually removed to an instrument such as a "scaler" which measures any accumulated radioactivity.
# The filter paper is static and is measured in situ by a radiation detector.
# The filter is a slowly moving strip and is measured by a radiation detector. These are commonly called "moving filter" devices and automatically advance the filter to present a clean area for accumulation, and thereby allow a plot of airborne concentration over time.
Commonly a semiconductor radiation detection sensor is used that can also provide spectrographic information on the contamination being collected.
A particular problem with airborne contamination monitors designed to detect alpha particles is that naturally occurring
radon
Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to b ...
can be quite prevalent and may appear as contamination when low contamination levels are being sought. Modern instruments consequently have "radon compensation" to overcome this effect.
Internal human contamination
Radioactive contamination can enter the body through
ingestion
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms, inge ...
,
inhalation
Inhalation (or inspiration) happens when air or other gases enter the lungs.
Inhalation of air
Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
,
absorption, or
injection
Injection or injected may refer to:
Science and technology
* Injective function, a mathematical function mapping distinct arguments to distinct values
* Injection (medicine), insertion of liquid into the body with a syringe
* Injection, in broadca ...
. This will result in a
committed dose
The committed dose in radiological protection is a measure of the stochastic health risk due to an intake of radioactive material into the human body. Stochastic in this context is defined as the ''probability'' of cancer induction and genetic dam ...
.
For this reason, it is important to use
personal protective equipment
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, elect ...
when working with radioactive materials. Radioactive contamination may also be ingested as the result of eating contaminated plants and animals or drinking contaminated water or milk from exposed animals. Following a major contamination incident, all potential pathways of internal exposure should be considered.
Successfully used on
Harold McCluskey,
chelation therapy
Chelation therapy is a medical procedure that involves the administration of chelating agents to remove heavy metals from the body. Chelation therapy has a long history of use in clinical toxicology and remains in use for some very specific medic ...
and other treatments exist for internal radionuclide contamination.
Decontamination

Cleaning up contamination results in
radioactive waste
Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...
unless the radioactive material can be returned to commercial use by
reprocessing. In some cases of large areas of contamination, the contamination may be mitigated by burying and covering the contaminated substances with concrete, soil, or rock to prevent further spread of the contamination to the environment. If a person's body is contaminated by ingestion or by injury and standard cleaning cannot reduce the contamination further, then the person may be permanently contaminated.
Contamination control products have been used by the U.S. Department of Energy (DOE) and the commercial nuclear industry for decades to minimize contamination on radioactive equipment and surfaces and fix contamination in place. "Contamination control products" is a broad term that includes fixatives, strippable coatings, and
decontamination gels. A ''fixative'' product functions as a permanent coating to stabilize residual loose/transferable radioactive contamination by fixing it in place; this aids in preventing the spread of contamination and reduces the possibility of the contamination becoming airborne, reducing workforce exposure and facilitating future deactivation and decommissioning (D&D) activities. ''Strippable coating'' products are loosely adhered to paint-like films and are used for their decontamination abilities. They are applied to surfaces with loose/transferable radioactive contamination and then, once dried, are peeled off, which removes the loose/transferable contamination along with the product. The residual radioactive contamination on the surface is significantly reduced once the strippable coating is removed. Modern strippable coatings show high decontamination efficiency and can rival traditional mechanical and chemical decontamination methods. ''Decontamination gels'' work in much the same way as other strippable coatings. The results obtained through the use of contamination control products are variable and depend on the type of substrate, the selected contamination control product, the contaminants, and the environmental conditions (e.g., temperature, humidity, etc.
Some of the largest areas committed to be decontaminated are in the
Fukushima Prefecture
is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,771,100 () and has a geographic area of . Fukushima Prefecture borders Miyagi Prefecture and Yamagata Prefecture ...
, Japan. The national government is under pressure to
clean up radioactivity due to the
Fukushima nuclear accident of March 2011 from as much land as possible so that some of the 110,000 displaced people can return. Stripping out the key radioisotope threatening health (
caesium-137) from low-level waste could also dramatically decrease the volume of waste requiring special disposal. A goal is to find techniques that might be able to strip out 80 to 95% of the caesium from contaminated soil and other materials, efficiently and without destroying the organic content in the soil. One being investigated is termed hydrothermal blasting. The caesium is broken away from soil particles and then precipitated with ferric
ferricyanide (
Prussian blue
Prussian blue (also known as Berlin blue, Brandenburg blue, Parisian and Paris blue) is a dark blue pigment produced by oxidation of ferrous ferrocyanide salts. It has the chemical formula . It consists of cations, where iron is in the oxidat ...
). It would be the only component of the waste requiring special burial sites. The aim is to get annual exposure from the contaminated environment down to one
millisievert (mSv) above background. The most contaminated area where radiation doses are greater than 50 mSv/year must remain off-limits, but some areas that are currently less than 5 mSv/year may be decontaminated allowing 22,000 residents to return.
To help protect people living in geographical areas which have been radioactively contaminated, the
International Commission on Radiological Protection
The International Commission on Radiological Protection (ICRP) is an independent, international, non-governmental organization, with the mission to protect people, animals, and the environment from the harmful effects of ionising radiation. Its ...
has published a guide: "Publication 111 – Application of the Commission's Recommendations to the Protection of People Living in Long-term Contaminated Areas after a Nuclear Accident or a Radiation Emergency".
Contamination hazards
Low-level contamination
The hazards to people and the environment from radioactive contamination depend on the nature of the radioactive contaminant, the level of contamination, and the extent of the spread of contamination. Low levels of radioactive contamination pose little risk, but can still be detected by radiation instrumentation. If a survey or map is made of a contaminated area, random sampling locations may be labeled with their activity in
becquerels or
curies on contact. Low levels may be reported in
counts per minute
The measurement of ionizing radiation is sometimes expressed as being a ''rate'' of counts per unit time as registered by a radiation monitoring instrument, for which counts per minute (cpm) and counts per second (cps) are commonly used quantitie ...
using a
scintillation counter
A scintillation counter is an instrument for detecting and measuring ionizing radiation by using the Electron excitation, excitation effect of incident radiation on a Scintillation (physics), scintillating material, and detecting the resultant li ...
.
In the case of low-level contamination by isotopes with a short half-life, the best course of action may be to simply allow the material to naturally
decay. Longer-lived isotopes should be cleaned up and properly disposed of because even a very low level of radiation can be life-threatening when in long exposure to it.
Facilities and physical locations that are deemed to be contaminated may be cordoned off by a
health physicist and labeled "Contaminated area." Persons coming near such an area would typically require
anti-contamination clothing ("anti-Cs").
High-level contamination
High levels of contamination may pose major risks to people and the environment. People can be exposed to potentially lethal radiation levels, both externally and internally, from the spread of contamination following an
accident
An accident is an unintended, normally unwanted event that was not deliberately caused by humans. The term ''accident'' implies that the event may have been caused by Risk assessment, unrecognized or unaddressed risks. Many researchers, insurers ...
(or a
deliberate initiation) involving large quantities of radioactive material. The
biological effects of external exposure to radioactive contamination are generally the same as those from an external radiation source not involving radioactive materials, such as
x-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
machines, and are dependent on the
absorbed dose
Absorbed dose is a dose quantity which represents the specific energy (energy per unit mass) deposited by ionizing radiation in living matter. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protecti ...
.
When radioactive contamination is being measured or mapped ''
in situ
is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...
'', any location that appears to be a
point source
A point source is a single identifiable ''localized'' source of something. A point source has a negligible extent, distinguishing it from other source geometries. Sources are called point sources because, in mathematical modeling, these sources ...
of radiation is likely to be heavily contaminated. A highly contaminated location is colloquially referred to as a "hot spot." On a map of a contaminated place, hot spots may be labeled with their "on contact" dose rate in mSv/h. In a contaminated facility, hot spots may be marked with a sign, shielded with bags of
lead shot, or cordoned off with warning tape containing the
radioactive trefoil symbol.
The hazard from contamination is the emission of ionizing radiation. The principal radiations which will be encountered are alpha, beta and gamma, but these have quite different characteristics. They have widely differing penetrating powers and radiation effects, and the accompanying diagram shows the penetration of these radiations in simple terms. For an understanding of the different ionising effects of these radiations and the weighting factors applied, see the article on
absorbed dose
Absorbed dose is a dose quantity which represents the specific energy (energy per unit mass) deposited by ionizing radiation in living matter. Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protecti ...
.
Radiation monitoring involves the measurement of radiation dose or radionuclide contamination for reasons related to the assessment or control of exposure to radiation or radioactive substances, and the interpretation of the results. The methodological and technical details of the design and operation of environmental radiation monitoring programmes and systems for different radionuclides, environmental media and types of facility are given in IAEA Safety Standards Series No. RS–G-1.8 and in IAEA Safety Reports Series No. 64.
Health effects of contamination
Biological effects
Radioactive contamination by definition emits ionizing radiation, which can irradiate the human body from an external or internal origin.
External irradiation
This is due to radiation from contamination located outside the human body. The source can be in the vicinity of the body or can be on the skin surface. The level of health risk is dependent on duration and the type and strength of irradiation. Penetrating radiation such as gamma rays, X-rays, neutrons or beta particles pose the greatest risk from an external source. Low penetrating radiation such as alpha particles have a low external risk due to the shielding effect of the top layers of skin. See the article on
sievert
The sievert (symbol: SvPlease note there are two non-SI units that use the same Sv abbreviation: the sverdrup and svedberg.) is a derived unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizin ...
for more information on how this is calculated.
Internal irradiation
Radioactive contamination can be ingested into the human body if it is airborne or is taken in as contamination of food or drink, and will irradiate the body internally. The art and science of assessing internally generated radiation dose is
Internal dosimetry
Internal dosimetry is the science of internal ionising radiation dose assessment due to radionuclides incorporated inside the human body.
Radionuclides deposited within a body will irradiate tissues and organs and give rise to committed dose unt ...
.
The biological effects of ingested
radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...
s depend greatly on the activity, the biodistribution, and the removal rates of the radionuclide, which in turn depends on its chemical form, the particle size, and route of entry. Effects may also depend on the chemical
toxicity
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...
of the deposited material, independent of its radioactivity. Some radionuclides may be generally distributed throughout the body and rapidly removed, as is the case with
tritiated water.
Some organs concentrate certain elements and hence radionuclide variants of those elements. This action may lead to much lower removal rates. For instance, the
thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...
gland takes up a large percentage of any
iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
that enters the body. Large quantities of inhaled or ingested
radioactive iodine
There are 40 known isotopes of iodine (53I) from 108I to 147I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element.
Its longest-lived radioactive isotope, 129I, has a half-life of 16.14 million year ...
may impair or destroy the thyroid, while other tissues are affected to a lesser extent. Radioactive iodine-131 is a common
fission product; it was a major component of the radioactivity released from the
Chernobyl disaster
On 26 April 1986, the no. 4 reactor of the Chernobyl Nuclear Power Plant, located near Pripyat, Ukrainian Soviet Socialist Republic, Ukrainian SSR, Soviet Union (now Ukraine), exploded. With dozens of direct casualties, it is one of only ...
, leading to nine fatal cases of pediatric
thyroid cancer
Thyroid cancer is cancer that develops from the tissues of the thyroid gland. It is a disease in which cells grow abnormally and have the potential to spread to other parts of the body. Symptoms can include swelling or a lump in the neck, ...
and
hypothyroidism
Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...
. On the other hand, radioactive iodine is used in the diagnosis and treatment of many diseases of the thyroid precisely because of the thyroid's selective uptake of iodine.
The radiation risk proposed by the
International Commission on Radiological Protection
The International Commission on Radiological Protection (ICRP) is an independent, international, non-governmental organization, with the mission to protect people, animals, and the environment from the harmful effects of ionising radiation. Its ...
(ICRP) predicts that an effective dose of one
sievert
The sievert (symbol: SvPlease note there are two non-SI units that use the same Sv abbreviation: the sverdrup and svedberg.) is a derived unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizin ...
(100 rem) carries a 5.5% chance of developing cancer. Such a risk is the sum of both internal and external radiation doses.
The ICRP states "Radionuclides incorporated in the human body irradiate the tissues over time periods determined by their physical half-life and their biological retention within the body. Thus they may give rise to doses to body tissues for many months or years after the intake. The need to regulate exposures to radionuclides and the accumulation of radiation dose over extended periods of time has led to the definition of committed dose quantities".
The ICRP further states "For internal exposure, committed effective doses are generally determined from an assessment of the intakes of radionuclides from bioassay measurements or other quantities (e.g., activity retained in the body or in daily excreta). The radiation dose is determined from the intake using recommended dose coefficients".
[ICRP publication 103 – Paragraph 144.]
The ICRP defines two dose quantities for individual committed dose:
Committed equivalent dose, H
T(''t'') is the time integral of the equivalent dose rate in a particular tissue or organ that will be received by an individual following intake of radioactive material into the body by a Reference Person, where ''t'' is the integration time in years.
[ICRP publication 103 – Glossary.]
This refers specifically to the dose in a specific tissue or organ, in a similar way to external equivalent dose.
Committed effective dose, E(''t'') is the sum of the products of the committed organ or tissue equivalent doses and the appropriate tissue weighting factors ''W''
T, where ''t'' is the integration time in years following the intake. The commitment period is taken to be 50 years for adults, and to age 70 years for children.
This refers specifically to the dose to the whole body, in a similar way to external effective dose.
Social and psychological effects
A 2015 report in ''
Lancet'' explained that serious impacts of nuclear accidents were often not directly attributable to radiation exposure, but rather social and psychological effects.
[ The consequences of low-level radiation are often more ]psychological
Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...
than radiological. Because damage from very low-level radiation cannot be detected, people exposed to it are left in anguished uncertainty about what will happen to them. Many believe they have been fundamentally contaminated for life and may refuse to have children for fear of birth defect
A birth defect is an abnormal condition that is present at birth, regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth de ...
s. They may be shunned by others in their community who fear a sort of mysterious contagion.
Forced evacuation from a radiological or nuclear accident may lead to social isolation, anxiety, depression, psychosomatic medical problems, reckless behavior, even suicide. Such was the outcome of the 1986 Chernobyl nuclear disaster in Ukraine. A comprehensive 2005 study concluded that "the mental health impact of Chernobyl is the largest public health problem unleashed by the accident to date".[ Frank N. von Hippel, a U.S. scientist, commented on 2011 ]Fukushima nuclear disaster
The Fukushima nuclear accident was a major nuclear accident at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan, which began on 11 March 2011. The cause of the accident was the 2011 Tōhoku earthquake and tsunami, which ...
, saying that "fear of ionizing radiation could have long-term psychological effects on a large portion of the population in the contaminated areas". Evacuation and long-term displacement of affected populations create problems for many people, especially the elderly and hospital patients.[Arifumi Hasegawa, Koichi Tanigawa, Akira Ohtsuru, Hirooki Yabe, Masaharu Maeda, Jun Shigemura, et al]
Health effects of radiation and other health problems in the aftermath of nuclear accidents, with an emphasis on Fukushima
''The Lancet
''The Lancet'' is a weekly peer-reviewed general medical journal, founded in England in 1823. It is one of the world's highest-impact academic journals and also one of the oldest medical journals still in publication.
The journal publishes ...
'', 1 August 2015.
Such great psychological danger does not accompany other materials that put people at risk of cancer and other deadly illness. Visceral fear is not widely aroused by, for example, the daily emissions from coal burning, although, as a National Academy of Sciences study found, this causes 10,000 premature deaths a year in the US population of 317,413,000. Medical errors leading to death in U.S. hospitals are estimated to be between 44,000 and 98,000. It is "only nuclear radiation that bears a huge psychological burden – for it carries a unique historical legacy".[
]
See also
*Chemical hazard
Chemical hazards are Hazard, hazards present in Dangerous goods, hazardous chemicals and hazardous materials. Exposure to certain chemicals can cause Acute health hazard, acute or long-term adverse health effects. Chemical hazards are usually cl ...
*Criticality accident
A criticality accident is an accidental uncontrolled nuclear fission chain reaction. It is sometimes referred to as a critical excursion, critical power excursion, divergent chain reaction, or simply critical. Any such event involves the uninten ...
* Human decontamination
*Lists of nuclear disasters and radioactive incidents
These are lists of nuclear disasters and radioactive incidents.
Main lists
* List of nuclear and radiation accidents and incidents
* List of nuclear and radiation accidents by death toll
* List of civilian nuclear accidents
* List o ...
* Low-background steel
*Nuclear and radiation accidents
A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility." Examples include radiation poisoning, lethal effect ...
* Nuclear debate (disambiguation)
*Nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...
* Radiation biology
* Radiation exposure (disambiguation)
*Radiophobia
Radiophobia is an irrational or excessive fear of ionizing radiation, leading to overestimating the health risks of radiation compared to other risks. It can impede rational decision-making and contribute to counter-productive behavior and poli ...
*Relative biological effectiveness
In radiobiology, the relative biological effectiveness (often abbreviated as RBE) is the ratio of biological effectiveness of one type of ionizing radiation relative to another, given the same amount of absorbed energy. The RBE is an empirical ...
* Rongelap Atoll
* Soviet submarine K-19
* Washdown
* :Deaths by acute radiation syndrome
References
* Measurement Good Practice Guide No. 30 "Practical Radiation Monitoring" Oct 2002 – National Physical Laboratory, Teddington
External links
Q&A: Health effects of radiation exposure
''BBC News'', 21 July 2011.
Alliance for Nuclear Responsibility
training guide
Brookhaven National Laboratory Training Guide.
International Fund for Animal Welfare report on impact of radiation on animals
{{DEFAULTSORT:Radioactive Contamination
Radioactive waste
Nuclear safety and security
Radiobiology
Pollution
Radiation accidents and incidents
Radiation protection