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Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. [1] [2] [3]


Types of contamination

Within the sciences, the word "contamination" can take on a variety of subtle differences in meaning, whether the contaminant is a solid or a liquid, [3] as well as the variance of environment the contaminant is found to be in. [2] A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process. [2] The following represent examples of different types of contamination based on these and other variances.

Chemical contamination

In chemistry, the term "contamination" usually describes a single constituent, but in specialized fields the term can also mean chemical mixtures, even up to the level of cellular materials. All chemicals contain some level of impurity. Contamination may be recognized or not and may become an issue if the impure chemical is mixed with other chemicals or mixtures and causes additional chemical reactions. The resulting chemical reactions from the presence of an impurity may at times be beneficial, in which case the label "contaminant" may be replaced with "reactant" or "catalyst." (This may be true even in physical chemistry, where, for example, the introduction of an impurity in an intrinsic semiconductor positively increases conductivity. [4] If the additional reactions are detrimental, other terms are often applied such as "toxin," "poison," or pollutant, depending on the type of molecule involved. [5] Chemical decontamination of substance can be achieved through decomposition, neutralization, and physical processes, though a clear understanding of the underlying chemistry is required. [6] Contamination of pharmaceutics and therapeutics is notoriously dangerous and construct both perceptual and technical challenges. [7]

Environmental contamination

In environmental chemistry, the term "contamination" is in some cases virtually equivalent to pollution, where the main interest is the harm done on a large scale to humans, organisms, or environments. An environmental contaminant may be chemical in nature, though it may also be a biological (pathogenic bacteria, virus, invasive species) or physical (energy) agent. [8] Environmental monitoring is one mechanism available to scientists to catch contamination activities early before they become too detrimental.

Agricultural contamination

Another type of environmental contaminant can be found in the form of genetically modified organisms (GMOs), specifically when they come in contact with organic agriculture. This sort of contamination can result in the decertification of a farm. [9] This sort of contamination can at times be difficult to control, necessitating mechanisms for compensating farmers where there has been contamination by GMOs. [10] A Parliamentary Inquiry in Western Australia considered a range of options for compensating farmers whose farms had been contaminated by GMOs but ultimately settled on recommending no action. [11]

Food, beverage, and pharmaceutical contamination

In food chemistry and medicinal chemistry, the term "contamination" is used to describe harmful intrusions, such as the presence of toxins or pathogens in food or pharmaceutical drugs. [6] [12] [13] [14] [15]

Radioactive contamination

In environments where nuclear safety and radiation protection are required, radioactive contamination is a concern. Radioactive substances can appear on surfaces, or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable, and processes can give rise to their presence in such places. [16] [17] Several examples of radioactive contamination include:

Note that the term "radioactive contamination" may have a connotation that is not intended. The term refers only to the presence of radioactivity, and gives no indication itself of the magnitude of the hazard involved. However, radioactivity can be measured as a quantity in a given location or on a surface, or on a unit area of a surface, such as a square meter or centimeter.

Like environmental monitoring, radiation monitoring can be employed to catch contamination activities early before they become too detrimental.

Interplanetary contamination

Interplanetary contamination occurs when a planetary body is biologically contaminated by a space probe or spacecraft, either deliberately or unintentionally. This can work both on arrival to the foreign planetary body and upon return to Earth. [20]

Contaminated evidence

In forensic science, evidence can become contaminated. Contamination of fingerprints, hair, skin, or DNA—from first responders or from sources not related to the ongoing investigation, such as family members or friends of the victim who are not suspects—can lead to wrongful convictions, mistrials, or the dismissal of evidence. [21] [22]

Contaminated samples

Contamination on agar plate Contamination on agar plate.jpg
Contamination on agar plate

In the biological sciences, accidental introduction of "foreign" material can seriously distort the results of experiments where small samples are used. In cases where the contaminant is a living microorganism, it can often multiply and take over the experiment, especially cultures, and render them useless. A similar affect can be seen in geology, geochemistry, and archaeology, where even a few grains of a material can distort results of sophisticated experiments. [23]

Related Research Articles

Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a "physical science", together called the "physical sciences".

Radioactive waste Unwanted or unusable radioactive materials

Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons reprocessing. The storage and disposal of radioactive waste is regulated by government agencies in order to protect human health and the environment.

Nuclear fallout Residual radioactive material following a nuclear blast

Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes. The amount and spread of fallout is a product of the size of the weapon and the altitude at which it is detonated. Fallout may get entrained with the products of a pyrocumulus cloud and fall as black rain. This radioactive dust, usually consisting of fission products mixed with bystanding atoms that are neutron-activated by exposure, is a form of radioactive contamination.

Chemical waste

Chemical waste is a waste that is made from harmful chemicals. Chemical waste may fall under regulations such as COSHH in the United Kingdom, or the Clean Water Act and Resource Conservation and Recovery Act in the United States. In the U.S., the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA), as well as state and local regulations also regulate chemical use and disposal. Chemical waste may or may not be classed as hazardous waste.

Nuclear chemistry branch of chemistry concerned with radioactivity, transmutation and other nuclear processes

Nuclear chemistry is the sub-field of chemistry dealing with radioactivity, nuclear processes, and transformations in the nuclei of atoms, such as nuclear transmutation and nuclear properties.

Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.

Nuclear and radiation accidents and incidents Severe disruptive events involving fissile or fusile materials

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 lethal effects to individuals, large radioactivity release to the environment, reactor core melt." The prime example of a "major nuclear accident" is one in which a reactor core is damaged and significant amounts of radioactive isotopes are released, such as in the Chernobyl disaster in 1986 and Fukushima Daiichi nuclear disaster in 2011.

Radioactive contamination US safety regulations for nuclear power and weapons

Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases, where their presence is unintended or undesirable.

Environmental chemistry The scientific study of the chemical and phenomena that occur in natural places

Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source. It can be defined as the study of the sources, reactions, transport, effects, and fates of chemical species in the air, soil, and water environments; and the effect of human activity and biological activity on these. Environmental chemistry is an interdisciplinary science that includes atmospheric, aquatic and soil chemistry, as well as heavily relying on analytical chemistry and being related to environmental and other areas of science.

Soil contamination Pollution of land by human-made chemicals or other alteration

Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotics (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting cleanups are time-consuming and expensive tasks, requiring extensive amounts of geology, hydrology, chemistry, computer modeling skills, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.

Red Forest Forest within the Chernobyl Exclusion Zone in Ukraine

The Red Forest is the 10-square-kilometer area surrounding the Chernobyl Nuclear Power Plant within the Exclusion Zone located in Polesia. The name "Red Forest" comes from the ginger-brown color of the pine trees after they died following the absorption of high levels of radiation from the Chernobyl accident on 26 April 1986. In the post-disaster cleanup operations, the Red Forest was bulldozed and buried in "waste graveyards". The site of the Red Forest remains one of the most contaminated areas in the world today.

Food contaminant

Food contamination refers to the presence of harmful chemicals and microorganisms in food, which can cause consumer illness. This article addresses the chemical contamination of foods, as opposed to microbiological contamination, which can be found under foodborne illness.

Environmental impact of nuclear power Overview of the environmental impact of nuclear power

The environmental impact of nuclear power results from the nuclear fuel cycle, operation, and the effects of nuclear accidents.

Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the subsurface. Globally, between 25 per cent and 40 per cent of the world's drinking water is drawn from boreholes and dug wells. Groundwater is also used by farmers to irrigate crops and by industries to produce everyday goods. Most groundwater is clean, but groundwater can become polluted, or contaminated as a result of human activities or as a result of natural conditions.

Radiation monitoring

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.

Environmental monitoring

Environmental monitoring describes the processes and activities that need to take place to characterize and monitor the quality of the environment. Environmental monitoring is used in the preparation of environmental impact assessments, as well as in many circumstances in which human activities carry a risk of harmful effects on the natural environment. All monitoring strategies and programs have reasons and justifications which are often designed to establish the current status of an environment or to establish trends in environmental parameters. In all cases, the results of monitoring will be reviewed, analyzed statistically, and published. The design of a monitoring program must therefore have regard to the final use of the data before monitoring starts.

In situ chemical oxidation (ISCO), a form of advanced oxidation process, is an environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers directly into the contaminated medium to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation.

Bioremediation of radioactive waste

Bioremediation of radioactive waste or bioremediation of radionuclides is an application of bioremediation based on the use of biological agents bacteria, plants and fungi to catalyze chemical reactions that allow the decontamination of sites affected by radionuclides. These radioactive particles are by-products generated as a result of activities related to nuclear energy and constitute a pollution and a radiotoxicity problem due to its unstable nature of ionizing radiation emissions.

A radioactive nanoparticle is a nanoparticle that contains radioactive materials. Radioactive nanoparticles have applications in medical diagnostics, medical imaging, toxicokinetics, and environmental health, and are being investigated for applications in nuclear nanomedicine. Radioactive nanoparticles present special challenges in operational health physics and internal dosimetry that are not present for other substances, although existing radiation protection measures and hazard controls for nanoparticles generally apply.

The Chernobyl disaster remains the major and most detrimental nuclear catastrophe which completely altered the radioactive background of the Northern Hemisphere. It happened in April 1986 on the territory of the former Soviet Union. The catastrophe led to the increase of radiation in nearly one million times in some parts of Europe and North America compared to the pre-disaster state Air, water, soils, vegetation and animals were contaminated to a varying degree. Apart from Ukraine and Belarus as the worst hit areas, adversely affected countries included Russia, Austria, Finland and Sweden. The full impact on the aquatic systems, including primarily adjacent valleys of Pripyat river and Dnieper river, are still unexplored.


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