Contamination
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Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc.<ref name="MWContaminate">Template:Cite Merriam-Webster</ref><ref name="DonovanContam01">Template:Cite book</ref><ref name="RamstorpInto08">Template:Cite book</ref>
Types of contaminationEdit
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,<ref name="RamstorpInto08" /> as well as the variance of environment the contaminant is found to be in.<ref name="DonovanContam01" /> A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process.<ref name="DonovanContam01" /> The following represent examples of different types of contamination based on these and other variances.
Chemical contaminationEdit
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 causes additional chemical reactions when mixed with other chemicals or mixtures. Chemical reactions resulting 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.<ref name="MoudgilText14">Template:Cite book</ref>) If the additional reactions are detrimental, other terms are often applied such as "toxin", "poison", or pollutant, depending on the type of molecule involved.<ref name="AltersBio00">Template:Cite book</ref> Chemical decontamination of substance can be achieved through decomposition, neutralization, and physical processes, though a clear understanding of the underlying chemistry is required.<ref name="MidcalfPharma04">Template:Cite book</ref> Contamination of pharmaceutics and therapeutics is notoriously dangerous and creates both perceptual and technical challenges.<ref>Template:Cite journal</ref>
Environmental contaminationEdit
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.<ref name="ValleroEnviro10">Template:Cite book</ref> Environmental monitoring is one mechanism available to scientists to detect contamination activities early before they become too detrimental.
Agricultural contaminationEdit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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.<ref name="PaullOrganic14">Template:Cite journal</ref> This sort of contamination can at times be difficult to control, necessitating mechanisms for compensating farmers where there has been contamination by GMOs.<ref name="PaullComp18">Template:Cite journal</ref> 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.<ref>Paull, John (2019) Contamination of Farms by Genetically Modified Organisms (GMOs): Options for Compensation Template:Webarchive, Journal of Organics, 6(1):31–46.</ref>
Food, beverage, and pharmaceutical contaminationEdit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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.<ref name="MidcalfPharma04" /><ref name="BohrerSources12">Template:Cite book</ref><ref name="DikemanEncyclo14">Template:Cite book</ref><ref name="WilsonMicro08">Template:Cite book</ref><ref>Ogbede, J.U., Giaever, G. & Nislow, C. A genome-wide portrait of pervasive drug contaminants. Sci Rep 11, 12487 (2021). https://doi.org/10.1038/s41598-021-91792-1 Template:Webarchive</ref>
Radioactive contaminationEdit
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.<ref name="IAEASafety07">Template:Cite book</ref><ref name="IAEAProgrammes10">Template:Cite book</ref> Several examples of radioactive contamination include:
- residual radioactive material remaining at a site after the completion of decommissioning of a site where there was a nuclear reactor, such as a power plant, experimental reactor, isotope reactor, or a nuclear powered ship or submarine<ref name="ChatzisDecomm17">{{#invoke:citation/CS1|citation
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- ingested or absorbed radioactive material that contaminates a biological entity, whether unintentionally or intentionally (such as with radiopharmaceuticals<ref name="StanfordRadiation17">{{#invoke:citation/CS1|citation
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- escape of elements after nuclear accident, such as the contamination of Iodine-131 and Caesium-137 after the nuclear disaster in Chernobyl, Ukraine.<ref>Template:Cite journal</ref>
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-causing activities before much harm.
Interplanetary contaminationEdit
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.<ref name="CockellPlanetary05">Template:Cite journal</ref>
Contaminated evidenceEdit
{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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 dismissal of evidence.<ref name="TaupinIntro13">Template:Cite book</ref><ref name="GeddesHow12">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Contaminated samplesEdit
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 to dominate the sample and render it useless, as in contaminated cell culture lines. 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.<ref name="AbzalovApplied16">Template:Cite book</ref>
Food contaminant detection methodEdit
The conventional food contaminant test methods may be limited by complicated/tedious sample preparing procedure, long testing time, sumptuous instrument, and professional operator.<ref name="Chiou 2243–2264">Template:Cite journal</ref> However, some rapid, novel, sensitive, and easy to use and affordable methods were developed including:
- Cyanidin quantification by naphthalimide-based azo dye colorimetric probe.<ref>Template:Cite journal</ref>
- Lead quantification by modified immunoassay test strip based on a heterogeneously sized gold amplified probe.<ref>Template:Cite journal</ref>
- Microbial toxin by HPLC with UV-Vis or fluorescence detection<ref>Template:Cite journal</ref> and competitive immunoassays with ELISA configuration.<ref>Template:Cite journal</ref>
- Bacterial virulence genes detection reverse-transcription polymerase chain reaction (RT-PCR) and DNA colony hybridization.<ref>Template:Cite journal</ref>
- Pesticide detection and quantification by strip-based immunoassay,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> a test strip based on functionalized AuNPs,<ref>Template:Cite journal</ref> and test strip, surface-enhanced raman spectroscopy (SERS).<ref name="Chiou 2243–2264"/>
- Enrofloxacin (chickens antibiotic) quantification by a Ru(phen)3 2+- doped silica fluorescent nanoparticle (NP) based immunochromatographic test strip and a portable fluorescent strip reader.<ref>Template:Cite journal</ref>
- Nitrite quantification by The PRhB-based electrochemical sensors<ref>Template:Cite journal</ref> and Ion selective electrodes (ISEs).<ref>Template:Cite journal</ref>