Contamination

Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for physical body, natural environment, workplace, etc.[1][2][3]

Types of contamination

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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

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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.[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 creates both perceptual and technical challenges.[7]

Environmental contamination

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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 detect contamination activities early before they become too detrimental.

Agricultural contamination

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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

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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

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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-causing activities before much harm.

Interplanetary contamination

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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.[21]

Contaminated evidence

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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.[22][23]

Contaminated samples

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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 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.[24]

Food contaminant detection method

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The conventional food contaminant test methods may be limited by complicated/tedious sample preparing procedure, long testing time, sumptuous instrument, and professional operator.[25] However, some rapid, novel, sensitive, and easy to use and affordable methods were developed including:

  • Cyanidin quantification by naphthalimide-based azo dye colorimetric probe.[26]
  • Lead quantification by modified immunoassay test strip based on a heterogeneously sized gold amplified probe.[27]
  • Microbial toxin by HPLC with UV-Vis or fluorescence detection[28] and competitive immunoassays with ELISA configuration.[29]
  • Bacterial virulence genes detection reverse-transcription polymerase chain reaction (RT-PCR) and DNA colony hybridization.[30]
  • Pesticide detection and quantification by strip-based immunoassay,[31][32] a test strip based on functionalized AuNPs,[33] and test strip, surface-enhanced raman spectroscopy (SERS).[25]
  • 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.[34]
  • Nitrite quantification by The PRhB-based electrochemical sensors[35] and Ion selective electrodes (ISEs).[36]

See also

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References

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  2. ^ a b c Donovan, R.P. (2001). "1. Introduction". In Donovan, R.P. (ed.). Contamination-Free Manufacturing for Semiconductors and Other Precision Products. CRC Press. pp. 1–3. ISBN 9780824703806. Archived from the original on 2020-02-08. Retrieved 2019-07-15.
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  16. ^ International Atomic Energy Agency (2007). IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection, 2007 Edition (PDF). International Atomic Energy Agency. p. 227. ISBN 978-9201007070. Archived (PDF) from the original on 18 January 2020. Retrieved 11 April 2019.
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  31. ^ Blažková, Martina; Rauch, Pavel; Fukal, Ladislav (2010-05-15). "Strip-based immunoassay for rapid detection of thiabendazole". Biosensors and Bioelectronics. 25 (9): 2122–2128. doi:10.1016/j.bios.2010.02.011. ISSN 0956-5663. PMID 20236817.
  32. ^ Holubová-Mičková, Barbora; Blažková, Martina; Fukal, Ladislav; Rauch, Pavel (2010-07-01). "Development of colloidal carbon-based immunochromatographic strip for rapid detection of carbaryl in fruit juices". European Food Research and Technology. 231 (3): 467–473. doi:10.1007/s00217-010-1301-z. ISSN 1438-2385. S2CID 97326355.
  33. ^ Imene, Boussouar; Cui, ZhiMin; Zhang, Xiaoyan; Gan, Bing; Yin, Yanchao; Tian, Yuanyuan; Deng, Hongtao; Li, Haibing (2014-08-01). "4-Amino-3-mercaptobenzoic acid functionalized gold nanoparticles: Synthesis, selective recognition and colorimetric detection of cyhalothrin". Sensors and Actuators B: Chemical. 199: 161–167. doi:10.1016/j.snb.2014.03.097. ISSN 0925-4005.
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  36. ^ Parks, Sophie E.; Irving, Donald E.; Milham, Paul J. (2012-02-01). "A critical evaluation of on-farm rapid tests for measuring nitrate in leafy vegetables". Scientia Horticulturae. 134: 1–6. doi:10.1016/j.scienta.2011.10.015. ISSN 0304-4238.
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