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, as well as the variance of environment the contaminant is found to be in. A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process. The following represent examples of different types of contamination based on these and other variances.

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.{{cite book |url=https://books.google.com/books?id=qWfkBQAAQBAJ&pg=PA278 |title=Textbook of Physical Chemistry |author=Moudgil, H.K. |publisher=PHI Learning |page=278 |year=2014 |isbn=9788120350625 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130129/https://books.google.com/books?id=qWfkBQAAQBAJ&pg=PA278 |url-status=live }}) If the additional reactions are detrimental, other terms are often applied such as "toxin", "poison", or pollutant, depending on the type of molecule involved.{{cite book |url=https://books.google.com/books?id=GRDUIbQwGc8C&pg=PA828 |title=Biology: Understanding Life |author=Alters, S. |publisher=Jones & Bartlett Learning |page=828 |year=2000 |isbn=9780763708375 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130130/https://books.google.com/books?id=GRDUIbQwGc8C&pg=PA828 |url-status=live }} Chemical decontamination of substance can be achieved through decomposition, neutralization, and physical processes, though a clear understanding of the underlying chemistry is required.{{cite book |url=https://books.google.com/books?id=XFaKhSPhoakC&pg=PA239 |title=Pharmaceutical Isolators: A Guide to Their Application, Design and Control |author=Midcalf, B. |publisher=Pharmaceutical Press |pages=88–89 |year=2004 |isbn=9780853695738 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130132/https://books.google.com/books?id=XFaKhSPhoakC&pg=PA239 |url-status=live }} Contamination of pharmaceutics and therapeutics is notoriously dangerous and creates both perceptual and technical challenges.{{Cite journal|last1=Abdin|first1=Ahmad Yaman|last2=Yeboah|first2=Prince|last3=Jacob|first3=Claus|date=January 2020|title=Chemical Impurities: An Epistemological Riddle with Serious Side Effects|journal=International Journal of Environmental Research and Public Health|language=en|volume=17|issue=3|pages=1030|doi=10.3390/ijerph17031030|pmc=7038150|pmid=32041209|doi-access=free}}

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.{{cite book |chapter-url=https://books.google.com/books?id=pELzLWVn4rwC&pg=PA289 |chapter=6. Fundamentals of Environmental Chemistry |title=Environmental Contaminants: Assessment and Control |author=Vallero, D.A. |publisher=Elsevier |pages=289–332 |year=2010 |isbn=9780080470351 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130133/https://books.google.com/books?id=pELzLWVn4rwC&pg=PA289 |url-status=live }} Environmental monitoring is one mechanism available to scientists to detect contamination activities early before they become too detrimental.

{{Main|Biocontainment of genetically modified organisms}}

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.{{cite journal |title=Editorial: Organic Versus GMO Farming: Contamination, What Contamination? |journal=Journal of Organic Systems |author=Paull, J. |volume=9 |issue=1 |pages=2–4 |year=2014 |url=http://www.organic-systems.org/journal/91/index.html |access-date=2019-04-12 |archive-date=2018-04-21 |archive-url=https://web.archive.org/web/20180421122326/http://www.organic-systems.org/journal/91/index.html |url-status=live }} This sort of contamination can at times be difficult to control, necessitating mechanisms for compensating farmers where there has been contamination by GMOs.{{cite journal |title=Compensation for GMO contamination |journal=International Sustainable Development Research Society Newsletter |author=Paull, J. |issue=3 |year=2018 |page=8 |url=http://orgprints.org/33919/ |access-date=2019-04-12 |archive-date=2020-01-19 |archive-url=https://web.archive.org/web/20200119055610/https://orgprints.org/33919/ |url-status=live }} 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.Paull, John (2019) [https://www.academia.edu/40200835/Contamination_of_Farms_by_Genetically_Modified_Organisms_GMOs_Options_for_Compensation Contamination of Farms by Genetically Modified Organisms (GMOs): Options for Compensation] {{Webarchive|url=https://web.archive.org/web/20190921081224/https://www.academia.edu/40200835/Contamination_of_Farms_by_Genetically_Modified_Organisms_GMOs_Options_for_Compensation |date=2019-09-21 }},

Journal of Organics, 6(1):31–46.

{{Main|Food contaminant|List of medicine contamination incidents}}

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.{{cite book |url=https://books.google.com/books?id=w-u6D7mbNdcC |chapter=Preface |title=Sources of Contamination in Medicinal Products and Medical Devices |author=Bohrer, D. |publisher=John Wiley & Sons |year=2012 |isbn=9781118449059 |access-date=2019-04-12 |archive-date=2021-12-04 |archive-url=https://web.archive.org/web/20211204041514/https://books.google.com/books?id=w-u6D7mbNdcC |url-status=live }}{{cite book |chapter-url=https://books.google.com/books?id=vL9dAwAAQBAJ&pg=PA497 |chapter=Environmental Contaminants |title=Encyclopedia of Meat Sciences |author=Rose, M. |editor=Dikeman, M. |editor2=Devine, C. |publisher=Elsevier |edition=2nd |volume=1 |pages=497–501 |year=2014 |isbn=9780123847348 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130136/https://books.google.com/books?id=vL9dAwAAQBAJ&pg=PA497 |url-status=live }}{{cite book |url=https://books.google.com/books?id=zUPgf8NUIXIC |chapter=Preface: Food—A necessity and a threat |title=Microbial Food Contamination |editor=Wilson, C.L. |publisher=CRC Press |pages=xi–xvi |year=2008 |isbn=9781420008470 |access-date=2019-04-12 |archive-date=2021-12-04 |archive-url=https://web.archive.org/web/20211204041410/https://books.google.com/books?id=zUPgf8NUIXIC |url-status=live }}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 {{Webarchive|url=https://web.archive.org/web/20211204041501/https://www.nature.com/articles/s41598-021-91792-1 |date=2021-12-04 }}

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.{{cite book |url=https://www-pub.iaea.org/MTCD/publications/PDF/Pub1290_web.pdf |title=IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection, 2007 Edition |author=International Atomic Energy Agency |pages=227 |year=2007 |publisher=International Atomic Energy Agency |isbn=978-9201007070 |access-date=11 April 2019 |archive-date=18 January 2020 |archive-url=https://web.archive.org/web/20200118021212/https://www-pub.iaea.org/MTCD/publications/PDF/Pub1290_web.pdf |url-status=live }}{{cite book |url=https://www.iaea.org/publications/8242/programmes-and-systems-for-source-and-environmental-radiation-monitoring |title=Programmes and Systems for Source and Environmental Radiation Monitoring, Safety Reporsts Series No. 64 |author=International Atomic Energy Agency |pages=234 |year=2010 |publisher=International Atomic Energy Agency |isbn=9789201124098 |access-date=11 April 2019 |archive-date=24 December 2019 |archive-url=https://web.archive.org/web/20191224211121/https://www.iaea.org/publications/8242/programmes-and-systems-for-source-and-environmental-radiation-monitoring |url-status=live }} 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{{cite web |url=https://www.iaea.org/newscenter/news/decommissioning-and-environmental-remediation-an-overview |title=Decommissioning and Environmental Remediation: IAEA Conference to Start on Monday |author=Chatzis, I. |publisher=International Atomic Energy Agency |date=26 July 2017 |access-date=11 April 2019 |archive-date=21 May 2016 |archive-url=https://web.archive.org/web/20160521130707/https://www.iaea.org/newscenter/news/decommissioning-and-environmental-remediation-an-overview |url-status=live }}
• ingested or absorbed radioactive material that contaminates a biological entity, whether unintentionally or intentionally (such as with radiopharmaceuticals{{cite web |url=https://ehs.stanford.edu/wp-content/uploads/sops/Hospital-Guidance-document.pdf |title=Radiation Protection Guidance for Hospital Staff |author=Stanford Environmental Health and Safety |page=21 |date=29 June 2017 |access-date=11 April 2019 |archive-date=5 March 2018 |archive-url=https://web.archive.org/web/20180305200426/https://ehs.stanford.edu/wp-content/uploads/sops/Hospital-Guidance-document.pdf |url-status=live }}
• escape of elements after nuclear accident, such as the contamination of Iodine-131 and Caesium-137 after the nuclear disaster in Chernobyl, Ukraine.{{Cite journal |last=von Wehrden |first=Henrik |date=28 December 2011 |title=Consequences of nuclear accidents for biodiversity and ecosystem services |url=http://fox.leuphana.de/portal/de/publications/consequences-of-nuclear-accidents-for-biodiversity-and-ecosystem-services(0f971799-c8ce-422e-844c-6e0ec1ae1b0a).html|journal=Conservation Letters |volume=5 |issue=2 |pages=81–89 |doi=10.1111/j.1755-263X.2011.00217.x |s2cid=83193558 |via=Society of Conservation Biology|doi-access=free }}

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 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.{{cite journal |title=Planetary protection—A microbial ethics approach |journal=Space Policy |author=Cockell, C.S. |volume=21 |issue=4 |pages=287–292 |year=2005 |doi=10.1016/j.spacepol.2005.08.003|bibcode=2005SpPol..21..287C }}

{{Main|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 dismissal of evidence.{{cite book |url=https://books.google.com/books?id=dw2xqTVgyPsC&pg=PA134 |title=Introduction to Forensic DNA Evidence for Criminal Justice Professionals |author=Taupin, J.M. |publisher=CRC Press |pages=134–8 |year=2013 |isbn=9781439899090 |access-date=2019-04-12 |archive-date=2020-02-08 |archive-url=https://web.archive.org/web/20200208130140/https://books.google.com/books?id=dw2xqTVgyPsC&pg=PA134 |url-status=live }}{{cite web |url=https://www.newscientist.com/article/mg21328475-000-how-dna-contamination-can-affect-court-cases/ |title=How DNA Contamination Can Affect Court Cases |author=Geddes, L. |work=New Scientist |date=11 January 2012 |access-date=11 April 2019 |archive-date=12 April 2016 |archive-url=https://web.archive.org/web/20160412235503/https://www.newscientist.com/article/mg21328475-000-how-dna-contamination-can-affect-court-cases/ |url-status=live }}

File:Contamination on agar plate.jpg

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.{{cite book |url=https://books.google.com/books?id=Oy3RDAAAQBAJ&pg=PA387 |title=Applied Mining Geology |author=Abzalov, M. |publisher=Springer |page=387 |year=2016 |isbn=9783319392646 |access-date=2019-04-12 |archive-date=2020-08-07 |archive-url=https://web.archive.org/web/20200807052437/https://books.google.com/books?id=Oy3RDAAAQBAJ&pg=PA387 |url-status=live }}

The conventional food contaminant test methods may be limited by complicated/tedious sample preparing procedure, long testing time, sumptuous instrument, and professional operator.{{Cite journal |last1=Chiou |first1=Jiachi |last2=Leung |first2=Arthur Ho Hon |last3=Lee |first3=Hang Wai |last4=Wong |first4=Wing-tak |date=2015-11-01 |title=Rapid testing methods for food contaminants and toxicants |url= |journal=Journal of Integrative Agriculture |language=en |volume=14 |issue=11 |pages=2243–2264 |doi=10.1016/S2095-3119(15)61119-4 |issn=2095-3119|doi-access=free |bibcode=2015JIAgr..14.2243C }} However, some rapid, novel, sensitive, and easy to use and affordable methods were developed including:

• Cyanidin quantification by naphthalimide-based azo dye colorimetric probe.{{Cite journal |last1=Garg |first1=Bhaskar |last2=Yan |first2=Linyin |last3=Bisht |first3=Tanuja |last4=Zhu |first4=Chaoyuan |last5=Ling |first5=Yong-Chien |date=2014-08-15 |title=A phenothiazine-based colorimetric chemodosimeter for the rapid detection of cyanide anions in organic and aqueous media |url=https://pubs.rsc.org/en/content/articlelanding/2014/ra/c4ra06440b |journal=RSC Advances |language=en |volume=4 |issue=68 |pages=36344–36349 |doi=10.1039/C4RA06440B |bibcode=2014RSCAd...436344G |issn=2046-2069|url-access=subscription }}
• Lead quantification by modified immunoassay test strip based on a heterogeneously sized gold amplified probe.{{Cite journal |last1=Kuang |first1=Hua |last2=Xing |first2=Changrui |last3=Hao |first3=Changlong |last4=Liu |first4=Liqiang |last5=Wang |first5=Libing |last6=Xu |first6=Chuanlai |date=April 2013 |title=Rapid and Highly Sensitive Detection of Lead Ions in Drinking Water Based on a Strip Immunosensor |journal=Sensors |language=en |volume=13 |issue=4 |pages=4214–4224 |doi=10.3390/s130404214 |issn=1424-8220 |pmc=3673080 |pmid=23539028 |bibcode=2013Senso..13.4214K |doi-access=free }}
• Microbial toxin by HPLC with UV-Vis or fluorescence detection{{Cite journal |last1=Copetti |first1=Marina V. |last2=Iamanaka |first2=Beatriz T. |last3=Pitt |first3=John I. |last4=Taniwaki |first4=Marta H. |date=2014-05-16 |title=Fungi and mycotoxins in cocoa: From farm to chocolate |url= http://repositorio.ital.sp.gov.br/jspui/handle/123456789/364|journal=International Journal of Food Microbiology |language=en |volume=178 |pages=13–20 |doi=10.1016/j.ijfoodmicro.2014.02.023 |pmid=24667314 |issn=0168-1605}} and competitive immunoassays with ELISA configuration.{{Cite journal |last=Maragos |first=Chris |date=December 2009 |title=Fluorescence Polarization Immunoassay of Mycotoxins: A Review |journal=Toxins |language=en |volume=1 |issue=2 |pages=196–207 |doi=10.3390/toxins1020196 |issn=2072-6651 |pmc=3202780 |pmid=22069541 |doi-access=free }}
• Bacterial virulence genes detection reverse-transcription polymerase chain reaction (RT-PCR) and DNA colony hybridization.{{Cite journal |last1=Zhu |first1=Kui |last2=Dietrich |first2=Richard |last3=Didier |first3=Andrea |last4=Doyscher |first4=Dominik |last5=Märtlbauer |first5=Erwin |date=April 2014 |title=Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins |journal=Toxins |language=en |volume=6 |issue=4 |pages=1325–1348 |doi=10.3390/toxins6041325 |issn=2072-6651 |pmc=4014736 |pmid=24732203 |doi-access=free }}
• Pesticide detection and quantification by strip-based immunoassay,{{Cite journal |last1=Blažková |first1=Martina |last2=Rauch |first2=Pavel |last3=Fukal |first3=Ladislav |date=2010-05-15 |title=Strip-based immunoassay for rapid detection of thiabendazole |url= |journal=Biosensors and Bioelectronics |language=en |volume=25 |issue=9 |pages=2122–2128 |doi=10.1016/j.bios.2010.02.011 |pmid=20236817 |issn=0956-5663}}{{Cite journal |last1=Holubová-Mičková |first1=Barbora |last2=Blažková |first2=Martina |last3=Fukal |first3=Ladislav |last4=Rauch |first4=Pavel |date=2010-07-01 |title=Development of colloidal carbon-based immunochromatographic strip for rapid detection of carbaryl in fruit juices |url=https://doi.org/10.1007/s00217-010-1301-z |journal=European Food Research and Technology |language=en |volume=231 |issue=3 |pages=467–473 |doi=10.1007/s00217-010-1301-z |s2cid=97326355 |issn=1438-2385|url-access=subscription }} a test strip based on functionalized AuNPs,{{Cite journal |last1=Imene |first1=Boussouar |last2=Cui |first2=ZhiMin |last3=Zhang |first3=Xiaoyan |last4=Gan |first4=Bing |last5=Yin |first5=Yanchao |last6=Tian |first6=Yuanyuan |last7=Deng |first7=Hongtao |last8=Li |first8=Haibing |date=2014-08-01 |title=4-Amino-3-mercaptobenzoic acid functionalized gold nanoparticles: Synthesis, selective recognition and colorimetric detection of cyhalothrin |url= |journal=Sensors and Actuators B: Chemical |language=en |volume=199 |pages=161–167 |doi=10.1016/j.snb.2014.03.097 |bibcode=2014SeAcB.199..161I |issn=0925-4005}} and test strip, surface-enhanced raman spectroscopy (SERS).
• 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.{{Cite journal |last1=Huang |first1=Xiaolin |last2=Aguilar |first2=Zoraida P. |last3=Li |first3=Huaiming |last4=Lai |first4=Weihua |last5=Wei |first5=Hua |last6=Xu |first6=Hengyi |last7=Xiong |first7=Yonghua |date=2013-05-21 |title=Fluorescent Ru(phen) 3 2+ -Doped Silica Nanoparticles-Based ICTS Sensor for Quantitative Detection of Enrofloxacin Residues in Chicken Meat |url=https://pubs.acs.org/doi/10.1021/ac400502v |journal=Analytical Chemistry |language=en |volume=85 |issue=10 |pages=5120–5128 |doi=10.1021/ac400502v |pmid=23614687 |issn=0003-2700|url-access=subscription }}
• Nitrite quantification by The PRhB-based electrochemical sensors{{Cite journal |last1=Lu |first1=Limin |last2=Zhang |first2=Ou |last3=Xu |first3=Jingkun |last4=Wen |first4=Yangping |last5=Duan |first5=Xuemin |last6=Yu |first6=Hongmei |last7=Wu |first7=Liping |last8=Nie |first8=Tao |date=2013-05-01 |title=A facile one-step redox route for the synthesis of graphene/poly (3,4-ethylenedioxythiophene) nanocomposite and their applications in biosensing |url= |journal=Sensors and Actuators B: Chemical |language=en |volume=181 |pages=567–574 |doi=10.1016/j.snb.2013.02.024 |bibcode=2013SeAcB.181..567L |issn=0925-4005}} and Ion selective electrodes (ISEs).{{Cite journal |last1=Parks |first1=Sophie E. |last2=Irving |first2=Donald E. |last3=Milham |first3=Paul J. |date=2012-02-01 |title=A critical evaluation of on-farm rapid tests for measuring nitrate in leafy vegetables |url= |journal=Scientia Horticulturae |language=en |volume=134 |pages=1–6 |doi=10.1016/j.scienta.2011.10.015 |bibcode=2012ScHor.134....1P |issn=0304-4238}}

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