Editing Perchlorate (section)

==Contamination in environment==
Perchlorates are of concern because of uncertainties about toxicity and health effects at low levels in drinking water, impact on ecosystems, and indirect exposure pathways for humans due to accumulation in vegetables.<ref name="Sridhar Susarla 1999"/> They are water-soluble, exceedingly mobile in aqueous systems, and can persist for many decades under typical groundwater and surface water conditions.<ref name="ReferenceA"/>

===Industrial origin===
Perchlorates are used mostly in [[rocket propellant]]s but also in disinfectants, bleaching agents, and herbicides. Perchlorate contamination is caused during both the manufacture and ignition of rockets and fireworks.<ref name="Kucharzyk">{{cite journal|last=Kucharzyk|first=Katarzyna|title=Development of drinking water standards for perchlorate in the United States |date=2009 |doi=10.1016/j.jenvman.2009.09.023|volume=91|issue=2|journal=Journal of Environmental Management |pages=303–310|pmid=19850401|bibcode=2009JEnvM..91..303K }}</ref> Fireworks are also a source of perchlorate in lakes.<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Fireworks Displays Linked To Perchlorate Contamination In Lakes |url=https://www.sciencedaily.com/releases/2007/05/070528095714.htm |work=Science Daily |location=Rockville, MD |date=2007-05-28}}</ref> Removal and recovery methods of these compounds from explosives and rocket propellants include high-pressure water washout, which generates aqueous ammonium perchlorate.

===In U.S. drinking water===
In 2000, perchlorate contamination beneath the former flare manufacturing plant [[Olin Corporation]] Flare Facility, [[Morgan Hill, California]] was first discovered several years after the plant had closed. The plant had used potassium perchlorate as one of the ingredients during its 40 years of operation. By late 2003, the State of California and the [[Santa Clara Valley Water District]] had confirmed a groundwater plume currently extending over nine miles through residential and agricultural communities.{{citation needed|date=November 2017}}
The California Regional Water Quality Control Board and the [[Santa Clara Valley Water District]] have engaged{{when|date=November 2017}} in a major outreach effort, a [[water well test]]ing program has been underway for about 1,200 residential, municipal, and agricultural wells. Large ion exchange treatment units are operating in three public water supply systems which include seven municipal wells with perchlorate detection. The [[potentially responsible parties]], Olin Corporation and Standard Fuse Incorporated, have been supplying bottled water to nearly 800 households with private wells,{{when|date=November 2017}} and the Regional Water Quality Control Board has been overseeing cleanup efforts.<ref>{{cite web |url=http://archive.epa.gov/region9/toxic/web/html/per_ca.html#olin |title=Perchlorate in the Pacific Southwest: California |website=EPA – Region 9 |publisher=EPA |location=San Francisco, CA}}</ref>

The source of perchlorate in California was mainly attributed to two manufacturers in the southeast portion of the Las Vegas Valley in Nevada, where perchlorate has been produced for industrial use.<ref>{{cite web |url=https://www.lvvwd.com/wq/facts_perchlorate.html |title=Perchlorate |website=Las Vegas Valley Water District |location=Las Vegas, NV |access-date=2017-07-06 |archive-date=2016-11-04 |archive-url=https://web.archive.org/web/20161104210252/https://www.lvvwd.com/wq/facts_perchlorate.html |url-status=dead }}</ref> This led to perchlorate release into [[Lake Mead]] in Nevada and the [[Colorado River]] which affected regions of Nevada, California and [[Arizona]], where water from this reservoir is used for consumption, irrigation and recreation for approximately half the population of these states.<ref name="Kucharzyk"/> Lake Mead has been attributed{{when|date=November 2017}} as the source of 90% of the perchlorate in Southern Nevada's drinking water. Based on sampling, perchlorate has been affecting 20&nbsp;million people, with highest detection in [[Texas]], southern California, [[New Jersey]], and Massachusetts, but intensive sampling of the [[Great Plains]] and other middle state regions may lead to revised estimates with additional affected regions.<ref name="Kucharzyk"/> An action level of 18&nbsp;μg/L has been adopted{{when|date=November 2017}} by several affected states.<ref name="ReferenceA"/>

In 2001, the chemical was detected at levels as high as 5&nbsp;μg/L at [[Joint Base Cape Cod]] (formerly [[Massachusetts Military Reservation]]), over the [[Massachusetts]] then state regulation of 2&nbsp;μg/L.<ref>{{cite web |url=http://jbcc-iagwsp.org/groundwater/papers/EPATSP2001Perchlorat%20pres.pdf |last=Clausen |first=Jay |title=Perchlorate, Source and Distribution in Groundwater at Massachusetts Military Reservation |date=November 2001 |id=Presentation at U.S. EPA Technical Support Project Semi-Annual Meeting, Cambridge, MA}}</ref><ref>{{cite web |url=http://www.mass.gov/eea/docs/dep/water/laws/i-thru-z/perchlorate-310cmr22-07282006.pdf |title=Inorganic Chemical Maximum Contaminant Levels, Monitoring Requirements and Analytical Methods |access-date=2017-07-05 |publisher=Massachusetts Office of Energy and Environmental Affairs |id=''Code of Massachusetts Regulations'' (CMR), 310 CMR 22.06 |archive-date=2017-02-28 |archive-url=https://web.archive.org/web/20170228075214/http://www.mass.gov/eea/docs/dep/water/laws/i-thru-z/perchlorate-310cmr22-07282006.pdf |url-status=dead }}</ref>

As of 2009, low levels of perchlorate had been detected in both drinking water and [[groundwater]] in 26 states in the U.S., according to the [[United States Environmental Protection Agency|Environmental Protection Agency]] (EPA).<ref>{{cite journal |last1=Brandhuber |first1=Philip |last2=Clark |first2=Sarah |last3=Morley |first3=Kevin |date=November 2009 |title=A review of perchlorate occurrence in public drinking water systems |url=https://www.epa.gov/sites/production/files/2015-09/documents/12004-exhibita.pdf |journal=Journal of the American Water Works Association |volume=101 |issue=11 |pages=63–73 |doi=10.1002/j.1551-8833.2009.tb09991.x|bibcode=2009JAWWA.101k..63B |s2cid=17523940 }}</ref>

===In food===
In 2004, the chemical was found in cow's milk in California at an average level of 1.3 [[parts per billion]] (ppb, or μg/L), which may have entered the cows through feeding on crops exposed to water containing perchlorates.<ref name=AP2004>[[Associated Press]]. "[https://www.nbcnews.com/id/wbna5268705 Toxic chemical found in California milk]". ''[[NBC News]]''. June 22, 2004.</ref>
A 2005 study suggested [[human breast milk]] had an average of 10.5&nbsp;μg/L of perchlorate.<ref>McKee, Maggie. "[https://www.newscientist.com/article.ns?id=dn7057 Perchlorate found in breast milk across US] {{Webarchive|url=https://web.archive.org/web/20080927031838/http://www.newscientist.com/article.ns?id=dn7057 |date=2008-09-27 }}". ''[[New Scientist]]''. February 23, 2005</ref>

===From minerals and other natural occurrences===
In some places, there is no clear source of perchlorate, and it may be naturally occurring. Natural perchlorate on Earth was first identified in terrestrial nitrate deposits /fertilizers of the [[Atacama Desert]] in Chile as early as the 1880s<ref>Ericksen, G. E. "Geology and origin of the Chilean nitrate deposits"; U.S. Geological Survey Prof. Paper 1188; USGS: Reston, VA, 1981, 37 pp.</ref> and for a long time considered a unique perchlorate source. The perchlorate released from historic use of Chilean nitrate based fertilizer which the U.S.imported by the hundreds of tons in the early 19th century can still be found in some groundwater sources of the United States, for example Long Island, New York.<ref>{{cite journal |author1=Böhlke J. K. |author2=Hatzinger P. B. |author3=Sturchio N. C. |author4=Gu B. |author5=Abbene I. |author6=Mroczkowski S. J. |year = 2009 | title = Atacama perchlorate as an agricultural contaminant in groundwater: Isotopic and chronologic evidence from Long Island, New York |journal = Environmental Science & Technology |volume = 43 |issue = 15| pages = 5619–5625 |doi=10.1021/es9006433|pmid=19731653 |bibcode=2009EnST...43.5619B }}</ref> Recent improvements in analytical sensitivity using ion chromatography based techniques have revealed a more widespread presence of natural perchlorate, particularly in subsoils of Southwest USA,<ref>{{cite journal |author1=Rao B. |author2=Anderson T. A. |author3=Orris G. J. |author4=Rainwater K. A. |author5=Rajagopalan S. |author6=Sandvig R. M. |author7=Scanlon B. R.|author7-link= Bridget Scanlon |author8=Stonestrom S. A. |author9=Walvoord M. A. |author10=Jackson W. A. |year = 2007 |title = Widespread NaturalPerchlorate in Unsaturated zones of the Southwest United States |journal = Environ. Sci. Technol. |volume = 41 |issue = 13|pages = 4522–4528 |doi=10.1021/es062853i|pmid=17695891 |bibcode=2007EnST...41.4522R }}</ref> salt evaporites in California and Nevada,<ref>Orris, G. J.; Harvey, G. J.; Tsui, D. T.; Eldridge, J. E. Preliminaryanalyses for perchlorate in selected natural materials and theirderivative products; USGS Open File Report 03-314; USGS, U.S.Government Printing Office: Washington, DC, 2003.</ref> Pleistocene groundwater in New Mexico,<ref>{{cite journal |author1=Plummer L. N. |author2=Bohlke J. K. |author3=Doughten M. W. | year = 2005 | title = Perchlorate in Pleistocene and Holocene groundwater in North-Central New Mexico | doi = 10.1021/es051739h |pmid=16570594 | journal = Environ. Sci. Technol. | volume = 40 | issue = 6| pages = 1757–1763| bibcode = 2006EnST...40.1757P }}</ref> and even present in extremely remote places such as [[Antarctica]].<ref name="S. P. Kounaves et al. 2010 2360–2364">{{cite journal | doi = 10.1021/es9033606 | title = Natural Perchlorate in the Antarctic Dry Valleys and Implications for its Global Distribution and History | author = S. P. Kounaves| journal = [[Environmental Science & Technology]] | volume = 44 | issue = 7 |pages = 2360–2364 | year = 2010 | pmid = 20155929|bibcode = 2010EnST...44.2360K |display-authors=etal}}</ref> The data from these studies and others indicate that natural perchlorate is globally deposited on Earth with the subsequent accumulation and transport governed by the local hydrologic conditions.

Despite its importance to environmental contamination, the specific source and processes involved in natural perchlorate production remain poorly understood. Laboratory experiments in conjunction with isotopic studies<ref>{{cite journal | author = Böhlke, Karl John, Sturchio Neil C., Gu Baohua, Horita Juske, Brown Gilbert M., Jackson W. Andrew, Batista Jacimaria, Hatzinger Paul B. | year = 2005 | title = Perchlorate isotope forensics | journal = Analytical Chemistry | volume = 77 | issue = 23| pages = 7838–7842 | doi=10.1021/ac051360d| pmid = 16316196 | bibcode = 2005AnaCh..77.7838B }}</ref> have implied that perchlorate may be produced on earth by oxidation of chlorine species through pathways involving ozone or its photochemical products.<ref>{{cite journal | author = Rao B., Anderson T. A., Redder A., Jackson W. A. | year = 2010 | title = Perchlorate Formation by Ozone Oxidation of AqueousChlorine/Oxy-Chlorine Species: Role of ClxOy Radicals | journal = Environ. Sci. Technol. | volume = 44 | issue = 8| pages = 2961–2967 | doi=10.1021/es903065f| pmid = 20345093 | bibcode = 2010EnST...44.2961R }}</ref><ref>{{cite journal | author = Catling, D. C., M. W. Claire, K. J. Zahnle, R. C. Quinn, B. C. Clark, M. H. Hecht, and S. Kounaves | year = 2010 | title = Atmospheric origins of perchlorate on Mars and in the Atacama | journal = J. Geophys. Res. | volume = 115 | issue = E1| pages = E00E11 | doi= 10.1029/2009JE003425| pmid = 32487988 | pmc = 7265485 | bibcode = 2010JGRE..115.0E11C }}</ref> Other studies have suggested that perchlorate can also be formed by lightning activated oxidation of chloride aerosols (e.g., chloride in sea salt sprays),<ref>{{cite journal |author1=Dasgupta P. K. |author2=Martinelango P. K. |author3=Jackson W. A. |author4=Anderson T. A. |author5=Tian K. |author6=Tock R.W. |author7=Rajagopalan S. |year = 2005 |title = The origin of naturally occurring perchlorate: the role ofatmospheric processes |journal = Environmental Science & Technology |volume = 39 | issue = 6|pages = 1569–1575 |doi=10.1021/es048612x|pmid=15819211 |bibcode=2005EnST...39.1569D }}</ref> and ultraviolet or thermal oxidation of chlorine (e.g., bleach solutions used in swimming pools) in water.<ref>{{cite journal |author1=Rao B. |author2=Estrada N |author3=Mangold J. |author4=Shelly M. |author5=Gu B. |author6=Jackson W. A. | year = 2012 | title = Perchlorate production byphotodecomposition of aqueous chlorine |journal = Environ. Sci. Technol. |volume = 46 |issue = 21|pages =11635–11643| doi = 10.1021/es3015277|pmid=22962844 |bibcode=2012EnST...4611635R}}</ref><ref>{{cite journal |author1=Stanford B. D. |author2=Pisarenko A. N. |author3=Snyder S. A. |author4=Gordon G. |year = 2011 |title = Perchlorate, bromate, and chlorate in hypochlorite solutions: Guidelines for utilities | journal = Journal of the American Water Works Association | volume = 103 |issue = 6|page = 71|doi=10.1002/j.1551-8833.2011.tb11474.x |bibcode=2011JAWWA.103f..71S |s2cid=21620375 }}</ref><ref>{{cite journal |author = William E. Motzer |title = Perchlorate: Problems, Detection, and Solutions |pages = 301–311 |doi = 10.1006/enfo.2001.0059 |journal = Environmental Forensics |volume = 2 |issue = 4 |year = 2001|bibcode = 2001EnvFo...2..301M |s2cid = 95709844 }}</ref>

===From nitrate fertilizers===
Although perchlorate as an environmental contaminant is usually associated with the manufacture, storage, and testing of [[solid rocket motor]]s,<ref name="Matthew L. Magnuson 2000">{{cite journal |author1=Magnuson Matthew L. |author2=Urbansky Edward T. |author3=Kelty Catherine A. | year = 2000 | title = Determination of Perchlorate at Trace Levels in Drinking Water by Ion-Pair Extraction with Electrospray Ionization Mass Spectrometry | journal = Analytical Chemistry | volume = 72 |issue=1 | pages = 25–29| doi=10.1021/ac9909204|pmid=10655630 }}</ref> contamination of perchlorate has been focused as a side effect of the use of natural nitrate [[fertilizer]] and its release into ground water. The use of naturally contaminated nitrate fertilizer contributes to the infiltration of perchlorate anions into the ground water and threaten the water supplies of many regions in the US.<ref name="Matthew L. Magnuson 2000"/>

One of the main sources of perchlorate contamination from natural nitrate fertilizer use was found to come from the fertilizer derived from Chilean [[caliche]] ([[calcium carbonate]]), because Chile has rich source of naturally occurring perchlorate anion.<ref name="S.K. Brown, M.L. Magnuson 2001">{{cite journal |author1=Urbansky T. |author2=Brown S.K. |author3=Magnuson M.L. |author4=Kelty C.A. | year = 2001 | title = Perchlorate levels in samples of sodium nitrate fertilizer derived from Chilean caliche | url = https://zenodo.org/record/1259965| journal = Environmental Pollution | volume = 112 | issue = 3| pages = 299–302| doi=10.1016/s0269-7491(00)00132-9|pmid=11291435 }}</ref> Perchlorate concentration was the highest in Chilean nitrate, ranging from 3.3 to 3.98%.<ref name="ReferenceA"/> Perchlorate in the solid fertilizer ranged from 0.7 to 2.0&nbsp;mg g<sup>−1</sup>, variation of less than a factor of 3 and it is estimated that sodium nitrate fertilizers derived from Chilean caliche contain approximately 0.5–2&nbsp;mg g<sup>−1</sup> of perchlorate anion.<ref name="S.K. Brown, M.L. Magnuson 2001"/> The direct ecological effect of perchlorate is not well known; its impact can be influenced by factors including rainfall and irrigation, dilution, natural attenuation, soil adsorption, and bioavailability.<ref name="S.K. Brown, M.L. Magnuson 2001"/> Quantification of perchlorate concentrations in nitrate fertilizer components via [[ion chromatography]] revealed that in horticultural fertilizer components contained perchlorate ranging between 0.1 and 0.46%.<ref name="ReferenceA">{{cite journal |author1=Susarla Sridhar |author2=Collette T. W. |author3=Garrison A. W. |author4=Wolfe N. L. |author5=McCutcheon S. C. | year = 1999 | title = Perchlorate Identification in Fertilizers | journal = Environmental Science and Technology | volume = 33 | issue = 19| pages = 3469–3472| doi=10.1021/es990577k|bibcode=1999EnST...33.3469S}}</ref>