Editing Chromium (section)

== Precautions ==
{{Main|Chromium toxicity}}

Water-insoluble chromium(III) compounds and chromium metal are not considered a health hazard, while the toxicity and carcinogenic properties of chromium(VI) have been known for a long time.<ref name="Barceloux">{{cite journal|title = Chromium|first1 = Donald G|last1 = Barceloux|journal = Clinical Toxicology|volume = 37|issue = 2|pages = 173–194|date = 1999|doi = 10.1081/CLT-100102418|last2 = Barceloux|first2 = Donald|pmid = 10382554}}</ref> Because of the specific [[Transport protein|transport]] mechanisms, only limited amounts of chromium(III) enter the cells. Acute oral toxicity ranges between 50 and 150&nbsp;mg/kg.<ref name="Katz">{{cite journal |title = The toxicology of chromium with respect to its chemical speciation: A review |first1 = SA|last1 = Katz|journal = Journal of Applied Toxicology|volume = 13|issue = 3|pages = 217–224|date = 1992|doi = 10.1002/jat.2550130314|pmid = 8326093|last2 = Salem|first2 = H|s2cid = 31117557}}</ref> A 2008 review suggested that moderate uptake of chromium(III) through dietary supplements poses no genetic-toxic risk.<ref name="Eastmond">{{cite journal
|last1 = Eastmond |first1 = DA |date = 2008|title = Trivalent Chromium: Assessing the Genotoxic Risk of an Essential Trace Element and Widely Used Human and Animal Nutritional Supplement |journal = Critical Reviews in Toxicology |volume = 38 |issue = 3 |pages = 173–190 |doi = 10.1080/10408440701845401 |last2 = MacGregor|first2 = JT|last3 = Slesinski|first3 = RS|pmid = 18324515|s2cid = 21033504 }}</ref> In the US, the [[Occupational Safety and Health Administration]] (OSHA) has designated an air [[permissible exposure limit]] (PEL) in the workplace as a time-weighted average (TWA) of 1&nbsp;mg/m<sup>3</sup>. The [[National Institute for Occupational Safety and Health]] (NIOSH) has set a [[recommended exposure limit]] (REL) of 0.5&nbsp;mg/m<sup>3</sup>, time-weighted average. The [[IDLH]] (immediately dangerous to life and health) value is 250&nbsp;mg/m<sup>3</sup>.<ref>{{PGCH|0141}}</ref>

=== Chromium(VI) toxicity ===
The acute [[mouth|oral]] [[toxicity]] for [[Hexavalent chromium|chromium(VI)]] ranges between 1.5 and 3.3&nbsp;mg/kg.<ref name="Katz" /> In the body, chromium(VI) is reduced by several mechanisms to chromium(III) already in the blood before it enters the cells. The chromium(III) is excreted from the body, whereas the chromate ion is transferred into the cell by a transport mechanism, by which also [[sulfate]] and [[phosphate]] ions enter the cell. The acute toxicity of chromium(VI) is due to its strong [[Redox|oxidant]] properties. After it reaches the blood stream, it damages the kidneys, the liver and blood cells through oxidation reactions. [[Hemolysis]], [[renal]], and liver failure result. Aggressive dialysis can be therapeutic.<ref name="Dayan">{{cite journal |title = Mechanisms of chromium toxicity, carcinogenicity and allergenicity: Review of the literature from 1985 to 2000 |first1 = AD|last1 = Dayan |journal = Human & Experimental Toxicology |volume=20 |issue=9|pages = 439–451 |date=2001 |doi = 10.1191/096032701682693062 |last2 = Paine |first2 = AJ |s2cid = 31351037|pmid=11776406|doi-access = free | bibcode=2001HETox..20..439D }}</ref>

The [[carcinogenity]] of chromate dust has been known for a long time, and in 1890 the first publication described the elevated cancer risk of workers in a chromate dye company.<ref>{{cite journal |title = A case of adeno-carcinoma of the left inferior turbinated body, and perforation of the nasal septum, in the person of a worker in chrome pigments |first = D.|last = Newman |journal = Glasgow Medical Journal |volume = 33|pages = 469–470 |date=1890}}</ref><ref name="Langard">{{cite journal |title = One Hundred Years of Chromium and Cancer: A Review of Epidemiological Evidence and Selected Case Reports |first = S |last = Langard |journal = American Journal of Industrial Medicine |volume = 17 |issue = 2|pages = 189–214 |date = 1990 |doi = 10.1002/ajim.4700170205 |pmid = 2405656}}</ref> Three mechanisms have been proposed to describe the [[genotoxicity]] of chromium(VI). The first mechanism includes highly reactive [[hydroxyl radical]]s and other reactive radicals which are by products of the reduction of chromium(VI) to chromium(III). The second process includes the direct binding of chromium(V), produced by reduction in the cell, and chromium(IV) compounds to the [[DNA]]. The last mechanism attributed the genotoxicity to the binding to the DNA of the end product of the chromium(III) reduction.<ref name="Cohen">{{cite journal |title = Mechanisms of chromium carcinogenicity and toxicity |first1 = MD|last1 = Cohen|journal = Critical Reviews in Toxicology |volume=23 |issue = 3|pages=255–281 |date=1993 |doi = 10.3109/10408449309105012 |last2 = Kargacin |first2 = B |last3 = Klein |first3 = CB |last4 = Costa |first4 = M |pmid = 8260068 }}</ref><ref>{{cite book|title=Methods to Develop Inhalation Cancer Risk Estimates for Chromium and Nickel Compounds|date=2011|publisher=U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Health and Environmental Impacts Division|location=Research Triangle Park, NC|url=https://purl.fdlp.gov/GPO/gpo56032|access-date=19 March 2015|archive-date=22 April 2021|archive-url=https://web.archive.org/web/20210422173119/https://permanent.fdlp.gov/gpo56032/ni_cr_methods_final_report_cover.pdf|url-status=live}}</ref>

Chromium salts (chromates) are also the cause of [[allergic reaction]]s in some people. Chromates are often used to manufacture, amongst other things, leather products, paints, cement, mortar and anti-corrosives. Contact with products containing chromates can lead to allergic [[contact dermatitis]] and irritant dermatitis, resulting in ulceration of the skin, sometimes referred to as "chrome ulcers". This condition is often found in workers that have been exposed to strong chromate solutions in electroplating, tanning and chrome-producing manufacturers.<ref>{{cite web|publisher = DermNet NZ|last = Ngan|first = V|date = 2002|title = Chrome Allergy|url = http://dermnetnz.org/dermatitis/chrome-allergy.html|access-date = 7 June 2008|archive-date = 7 July 2016|archive-url = https://web.archive.org/web/20160707102208/http://www.dermnetnz.org/dermatitis/chrome-allergy.html|url-status = live}}</ref><ref>{{cite journal|title = Investigation of the threshold for allergic reactivity to chromium|last1 = Basketter|first1 = David|last2 = Horev|first2 = L|last3 = Slodovnik|first3 = D|last4 = Merimes|first4 = S|last5 = Trattner|first5 = A|last6 = Ingber|first6 = A|journal = Contact Dermatitis|volume = 44|issue = 2|pages = 70–74|date = 2000|doi = 10.1034/j.1600-0536.2001.440202.x|pmid = 11205406|s2cid = 45426346}}</ref>

=== Environmental issues ===
Because chromium compounds were used in [[dye]]s, [[paint]]s, and [[leather]] [[Tanning (leather)|tanning]] compounds, these compounds are often found in soil and [[groundwater]] at active and abandoned industrial sites, needing [[environmental cleanup]] and [[Environmental remediation|remediation]]. [[Primer (paint)|Primer paint]] containing hexavalent chromium is still widely used for [[aerospace]] and [[automobile]] refinishing applications.<ref>{{Cite book|first = Randall C|last = Baselt|title = Disposition of Toxic Drugs and Chemicals in Man|edition = 8th|publisher = Biomedical Publications|date=2008 |pages = 305–307|isbn = 978-0-9626523-7-0|place = Foster City}}</ref>

In 2010, the [[Environmental Working Group]] studied the drinking water in 35 American cities in the first nationwide study. The study found measurable hexavalent chromium in the tap water of 31 of the cities sampled, with [[Norman, Oklahoma]], at the top of list; 25 cities had levels that exceeded California's proposed limit.<ref>{{cite news|url = https://news.yahoo.com/s/afp/healthusenvironmentpollutionwater|archive-url = https://web.archive.org/web/20101223164916/http://news.yahoo.com/s/afp/healthusenvironmentpollutionwater|archive-date = 23 December 2010|work = [[Yahoo News]]|title = US water has large amounts of likely carcinogen: study|date = 19 December 2010|access-date = 19 December 2010}}</ref>

The more toxic hexavalent chromium form can be reduced to the less soluble trivalent oxidation state in soils by organic matter, ferrous iron, sulfides, and other reducing agents, with the rates of such reduction being faster under more acidic conditions than under more alkaline ones.  In contrast, trivalent chromium can be oxidized to hexavalent chromium in soils by manganese oxides, such as Mn(III) and Mn(IV) compounds. Since the solubility and toxicity of chromium (VI) are greater than those of chromium (III), the oxidation-reduction conversions between the two oxidation states have implications for movement and bioavailability of chromium in soils, groundwater, and plants.<ref>{{Cite journal|last=James|first=Bruce|date=1996|title=The challenge of remediating chromium-contaminated soil|journal=Environmental Science and Technology|volume=30|issue=6|pages=248A–251A|doi=10.1021/es962269h|pmid=21648723}}</ref>
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