Editing Chrome plating (section)

==Health and environmental concerns==
Hexavalent chromium is the most toxic form of chromium. In the U.S., the [[United States Environmental Protection Agency|Environmental Protection Agency]] regulates it heavily. The EPA lists hexavalent chromium as a [[hazardous air pollutant]] because it is a human [[carcinogen]], a "priority pollutant" under the [[Clean Water Act]], and a "hazardous constituent" under the [[Resource Conservation and Recovery Act]]. Due to its low cathodic efficiency and high solution [[viscosity]], a toxic mist of water and hexavalent chromium is released from the bath.  [[Wet scrubber]]s are used to control these emissions. The liquid from the wet scrubbers is treated to [[precipitate]] the chromium and remove it from the wastewater before it is discharged.<ref name="newmoa"/>

Additional toxic waste created from hexavalent chromium baths include [[lead chromate]]s, which form in the bath because [[lead]] anodes are used. [[Barium]] is also used to control the sulfate concentration, which leads to the formation of [[barium sulfate]] (BaSO<sub>4</sub>).<ref name="newmoa"/>

Trivalent chromium is intrinsically less toxic than hexavalent chromium. Because of the lower toxicity it is not regulated as strictly, which reduces [[overhead cost]]s. Other health advantages include higher cathode efficiencies, which lead to less chromium air emissions; lower concentration levels, resulting in less chromium waste and anodes that do not decompose.<ref name="newmoa"/>

Maintaining a bath [[surface tension]] less than 35 dyn/cm is necessary to prevent plating solution from becoming airborne when bubbles rise to the surface and pop. This requires a frequent cycle of treating the bath with a wetting agent fume suppressant and confirming the effect on surface tension.<ref>{{cite web |url=http://www.epa.gov/ttn/atw/chrome/chromepg.html |title=Rule and Implementation Information for Chromium Electroplating&#124; Technology Transfer Network Air Technical Web site &#124; US EPA |access-date=2010-08-20 |url-status=live |archive-url=https://web.archive.org/web/20101130224220/http://www.epa.gov/ttn/atw/chrome/chromepg.html |archive-date=2010-11-30 }}</ref> Usually, surface tension is measured with a [[Stalagmometric method|stalagmometer]] or [[tensiometer (surface tension)|tensiometer]]. This method is, however, tedious and suffers from inaccuracy (errors up to 22 dyn/cm have been reported), and is dependent on the user's experience and capabilities.<ref>{{cite web |url=http://www.nmfrc.org/crarchive/jan08b.cfm |title=Surface Technology Environmental Resource Center - STERC |access-date=2010-08-20 |url-status=dead |archive-url=https://web.archive.org/web/20100707153710/http://www.nmfrc.org/crarchive/jan08b.cfm |archive-date=2010-07-07 }}</ref>

While they are effective for the control of toxic airborne chromium, many widely used wetting agent fume suppressants are toxic themselves because they contain [[perfluoroalkyl substances]] (PFAS), which are hazardous chemicals that can cause long-term health effects.<ref name="PFAS">{{cite web |last1=Gilchrist |first1=Maya |title=PFAS in the metal plating and finishing industry |url=https://www.pca.state.mn.us/sites/default/files/gp3-05.pdf |website=Minnesota Pollution Control Agency |access-date=22 March 2023}}</ref> This makes electroplating one of the jobs with the highest risk of occupational exposure to PFAS, but not as high as firefighters using fluorinated [[Firefighting foam#Synthetic foams|aqueous film forming foams]].<ref name="RotanderKärrman2015">{{cite journal |last1=Rotander |first1=Anna |last2=Kärrman |first2=Anna |last3=Toms |first3=Leisa-Maree L. |last4=Kay |first4=Margaret |last5=Mueller|first5=Jochen F.|last6=Gómez Ramos|first6=María José|title=Novel Fluorinated Surfactants Tentatively Identified in Firefighters Using Liquid Chromatography Quadrupole Time-of-Flight Tandem Mass Spectrometry and a Case-Control Approach|journal=Environmental Science & Technology |volume=49 |issue=4 |year=2015 |pages=2434–2442 |issn=0013-936X |doi=10.1021/es503653n|pmid=25611076 |bibcode=2015EnST...49.2434R }}</ref> In addition to their detrimental effects on human health, PFAS are persistent pollutants that cause significant [[bioaccumulation]] and [[biomagnification]], putting animals at the highest [[trophic level]] at the highest risk for toxic effects.<ref name="Danish">{{cite web |last1=Kjølholt |first1=Jesper |last2=Astrup Jensen |first2=Allan |last3=Warming |first3=Marlies |title=Short-chain Polyfluoroalkyl Substances (PFAS) |url=https://www2.mst.dk/Udgiv/publications/2015/05/978-87-93352-15-5.pdf |website=Ministry of Environment of Denmark Environmental Protection Agency |publisher=The Danish Environmental Protection Agency |access-date=22 March 2023}}</ref>
<ref name="Epa">{{cite web |title=Chromium Electroplating |url=https://www.epa.gov/stationary-sources-air-pollution/chromium-electroplating-and-anodizing |website=United States Environmental Protection Agency |accessdate=2024-06-13}}</ref>