六價鉻

六價鉻，又稱鉻(VI)或Cr(VI)，是任何含有氧化態+6的鉻的化合物。幾乎所有的鉻礦都是通過一種六價鉻化合物——重鉻酸鈉加工的。六價鉻是所有由鉻製成的材料的關鍵。1985年人們約生產了136,000公噸（150,000英噸）的六價鉻。^[1]

三氧化鉻是六價鉻的例子

六價鉻化合物包括三氧化鉻以及各種鉻酸鹽和重鉻酸鹽。六價鉻用於紡織染料、木材防腐（英語：Wood preservation）、防蝕劑（英語：Corrosion inhibitor）、鉻酸鹽轉化塗層（英語：Chromate conversion coating）以及各種小眾用途。六價鉻化合物的工業用途包括染料、油漆、油墨和塑料中的鉻酸鹽顏料，作為防腐劑添加到油漆、底漆和其他表面塗層中的鉻酸鹽以及電鍍到金屬部件上以提供裝飾或保護塗層的鉻酸。在進行如在不鏽鋼上進行焊接或熔化鉻金屬等「熱加工」時，也會形成六價鉻。在這些情況下的鉻最初不是六價的，但過程中涉及的高溫會使鉻被氧化，將鉻轉化為六價。^[2]六價鉻也存在於飲用水和公共供水系統中。^[3][4]

由於六價鉻的氧化性，它有毒且具會致癌（國際癌症研究機構一類致癌物）。如果吸入六價鉻，會導致肺癌。此外，人們還觀察到接觸六價鉻與鼻子和鼻竇的癌症之間存在正相關。^[5]許多職業的工人都會接觸到六價鉻，其中有問題的暴露發生在處理含有鉻酸鹽的產品的工人以及研磨和焊接不鏽鋼的工人中。^[6]接觸六價鉻的工人患肺癌、哮喘或鼻上皮和皮膚損傷的風險增加。^[2]

參考資料

1. Anger, Gerd; Halstenberg, Jost; Hochgeschwender, Klaus; Scherhag, Christoph; Korallus, Ulrich; Knopf, Herbert; Schmidt, Peter; Ohlinger, Manfred, Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, 2005, doi:10.1002/14356007.a07_067
2. 29 CFR OSHA General Industry 1910
3. Xie, Yun; Holmgren, Stephanie; Andrews, Danica M. K.; Wolfe, Mary S. Evaluating the Impact of the U.S. National Toxicology Program: A Case Study on Hexavalent Chromium. Environmental Health Perspectives. 2017, 125 (2): 181–188. PMC 5289905 . PMID 27483499. doi:10.1289/ehp21.
4. What is chromium-6 and how did it infiltrate America's drinking water?. PBS NewsHour. September 21, 2016 [September 23, 2019]. （原始內容存檔於2019-09-23）.
5. IARC. Volume 100C: Arsenic, Metals, Fibres, and Dusts (PDF). Lyon: International Agency for Research on Cancer. 2012 [17–24 March 2009] [2020-01-05]. ISBN 978-92-832-0135-9. （原始內容 (PDF)存檔於2020-03-17）. There is sufficient evidence in humans for the carcinogenicity of chromium (VI) compounds. Chromium (VI) compounds cause cancer of the lung. Also positive associations have been observed between exposure to Chromium (VI) compounds and cancer of the nose and nasal sinuses. There is sufficient evidence in experimental animals for the carcinogenicity of chromium (VI) compounds. Chromium (VI) compounds are carcinogenic to humans (Group 1).
6. IARC. Volume 49: Chromium, Nickel, and Welding (PDF). Lyon: International Agency for Research on Cancer. 1999-11-05 [1990] [2006-07-16]. ISBN 978-92-832-1249-2. （原始內容 (PDF)存檔於2008-12-24）. There is sufficient evidence in humans for the carcinogenicity of chromium[VI] compounds as encountered in the chromate production, chromate pigment production and chromium plating industries.

外部連結

• ATSDR Case Studies in Environmental Medicine: Chromium Toxicity （頁面存檔備份，存於網際網路檔案館） U.S. Department of Health and Human Services
• Hexavalent Chromium National Emphasis Program （頁面存檔備份，存於網際網路檔案館）
• Economou-Eliopoulos, Maria; Megremi, Ifigenia; Vasilatos, Charalampos. Factors controlling the heterogeneous distribution of Cr(VI) in soil, plants and groundwater: Evidence from the Assopos basin, Greece. Chemie der Erde – Geochemistry. 2011, 71 (1): 39–52. Bibcode:2011ChEG...71...39E. doi:10.1016/j.chemer.2011.01.001.
• 3M US: OSHA Hexavalent Chromium Standard – An overview of the Chromium Six (CrVI) standard
• Michaels, David; Monforton, Celeste; Lurie, Peter. Selected science: An industry campaign to undermine an OSHA hexavalent chromium standard. Environmental Health. 2006, 5: 5. PMC 1402271 . PMID 16504102. doi:10.1186/1476-069X-5-5.
• Australian National Pollutant Inventory Chromium VI fact sheet （頁面存檔備份，存於網際網路檔案館）
• US OSHA Health and Safety Topics: Hexavalent Chromium" （頁面存檔備份，存於網際網路檔案館）
• National Institute for Occupational Safety and Health – Hexavalent Chromium （頁面存檔備份，存於網際網路檔案館）
• M. Economou-Eliopoulos; D. Antivachi; Ch. Vasilatos; Megremi, I. Evaluation of the CR(VI) and other toxic element contamination and their potential sources: The case of the Thiva basin (Greece). Geoscience Frontiers. 2012, 3 (4): 523–539. doi:10.1016/j.gsf.2011.11.010 .