Chromium (Cr; Atomic number 24) is a naturally occurring 3d-transition element. Chromium is Earth's seventh most abundant element at an average concentration of 125 mg/kg in Earth's crust.[1][2] The oxidation states of chromium range from -4 to +6; the most stable forms are trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)].
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Hexavalent chromium [Cr (VI)] is one of the valence states (+6) of the element chromium. It is usually produced by an industrial process. Cr (VI) is known to cause cancer. In addition, it …
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hexavalent chromium and the toxic substances listed in Appendix C that are causing . 4 (or are capable of causing) occupational illnesses. By targeting inspections to workplaces known or likely to perform tasks associated with Cr(VI) overexposures, it
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Under normal environmental pH values, hexavalent chromium is found exclusively as HCrO 4 – at pH < 6.5 and chromate at pH > 6.5. Cr(VI) in ground water is a byproduct of many industrial processes (1,4−7) and can be formed by the …
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Hexavalent chromium can irritate the nose, throat, and lungs. Repeated or prolonged exposure can damage the mucous membranes of the nasal passages and result in ulcers. In severe …
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Hexavalent chromium exposure is associated with altered gene expression profiles and its disruption of the epigenome is an important contributor to the progression of carcinogenesis. Recent advances in our understanding of the genome's spatial organization highlight its importance in the maintenance of the transcriptome.
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What is hexavalent chromium? Hexavalent chromium (or chromium-6) is a highly toxic form of the naturally occurring metal chromium. It is a well-known human carcinogen when inhaled, and recent evidence indicates it can cause stomach or gastrointestinal cancer when ingested in drinking water. However, a different form, trivalent chromium, is an ...
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(4) Hexavalent chromium painting operations. Some metal finishing operations apply paints with higher concentrations of hexavalent chromium to a line of parts, particularly for aerospace applications when a high degree of corrosion protection is needed for critical product performance. Paints are generally applied in such operations with some ...
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Some hexavalent compounds, such as chromium(VI) oxide (or chromic acid), and the ammonium and alkali metal salts (e.g., sodium and potassium) of chromic acid are readily soluble in water.
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NIOSH reviews the following aspects of workplace exposure to Cr (VI) compounds: the potential for exposures (Chapter 2), analytical methods and considerations (Chapter 3), human health effects (Chapter 4), experimental …
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Hexavalent chromium can irritate the nose, throat, and lungs. Repeated or prolonged exposure can damage the mucous membranes of the nasal passages and result in ulcers. In severe cases, exposure causes perforation of the septum (the wall separating the nasal passages). Some employees become allergic to hexavalent chromium so that inhaling the ...
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Hexavalent chromium exposure occurs through breathing it in, ingesting it in food or water, or direct contact with the skin. What are the known health effects of inhaling hexavalent chromium? Hexavalent chromium …
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(2) This prohibition does not apply to hexavalent chromium produced as a by-product of manufacturing processes. (c) If authorization for incorporation of hexavalent chromium in a deliverable or construction material is required, the Contractor shall submit a request to the Contracting Officer. (d) Subcontracts.
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After the much publicized controversy of hexavalent chromium contamination of drinking water in the Hinkley community in California due to industrial operations, the issue of chromium contamination and its attendant health effects remain highly controversial.3,4 The World Health Organization considers Cr(VI) to be a Group 1 carcinogen to humans.
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Typical hexavalent chromium bath composition is as follows: (a) electrolytic solution: chromic acid, (b) anode: lead with tin up to 7%; (c) operating temperature: 45–60 °C, (d) plating current: 1.5–3.0 kA/m 2. About 35% of used …
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Hexavalent Chromium Cr(VI) 30.0002 mg/m (I) 0.0005 mg/m3 (I) Legend: mg/m3 = milligram per meter cubed Note: (I) Measured as inhalable fraction of the aerosol. 2 2. Sampling Plan Overview. a. Air sampling will be performed, at each installation, throughout all identified
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Cr is prone to oxidation into hexavalent chromium (Cr(VI)) by O 2 2, manganese oxide minerals 3, and H 2 O 2 4, which contaminates surface water, groundwater, and drinking …
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Hexavalent chromium [Cr(VI)] is a global environmental pollutant that increases risk for several types of cancers and is increasingly being recognized as a neurotoxicant. ... and brain) and disease, (3) (chromium) and brain levels, 4) ((chromium) and neurologic), (5) ((chromium) and neurotoxicity). Additionally, search terms "chromate ...
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In this criteria document, the National Institute for Occupational Safety and Health (NIOSH) reviews the critical health effects studies of hexavalent chromium (Cr[VI]) compounds in order to update its assessment of the potential health effects of occupational exposure to Cr(VI) compounds and its recommendations to prevent and control these workplace exposures.
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restricts its focus to hexavalent chromium compounds, which are a group of substances that contain chromium in the hexavalent (+6) oxidation state, denoted as Cr(VI). Cr(VI) compounds have many industrial applications, including pigment manufacturing, corrosion inhibition and metal finishing. Because many Cr(VI)
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Abstract. Background: Hexavalent chromium [Cr(VI)] is an occupational carcinogen that can cause lung and nasal cancers, but its association with mortality and incidence in many other cancers is unclear. Objectives: In this meta-analysis, we aimed to evaluate the relationship between exposure to Cr(VI) and the mortality and incidence of human cancers. ...
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Detecting Hexavalent Chromium. A wide range of substances were tested, hexavalent chromium also known as Chromium-6 was included on the list. Our system registered results between 3-4 parts per billion (ppb) well under the EPA and MassDEP Departments standard of 100 ppb for total chromium which adds together trivalent chromium (Chromium-3) …
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Chromium (VI), also known as Hexavalent Chromium, is a toxic form of the metallic element Chromium and is typically generated through industrial processes. It can be present in solution or solid and can be generated as a dust, fume or mist from workplace activities where chromates, dichromates and chromic acid are used.
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4.3. Hexavalent Chromium [Cr (VI)]– A chromium with a valence state of positive six (+6), in any form and in any compound. 4.4. Exposure Assessment – intentional, documented, use of standardized assessment tool [e.g. qualitative ratings yielding overall risk ranking].
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EPA released the draft IRIS Toxicological Review of Hexavalent Chromium (External Review Draft) for public comment and subsequent external peer review by EPA's Science Advisory Board (SAB). Also, the EPA-led Interagency Science Consultation draft was released with comments. [Federal Register Notice Oct 20, 2022] Sep ...
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Staff Report -4- Chromium (hexavalent) MCL Administrative Draft 1. Estimated Total Costs of Monitoring and Treatment The estimated total annualized monitoring and treatment costs for water sources with concentrations of hexavalent chromium greater than the proposed MCL of …
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Hexavalent chromium is an established human carcinogen in certain occupational settings as a result of inhalation exposure. Hexavalent chromium compounds have been found in drinking water. The long-term …
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hexavalent chromium plume. 1 mile long x 1/2 mile wide x 100 ft. thick > 50ppb 900 - 1,000 Depth to the regional aquifer. feet Number of monitoring, extraction and injection wells installed in and around the plume. 37 Amount of chromium contamination in …
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A survey conducted from 1974 to 1975 provides estimates of chromium concentrations in U.S. drinking water. The survey reported the concentration of chromium in tap water in U.S. s was from 0.4 to 8.0 micrograms per liter (µg/L). [ATSDR 2000] (EPA's maximum contaminant level for chromium in drinking water is 100 µg/L.)
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In the hexavalent state, chromium exists as oxo species such as CrO3 and CrO42-) that are strongly oxidizing (Cotton and Wilkinson, 1980). The CAS Registry numbers and the solubilities of a few important hexavalent chromium compounds are given in Table 1. In solution, hexavalent chromium exists as hydrochromate (HCrO4-), chromate (CrO 4 2-),
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