Be advised it is entirely possible that one could exceed the TLV for hexavalent chromium while staying under the TLV for other fumes given off. It is important to realize hexavalent chromium has its own recommended threshold limit value (TLV) as established by the American Conference of Industrial Hygienists (ACGIH), and that this value may be lower than other components present as airborne contaminants.īecause hexavalent chromium is usually only a percentage of the dust fume and mist generated from a process, it may be worth investigating the percent contribution of Cr(VI) verse other materials in the airstream. Important Clarification Points: In your facility, you may be producing a dust, fume, or mist that contains hexavalent chromium. Hexavalent chromium may be present in a feedstock containing any form of chromium.Metallic chromium in the feedstock may be converted to hexavalent form.Thermal Spraying, including plasma, electric arc, and combustion (including HVOF).Welding and cutting of alloys containing chromium.Blending/sanding coatings containing chromium.Coatings containing chromates: dyes, paints, inks & plastics.There are a variety of industrial processes that can produce hexavalent chromium. Where Does Hexavalent Chromium Come From? At either of these levels, employers are required to take specific actions, and failure to take these actions may result in penalties. This is the concentration of airborne Cr(VI) present in a work environment and calculated as an 8-hour time-weighted average (TWA). The second exposure limit is called the Action Level (AL) which is currently at 2.5 µg/m3. This PEL of 5 µg/m3 was reduced from the previous standard of 52 µg/m3. The current PEL for hexavalent chromium is 5 µg/m3 for a single employee over an 8-hr shift. The Occupational Safety & Health Administration (OSHA) has defined two levels of exposure for hexavalent chromium: a Permissible Exposure Limit (PEL) and an Action Level (AL). Reading through articles and publications, you will see hexavalent chromium identified in different ways, including: Hex Chrome, Chromium (VI), Cr(VI), and Cr 6+. Hexavalent Chromium is the most toxic form of chromium. Hexavalent chromium shows up in predominantly three forms: 1) Trivalent Chromium, which occurs naturally as chrome ore and is also an essential nutrient for proper metabolism 2) Metallic or Elemental Chromium, typically found in aerospace alloys and 3) Hexavalent Chromium, typically from industrial processes like welding and thermal spray.
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