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What It Is
Hexavalent Chromium, Chromium 6, Cr(VI), Chromium 6 is a IARC-1 human carcinogen. The EPA estimates that 8 out of every 100 workers exposed to Cr(VI) develops lung cancer*.
Other risks to health by exposure to Chrome 6 are irritation to the eyes, lungs, nose, throat, and skin. Long term exposure to Cr(VI) can cause ulcerations to form on the skin, and a person can become so allergic to it that even the slightest exposure can cause a severe rash. Permanent eye damage can result from exposure, as well as damage and ulcerations on the mucous membranes in the nose.
On May 30, 2006 OSHA released a new standard** concerning hexavalent chromium, also referred to as CrVI and Cr6+, for welding, plating, and other processes.
What Can Cause Exposure, And Who Is At Risk?
Occupational exposure may occur among workers who:
Handle dry chromate-containing pigments
Weld, cut, or machine chromium-containing metals such as stainless steel
Operate chrome plating baths
Spray chromate-containing paints and coatings
Exposure Measurements
The OSHA “Action Level” for potential exposure to Chrome 6 is 2.5 micrograms / cubic meter or PEL (Permissible Exposure Limit ) which is 5 micrograms / cubic meter either of which is measured as an 8 hour time weighted average (TWA).
As per the OSHA Standard, “The Employer shall perform initial monitoring to determine the 8-hour TWA exposure for each employee on the basis of a sufficient number of personal breathing zone air samples to accurately characterize full shift exposure…”. In a nutshell, any employer who has workers with potential exposure to Chromium 6 must perform an initial air test to determine if the exposure level of employees is above or below the OSHA action Level of 2.5 micrograms / cubic meter.
If tested levels are less than the action level of 2.5 micrograms per cubic meter, then no other action need be taken unless a change in their process that alters exposure levels occurs. If this happens, an additional air test should be done.
If the air samples are equal or greater than 2.5 micrograms per cubic meter, the employer must continue air sampling every 6 months.
If testing shows a concentration of more than 5 micrograms per cubic meter, the employer must take “corrective action” and continue air sampling every 3 months.
What Defines “Corrective Action”?
Again, as per the OSHA Standard, “The employer shall use engineering and work practice controls to reduce and maintain employee exposure to chromium VI to or below the PEL unless the employer can demonstrate that such controls are not feasible.”
Engineering controls, such as the correct use of source capture fume extractors***, can help reduce the PEL levels enough to avoid implementing work practices that alter the process that creates the exposure, or the use of “Regulated Areas”. Source capture filtration can minimize or eliminate the need for a regulated area and all of the burdens that go with it.
What Are “Regulated Areas”?
Regulated Areas are the clearly marked space around a process that create Cr(VI) exposure levels equal to or greater than the PEL measurement of 5 micrograms per cubic meter.
For employees that work in or move through a Regulated Area, the employer must provide the following protective measures to limit exposure:
Respirators
Work Clothing or Uniforms
Laundry facilities for uniforms or work clothing
Change Rooms
Wash Rooms and Shower Facilities
Safety Areas for breaks and meals
Personal medical monitoring for EVERY employee who enters a Regulated Area
In addition, employers must monitor employees who enter a Regulated Area to make sure they do not eat, drink, smoke, chew gum, rub their eyes, or put their fingers in their mouths, among other things.
* http://www.epa.gov/iris/subst/0144.htm
** http://www.osha.gov/SLTC/hexavalentchromium/hex_regulatory_text.html
***Please bear in mind, the use of air cleaning equipment will not guarantee to get a specific user below the OSHA PEL of 5 micrograms / cubic meter. Many factors beyond the control of air cleaning equipment will impact the overall efficiency, including but not limited to, location of the hood or source capture device relative to the welding, cutting, machining, or process that causes exposure. Sidedrafts created by cooling fans, failure to replace filters when they become plugged, faulty filters due to either manufacturing error or mishandling by the user are just a few of the circumstances beyond control. Using fans to blow the fumes away from the welder may also bring the welder’s exposure below the PEL, but may create a new regulated area in the direction of the exhaust fans.
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