Hexavalent chromium (CrVI) compounds are a group of chemical substances that contain the metallic element chromium in its positive-6 valence (hexavalent) state. Workers in many different occupations are exposed to hexavalent chromium (CrVI). Occupational exposures occur mainly among workers who handle pigments containing dry chromate, spray paints and coatings containing chromate, operate chrome plating baths, and weld or cut metals containing chromium, such as stainless steel (OSHA, n.d.).
The Dangers of Hexavalent Chromium
All forms of hexavalent chromium are regarded as carcinogenic to workers. The risk of developing lung cancer increases with the amount of hexavalent chromium inhaled and the length of time the worker is exposed. Breathing high levels of hexavalent chromium can irritate or damage the nose, throat, and lungs, and prolonged skin contact can result in dermatitis and skin ulcers. Direct eye contact with chromic acid or chromate dusts can cause permanent eye damage. 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) (OSHA, n.d.). OSHA published a final standard for occupational exposure to hexavalent chromium on February 28, 2006 and it became effective on May 30, 2006. The standard covers occupational exposure to hexavalent chromium (CrVI) in general industry, construction, and shipyards. All three versions of the standard are very similar.
Permissible Exposure Limit (PEL
The new standard lowers OSHA''s permissible exposure limit (PEL) for hexavalent chromium, and for all of its compounds, from 52 to 5 micrograms of Cr(VI) per cubic meter of air as an 8-hour time- weighted average.
Respiratory Protection Requirements
Respirators are required in the following situations whenever exposure levels exceed the PEL: (3M, 2006)
- While engineering and work practice controls are being developed
- During maintenance and repair activities for which engineering and work practice controls are not feasible
- When all feasible engineering and work practice controls are implemented
- When employees are exposed above the PEL for fewer than 30 days per year and the employer has not elected to implement engineering and work practice controls
- Emergencies
Unlike other substance specific standards, there is no respirator selection table. The standard refers to 1910.134 for respirator selection and all other respiratory program requirements.
3M recommends the following respirator guidelines for protection against Hexavalent Chromium: (3M, 2006)
- N95 filters may be used where no oil aerosols are present
- R or P95 filters may be used where oil aerosols are present
- Filtering facepiece respirators and half facepiece respirators with appropriate filters may be used to 10 X PEL of 5 micrograms/m3 when qualitatively or quantitatively fit tested
- Full facepiece respirators with appropriate filters may be used to 10 X PEL of 5 micrograms/m3 when qualitatively fit test and may be used to 50 X PEL of 5 micrograms /m3 when quantitatively fit tested
- Loose fitting facepieces may be used to 25 X PEL
- Tight fitting full facepieces, hoods and helmets with supplied air or powered air purifying respirators may be used to 1000 X PEL
See
3M.com/OccSafety for product information and part numbers.
Impacts of Standard
Employers must reassess their exposure controls, including the adequacy of their respirator program, taking into consideration the lower exposure limit. If they have not done so already, employers in the affected industries should make an exposure determination to establish whether or not the new standard and its requirements apply, and if so, implement the necessary steps for compliance, including selection of proper respirators (3M, 2007).
References:
3M. (2007). Understanding the New Hexavalent Chromium Standard. Retrieved 24 May, 2007.
http://solutions.3m.com/wps/portal/3M/en_US/OH-ESHexChrom/Hexavalent_Chromium/
3M. (2006). Highlights of the New Hexavalent Chromium Standard. Retrieved 24 May, 2007.
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66ScY1COrrrrQ-
OSHA. (n.d.). Safety & Health Topics: Hexavalent Chromium. Retrieved 24 May, 2007.
http://www.osha.gov/SLTC/hexavalentchromium/index.html
