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Testing Welding Shops – Chromium (VI) (Hexavalent Chromium)

Testing Welding Shops

United States Department of Labor – OSHA

General Description

Synonyms: Ammonium Dichromate; Barium Chromate; tert-Butyl Chomate; Calcium Chromate; Chromium Trioxide; Chromium (VI) ion; Hexavalent Chromium; Lead Chromate; Potassium Chromate; Potassium Dichromate; Silver Chromate; Sodium Chromate; Sodium Dichromate; Strontium Chromate; Zinc Chromate; Zinc Dichromate

OSHA IMIS Code Number: 0689
IMIS Codes history: 0686, Chromic Acid & Chromates (as CrO3) prior to 5/30/2006; and 0473, tert-Butyl Chromate (as CrO3) prior to 5/30/2006

Chemical Abstracts Service (CAS) Registry Number: 1189-85-1 (tert-butyl chromate); 1333-82-0 (chromium (VI) trioxide); 1344-38-3 (basic lead chromate orange); 7440-47-3 (chromium); 7758-97-6 (lead chromate); 7775-11-3 (sodium chromate); 7778-50-9 (potassium dichromate); 7784-01-2 (silver chromate); 7789-00-6 (potassium chromate); 7789-06-2 (strontium chromate); 7789-09-5 (ammonium dichromate); 7789-12-0 (sodium dichromate dehydrate); 7789-98-9 (ammonium chromate); 10294-40-3 (barium chromate); 10588-01-9 (sodium dichromate); 12656-85-8 (molybdenum orange); 13530-65-9 (zinc chromate); 13765-19-0 (calcium chromate); 14018-95-2 (zinc dichromate); 14986-48-2 (chromium (VI) chloride); 18454-12-1 (lead chromate oxide); 18540-29-9 (Hexavalent Chromium)

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: GB6650000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1755 154 (acid solution); 1463 141 (acid, solid)

NIOSH Pocket Guide to Chemical Hazards, Chromic Acid and Chromates: chemical description, physical properties, potentially hazardous incompatibilities, and more

Permissible Exposure Limit (PEL). The employer shall ensure that no employee is exposed to an airborne concentration of Chromium (VI) in excess of 5 micrograms per cubic meter of air (5 µg/m3), calculated as an 8-hour time-weighted average (TWA).

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 29 CFR 1910.1000 Z-1 Table29 CFR 1910.1026 0.005 mg/m3 or

5 micrograms/m3 TWA; 0.0025 mg/m3 or 2.5 micrograms/m3 Action Level; 0.025 mg/m3 or 25 micrograms/m3 TWA (Painting of aerospace industry’s aircraft or large aircraft parts).

NOTE: Applies to all occupational exposures to Chromium (VI) except application of pesticides regulated by the Environmental Protection Agency or another Federal government agency (e.g., the treatment of wood with preservatives); Portland cement; or where the employer has objective data demonstrating that a material containing chromium or a specific process, operation, or activity involving chromium cannot release dusts, fumes, or mists of chromium (VI) in concentrations at or above 0.5 µg/m3 as a TWA under any expected conditions of use.

Construction Industry:29 CFR 1926.55 Appendix A29 CFR 1926.1126 0.005 mg/m3 or 5 micrograms/m3 TWA; 0.0025 mg/m3 or 2.5 micrograms/m3 Action Level. 

NOTE: Applies to all occupational exposures to Chromium (VI) except application of pesticides regulated by the Environmental Protection Agency or another Federal government agency (e.g., the treatment of wood with preservatives); portland cement; or where the employer has objective data demonstrating that a material containing chromium or a specific process, operation, or activity involving chromium cannot release dusts, fumes, or mists of chromium (VI) in concentrations at or above 0.5 µg/m3 as a TWA under any expected conditions of use.

Maritime:29 CFR 1915.1000 Table Z-Shipyards29 CFR 1915.1026 0.005 mg/m3 or 5 micrograms/m3 TWA; 0.0025 mg/m3 or 2.5 micrograms/m3 Action Level. 

NOTE: Applies to all occupational exposures to Chromium (VI) except application of pesticides regulated by the Environmental Protection Agency or another Federal government agency (e.g., the treatment of wood with preservatives); portland cement; or where the employer has objective data demonstrating that a material containing chromium or a specific process, operation, or activity involving chromium cannot release dusts, fumes, or mists of chromium (VI) in concentrations at or above 0.5 µg/m3 as a TWA under any expected conditions of use.

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): Metal and Cr(III) cmpds, as Cr, 0.5 mg/m3 TWA, Appendix A4 – Not Classifiable as a Human Carcinogen; Water-Soluble Cr(VI) cmpds, as Cr, 0.05 mg/m3 TWA, Appendix A1 – Confirmed Human Carcinogen, BEI; Insoluble Cr(VI) cmpds, as Cr, 0.01 mg/m3 TWA, Appendix A1 – Confirmed Human Carcinogen; Strontium Chromate, as Cr, 0.0005 mg/m3 TWA, Appendix A2 – Suspected Human Carcinogen.

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL):0.001 mg Cr(VI)/m3 10-hr TWA; Carcinogenic; Appendix A – NIOSH Potential Occupational Carcinogens; Appendix C – Supplementary Exposure Limits.

Health Factors

Carcinogenic Classification:

Environmental Protection Agency (EPA): Group A, known human carcinogen by the inhalation route of exposure

National Toxicology Program (NTP): Known to be a human carcinogen [135 KB PDF, 4 pages]

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH):

15 mg/m3 [as Cr (VI)]

Potential Symptoms: Irritation of respiratory system; bronchitis, asthma, nosebleeds, nasal septum ulceration and perforation; liver, kidney damage; leukocytosis (increased blood leukocytes), leukopenia (reduced blood leukocytes), eosinophilia; eye injury, conjunctivitis; skin ulcer, irritant and allergic contact dermatitis; [potential occupational carcinogen] 

Health Effects: Lung cancer (HE1); Asthma (HE9); Nasal perforation, ulceration; dermatitis (HE14) 

Affected Organs: Blood, respiratory system, liver, kidneys, eyes, skin

Notes:

  1. OSHA’s new Hexavalent Chromium Standard (29 CFR 1910.1026; 1915.1026; and 1926.1126) was published on 2/28/06.
  2. Studies with cultured human lung cells demonstrate that hexavalent chromium can cause damage to DNA (clastogenicity).
  3. Skin-patch testing of patients sensitive to chromium (VI) showed a minimum eczema elicitation threshold at 0.03 µg/cm2/48 hr (1 ppm) of chromium (VI) and at 0.18 µg/cm2/48 hr (6 ppm) of chromium (III).
  4. EPA’s oral reference dose (RfD, the daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) of chromium (VI) is 0.003 mg/kg/day. EPA’s reference concentration (RfC) for particulate chromium (VI) is 0.0001 mg/m3.

Date Last Revised: 04/11/2006

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Chromic Acid and Chromates.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Chromium (VI) oxide.
  • EPA Air Toxics Website: Chromium Compounds. U.S. Environmental Protection Agency Technology Transfer Network.
  • No authors listed: Chromium Hexavalent Compounds [135 KB PDF, 4 pages]. Report on Carcinogens, (latest edition); U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program.
  • De Raeve, H., Vandecasteele, C., Demedts, M. and Nemery, B.: Dermal and respiratory sensitization to chromate in a cement floorer. Am. J. Ind. Med. 34(2): 169-176, 1998.
  • Hansen, M.B., Johansen, J.D. and Menne, T.: Chromium allergy: significance of both Cr(III) and Cr(VI). Contact Dermatitis 49(4): 206-212, 2003. • Nuyts, G.D., et al.: New occupational risk factors for chronic renal failure. Lancet 346(8966): 7-11, 1995.
  • Wise, S.S., et al.: Chromium is the proximate clastogenic species for lead chromate-induced clastogenicity in human bronchial cells. Mutat. Res. 560(1): 79-89, 2004.

Monitoring Methods used by OSHA

Three OSHA sampling and analytical methods for Cr (VI) are cited below:

Method ID-215 (version 2) is the most recent and focuses on air sampling, Method W4001 focuses on wipe sampling, and Method ID-215 is an older version of ID-215 (version 2) and contains some bulk and wipe sampling information.

Laboratory Sampling/Analytical Method:

Sampling media: low ash 37-mm or 25-mm PVC filter in polystyrene cassette. Do not use the preweighed custom-made cassettes with the aluminum cone that are intended for gravimetric sampling.

Chromium plating samples can be collected on either PVC filters or on quartz fiber filters coated with sodium hydroxide. The coated quartz fiber filters are preferred for sample stability.

CAUTION: Do not use the coated quartz fiber filters for any operation other than chromium plating.

Analytical Solvent: carbonate/bicarbonate buffer

Maximum Volume: 960 Liters Maximum Flow Rate: 2 L/min (TWA) current analytical method: Ion Chromatography; IC/UV method reference: OSHA Analytical Method (OSHA ID-215 (version 2))

Wipe Sampling Method:

Sampling media: 37-mm PVC filter or 37-mm binderless quartz fiber filters

method reference: OSHA Analytical Method (OSHA W4001)

method classification: Fully Validated