Hexavalent Chromium Content in Stainless Steel Welding Fumes Is Dependent on the Welding Process and Shield Gas Type

Details

• Personal Author:
  Antonini J ; Chen B ; Keane M ; Schwegler-Berry D ; Slaven, James E. ; Stone S
• Description:
  Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure CrVI concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low CrVI content. The gases used were 95% Ar/5% O2, 98% Ar/2% O2, 95% Ar/5%CO2, and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O2, Ar/CO2), short-circuit (SC) mode (Ar/CO2 low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O2). Results indicate large differences in CrVI in the fumes, with Ar/O2 (Pulsed) > Ar/O2 > Ar/CO2 > Ar/CO2 (SC) > He/Ar; values were 3000 +/- 300, 2800 +/- 85, 2600 +/- 120, 1400 +/- 190, and 320 +/- 290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of CrVI generation were 1.5, 3.2, 4.4, 1.3, and 0.46 ug/min; generation rates were also calculated in terms of ug CrVI per metre of wire used. The generation rates of CrVI increased with increasing O3 concentrations. Particle size measurements indicated similar distributions, but somewhat higher >0.6 um fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (0.6 um) and a fine (<0.6 um) fraction; analysis indicated that CrVI is primarily associated with particles <0.6 um. The conclusion of the study is that CrVI concentrations vary significantly with welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen CrVI exposures in workplaces by selecting low CrVI-generating processes. Short-circuit processes generated less CrVI than axial-spray methods, and inert gas shielding gave lower CrVI content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O2 process were both identified as having substantially lower CrVI generation rates per unit of wire used relative to the other processes studied. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Chromium Occupational Health Particulate Matter Safety Welding
• Keywords:
  Chromium-compounds Fumes Gas-welders Particulates Welding-industry
• ISSN:
  1464-0325
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  418-424
• Volume:
  11
• Issue:
  2
• NIOSHTIC Number:
  nn:20034985
• Citation:
  J Environ Monit 2009 Feb; 11(2):418-424
• Contact Point Address:
  Michael Keane, National Institute for Occupational Safety and Health, Health Effects Laboratory Division, 1095 Willowdale Rd, Morgantown, WV 26505, USA
• Email:
  mjk3@cdc.gov
• CAS Registry Number:
  Chromium(6+) (CAS RN 18540-29-9) ; Ozone (CAS RN 10028-15-6)
• Federal Fiscal Year:
  2009
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Environmental Monitoring
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:b697ab81d471d9cda9e3fdc79bbc9b59d242e4bb4a2f0bbd06e80e15bd17e877236c76d6bde1f718990f7503ea35904c4f7f3912c6c259b311e7160e821fd752
• Download URL:
  https://stacks.cdc.gov/view/cdc/186991/cdc_186991_DS1.pdf
• File Type:
  [PDF - 210.40 KB ]