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Size distribution and estimated respiratory deposition of total chromium, hexavalent chromium, manganese, and nickel in gas metal arc welding fume aerosols.

Cena-LG; Chisholm-WP; Keane-MJ; Cumpston-A; Chen-BT
Aerosol Sci Tech 2014 Dec; 48(12):1254-1263
Welders are exposed to fumes containing Mn from mild steel and Cr, Cr(VI), Mn and Ni from stainless steel. These metals have been associated with adverse health effects ranging from asthma, neurological diseases, and lung cancer. A laboratory study was conducted to determine the mass of total Cr, Cr(VI), Mn and Ni in 15 size fractions for fumes generated from gas-metal arc welding of mild and stainless steel. Samples were collected using a multiple orifice uniform deposition impactor (MOUDI) and Nano MOUDI with polyvinyl chloride filters on each stage. The filters were analyzed by inductively coupled plasma mass spectrometry for total Cr, Mn and Ni and by ion chromatography for Cr(VI). Limits of detection and quantitation were experimentally calculated and percent recoveries were measured from samples spiked with metals in solution and from dry certified welding fume reference material. The fraction of Cr(VI) in total Cr was estimated by calculating the ratio of Cr(VI) to total Cr mass for each particle size range. The percentage of each metal expected to deposit in the head airways, tracheobronchial region and alveolar region were also estimated according to respiratory deposition models. The weight percent of Mn in mild steel welding fumes was 9.2% (+6.8%). For stainless steel welding fumes, the weight percentages were 8.4% (+5.4%) for total Cr, 12.2% (+6.5%) for Mn, 2.1% (+1.5%) for Ni and 0.5% (+0.4%) for Cr(VI). All metals in both steel types presented a submicron fraction between 0.04 and 0.6 um. In addition to this fraction, total Cr and Ni also presented a fraction <0.03 um, indicating a multimodal size distribution. On average 6% of the Cr was found in the Cr(VI) valence state. Particle size did not appear to affect the contribution of Cr(VI) relative to total Cr as there was no statistical difference between the smallest and largest mean Cr(VI) to total Cr mass ratio (p-value=0.19). The predicted total respiratory deposition for the investigated metal particles was approximately 20%. The sites of principal deposition were the head airways (7-10%) and the alveolar region (8-9%). For Cr(VI), the estimated deposition was highest in the alveolar region (8.8%).
Welding; Welders; Exposure-levels; Risk-factors; Fumes; Steel-compounds; Metallic-compounds; Health-hazards; Bronchial-asthma; Neurological-diseases; Lung-cancer; Arc-welding; Particulates; Statistical-analysis
Lorenzo G. Cena, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26508
7440-47-3; 18540-29-9; 7439-96-5; 7440-02-0
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Aerosol Science and Technology
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division