Hexavalent Chromium Dissociation from Overspray Particles into Fluid for Three Aircraft Primers
Date of Award
Master of Science
Department of Systems Engineering and Management
Peter T. LaPuma, PhD
DOD and industry use chromate-containing primers extensively to inhibit corrosion on metal assets. Chromate contains Cr6+, a human carcinogen, but there is little epidemiological evidence of increased lung cancer among spray painters. Using bio-aerosol impingers, overspray particles from three primers (solvent-borne epoxy, water-borne epoxy, and solvent-borne polyurethane) were collected into water to test the hypothesis that the paint matrix inhibits Cr6+ release into water, under the premise that this simulates Cr6+ release from particles into lung fluid. Particles were allowed to reside in water for 1 or 24 hours, then separated from the water by centrifugation, and the water tested for Cr6+. The mean fractions of Cr6+ released into the water after 1 and 24 hours for each primer (95% confidence) were: 70 5% and 85 5% (solvent epoxy), 74 4% and 84 4% (water epoxy), and 94 3% and 95 2% (polyurethane). Solvent and water epoxy primer 24-hour Cr6+ release ranged from 100% dissociation to 33% and 48%, respectively. Correlations between Cr6+ distribution with particle size and % Cr6+ dissociated from each sample indicate that particles < 5 mm release a larger fraction of Cr6+ during the first 24 hours vs. particles > 5 micrometers.
DTIC Accession Number
Schilke, Richard A., "Hexavalent Chromium Dissociation from Overspray Particles into Fluid for Three Aircraft Primers" (2002). Theses and Dissertations. 4434.