Health Hazard Evaluation Report: HETA-2009-0085-3107, Consolidation Coal Company, Blacksville, West Virginia, April 2010. Evaluation of Isocyanate Exposure during Polyurethane Foam Application and Silica Exposure during Rock Dusting at an Underground Coal Mine

摘要

NIOSH received a request for an HHE from the United Mine Workers of America, Local 1702 representing employees at the Consolidation Coal Company Blacksville No. 2 Mine in Blacksville, West Virginia. The HHE request concerned potential exposure to MDI during the application of polyurethane foam and exposure to silica and asbestos during rock dusting. In an initial evaluation on March 31, 2009, we sampled the surface of the foam applicator gun for MDI contamination and collected bulk samples of the rock dust for silica and asbestos analysis. During a second evaluation on September 14-17, 2009, we collected PBZ air samples on day-shift rock dusters for respirable silica and dust. We did not detect MDI on the surface of the foam applicator gun. The bratticeman who applied the foam wore nitrile gloves that protected his skin from MDI. Inhalation exposure to MDI is unlikely because the foam was not aerosolized during application and does not readily evaporate due to its low vapor pressure. Low levels of silica were found in bulk samples of rock dust. Asbestos was not present in the rock dust. The PBZ air concentrations of respirable silica were below applicable OELs. However, according to a statistical analysis, there is a 73% probability that the rock dusters' PBZ concentrations may exceed the ACGIH TLV 5% of the time. Because of the potential for overexposure to respirable silica, we recommend continued use of N95 filtering facepiece respirators. Additionally, the company should implement a written respiratory protection program that incorporates medical evaluations and respirator fit testing.