Health Hazard Evaluation Report: HHE-2013-0061-3244, November 2015. Evaluation of Erionite and Silica Exposure During Forestry Activities.

摘要

A federal government agency requested a health hazard evaluation. The agency wanted to know about the hazards from erionite exposure. In some areas of the Custer National Forest where its employees worked, the agency knew or suspected the presence of erionite. Erionite is a mineral that occurs in nature in most areas in the western United States. Erionite fibers can cause health effects like those seen with exposure to asbestos. Crystalline silica is another mineral found in many geologic formations. We took air samples and analyzed them for erionite and silica. We took rock and soil samples and analyzed them for erionite. We considered the samples positive for erionite when they met several criteria. One criterion was that the fibers were longer than 5 micrometers. Another was that the fibers had a length to width aspect ratio greater than 3:1. The final criterion was that the fibers contain silicon, aluminum, and at least one of the elements calcium, sodium, or potassium. We found erionite fibers in the air, rock, and soil samples. We did not find overexposures to respirable crystalline silica. But, some air samples taken during specific tasks contained silica.