Mine Safety and Health Administration
Contact: (703) 235-1452
April 18, 1995
RESULTS OF NIOSH-MSHA STUDY REVEAL EIGHT CASES OF SILICOSIS
The Department of Labor's Mine Safety and Health Administration (MSHA), in collaboration with the National Institute for Occupational Safety and Health (NIOSH), has released the results of a study identifying eight cases of silicosis among surface coal drillers and miners in Pennsylvania. Silicosis is an incurable and often disabling lung disease caused by silica dust. At mine sites, silica is generated during the drilling and crushing of rock and loading of mined material.
Two of the eight individuals with silicosis also were identified with progressive massive fibrosis (PMF), a condition in which large masses of lung tissue become scarred. PMF can lead to reduced lung function and premature death.
Silicosis has long been recognized as a serious health hazard in the mining industry and has been regulated by the federal government since passage of the Coal Mine Health and Safety Act of 1969. In that legislation, Congress required he agency to develop a formula to reduce the amount of respirable dust in the mine below that normally allowed (2.0 mg/m3) whenever the quartz (crystalline silica) content in the atmosphere is greater than 5 percent. This requirement was based on the recognition that the toxicity of coal mine dust increases when higher levels of quartz are found.
According to NIOSH director Linda Rosenstock, "These results are of great concern. They underscore the importance of effective dust controls to prevent lung disease."
"We want miners and mine operators to recognize this problem and help us take steps to prevent silicosis," said J. Davitt McAteer, assistant labor secretary for mine safety and health. "The agency will be distributing both a video and a dust control problem guide to further educate the mining community about proper use of dust controls at mines. We all must work together to prevent lung diseases caused by dust."
The study, which was conducted in the summer of 1994, involved 150 miners from the Johnstown and Clearfield, Pa., areas, who volunteered for an x-ray screening program. NIOSH administered a work and health-history questionnaire, chest x-rays and spirometry (breathing tests).
Ninety-one of the 150 miner-participants reported having at least some experience in surface drilling. Seven were classified by NIOSH as having silicosis. Fifty-nine participants reported they had never performed drilling operations; one of these - a mechanic - was classified as having silicosis. NIOSH has notified all miners of their results and is keeping the identities of the miners and the mines confidential.
The "Johnstown study" came on the heels of the implementation of MSHA's drill dust control standard in April 1994. The regulations require coal mine operators to install and maintain dust control devices on all surface drills. MSHA inspectors may take enforcement action based on a visual observation of the drill that indicates the drill dust controls are inadequate.
"These new measures are providing better protection for miners engaged in rock drilling," said McAteer. "However, in view of the preliminary findings from the NIOSH study, MSHA plans to step up efforts to ensure that the new regulations are being followed and that they are effective in protecting workers from overexposure.
"We will also focus our attention on other surface miners who may be exposed to silica dust such as bulldozer operators, truck drivers and front-end loader operators. And we will target mines located in geographic areas that are known to have a high quartz content. We also intend to improve our ability to detect silica in respirable dust samples by using state-of-the-art instruments."
Late last year, MSHA conducted health inspections at all 880 active surface coal mines in the U.S. to determine compliance with the drill dust control regulation and with the agency's silica standard. Inspectors distributed information on silica hazards, collected dust samples to evaluate dust exposure levels, and issued more than 140 citations for failure to properly maintain dust controls on surface drills. The dust sampling identified overexposures to crystalline silica among bulldozer operators, front-end loader operators and refuse truck drivers.
To aid MSHA in determining which coal miners are being exposed to high levels of quartz, the agency is refining the analytical procedure used to calculate the percent of quartz in MSHA-collected respirable coal mine dust samples. New weighing instrumentation will be used to both pre-weigh and post-weigh filters to improve the agency's ability to determine quartz in such samples.
The issue of silica exposure and the methods used by the agency to evaluate dust exposures are among topics to be addressed by a Department of Labor advisory committee. The committee will take a broad look at ways to eliminate both silicosis and black lung among coal miners.
To receive a copy of the NIOSH report on silicosis, please contact MSHA's Office of Public Affairs, (703) 235-1452 or NIOSH at (202) 260-9727.