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Work-safety agency issues guidelines to limit exposure to erionite

Federal occupational safety officials are urging workers in western states to take measures to limit their exposure to erionite, a naturally occurring mineral similar to asbestos.


Erionite is a silicate mineral formed from weathered volcanic ash. Like asbestos, erionite is considered harmless until it is disturbed and microscopic fibers become airborne. Until recently, the risks to American workers of exposure were considered small.


But an advisory issued by the National Institutes for Occupational Safety and Health (NIOSH) points to a growing body of evidence that more workers, in particular those employed in road construction and in gravel pits, may be at greater risk than previously known.


Moreover, since 2008, a number of studies suggest erionite may be even more deadly than asbestos, a known carcinogen that causes mesothelioma and other respiratory illness.


The NIOSH advisory cited the first study of the hazards of erionite in the United States. Published in July, the research focused on Dunn County, N.D., where more than 300 miles of roads had been surfaced with erionite-containing gravel since the 1980s.


The research team, led by Michele Carbone, director of the University of Hawaii Cancer Center, found that erionite in North Dakota shared physical and chemical properties with erionite from three villages located in the Cappadocian region of Central Anatolia in Turkey, where it was commonly used to build homes. Previous research by Carbone estimated that mesothelioma was responsible for more than half of all deaths in the villages. The study led to moving villagers away from areas with high levels of erionite into new housing built out of erionite-free materials.


Carbone said California, Oregon, Arizona, Nevada and other states have erionite deposits, but the possibility of exposure elsewhere in the U.S. has not yet been investigated. He warned that the long latency period of mesothelioma — it can take decades for the disease to emerge — and the fact that many erionite deposits have only been mined in the past few decades suggests that the number of cases could soon be on the rise.


NIOSH said that while little is known about erionite in the U.S., occupational exposure to airborne fibers “should be considered at least as hazardous” as asbestos exposure. The agency’s 14 recommendations to limit erionite exposure are based on existing guidelines for working with asbestos, including:


  • Training workers about the potential hazards of erionite and control methods for reducing exposure;
  • Using wet methods to reduce dust for road and other work such as in quarries where erionite is present;
  • Establishing decontamination protocols including change of clothing, showering before leaving the worksite, and appropriate cleaning/disposal of personal protective equipment;
  • Ensuring work clothing is not washed at home to prevent erionite fibers from being brought home on clothes and boots; and
  • Following Environmental Protection Agency procedures for proper disposal of waste and debris that contain erionite.


The agency said more data on how workers are exposed to erionite and the associated risks are needed before occupational limits can be established. Both the EPA and the World Health Organization say there is no safe level of asbestos exposure.