The reclassification of crystalline silica by the International Agency for Research on Cancer to the category of "carcinogenic to humans" seems to have initiated a flurry of regulatory activity regarding silica by the Occupational Safety and Health Administration, the National Toxicology Program, and the American Conference of Governmental Industrial comprehensive health standard for crystalline silica. The NTP has recently reviewed the medicine literature regarding the carcinogenicity of crystalline silica and has published its intent to reclassify respirable crystalline silica from " reasonably anticipated to be a carcinogen" to the category of " known to be a carcinogen". Finally, the ACGIH is evaluation its classification for crystalline silica and is considering cutting in half the threshold limit value for quartz. The specifics of these actions and the current status will be reviewed.
