By Janet Raloff
Most people know vermiculite as that foam-like mineral that gets mixed into potting soil or poured into attic spaces as lightweight insulating pebbles. Last week, the Environmental Protection Agency and the federal Agency for Toxic Substances and Disease Registry issued a joint warning about vermiculite: If it’s a decade or more old, it may be laced with asbestos, a potent lung carcinogen.
The federal agencies report that most U.S. vermiculite mined prior to 1990 came from a site near Libby, Mont., where a natural asbestos deposit ran through the mine, tainting much of the vermiculite.