Top federal safety officials urged the Occupational Safety and Health Administration in 2006 to adopt regulations to prevent deadly dust explosions, but it has failed to do so.

In the past 28 years, about 300 dust explosions have killed more than 120 workers and injured several hundred others. Most are preventable by removing dust as it builds up, experts say.

But that has not been required by OSHA. The U.S. Chemical Safety Board said in a report in 2006 that OSHA "inadequately addresses" the problem, except for in grain plants and silos.

"This is an extremely dangerous component that is not regulated," former Safety Board chairwoman Carolyn Merritt said Friday. "There should be an outcry."

ASSOCIATED PRESS