Federal inspections will be carried out at hundreds of plants where combustible dust is a workplace hazard, said Ed Foulke, Jr., head of OSHA, Monday at a sugar refinery where dust is suspected of causing a deadly explosion.

Foulke announced the inspections while visiting the Imperial Sugar refinery in Port Wentworth, Georgia, where a blast on February 7 killed 12 workers injured dozens more.

Foulke said OSHA has not completed its investigation of the explosion but is sending letters to 30,000 companies that deal with combustible dust to discuss the dangers, according to the Associated Press.

A preliminary investigation determined the explosion was caused by airborne sugar dust in a basement area beneath the refinery's three giant storage silos, but what ignited the dust has not yet been determined, AP reported.

Also Monday, Rep. John Barrow, D-GA., and Rep. George Miller, D-CA., chairman of the House Education and Labor Committee, said they will introduce a bill to force OSHA to issue new regulations governing industrial dust. Miller scheduled a hearing on the issue for March 12.

Foulke said Monday that more work must be done to determine whether existing standards on ventilation and factory housekeeping can be used to address existing concerns, and to determine how a standard can be crafted so it makes sense for different industries with different types of dust.