Federal regulators are proposing a $12,288 fine in response to an explosion and fire at a Belle chemical plant that killed a worker and injured three other people. The Gazette-Mail reports the U.S. Occupational Safety and Health Administration proposed that Optima Belle LLC pay the penalty in a citation this month, saying the plant violated federal code by leaving employees exposed to recognized hazards. Regulators say Optima Belle can contest the fine or abate the violation by developing new policies.