INSTITUTE, W.Va.  Last August, an explosion tore through the Bayer CropScience chemical plant here, killing two employees and raising the fears of residents in what has long been known as Chemical Valley.

Now, a federal agency wants to hold a public hearing to lay out its preliminary findings about what caused the accident. But Bayer, citing a terrorism-related federal law, is trying to limit what the agency can disclose.

Bayer contends that because it has a dock for barge shipments on the adjacent Kanawha River, its entire 400-acre site qualifies under the 2002 federal Maritime Transportation Security Act. It has asked the Coast Guard, which has jurisdiction under the act, to review the public release of “sensitive security information.”

The agency that wants to hold the hearing, the Chemical Safety and Hazard Investigation Board, says it is the first time in its 11 years of operation that a company has tried to limit what could be discussed publicly, and the first time the maritime act has been invoked this way.