LITTLE ROCK, Ark. (AP) — Of the 180 facilities in Arkansas that are listed as storing fertilizer, just one has both anhydrous ammonia and ammonium nitrate, according to the Arkansas Department of Agriculture.

The two compounds were stored at a Texas fertilizer plant where a deadly explosion occurred April 17. The cause of the blast remains undetermined and under investigation.

In Arkansas, El Dorado Chemical Co. in El Dorado uses anhydrous ammonia to produce ammonium nitrate and other products, plant manager Greg Withrow told the Arkansas Democrat-Gazette ( ).

"It's the raw material for this facility," Withrow said, adding that the plant stores up to 10,000 tons of anhydrous ammonia at any given time.

"We manage our plant safely," Withrow said. "There are risks in everything we do every day, but the chemical industry itself has one of the lowest incident rates of any industry."

Both anhydrous ammonia and ammonium nitrate are commonly used as fertilizers, with ammonium nitrate being the more volatile. It was a component of the bomb used by Timothy McVeigh to destroy the Alfred P. Murrah Federal Building in Oklahoma City in 1995.

Most of the fertilizer stored in Arkansas is kept by county cooperatives or by agriculture retailers or wholesalers, according to Jamey Johnson, director of the fertilizer division at the state Plant Board.

In Arkansas, the primary use of anhydrous ammonia is as a refrigerant in cold storage warehouses and large air conditioning systems, said Kenny Harmon, hazardous materials program manager for the state Department of Emergency Management.

The El Dorado plant, founded in 1940 and now with about 200 employees, has not reviewed company protocols following the Texas explosion, Withrow said.

"Once investigators release their findings, we'll definitely look at it to help improve our safety," Withrow said.

Industrial manufacturing is part of life in El Dorado, said Mayor Frank Hesh.

"Certainly, we do have concerns," Hesh said. "The city is literally surrounded by industries that manufacture hazardous materials."

In addition to the chemical company, El Dorado is home to the Lion Oil refinery, Great Lakes Chemical Corp. and Clean Harbors Environmental Services.