"The explosion on April 17, 2013, at the West Fertilizer Company fertilizer distribution facility in West, TX, has led to questions about the oversight and regulation of agricultural fertilizer. Facilities holding chemicals must comply with regulations attempting to ensure occupational safety, environmental protection, and homeland security. In addition to federal regulation requiring reporting and planning for ammonium nitrate and anhydrous ammonia, most state and some local governments have laws and regulations regarding the handling of either or both of these chemicals. The West Fertilizer Company possessed a variety of agricultural chemicals at its retail facility, but policy interest has focused on two chemicals: ammonium nitrate and anhydrous ammonia. Ammonium nitrate is a solid that is primarily used as a fertilizer whose use generally occurs without incident. In combination with a fuel source and certain conditions, such as added heat or shock, confinement, or contamination, ammonium nitrate can pose an explosion hazard. Such accidents have rarely occurred, but have historically had high impacts. For example, the ammonium nitrate explosion in 1947 in Texas City, TX, where two ships carrying ammonium nitrate caught fire and exploded, destroyed the entire dock area, including numerous oil tanks, dwellings, and business buildings. The bomb used in 1995 to attack the Murrah Federal Building contained ammonium nitrate as a component of its explosives."
CRS Report for Congress, R43070