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. Congressional policymakers have expressed concern and requested information about coordination among federal regulatory agencies and the efficacy of agency regulations. Different federal agencies apply a variety of regulatory structures to these chemicals. These regulations meet different policy rationales, goals, and purposes. Some attempt to ensure occupational safety, others environmental protection, and still others security. As a consequence, various federal, state, and local agencies collect mission-relevant information about chemical holdings, with some entities gaining a narrower, or broader, understanding of a facility's chemical inventories. 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. In 2012, the West Fertilizer Company had reported to the U.S. Environmental Protection Agency (EPA) and the state of Texas the presence of 110,000 pounds of anhydrous ammonia and 270 tons of ammonium nitrate , and had complied with certain provisions of the Clean Air Act, but the West facility may not have complied with all reporting requirements. For example, the facility had not contacted the Department of Homeland Security (DHS), which should have received information about ammonium nitrate or anhydrous ammonia stored at the facility. The DHS notes that the West Fertilizer Company facility might not have qualified as a regulated high-risk facility even if it had reported its chemical holdings. 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. States regulate worker and environmental protection, product efficacy and safety, chemical sales and storage, and security. In addition, states may enforce standards such building, plumbing, mechanical, electrical, and fire codes. Local zoning laws may dictate placement of a facility within a community. Many states require registration to track the sellers and sales of fertilizer. This report will focus on some of the federal regulatory programs overseeing storage of ammonium nitrate and anhydrous ammonia by retailers. The report will not address federal regulation of material in transport. It will discuss federal occupational safety, environmental, and security statutes and regulations applicable to each chemical. Select policy issues regarding these federal regulatory programs will be highlighted. It does not address various law enforcement activities related to tracking of anhydrous ammonia used for illegal drug synthesis (e.g., methamphetamine). Domestic production capacity of ammonium nitrate is approximately 7 million tons, and it is produced worldwide. The vast majority of ammonium nitrate use occurs without incident. Most experts consider ammonium nitrate itself as a stable chemical with few handling restrictions, but, in combination with a fuel source, it can pose an explosion hazard. Ammonium nitrate requires certain conditions, such as added heat or shock, confinement, or contamination to explode. Ammonium nitrate in combination with certain additives is widely used as a type of explosive known as a blasting agent. Ammonium nitrate is also used as a fertilizer. Ammonium nitrate is suspected as the source of the explosion at the West Fertilizer Company. Accidental explosions of ammonium nitrate have resulted in loss of lives and destruction of property. These accidents have rarely occurred, but have had high impacts. For example, the ammonium nitrate explosion in 1947 in Texas City, TX, where two ships carrying ammonium nitrate coated in wax and stored in paper bags caught fire and exploded, destroyed the entire dock area, including numerous oil tanks, dwellings, and business buildings. Because of this history, and its inherent characteristics, a variety of federal agencies have authority to regulate ammonium nitrate, some of which has been delegated to state agencies. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) of the Department of Justice (DOJ) regulates ammonium-nitrate-based blasting agents, but it does not regulate ammonium nitrate as fertilizer. The ATF has issued regulations regarding the necessary distance to be maintained between ammonium nitrate and other explosive materials. The ATF and the fertilizer industry have undertaken joint voluntary efforts to secure ammonium nitrate fertilizer, predominantly through "know your customer" programs. While often used for legitimate purposes, malicious actors might also use ammonium nitrate fertilizer as part of an improvised explosive device. For example, the bombing of the Murrah Federal Building in Oklahoma City, OK, used ammonium nitrate, along with other chemicals, as the primary explosive material. The ease with which ammonium nitrate fertilizer can be transformed into ammonium-nitrate-based blasting agent has led to increased scrutiny of its storage and transfer in order to prevent misappropriation and misuse. For this reason, the Department of Homeland Security (DHS) has multiple statutory authorities under which it regulates ammonium nitrate for security purposes. In general, DHS authorities fall into two categories: securing facilities containing ammonium nitrate and tracking the transfer of ammonium nitrate. Since 2002, the U.S. Coast Guard (USCG) has regulated security at certain stationary facilities adjacent to waterways under the authority of the Maritime Transportation Security Act (MTSA, P.L. 107-295 ). In 2006, when Congress authorized DHS to regulate high-risk chemical facilities for security purposes in P.L. 109-295 (Department of Homeland Security Appropriations Act, 2007), it exempted those facilities already regulated under MTSA. Congress also authorized DHS to oversee the sale and transfer of ammonium nitrate in P.L. 110-161 (Consolidated Appropriations Act, 2008). The DHS, through the USCG, regulates security at facilities located adjacent to any waters subject to U.S. jurisdiction. Note that this regulatory requirement is irrespective of the presence of chemicals at the facility, but would capture any facility storing ammonium nitrate adjacent to waterways. The USCG implemented MTSA through a series of regulations issued in October 2003. The MTSA requires the creation of an area security plan, assessment of security vulnerabilities at the facility, and the creation of a facility security plan. The USCG creates the area security plan. Either the USCG or the regulated facility performs a vulnerability assessment of the regulated facility. Based on this vulnerability assessment, the facility must develop and implement a security plan consistent with the broader USCG area maritime transportation security plan. The facility must update this plan every five years, and the USCG inspects the facility's implementation of the plan. In 2007, DHS issued an interim final rule establishing the Chemical Facility Anti-Terrorism Standards (CFATS), the regulatory program by which it implements its chemical facility security authority. Under the CFATS interim final rule, the Secretary of Homeland Security determines which chemical facilities must meet regulatory security requirements, based on the degree of risk posed by each facility. The DHS lists 322 "chemicals of interest" and screening threshold quantities for each chemical to determine the need to comply with CFATS. The DHS considers each chemical in the context of three threats: release; theft or diversion; and sabotage and contamination. The regulation includes as chemicals of interest both pure ammonium nitrate and ammonium nitrate with more than 0.2% combustible substances, including any organic substance calculated as carbon, to the exclusion of any other added substance. It identifies them as theft or diversion and release threats respectively. The screening threshold quantity differs depending on the ammonium nitrate. Facilities possessing at least 5,000 pounds (400 pounds if packaged for transportation) of ammonium nitrate with more than 0.2% combustible substances are potentially high-risk facilities and must participate in the CFATS regulations. Facilities possessing at least 2,000 pounds of transportable fertilizer mixture containing at least 33% ammonium nitrate are potentially high-risk facilities and must participate in the CFATS regulations. According to DHS, "This [screening threshold quantity] is geared toward ensuring that DHS secures [ammonium nitrate] inventories at major manufacturing and distribution facilities, as opposed to individual farmers involved mainly in the application of [ammonium nitrate]." Chemical facilities with greater than specified quantities of chemicals of interest must submit information to DHS. This information-gathering process is called the "Top-Screen." It enables DHS to determine each facility's risk status based on the information received. If a facility comes into possession of any of the chemicals of interest at the corresponding quantities, it must complete and submit a Top-Screen within 60 calendar days. Also, the CFATS rule states that DHS may contact and instruct specific facilities to complete and submit Top-Screen information. Facilities that DHS deems high risk must meet CFATS requirements, which include performing a security vulnerability assessment, developing a site security plan, implementing the security plan, and then being inspected by DHS for compliance. See Figure 1 . Several types of facilities are exempt from the CFATS regulation. The statute exempts any facility that is: defined as a water system or wastewater treatment works; owned or operated by the Department of Defense or Department of Energy; regulated by the Nuclear Regulatory Commission (NRC); or regulated under MTSA. Many of these types of facilities comply with other security requirements. The DHS has implemented a regulatory extension for agricultural chemical users, though not distributors or retailers. Indeed, DHS stated in the CFATS interim final rule that "if a retail establishment does exceed any of these [screening threshold quantities], the retail establishment will have to complete the Top-Screen." The CFATS rule does not, however, impose any limitations on the sale or transfer of ammonium nitrate. In 2007, Congress enacted Section 563 of P.L. 110-161 (Secure Handling of Ammonium Nitrate), authorizing DHS to "regulate the sale and transfer of ammonium nitrate by an ammonium nitrate facility ... to prevent the misappropriation or use of ammonium nitrate in an act of terrorism."