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Government Should Focus On Controlling Access To Explosives And Using Existing Detection Technologies To Prevent Illegal Bombings

March 9, 1998
National Academy Of Sciences
Additives that improve detection of explosives before detonation or determine their origins after a blast are not yet practical enough for broad use in the United States, concludes a committee of the National Research Council in a new report. Nor is there a practical method available to neutralize the explosive properties of ammonium nitrate, a commonly available fertilizer that was used in the 1995 Oklahoma City bombing.

WASHINGTON -- Additives that improve detection of explosives before detonationor determine their origins after a blast are not yet practical enough for broaduse in the United States, concludes a committee of the National Research Councilin a new report. Nor is there a practical method available to neutralize theexplosive properties of ammonium nitrate, a commonly available fertilizer thatwas used in the 1995 Oklahoma City bombing.

Instead, voluntary commercial controls and regulatory action, together withwider use of present methods for detecting explosives, offer the best means ofreducing the threat from illegal bombings until better technologies can bedeveloped, says the report, Containing the Threat From IllegalBombings.

"Some of the proposed concepts for altering explosive materials are technicallyfeasible, but their safety, effectiveness, cost, and environmental effects mustbe addressed before implementation can be recommended," said committee co-chairMarye Anne Fox, vice president for research and Waggoner Regents Chair inChemistry, University of Texas at Austin. "The findings to date support the useof chemical markers only to improve detection of plastic and sheet explosives,which pose a considerable risk in facilities such as airports. Limitingcriminal access to explosive materials and developing better methods to detectexplosives are important strategies to deter would-be bombers and increase thechances they will be caught."

One key strategy is prohibiting the retail sale of the types of packagedammonium nitrate fertilizers that can be detonated, unless consumers produceidentification and retailers keep accurate records of transactions, thecommittee said. Although many common chemicals potentially can be used to makeexplosives into terrorist bombs, ammonium nitrate is by far the most accessibleingredient. It is produced in enormous quantities for fertilizer and forblasting agents used in mining and other industries.

In the wake of the 1993 World Trade Center and 1995 Oklahoma City bombings, thethreat of terrorist attacks has become an issue of national concern. Congressasked the National Research Council to investigate technologies for tagging orphysically altering explosive materials, and to examine the feasibility ofcontrolling access to these materials to prevent terrorist attacks.

Explosive materials may be altered by mixing additives to make them moredifficult to detonate, or by adding detection markers or identification taggantsso their origins can be traced before or after detonation. Detection markers,such as chemical additives, can help law enforcement officers find explosivesbefore a blast. Identification taggants -- for example, particulate additivescontaining coded information -- are used to determine a bomb's origins before orafter detonation.

About 2,000 illegal bombings occur annually in the United States, but only asmall percentage involve loss of life, injuries, or significant property damage. Although seldom used in such bombings, commercial "high explosives" -- whichinclude dynamite and ammonium nitrate mixed with fuel oil -- can havedevastating consequences, particularly in large bombs. The most frequently usedmaterials are commercial "low explosives," such as gunpowder and fillerscommonly found in fireworks. (Black and smokeless powders -- low explosiveswhich are used in about one-third of all illegal bombings -- were excluded fromthe committee's study and are being similarly assessed by another NationalResearch Council committee.)

A Strategy for Controlling Illegal Use of Explosives

The problem of illegal bombings is difficult to address from a policyperspective, the report notes. About 5 billion pounds of commercial highexplosives are used annually in the United States for legitimate purposes, butthe quantity used in illegal bombings is small. Policy measures that attempt toaddress the illegal use of explosives will inevitably impinge on everydaycommerce, the committee said. Complying with new regulations also could becostly for the private sector and consumers. But if terrorist bombings were toincrease substantially, the savings in lives, property damage, and enhancedsecurity could justify the costs.

Given these concerns, the committee called for the federal government to sponsorresearch to develop safe taggants for possible future use and to be ready toadopt progressively stronger measures to deter terrorist bombings, based onfederal policy-makers' assessments of threats to public safety. "The keys tothis strategy are flexibility, and conducting rigorous testing and developmentof tagging technologies now rather than later," said committee co-chair EdwardM. Arnett, Reynolds Professor of Chemistry Emeritus, Duke University, Durham,N.C. "Some policy measures could be put into practice at the present time, butothers should be adopted only if the level of threat increases."

At Current Levels of Threat

After examining a variety of technologies for marking explosives using eitherdetection markers or identification taggants, the committee recommended againstbroad-based implementation of a taggant program at the present time. However,it affirmed a recommendation by the United Nations' Council of the InternationalCivil Aviation Organization (ICAO), which called for the use of chemicaldetection markers in plastic and sheet explosives to allow for better detectionby currently available commercial equipment. After the 1988 downing of Pan AmFlight 103 over Lockerbie, Scotland, 34 countries, including the United States,ratified a convention requiring the marking of these explosives. Theinternational convention must be approved by one more nation to enter intoforce, but already has been implemented by the United States.

The committee also recommended deploying explosive detection equipment morewidely -- and developing better equipment to detect unmarked explosives -- infacilities other than airports, such as federal courthouses, large publicbuildings, and power plants. Cost, effectiveness, and assessed level of threatare factors that should determine the extent of installation throughout thecountry.

Although detection markers are being added to plastic and sheet explosives, thecommittee said further research on both markers and identification taggants isneeded before implementation occurs in other types of commercial explosives,such as dynamite. Both approaches, while technically feasible, must undergofurther testing to address concerns about long-term effects to the environment,economic costs, and safety issues.

Despite considerable international efforts to make fertilizer-grade ammoniumnitrate less explosive or render it inert, the committee found that currentlythere is no practical method that would make the material considerably lessexplosive without seriously affecting its use as a fertilizer. More research isneeded to develop such methods. Meanwhile, the government should developstandard tests to evaluate the extent to which any proposed additives can renderammonium nitrate-based fertilizers inert.

A federal licensing program should be adopted for restricting the purchase ofcommercial explosives, the committee said. Greater enforcement of existingregulations for securely storing explosives is necessary as well. Statecontrols for purchasing explosives vary widely and federal regulations are laxcompared with some countries.

In addition, the "Be Aware for America" program -- developed by the fertilizerindustry and coordinated with the Bureau of Alcohol, Tobacco, and Firearms forsales of bulk nitrate fertilizers -- should be strengthened, the report says. This voluntary program, which encourages sellers to report suspicious fertilizerpurchases, would benefit from more rigorous implementation and greaterinvolvement with local and national law enforcement authorities.

Options if the Threat Increases

The committee also outlined actions that should be taken if the level of threatto public safety increases. Given an escalation of terrorist attacks againstthe public or the U.S. government, tagging some explosives, such as detonators,with detection markers may be a suitable emergency control. A program shouldthen be implemented that utilizes the best available taggant technology. Inaddition, buyers would need to show identification to make bulk purchases ofammonium nitrate fertilizers and chemicals, such as sodium chlorate andpotassium perchlorate, that can be used to make explosives. Vendors would needto keep records of such purchases.

If the threat of terrorism were to increase greatly, other measures should beconsidered, such as adding ultra low-level, radiation-emitting detection markersto plastic explosives and detonators and establishing a program using the bestavailable technique for making fertilizer-grade ammonium nitrate less explosiveor completely inert. Both approaches, however, would require considerableresearch and development before they could be workable. Increased controls oncommerce would be necessary as well. Sellers would need licenses and buyerswould need permits to purchase nitrate-based fertilizers and chemicals such assodium nitrate and potassium chlorate.

In parallel with this strategy of progressively stronger measures for taggingand regulating explosives and making them inert, the report also recommendsinstituting a single national databank to record incidents involving stolenexplosives and criminal bombings. Federal and law enforcement agencies alreadycollect some of these data, but a single source with uniform, detailedinformation would be valuable in developing a broad-based approach tosuppressing illegal bombings nationwide.

The study was funded by the U.S. Department of the Treasury. The NationalResearch Council is the principal operating agency of the National Academy ofSciences and the National Academy of Engineering. It is a private, non-profitinstitution that provides science and technology advice under a congressionalcharter.

*Copies of Containing the Threat from Illegal Bombings: An IntegratedNational Strategy for Marking, Tagging, Rendering Inert, and LicensingExplosives and Their Precursors are available from the National Academy Press; tel. (202) 334-3313 or1-800-624-6242. The cost of the report is $45.00 (prepaid) plus shippingcharges of $4.00 for the first copy and $.50 for each additional copy. Reporters may obtain a copy from the Office of News and Public Information atthe letterhead address (contacts listed above).

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National Academy Of Sciences. "Government Should Focus On Controlling Access To Explosives And Using Existing Detection Technologies To Prevent Illegal Bombings." ScienceDaily. ScienceDaily, 9 March 1998. <>.
National Academy Of Sciences. (1998, March 9). Government Should Focus On Controlling Access To Explosives And Using Existing Detection Technologies To Prevent Illegal Bombings. ScienceDaily. Retrieved May 22, 2017 from
National Academy Of Sciences. "Government Should Focus On Controlling Access To Explosives And Using Existing Detection Technologies To Prevent Illegal Bombings." ScienceDaily. (accessed May 22, 2017).