Chemistry has a bad name when it comes to the topic of terrorism. Many people associate chemistry with chemical weapons and warfare, even though applications from chemistry are more often used in counterterrorism. Chemistry plays an important role in counterproliferation, threat evaluation, modeling, detection, incident response, and chemical defense, including development and use of nonlethal devices. The war against terrorism is an interdisciplinary effort. Some of the fields of expertise applied to counterterrorism and requiring knowledge of chemistry include:

• Toxicology
• Microbiology
• Molecular Biology
• Veterinary Science
• Pathology
• Clinical Medicine
• Physics
• Policy Analysis

Five specific applications of chemistry to counterterrorism are described below:

Forensic Science
Forensic science is the comprehensive scientific analysis of material evidence in the context of the law. Forensic science is used to monitor and verify compliance with treaties and agreements regarding weapons of mass destruction. Chemical forensic evidence is used to identify the mechanisms and origins of conventional and nuclear weapons (including isotopic analysis) and suspicious letters and packages. Principles of chemistry apply to genetic testing to identify suspects and pathogens. Examples of forensic instruments used for field analysis include portable thin-layer chromatography systems that simultaneously scan multiple samples for high explosives and a sample collection technology based on solid-phase microextraction techniques.

Sampling
The demand for tighter aviation security has accelerated the development of portals for detecting explosives, chemical and biological weapons, and other dangerous or illegal substances. Some of these passageways are similar to the familiar metal detector portals in airports, but new technology focuses on collecting samples from the 'plume' of air surrounding potential terrorists. The air around a person, disturbed by body heat, contains traces of explosives or other residue that may be sticking on skin and clothing. Plume analysis may provide an elegant new method to identify prospective terrorists before they strike.

Detection
A limiting factor in a country's ability to protect against a terrorist attack is its state of detector technology. Although true for chemical and nuclear devices, this is particularly important for timely identification of biological agents. Biodetectors require unique DNA sequences or antibodies to identify and characterize pathogens. Two classes of biodetectors are especially promising: immunofluorescence-based sensors (agent-specific miniature flow cytometers) and DNA-recognition instruments (based on polymerase chain reaction or PCR). When used together, these two assays are capable of state-of-the-art detection and identification of biological agents.

• Detecting Illegal Substances

Countermeasures
Applications of chemistry are integral to defending against terrorist attacks. In some instances, chemical agents may be used to neutralize harmful materials. Also, chemistry is used in the development and testing of vaccines and antibiotics to be used in the event of biological attack. Civilian first responders to a terrorist attack have virtually no decontamination methods other than soap and water and maybe bleach, so chemists are working to develop an easy-to-use decontamination reagent to combat both chemical and biological agents.

Dogs
Dogs remain extremely effective at detecting illegal and hazardous materials. Also, analysis of canine olfaction is used to design instrumentation for ultra-sensitive mechanical detection of substances. If a security alert is issued, bomb-sniffing dogs are available to all major airports in the US. Dogs are used to find people, bombs, land mines, drugs, or anything with an odor that the dogs have been trained to find. Athough a dog's sensitivity is not superior to that of present analytical instruments, canine intelligence makes them better at accurately discriminating between substances.

• Detecting Illegal Substances