That’s because a group of University of Rhode Island researchers has found that chemicals used to make bombs remain in the hair of explosives handlers long after repeated washings.

The lead researcher, Professor of Chemistry Jimmie Oxley, one of the co-directors of URI's Forensic Science Partnership, has also found that when the research team members attached ordinary gauze to combs, they had effective collection devices.

"We are very excited about what we found, because I didn’t know what to expect to find in terms of persistence," Oxley said.

"We’re at the very early stages of developing a practical field technique to link the perpetrator to a crime," the chemist said. "(Oklahoma City bomber Timothy) McVeigh had (the explosive) PETN on his shirt. If someone like him changes his shirt, we could still test his hair."

The team's early findings are the result of a two-year, $320,000 grant awarded by the National Memorial Institute for the Prevention of Terrorism. Located in Oklahoma City. The institute was incorporated Sept. 23, 1999, and grew out of the desire of the survivors and families to have a living memorial of the Murrah Federal Building bombing of April 19, 1995.

Oxley, who titled the study "A New Source of Evidence: Explosive Traces in Hair," said she pursued the research because hair readily absorbs odors, such as those from cigarette smoke, it is being used for evidence of drug use and because it is washed less frequently than hands and clothes.

She wanted to know if all explosives are absorbed equally well, if hair color and type affect adsorption, and whether the explosive, with time and washing, remains persistent. Ultimately, she hopes to establish a protocol that can be established for law enforcement use. Adsorption is the surface assimilation of a gas, vapor or dissolve matter.

"We wanted to know if we could get the same chemicals out that we put in," said URI Chemistry Professor Louis Kirschenbuam.

The research is being conducted in two phases at both URI and in the United Kingdom, where subjects have been preparing dog-training aids. In the first phase at URI, cut hair was exposed to explosive vapors to see which ones were adsorbed. The persistence of adsorption was studied for washed and unwashed hair. In the U.K, researchers combed subjects’ hair before and after explosive handling. Then, subjects' hair was re-sampled after a time interval and shampooing. Phase 2 of the work being done at URI will study the significance of hair pigment, sex, and race, while Phase 2 in Great Britain will develop law enforcement protocols for recovery of explosive residues in hair.

Oxley's team has been examining absorption of common military explosives, such as TNT, PETN and RDX, as well TATP, the suicide bombers' explosive. RDX is the main component of C-4, while PETN is used in detonation cords, sheet explosives and plasticized explosives.

In the TNT-tainted hair exposed to air at URI for six days, only small decreases in TNT levels were detected. Hair tainted with TNT and PETN that was washed three times and rinsed still retained small levels of the explosive.

"Finding the chemicals after washing, that’s what might turn out to be important," Kirschenbaum said. "I think it’s safe to say that volatile chemicals can migrate into the hair. Once it’s on there, it's truly stuck."

In addition to Oxley and Kirschenbaum, team members are URI Chemistry Professor James Smith and chemistry graduate students Kajal Shinde and Kishore Marimganti.

Note: If no author is given, the source is cited instead.

• Detectors
• Nanotechnology
• Weapons Technology
• Chemistry
• Forensic Research
• Inorganic Chemistry

• Dynamite
• Firestorm
• Propellant
• Projectile
• Hygroscopy
• Chemical warfare