Teeth may be used to reveal level of radiation exposure in bomb explosion

Scientists are developing tools to use teeth enamel to test how much radiation a person has been exposed to in the case of a major emergency, like a dirty bomb explosion.

"Dental enamel is quite a remarkable material," said Barry Pass, a professor in the College of Dentistry at Howard University in Washington, D.C. "There's a world of information in the tooth," he added.

When a person is exposed to radiation, the energy can create free radicals in the body.

These are atoms that have an extra unpaired electron, which makes them unstable - in healthy tissue, they can harm regular molecules by stealing electrons and damaging DNA.

But free radicals can be a useful indicator of how much radiation a person has come in contact with.

Scientists are working on perfecting a process called Electron Paramagnetic Resonance (EPR) that can measure levels of free radicals in substances like teeth.

The technique could prove especially useful in gauging how much harm has been done after a major release of radiation from an accident or a radiation dispersal device, often called a dirty bomb.

The process works like this: Scientists need a small sample of a tooth - basically a tiny piece that can be carved out with a dental drill, and doesn't damage the remaining tooth.

Then, they apply microwave energy to the sample.

Free radicals will absorb microwave energy, so scientists can measure how much energy is left after passing through the tooth fragment to estimate how many free radicals are present.

"These free radicals are generated in proportion to the radiation exposure," Pass explained.

"The absorption of microwave energy is proportional to the concentration of these free radicals," he said.