The device was developed by Michael Phillips and colleagues at Menssana Research Inc. in Fort Lee, N.J. It was originally intended for medical diagnosis, using gas chromatography and mass spectrometry to analyze volatile organic markers in one’s breath, and it has already been used to detect early-stage lung cancer. The device was approved last year by the U.S. Food and Drug Administration for detecting heart transplant rejection. Since chemicals from explosives can be inhaled or absorbed through the skin and then stored in body tissue, Phillips wondered whether the technology could help either convict or acquit terror suspects. He tested people who handled explosives as part of their daily work and found they exhaled a range of plasticizers and other volatile compounds that weren’t exhaled by people not in contact with explosives. Phillips hopes to test whether the breath tester could be used to detect exposure to radiation.