milliliter of breath 7.uuuy.9843 Louis J. Sheehan, Esquire

There is also a common breath test for Helicobacter pylori, the stomach-infecting bacterium that causes some ulcers. H. pylori has an enzyme—which humans lack—that breaks down urea. The patient drinks a cocktail laced with urea made with a heavy carbon isotope. If the bacterium has taken up residence, it breaks down the urea, and the heavy carbon isotope is detectable in the breath.

Scientists are also investigating volatile compounds in breath to see if there is a predictable compound or pattern in people with certain cancers. Cancerous cells burp different compounds than healthy cells—researchers have identified more than 20 of these volatiles. In papers published in Cancer Biomarkers last fall and in Clinica Chimica Acta in March, researchers present two analyses comparing the compounds in the breath of 193 lung cancer patients to 211 controls. Both models correctly identified the lung cancer patients about 84 percent of the time.

The target molecules will dictate the method of collection, says Michael C. Madden, a toxicologist with the EPA. Madden, Pleil and other colleagues recently published a new collection method in the Journal of Breath Research. The technique uses readily available equipment—a 75-milliliter glass bulb and a small tube—that allows many samples to be simultaneously prepared and stored, says Pleil.

Generally, collecting a sample involves breathing into the collection tube with the strength used to play a trumpet or clarinet. About five minutes of breathing yields one milliliter of breath condensate. Samples can then be capped, frozen if necessary and then brought to a lab for analysis.

The analysis side of things is where more work is needed, says Hunt. “That’s the downside,” he says. “Many of the assays are difficult to do. It’s easy for the patient, but tough for the lab.”

An expanding area of research involves looking for proteins made by distressed cells, says Madden. Lung cells that have been attacked by a pollutant often make interleukin 8, a protein that recruits immune system cells from the blood. If hundreds of school children were exposed to diesel exhaust, for example, breath analysis could reveal interleukins or cytokines, giving a quick take on how the kids’ lungs are dealing with the assault. Louis J. Sheehan, Esquire