How Smelly Is Your Breath?

Science 2013-04-16

When someone says to you that your breath smells, you would usually wonder what you have eaten (or should have eaten). Bacteria are often at the origin of infections and many have a smell that is undetectable to humans. These odours are often specific to the different types of bacteria. The presence of specific bacteria, and hence a specific smell, can be indicative of a particular disease. For example, streptococcalbacteria can cause pneumonia and salmonellacan cause food poisoning. However, a new diagnosis could have the potential to detect microorganisms by the smell they produce with a bit of clever equipment giving a whole new meaning to the smell of your breath.

Volatile organic compounds in your breath that are exhaled can be detected and analysed using secondary electrospray ionisation mass spectrometry (SESI-MS). SESI-MS can detect very small quantities of particles in breath. If specific particles are known to be generated by a certain type of bacterial infection, then the patient can be given the appropriate treatment. This method of disease detection could significantly speed up the diagnosis process.

More recently, a research paper has been published that indicates that individuals may have a unique ‘breathprint’. A similar concept to a fingerprint, each individual’s genetic make-up and specific characteristics give a unique exhaled combination of volatile compounds. By analysing the breath of 11 healthy individuals over a period of nine days, the team from the Swiss Federal Institute of Technology were able to accurately distinguish between the participants 76% of the time. Each individual had a stable breathprint over the course of the experiment, suggesting that disease-causing bacteria could cause detectable alterations. If confirmed by further studies, this method of detecting bacterial infections could speed up the diagnosis procedure for many patients.

Another use of breath tests could be to identify stress. Scientists found that specific compounds increased in the breath under stressful conditions. Several more are thought to decrease. The initial tests put participants both in a very relaxing environment and a very stressful one. While stress could be detected with a breath test in these conditions, additional studies are required to see if it applies to more moderate levels of stress.

Breath could also be used to diagnose a major killer: cancer. Stomach cancer gives off odours that are not detectable to humans. However, a new test has been developed that successfully identified cancer in 90% of cases in a small clinical trial. Made of nanomaterials, the sensor is expected to be rolled out to larger clinical trials.

New uses for breath tests are being described on a regular basis. With the increase in sensitivity of particle detectors and laboratory analytical equipment, many more uses for breath tests and breathprints may be around the corner.