Our breath may be as unique as our fingerprint and could be used to diagnose medical conditions, Swiss scientists say.
Researchers from the Swiss Federal Institute of Technology and the University Hospital Zurich found that exhaled breath has a molecular "breathprint", which is believed to be unique to individuals.
The scientists propose breath can be analysed in much the same way as blood or urine, to test for infectious and metabolic diseases and diagnose cancer and organ failure.
Their findings have been published in online journal PLoS ONE.
The scientists, led by professor Renato Zenobi, took breath samples from 11 volunteers on four occasions over nine working days. The samples were run through a mass spectrometer, which measures the chemical compounds in the breath.
Some compounds, such as water and carbon dioxide, were the same across all participants. However, compounds which differed between participants remained the same for individuals in each of the samples taken.
"We did find some small variations during the day, but overall the individual pattern stays sufficiently constant to be useful for medical purposes," said Pablo Martinez-Lozano Sinues, senior scientist in Zenobi's research group.
The researchers are now collaborating with medical doctors at the Division of Pulmonology of the University Hospital Zurich to see how the findings can be used to test for medical conditions.
"If we find a consistent pattern in patients with a given lung disease, we can develop a diagnostic tool," Sinues said.
The researchers believe their chances are highest to find characteristic biomarkers in the exhaled breath of patients with lung diseases, but in the future hope to extend their methodology to other groups of diseases.
Compared to analysis of blood or urine, a significant advantage of the approach is the breath fingerprint is available within seconds after receiving the breath sample.
Another advantage is testing breath is non-invasive, unlike taking a blood sample with a needle.
"Our goal is to develop breath analysis to the point where it becomes competitive with the established analysis of blood and urine," said Malcolm Kohler, professor at the University Hospital Zurich, and one of the co-authors of the study.
In order for the use of breathprints to become widespread, the instrumentation will need to be improved. The highly sensitive and accurate mass spectrometers used for these analyses are currently large and expensive, Zenobi said.
"Small, portable mass spectrometers already exist; if their performance can be improved, they will eventually find their way into clinics and doctor's offices."