Chromatography Measures PM Exposure in Exhaled Breath

There have been many studies that have shown an association between exposure to environmental and occupational particulate matter in the air and human health. The World Health Organization states that air pollution is a major cause of death and disease across the globe. In fact, they suggest that there are an estimated 4.2 million premature deaths due to ambient air pollution from conditions such as heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.

Metabolomics - looking at small molecules

A recent paper published in the Journal of Breath Research has investigated how researchers might monitor exposure to particulate matter through chemicals in the exhaled breath. It seems that particles with specific surface characteristics or chemical composition can trigger signalling pathways through oxidative stress leading to inflammation. But research is also linking exposure to particulate matter with metabolic conditions including diabetes and obesity.

Metabolomics - one of the best methods for investigating metabolic effects - is the study of chemical processes involving metabolites. Metabolomics looks for the chemical fingerprints left behind after cellular processes have taken place. So, to investigate the metabolic effects of particulate matter on the body, researchers would compare the metabolomes of individuals exposed to particulate matter and those of healthy controls.

Metabolomic techniques including nuclear magnetic resonance and mass spectrometry. These are used alongside bioinformatics - software that can interpret biological data in metabolomics - to identify and quantify the small molecules that are the result of biological processes taking place in cells. The advances in techniques are discussed in the article, A Review of the Advances in High Resolution Accurate Mass Spectrometry for Industrialising Omics. The end point is to differentiate between the metabolites of healthy controls and affected subjects.

Monitoring exhaled breath

The research team behind the above referenced paper note that as the lung is the main pathway for the introduction of inhaled particulate matter into the body - perhaps the exhaled breath condensate is a convenient way to monitor the biomarkers of metabolic or oxidative stress. The research team also looked to validate a less costly method to determine some of the metabolites - namely an ion chromatography method.

Some of the metabolites that are often reported in exhaled breath metabolite studies include organic acids like acetate, formate and propionate acids - that are easily ionized in basic conditions. This means that a simple and cost-effective method like ion chromatography could be a complimentary alternative to sophisticated and expensive NMR studies. The team report that the method they validated identified eight anions in exhaled breath samples. They suggest that the formate/acetate ratio could be used to monitor the metabolic signature of workers exposed to certain types of particulate matter like quartz.