By Dr Michael Edmonds
The sequencing of the human genome has provided scientists with a great deal of information about the 20,000 to 25,000 genes coded by our DNA and is leading to a better understanding of hereditary based diseases. However, a complementary concept, the exposome, has been proposed to bring a greater understanding of the role exposure to environmental agents has in disease.
While we already know that individual agents such as DDT, xenoestrogens and polycyclic aromatics have been implicated in disease, the exposome goes much further and attempts to consider the total exposure an individual experiences over his or her lifetime, including exposure to internal (metabolites) and external (environmental) agents.
In order to assess an exposome, sensitive analytical techniques are required to detect minute traces of environmental agents and biomarkers in biological samples such as blood and urine. Mass spectrometry, nuclear magnetic resonance and capillary electrophoresis are some of the techniques capable of studying these compounds which may be present at parts per billion concentrations. In the future, ’lab on a chip’ devices could be applied to rapid and efficient determination of the exposome.
As well as studying the trace amounts of various environmental agents and metabolites in human blood and urine, the presence of biomarkers resulting from the interaction of environmental agents with biological components such as proteins, also provides valuable information about the exposome. For example, Professor Stephen Rappaport, at the
University of California, Berkley, is using mass spectrometry to study the biomarkers which form when reactive agents react with proteins such as albumin. Such biomarkers may provide a historical record of the presence of reactive agents which may otherwise be difficult to detect due to their reactivity or short lifespan.
In psychology, the relative effects that genetics and environment have on behaviour have been vigorously debated (e.g. nature vs nurture). In the biological and medical sciences, I suspect that the areas of genomic and exposomic research will confirm that human health is a complex interplay of genetic and environmental factors and will provide us with the tools to understand and reduce our risks of developing disease.
Arnaud, C., (2010), Exposing the Exposome, Chemical and Engineering News, August 16, pg 42-44.
Dr Michael Edmonds is an educator, researcher and manager at Christchurch Polytechnic Institute of Technology. He has strong interests in the communication and promotion of science.