Written in blood: advance notice of pollution-induced disease
How many contaminants have you been exposed to during your lifetime? None of us would be able to answer this question, but it would be very useful to know. EU-funded researchers are upgrading the techniques available for measuring environmental exposure, and searching blood samples for biomarkers that provide early warning of consequences for our health.
People are exposed to a cocktail of pollutants throughout their lifetime, but the exact composition of this blend — the so-called “exposome” — differs from one person to another.
The EXPOsOMICS project, which focuses on air- and waterborne pollutants, is advancing research into these personal contamination profiles. It is refining the methods used to detect and quantify exposure and searching for markers in our blood that show if these substances are about to make us ill.
The ability to spot this type of molecular fingerprint could help to prevent or treat pathologies linked to pollution, such as asthma, cardiovascular disease and various types of cancer, says project coordinator Paolo Vineis of Imperial College London. It could also help to inform risk assessment processes and public health policy.
Spotting the signs...
“There are many limitations in the way epidemiological studies are conducted regarding air pollution, for example to investigate the long-term effect of exposure,” Vineis explains. “One such limitation is in the characterisation and quantification of the specific exposures,” he notes. “In addition, traditionally we tended to refer to mortality or to the incidence of the diseases, but we know little about the intermediate steps.”
The partners involved in EXPOsOMICS set out to address these issues, notably by improving the techniques and methodologies used to determine and quantify exposure. How many pollutants are floating about in the air we breathe? Or in the water of our swimming pools? The project uses sophisticated tools to count the contaminants that come our way on an average day.
These tools include backpacks equipped to detect airborne pollutants. “In one experiment, some 200 people were invited to carry one of these throughout three separate 24-hour periods. This allowed us to identify their exposure second by second,” Vineis explains.
This exercise generated a huge amount of data, which the partners are still assessing. “But we already have some interesting results,” Vineis notes. “For example, we found that cooking is a major source of ultrafine particles in the air.”
Similarly detailed studies were carried out for waterborne pollutants in swimming pools, where measurements notably recorded contaminants exhaled in people’s breath.
...before there are symptoms
EXPOsOMICS draws on an exciting combination of short-term experimentation and long-term epidemiological research: it is securing new exposure information, but also benefits from biological material that the participating volunteers supplied years earlier as part of a prospective study. Blood collected from the project’s backpackers, for example, could thus be compared with samples they had donated decades ago, enabling the researchers to search for before-and-after differences in genes, proteins and metabolites.
These comparisons are expected to reveal changes in our molecular make-up that reflect the early stages of pollution damage. The scientists are using so-called “omics” techniques for these analyses, which enable them to detail and compare the molecules in the samples.
While these techniques are powerful, they are also quite expensive, says Vineis, and therefore it is not possible to carry out such analyses for the many thousands who have contributed the biological material studied in EXPOsOMICS. Statistical analysis and mathematical modelling are used to extrapolate the results of the omics analyses and guide research on the samples from the wider group.
“The final step will be to connect all these exposures and changes in molecules with specific diseases,” says Vineis. Such findings could, for example, make it easier to identify substances that can cause cancer, or support a review of acceptable limit values for various pollutants, he concludes. Change is in the air!