Department of Environmental and Occupational Health Université de Montréal
environment, just like our own body, is made of chemicals. Those
we usually fear most are man-made chemicals despite the fact
that some of the most toxic ones have a natural origin such as
the botulinum toxin or certain mushroom toxins. There are two
major approaches to monitoring exposure to “environmental
chemicals”. We can quantify their presence in the media
we are in contact with such as the air we breathe and the food
we eat. Alternately, we can measure the chemicals or their biotransformation
products in biological media such as blood, urine and hair. The
substance thus measured in a biological matrix is called a biomarker.
The extent of our knowledge on biomarkers varies. Consequently,
the interpretation we make of a biomarker measurement cannot
be identical for all biomarkers. Some reveal the mere presence
of the chemical in an organism without any further possible interpretation
whereas others can contribute to a full-scale risk assessment.
For biomonitoring to be fully exploitable as a health prevention
tool, we need to establish guideline values for the biomarkers.
These values can derive from the distribution of biomarker concentrations
in a reference population, from the knowledge of the relationship
between the exposure dose and the resulting biomarker concentration,
or from the relationship between a health outcome and the biomarker
concentrations. Some of the biomarkers success stories in the
establishment of public health policies include blood lead and
serum cotinine. The first was key to stopping the use of lead
tetraethyl as an antiknock agent in gas. The second contributed
to the various antismoking policies established over the recent
years. As such they were instrumental to improving public health.