At CDC, we define biomonitoring as the assessment of
internal dose by measuring the parent chemical, or it's metabolite, or
metabolites, or reaction product in human specimens.
By reaction product, I mean such things as adducts.
Often chemicals can react with proteins in the blood to form an adducts or
with DNA to form an adducts.
Now blood and urine are the most commonly used types of human specimens.
And there are a number of validated methods available for
many environmental chemicals that we may wish to measure.
When we wish to measure, these biomonitoring measurements are typically
made in human specimens, such as blood and urine.
A couple of points I'd like to make about biomonitoring.
These measurements that we make in blood or
urine, typically integrate all sources and routes of exposure.
For example, a blood lead measurement reveals the lead concentration in blood
that results from all sources of exposure, such as air, dust, water and
soil, as well as from all routes of exposure.
That is, from breathing, from ingestion, which includes transfer of lead from
hands to mouth, and then being swallowed, as well as from food and drinking water.
So, the biomonitoring measurement is something of an integrating measure.
Most biomonitoring measurements are made at very low concentrations.
In fact, often at trace concentrations,
very close to the analytical method of detection.
This is one reason that measurements require trained, experienced analysts and
validated methods and adherence to quality control and quality assurance procedures.
It's also now worthy that biomonitoring measurements are concentrations.
They are not, per say, exposures.
Because a biomonitoring measurement can be a useful indicator of an exposure that
has occurred, we sometimes refer to these as exposure biomarkers.