Biomonitoring is a scientific technique for assessing human exposures to
natural and synthetic chemicals, based on sampling and analysis of an
individual's tissues and fluids.
While blood, urine, breast milk and expelled air are most commonly measured,
hair, nails, fat, bone and other tissues may also be sampled.
This technique takes advantage of the knowledge that chemicals that have
entered the human body leave markers reflecting this exposure. The marker may be
the chemical itself. It may also be a breakdown product of the chemical or some
change in the body that is a result of the action of the chemical on the
For example, alterations in the levels of certain enzymes or other proteins
may serve as markers; so too might modifications of normal body processes, such
as the transfer of oxygen to tissues.