Summary of Biomonitoring Basics

Biomonitoring is a scientific technique for assessing human exposures to natural and synthetic compounds in the environment. It is based on analysis of human tissues and fluids and provides the only direct method of determining if people have been exposed to particular substances, what the magnitudes of their exposures are, and how these may be changing over time. Biomonitoring has become a more useful tool in recent years as the result of advancements in the capability to measure more and more minute amounts of chemicals in the human body.

With these new capabilities, the U.S. Centers for Disease Control and Prevention (CDC) has started an ambitious biomonitoring program that is aimed at increasing understanding of current and past exposures to natural and synthetic compounds in our environment. This program will provide baseline information that can be used to identify which compounds are present and in what amounts, to determine background levels of these compounds and, after repeated monitoring, to detect trends in exposures.

Because of the extensive resources needed for biomonitoring, only a limited number of people and compounds can be studied and only a few types of body fluids examined. In addition, because studies are done at just a few points in time, the results cannot provide information about how often individuals have been exposed, for how long or to what quantities of each substance. Thus, these data on body levels cannot be used to determine the doses people are exposed to on a daily basis.

Because almost all toxicity studies are based on the relationship between daily dose and adverse effect, and biomonitoring cannot provide dose information, measured body levels generally cannot be used to assess risk. Thus, the presence of a substance in the body, at any level, cannot be interpreted to mean that adverse effects are likely to occur.

Although it cannot be used to assess risk, exposure information collected through biomonitoring can be beneficial in a number of ways. It can identify environmental substances that have increased in concentration to levels that can be detected in humans and thus may contribute to the discovery of new sources of such compounds. Biomonitoring results can be used by physicians to diagnose individuals who have been exposed to excessive amounts of environmental chemicals, thereby making it possible to design appropriate interventions and treatments. Trends in monitoring data can be very useful in evaluating the success of policies designed to reduce the levels of particular compounds in the environment.

Scientists can also use biomonitoring data to provide direction for future research. These data may suggest the need for additional studies on the toxicity of certain substances and the environmental movement of others, as well as provide guidance for refining existing exposure estimates based on traditional, indirect exposure assessment methods. As a result of the CDC studies and others of their kind, public health experts may be better able to focus their efforts on substances that are present at the highest levels, rather than on those that are not detected or are only found at very low levels.