BACKGROUND

Although biomonitoring has been used in the occupational-health arena since the 1890s to monitor exposure to lead (Sexton et al. 2004), it has recently become more widely used for many applications. Biomonitoring has tremendous utility, providing an efficient and cost-effective means of measuring exposure. Biomonitoring data—when used in conjunction with available epidemiology, toxicology, or pharmacokinetic modeling3 data— can estimate a dose to assess how much has been absorbed into the body and can provide a measure of health risk. When gathered for the U.S. population, biomonitoring data can help to identify new chemicals that are found in the environment and in human tissues, monitor changes in exposures, and establish the distribution of exposures among the general population. The data can also be used to identify populations, such as infants and children, that might have higher exposures than the general population. State and local officials can use biomonitoring data to help to assess environmental risks in specific sites or populations (GAO 2000). In occupational and clinical medicine, biomonitoring can be used as a surveillance tool to help to interpret a clinical problem or to monitor an exposure trend.

Several salient examples highlight the contribution of biomonitoring data to robust public-health decisions and regulations. A case example is the measurement of blood lead, which has been extensively studied. Advances in biomonitoring have allowed scientists to measure blood lead at low concentrations and to correlate these concentrations with adverse health effects. That has resulted in the lowering by the Centers for Disease Control and Prevention (CDC) of blood lead concentrations of concern to 10 µg/dL, although no threshold for effects has been identified (CDC 2005). Blood lead concentrations collected in the CDC National Health and Nutrition Examination Survey (NHANES) from 1976 to 1980 provided impetus for Environmental Protection Agency (EPA) regulations that reduced lead in gasoline, in part on the basis of declining blood lead that paralleled declining gasoline lead (GAO 2000; Jackson et al. 2002).

3

Pharmacokinetics is defined as “the quantitative study of factors that control the time course for absorption, distribution, metabolism, and excretion of chemicals within the body” (Reddy et al. 2005). Pharmacokinetics was developed based on studies with therapeutic drugs. Toxicokinetics is a more recent term that has essentially the same meaning as pharmacokinetics, but refers specifically to non-drug substances, primarily toxic chemicals (McNaught and Wilkinson 1997). The committee uses the term pharmacokinetics, and by analogy pharmacodynamics (biological effect of chemical interaction with target sites in the body), as these terms were originally used and many of the key principles were first described within the context of therapeutic drugs.



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