Biomonitoring—one technique for assessing people’s exposure to chemicals—involves measuring the concentration of chemicals or their by- products in human specimens, such as blood or urine. While, biomonitoring has been used to monitor chemical exposures for decades, more recently, advances in analytic methods have allowed scientists to measure more chemicals, in smaller concentrations, using smaller samples of blood or urine. As a result, biomonitoring has become more widely used for a variety of applications, including public health research and measuring the impact of certain environmental regulations, such as the decline in blood lead levels following declining levels of gasoline lead. CDC conducts the most comprehensive biomonitoring program in the country under its National Biomonitoring Program and published the first, second, third and fourth National Report on Human Exposure to Environmental Chemicals—in 2001, 2003, 2005, and 2009, respectively— which reported the concentrations of certain chemicals or their by- products in the blood or urine of a representative sample of the U.S. population. For each of these reports, the CDC has increased the number of chemicals studied—from 27 in the first report, to 116 in the second, to 148 in the third, and to 212 in the fourth. Each report is cumulative (containing all the results from previous reports). These reports provide the most comprehensive assessment to date of the exposure of the U.S. population to chemicals in our environment including such chemicals as acrylamide, arsenic, BPA, triclosan, and perchlorate. These reports have provided a window into the U.S. population’s exposure to chemicals, and the CDC continues to develop new methods for collecting data on additional chemical exposures with each report. For decades, government regulators have used risk assessment to understand the health implications of commercial chemicals. Researchers use this process to estimate how much harm, if any, can be expected from exposure to a given contaminant or mixture of contaminants and to help regulators determine whether the risk is significant enough to require banning or regulating the chemical or other corrective action. Biomonitoring research is difficult to integrate into this risk assessment process, since estimates of human exposure to chemicals have historically been based on the concentration of these chemicals in environmental media and on information about how people are exposed. Biomonitoring data, however, provide a measure of internal dose that is the result of exposure to all environmental media and depend on how the human body processes and excretes the chemical. EPA has made limited use of biomonitoring data in its assessments of risks posed by chemicals. As we previously reported, one major reason for the agency’s limited use of such data is that, to date, there are no biomonitoring data for most commercial chemicals. The most comprehensive biomonitoring effort providing data relevant to the entire U.S. population includes only 212 chemicals, whereas EPA is currently focusing its chemical assessment and management efforts on the more than 6,000 chemicals that companies produce in quantities of more than 25,000 pounds per year at one site. Current biomonitoring efforts also provide little information on children. Large-scale biomonitoring studies generally omit children because it is difficult to collect biomonitoring data from them. For example, some parents are concerned about the invasiveness of taking blood samples from their children, and certain other fluids, such as umbilical cord blood or breast milk, are available only in small quantities and only at certain times. Thus, when samples are available from children, they may not be large enough to analyze. A second reason we reported for the agency’s limited use of biomonitoring data is that EPA often lacks the additional information needed to make biomonitoring studies useful in its risk assessment process. In this regard, biomonitoring provides information only on the level of a chemical in a person’s body but not the health impact. The detectable presence of a chemical in a person’s blood or urine does not necessarily mean that the chemical causes harm. While exposure to larger amounts of a chemical may cause an adverse health impact, a smaller amount may be of no health consequence. In addition, biomonitoring data alone do not indicate the source, route, or timing of the exposure, making it difficult to identify the appropriate risk management strategies. For most of the chemicals studied under current biomonitoring programs, more data on chemical effects are needed to understand whether the levels measured in people pose a health concern, but EPA’s ability to require chemical companies to develop such data is limited. As a result, EPA has made few changes to its chemical risk assessments or safeguards in response to the recent proliferation of biomonitoring data. For most chemicals, EPA would need additional data on the following to incorporate biomonitoring into risk assessment: health effects; the sources, routes, and timing of exposure; and the fate of a chemical in the human body. However, as we have discussed in prior reports, EPA will face difficulty in using its authorities under TSCA to require chemical companies to develop health and safety information on the chemicals. In January 2009, we added transforming EPA’s process for assessing and controlling toxic chemicals to our list of high-risk areas warranting attention by Congress and the executive branch. Subsequently, the EPA Administrator set forth goals for updated legislation that would give EPA the mechanisms and authorities to promptly assess and regulate chemicals. EPA has used some biomonitoring data in chemical risk assessment and management, but only when additional studies have provided insight on the health implications of the biomonitoring data. For example, EPA was able to use biomonitoring data on methylmercury—a neurotoxin that accumulates in fish—because studies have drawn a link between the level of this toxin in human blood and adverse neurological effects in children. EPA also used both biomonitoring and traditional risk assessment information to take action on certain perfluorinated chemicals. These chemicals are used in the manufacture of consumer and industrial products, including nonstick cookware coatings; waterproof clothing; and oil-, stain-, and grease-resistant surface treatments. EPA has several biomonitoring research projects under way, but the agency has no system in place to track progress or assess the resources needed specifically for biomonitoring research. For example, EPA awarded grants that are intended to advance the knowledge of children’s exposure to pesticides through the use of biomonitoring and of the potential adverse effects of these exposures. The grants issued went to projects that, among other things, investigated the development of less invasive biomarker than blood samples—such as analyses of saliva or hair samples—to measures of early brain development. Furthermore, EPA has studied the presence of an herbicide in 135 homes with preschool-age children by analyzing soil, air, carpet, dust, food, and urine as well as samples taken from subject’s hands. The study shed important light on how best to collect urine samples that reflect external dose of the herbicide and how to develop models that simulate how the body processes specific chemicals. Nonetheless, EPA does not separately track spending or staff time devoted to biomonitoring research. Instead, it places individual biomonitoring research projects within its larger Human Health Research Strategy. While this strategy includes some goals relevant to biomonitoring, EPA has not systematically identified and prioritized the data gaps that prevent it from using biomonitoring data. Nor has it systematically identified the resources needed to reach biomonitoring research goals or the chemicals that need the most additional biomonitoring-related research. Also, EPA has not coordinated its biomonitoring research with that of the many agencies and other groups involved in biomonitoring research, which could impair its ability to address the significant data gaps in this field of research. In addition to the CDC and EPA, several other federal agencies have been involved in biomonitoring research, including the U.S. Department of Health and Human Service’s Agency for Toxic Substances and Disease Registry, entities within the U.S. Department of Health and Human Service’s NIH, and the U.S. Department of Labor’s Occupational Safety and Health Administration. Several states have also initiated biomonitoring programs to examine state and local health concerns, such as arsenic in local water supplies or populations with high fish consumption that may increase mercury exposure. Furthermore, some chemical companies have for decades monitored their workforce for chemical exposure, and chemical industry associations have funded biomonitoring research. Finally, some environmental organizations have conducted biomonitoring studies of small groups of adults and children, including one study on infants. As we previously reported, a national biomonitoring research plan could help better coordinate research and link data needs with collection efforts. EPA has suggested chemicals for future inclusion in the CDC’s National Biomonitoring Program but has not gone any further toward formulating an overall strategy to address data gaps and ensure the progress of biomonitoring research. We have previously noted that to begin addressing the need for biomonitoring research, federal agencies will need to strategically coordinate their efforts and leverage their limited resources. Similarly, the National Academies of Science found that the lack of a coordinated research strategy allowed widespread exposures to go undetected, including exposure to flame retardants known as polybrominated diphenyl ethers—chemicals which may cause liver damage, among other things, according to some toxicological studies. The academy noted that a coordinated research strategy would require input from various agencies involved in biomonitoring and supporting disciplines. In addition to EPA, these agencies include the CDC, NIH, the Food and Drug Administration, and the U.S. Department of Agriculture. Such coordination could strengthen efforts to identify and possibly regulate the sources of the exposure detected by biomonitoring, since the most common sources—that is, food, environmental contamination, and consumer products—are under the jurisdiction of different agencies. We have recommended that EPA develop a comprehensive research strategy to improve its ability to use biomonitoring in its risk assessments. However, though EPA agreed with our recommendation, th agency still lacks such a comprehensive strategy to guide its own research efforts.