Biomonitoring

In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. The two best established biomonitoring programs in representative samples of the general population are those of the United States and Germany, although population-based programs exist in a few other countries. In 2001, the U.S. Centers for Disease Control and Prevention (CDC) began to publish its biennial National Report on Human Exposure to Environmental Chemicals, which reports a statistically representative sample of the U.S. population. Biomonitoring involves the use of organisms to assess environmental contamination, such as of surrounding air or water. It can be done qualitatively by observing and noting changes in organisms, or quantitatively by measuring accumulation of chemicals in organism tissues. By observing or measuring the effects the environment has on its resident organisms, pollution may be suspected or inferred. Historically, public health regulations have been based on theoretical risk calculations according to known levels of chemical substances in air, water, soil, food, other consumer products and other sources of potential exposure. Human biomonitoring offers the opportunity to analyze the actual internal levels of bodily substances from all potential routes of exposure at one time, which may contribute to improving risk assessments. Scientific advancements have made it possible to detect a greater number of chemical substances in smaller concentrations in the body, with some chemicals detectable at levels as low as parts per trillion. A single biomonitoring measurement is only one snapshot in time and may not accurately reflect the level of exposure over longer periods. In 2006 the U.S. National Research Council published a report, Human Biomonitoring for Environmental Chemicals. The report recognized the value of biomonitoring for better understanding exposure to environmental chemicals, and included several findings and recommendations to improve the utility of biomonitoring data for health risk assessment. In summary, the report called for more rigorous health-based criteria for selecting chemicals to include in biomonitoring studies; the development of tools and techniques to improve risk-based interpretation and communication of biomonitoring data; integration of biomonitoring into exposure assessment and epidemiological research; and exploration of bioethical issues around biomonitoring, including informed consent, confidentiality of results, and others. The issue of exposure to environmental chemicals has received attention as a result of televised reports by Bill Moyers for PBS and Anderson Cooper for CNN's 'Planet in Peril' series. The book Our Stolen Future, with a foreword by former Vice President Al Gore, also raised awareness by focusing on endocrine disruption. The CDC's Division of Laboratory Sciences within the National Center for Environmental Health has developed a National Biomonitoring Program, and has published the biennial National Report on Human Exposure to Environmental Chemicals since 2001. As the selection of chemicals is controversial, the CDC has identified influential criteria:Evidence of exposure in a U.S. population, presence and significance of health effects after a given level of exposure, desire to track public health initiatives to reduce exposure to a given agent, existing method for accurately measuring biologically relevant concentrations of the chemical, sufficient tissue specimens, in particular, blood and/or urine samples and cost-effectiveness. CDC established three criteria for removing chemicals from future surveys: a new replacement chemical (i.e., a metabolite or other chemical) is more representative of exposure than the chemical currently measured, or if after three survey periods, detection rates for all chemicals within a method-related group are less than 5 percent for all population subgroups (i.e., two sexes, three race/ethnicity groups, and the age groups used in the National Report), or if after three survey periods, levels of chemicals within a method-related group are unchanged or declining in all demographic subgroups documented in the National Report.