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In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances.^[1][2] Often, these measurements are done in blood and urine.^[3]

In 2001, the U.S. Centers for Disease Control and Prevention began to publish its biennial National Report on Human Exposure to Environmental Chemicals, which reports a statistically representative sample of the U.S. population.^[4] The Environmental Working Group has also conducted biomonitoring studies.^[5]

Overview

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.^[6] 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.^[7] A single biomonitoring measurement is only one snapshot in time and may not accurately reflect the level of exposure over longer periods.^[8]

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.^[9]

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.^[10] The book Our Stolen Future, with a foreward by former Vice President Al Gore, also raised awareness by focusing on endocrine disruption.

Surveys

• In the United States, the CDC first tested samples from the general population for lead and a few pesticides in 1976.^[11] In the late 1990s, the National Health and Nutrition Examination Survey (NHANES) program had a major expansion.^[11]
• Some U.S. states have received federal support^[12] and have established biomonitoring programs. In 2001, the CDC awarded planning grants to 33 states to assist in capacity building for expanding biomonitoring.^[13] The California Environmental Contaminant Biomonitoring Program (CECBP), is administered by the California Department of Public Health, and was established by law in 2006.^[14] Minnesota's Biomonitoring Pilot Program was established by law in 2007 and is run by the Minnesota Department of Health.^[15]
• The Environmental Working Group's (EWG) Human Toxome Project and the Canadian group Environmental Defence's Toxic Nation project have directed studies.^[5][16]
• In Germany, the German Environmental Survey (GerES) has been active since 1985,^[17][3] and in 1992 the Human Biomonitoring Commission of the German Federal Environment Agency was established.^[18]
• In Canada, Statistics Canada administers the Canadian Health Measures Survey, which includes biomonitoring for environmental chemicals.^[19] Health Canada administers a program called Mother-Infant Research on Environmental Chemicals, which focuses on 2,000 pregnant women and their infants.^[20]

National Report on Human Exposure to Environmental Chemicals

The CDC's Division of Laboratory Sciences within the National Center for Environmental Health has developed a National Biomonitoring Program, and publishes the biennial National Report on Human Exposure to Environmental Chemicals. As the selection of chemicals is controversial, the CDC has identified influential criteria:^[21]

• Evidence of exposure in a U.S. population
• The 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
• Cost-effectiveness.

CDC has also established three criteria for removing chemicals from future editions of the National Report:

• 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.^[22]

National Children's Study

In collaboration with the National Institute of Child Health and Development (NICHD), National Institute of Environmental Health Sciences and U.S. Environmental Protection Agency, the CDC's Environmental Health Laboratory has announced it will play a key role in the biomonitoring of the ongoing National Children's Study, which plans to follow 100,000 children across the United States from birth until age 21. The study was authorized as part of the Children's Health Act of 2000 and is the largest effort undertaken to address the effects of social, economic and environmental factors on a child's health.^[23]

Methods and chemicals

Chemicals and their metabolites can be detected in a variety of biological substances such as blood, urine, hair, semen, breast milk, or saliva.^[24] Breast milk is a favored matrix (substance) to measure lipophilic (fat-loving) persistent, bioaccumulative, and toxic (PBT) compounds during lactation; this exposure route is dominant for breastfeeding children.^[25] A lipophilic compound might also be detected in blood, while a hydrophilic (water-loving) compound might be detected in urine. Analytical methods used by the CDC include isotope dilution mass spectrometry, inductively coupled plasma mass spectrometry, or graphite furnace atomic absorption spectrometry.^[26]

Some of the detected chemicals include:

• Lead
• Mercury
• Arsenic
• Perchlorate
• Persistent organic pollutants

• Dioxins
• Furans
• Organochlorine pesticides

• DDT and DDE

• Perfluorinated compounds

• Bisphenol A (BPA)
• Polybrominated diphenyl ethers (PBDE)
• Polybrominated biphenyls (PBBs)
• Polychlorinated biphenyls (PCBs)
• Phthalates
• Oxybenzone (Benzophenone-3)
• Triclosan

Interpretation

The presence of an environmental chemical in the body does not necessarily indicate harm. A chemical's toxicity is determined by a range of factors, including its concentration and a person's individual susceptibility. Small amounts of a chemical may produce no health effects, whereas larger amounts may have an impact.^[26]

The presence of chemicals in the body has advanced more rapidly than the ability to interpret the potential health consequences of exposure.^[27] Scientific evaluations of health risks from chemicals typically involve toxicity studies in laboratory animals and subsequent extrapolation to humans. Such studies have been used to establish regulatory exposure standards, but their relation to levels measured in biomonitoring studies is not always known.

Communication

Participants in biomonitoring studies typically want to know whether the chemical compositions measured in their bodies indicate that they are healthy (or not); however, biomonitoring studies are not designed to answer this particular question. While biomonitoring is useful for assessing exposure, without other information, it is not alone useful in determining a person's health or likelihood of developing ill effects.^[8][28] According to the National Research Council, accurate communication of results is essential for the proper use of biomonitoring surveys, but states "there is no accepted standard for good biomonitoring communications".^[27]

Standards and guidelines that health professionals can use to communicate biomonitoring information are still evolving. Foster and Agzarian write, "Because of the lack of clear reference ranges and standards, however, it is unlikely that providing study subjects with their individual exposure results in the absence of information about the health significance of the results would create anxiety and anger among study subjects."^[8] An expert panel on Biomonitoring Equivalents has published guidelines for communicating information to the general public and health care providers.^[29]

Dr. Charles McKay of the Connecticut Poison Control Center provides a perspective to assist medical toxicologists with understanding human biomonitoring data^[30] is interviewed in a video titled "A Medical Doctor's Perspective on Biomonitoring", which is focused on helping the general public better understand biomonitoring.^[31]

Boston Consensus Project

In 2007, the Boston University School of Public Health organized a panel, the Boston Consensus Conference on Biomonitoring, for the purpose of educating residents about the scientific, legal and ethical issues of biomonitoring, and coming to an understanding of the lay panel's priorities and concerns related to measuring human exposure to environmental chemicals. The conference produced a report for public health policy makers and scientists who deal with or study the issues.^[32]

See also

• Biomarker
• Pharmacokinetics
• Exposure assessment
• Dose-response relationship

References

External links

• Biomonitoringinfo.org
• National Biomonitoring Program
• Human Biomonitoring for Environmental Chemicals, National Research Council
• Biomonitoring – EPA Needs to Coordinate Its Research Strategy and Clarify Its Authority to Obtain Biomonitoring Data, United States Government Accountability Office
• The heart of the matter on breastmilk and environmental chemicals: essential points for healthcare providers and new parents, Review
• The interpretation of trace element analysis in body fluids, Review