Biomonitoring: Population Exposures

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Scientists at CDC determine which environmental chemicals people have been exposed to by measuring how much of those chemicals actually get into people’s bodies. This is called biomonitoring. Most biomonitoring involves measuring the amount of a chemical or its breakdown product (metabolite) that is in a small sample of a person’s blood or urine. The amount of the chemical or metabolite in the blood or urine depends on the amount of the chemical that has entered the body. We know that some of them cause disease or illness in people. However, for most chemicals, we do not know if low level environmental exposures affect our health. Finding an environmental chemical in a person’s blood or urine does not mean that it causes health effects or disease.

We Track That

Biomonitoring data come from CDC’s National Health and Nutrition Examination Survey (NHANES). NHANES evaluates a nationally-representative sample of the U.S. population. It is designed for survey findings to reflect the nation as a whole, rather than individual counties or states.

The NHANES survey design does not allow use of the data to estimate exposure by state, city, or for specific areas associated with hazardous chemical exposures. For example, you cannot extract a subset of data and examine levels of blood lead that represent a state population. In addition, these biomonitoring data do not provide

  • data about specific sources of exposure, such as hazardous chemical sites or uses.
  • data about specific pathways of exposure, like breathing, eating, drinking, or touching.
  • information about specific products or environments.
  • regulatory guidelines or recommendations.
  • information about health effects related to chemical exposures.

Types of Data

Data about human exposure to environmental chemicals come from CDC’s National Health and Nutrition Examination Survey (NHANES) as presented in CDC’s National Report on Human Exposure to Environmental Chemicals. NHANES is an ongoing, complex survey that samples the U.S population. It collects different types of information to provide an assessment of the population’s overall health and nutrition.

The biomonitoring indicator below provides information about environmental chemicals or their metabolites (see box to the right) found in human urine or blood.

National Report on Human Exposure to Environmental Chemicals

This indicator shows concentrations of different environmental chemicals in urine or blood. These data tell you what levels of those environmental chemicals are found in urine and blood samples from people who are typical examples of the U.S. population. These data are available for the United States as a whole, not by county, state, or region. They do not provide information about specific sources of exposure, exposure pathways, or health effects from exposure.

Topic Areas

Tobacco Smoke

  • Cotinine


  • Arsenic
  • Cadmium
  • Lead
  • Mercury
  • Uranium

Volatile Organic Compounds (VOCs)

  • Benzene
  • Toluene

Disinfection By-Products

  • Chloroform

Per- and Polyfluorinated Substances (PFAS)

  • Per- and Polyfluorinated Substances (PFAS)

Personal Care and Consumer Products

  • Bisphenol A (BPA
  • Triclosan
  • Parabens
  • 2,5dichlorophenol
  • 2,4dichlorophenol


  • Organophosphorus
  • Pyrethroid

Polychoclic Aromatic Hydrocarbons (PAHs)

  • Polychoclic Aromatic
  • Hydrocarbons (PAHs)


  • Phthalates
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Data in Action

Biomonitoring data can be used to find environmental chemical exposures and to measure how common these exposures are in groups of people, such as the U.S. population. These data are often the best source of information for scientists, doctors, and health officials to help prevent or reduce exposure to some environmental chemicals. For example, public health workers could use biomonitoring data to find out what chemicals people are exposed to and the levels of the chemicals that are found. If efforts are needed to prevent or reduce exposure, biomonitoring data can show if those efforts work. Also, these data could be used to determine whether exposure levels are different among potentially vulnerable groups such as minorities and children.

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