The Fourth National Report on Human Exposure to Environmental Chemicals is the most comprehensive assessment to date of the exposure of the U.S. population to chemicals in our environment. CDC has measured 212 chemicals in people's blood or urine—75 of which have never before been measured in the U.S. population. What's new in the Fourth Report

The blood and urine samples were collected from participants in CDC's National Health and Nutrition Examination Survey, which is an ongoing survey that samples the U.S. population every two years. Each two year sample consists of about 2,400 persons. The Fourth Report includes findings from national samples for 1999–2000, 2001–2002, and 2003–2004. The data are analyzed separately by age, sex and race/ethnicity groups.

The Updated Tables, July 2010 provides additional data from the 2005-2006 survey period for 51 of the chemicals previously reported through 2004 in the Fourth Report and the new addition of four parabens and two phthalate metabolites in 2005-2006.

National Biomonitoring Program

The Program specializes in biomonitoring, which is the direct measurement of people's exposure to toxic substances in the environment by measuring the substances or their metabolites in human specimens, such as blood or urine. CDC currently measures more than 450 environmental chemicals and nutritional indicators in people.

Learn More

Environmental Health Laboratory

The CDC's Environmental Health Laboratory at the National Center for Environmental Health (NCEH) has been in the forefront of efforts to assess people's exposure to environmental chemicals.

Learn More