The Fourth National Report on Human Exposure to Environmental Chemicals 2009 and the Updated Tables, February 2011, together are the most comprehensive assessment of environmental chemical exposure in the U.S. population. Since 1999, CDC has measured 219 chemicals in people’s blood or urine. The Fourth Report, 2009, includes the findings from national samples for 1999-2000, 2001-2002, and 2003-2004.

The blood and urine samples were collected from participants in CDC’s National Health and Nutrition Examination Survey (NHANES), which obtains and releases health-related data from a nationally representative sample in two-year cycles.

The Updated Tables add more recent and new data to the Fourth Report, 2009. The Updated Tables are cumulative and include data reported in earlier updates. Therefore, the Updated Tables, February 2011 includes data that were reported in the previous Updated Tables, July 2010. The Updated Tables, February 2011 presents data from the 2005-2006 and 2007-2008 NHANES survey periods for 54 of the chemicals previously reported through 2004 in the Fourth Report, 2009, along with nine more recently added chemicals. The data are analyzed separately by age, sex, and racial/ethnic groups.