The Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables, February 2012 provides new data since the release of the Fourth Report, 2009. These data include updated tables for 66 chemicals in the Fourth Report, 2009 and tables for 34 new chemicals. Review this publication for the most recent and complete biomonitoring data.

The Updated Tables, February 2012, present data from the 2005-2006 and 2007-2008 survey periods and data for a few chemicals from the 2003-2004 survey period. The Updated Tables are cumulative and include data reported in earlier updates.

The Fourth National Report on Human Exposure to Environmental Chemicals, 2009, (the Fourth Report, 2009) presents data for 212 chemicals. The Fourth Report includes the findings from nationally representative samples for 1999-2004.

The blood and urine samples reported in both publications 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.