Physicians who treat patients suffering from the health effects of chemicals in the environment are always looking for the most accurate and reliable means of testing for body burden. Body burden refers to the amount of chemicals present in one's body at a given point in time. In the past, people were only tested for a chemical in the body when there was suspected poisoning; for example, if a child had ingested a paint chip, a blood test for lead would be sent to a toxicology lab to see if the level was elevated. The reference ranges used by toxicology labs are high because they are typically monitoring patients with high amounts of chemicals in the body, such as poisoning or occupational exposure. In the past two decades, doctors and other professionals have become aware of the health effects of daily low-dose chemical exposure in the general population. Determining the body burden of these individuals has lead to several large national studies.
Body Burden Studies
In March 2001, PBS aired a special revealing the results of journalist Bill Moyer's body burden tests. As part of a study of pollutant loads in the human body sponsored by the Mount Sinai School of Medicine in New York, samples of Bill Moyers's blood and urine were analyzed. Eighty-four distinct chemicals were found, many of which are known to be carcinogenic and hormone disruptors.1 In 2005, the Environmental Working Group did a body burden test on infants. It found an average of 200 industrial chemicals and pollutants in umbilical cord blood from 10 babies born in August and September 2004 in US hospitals. Tests revealed a total of 287 chemicals in the group.2 Also in 2005, the Toxic Free Coalition decided to run a body burden study on 10 people living in the state of Washington. They tested the hair, blood, and urine of 10 volunteers who did not have a job exposing them to chemicals. Every person tested had at least 26 and as many as 39 of the toxic chemicals in his or her body. This pollution in people came from everyday activities and products.3 The chemical industry criticized these studies for their small sample size; inconsistent testing methods, since some used blood, some urine, and some hair; the varying reference ranges used by different labs; and the fact that the tests were performed by environmental special interest groups. But then came the results of body burden tests from the Centers for Disease Control and Prevention (CDC).
The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the US. The survey is unique in that it combines interviews and physical examinations. NHANES is a major program of the National Center for Health Statistics (NCHS), which is part of the CDC and has the responsibility for producing vital and health statistics for the nation. The program began in the 1960s as a simple questionnaire; but in 1999, the survey became a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs. The survey examines a nationally representative sample of about 5000 persons each year in the US. Unbeknownst to many, one of the health measurements being gathered was body burden of chemicals.4
The CDC issued the First National Report on Human Exposure to Environmental Chemicals in March 2001. It presented exposure data for 27 chemicals from the 1999 NHANES. The second report, released in January 2003, presented exposure data for 116 environmental chemicals (including the 27 in the first report) for the noninstitutionalized, civilian US population during 1999 and 2000. The third report, released July 2005, lists 148 chemicals measured during 2001–2002, including detection of newer chemicals such as phthalates and lower reference ranges for chemicals. The fourth report was released in 2009 and presents data for 212 chemicals, including 75 previously untested compounds. It includes the findings from nationally representative samples in the US for 1999–2004. The fourth report, for the first time, also includes levels of solvents (30 different compounds) and provides adult values for mercury. In the majority of individuals tested, acrylamides, cotinine, trihalomethanes, bisphenol A, phthalates, chlorinated pesticides, triclosan, organophosphate pesticides, pyrethroids, heavy metals, aromatic hydrocarbons, polybrominated diphenyl ethers, benzophenone from sunscreen, perfluorocarbons from nonstick coatings, and a host of polychlorinated biphenyls and solvents were found.5
The goals of the CDC NHANES fourth report is more than establishing that body burden of chemicals exists. It is clear by now that the entire US population has some level of toxic chemicals in their bodies. The most recent report and updates establishes the prevalence of individuals with chemicals in their bodies whose levels exceed the safe limit. It also establishes reference values that can be used by physicians instead of relying on the reference ranges used by a particular laboratory. Proper reference ranges have been the biggest concern when testing patient body burden.
There have since been several updates to the fourth report, the most recent being August 2014.
This update was released soon after the updated tables for July 2014 because of errors in sampling weights that have recently been discovered by the NCHS in selected data files for NHANES 2011–2012.
Compared with the updated tables for September 2013, the August 2014 tables present data for 35 new chemicals and updates on 16 chemicals. It also has updated tables for 129 chemicals and new tables for 70 chemicals.6
Why did the CDC release updated tables? What is new and different? The updated tables include chemicals that have results available from the NHANES survey periods 2007–2008 or 2011–2012. New chemicals measured for the first time include ethyl mercury, methyl mercury, selenium, and manganese in whole blood. Urinary metabolites of several volatile organic compounds and urine manganese, strontium, and tin were measured in a special sample of adult smokers and nonsmokers. Chemicals with updated data in this release are serum cotinine (from cigarette smoke); urinary NNAL (from cigarette smoke); metals in whole blood; and urinary metabolites of pyrethroids, herbicides, and specific organophosphorus pesticides.7 This gives physicians more accurate reference ranges when testing patients for body burden of chemicals. The new tables also provide blood ranges based on age, ethnicity, and gender. Blood mercury tables differentiate total mercury, inorganic mercury, ethyl, and methyl mercury levels. There are tables for urinary levels of heavy metals as well. Again, these updated tables listed in the full Updates to the fourth report provide excellent references ranges that can be used to interpret testing for body burden. Here is a partial example of the updated table of blood cadmium and blood lead.
Blood Cadmium and Blood Lead: Geometric mean and selected percentiles of blood concentrations (in ug/L) for the US population from the NHANES. (pdf)
The NHANES National Report on Human Exposure to Environmental Chemicals is the largest body burden study on the general US population to date. Four reports have been published so far with the most recent being the fourth report published in 2009. Since the fourth report, there have been several updates to existing tables and new tables added as more and more chemicals are discovered in people in the US. The adverse health effects of these chemicals are clearly documented, and physicians are being asked by patients to test for the presence of these chemicals. The updated tables, some listed here, can provide better reference ranges than the ones used by labs. These guidelines will better detect small amounts of toxicants in the body and help link chemicals to certain health problems.
Dr. Marchese is the author of 8 Weeks to Women's Wellness. She maintains a private practice in Phoenix, Arizona, and teaches gynecology at Southwest College of Naturopathic Medicine. She was named in Phoenix Magazine's Top Doctor Issue as one of the top naturopathic physicians in Phoenix. Dr. Marchese is currently vice president of the Council on Naturopathic Medical Education and was recently appointed by Arizona Governor Jan Brewer to the State of Arizona Naturopathic Physicians Medical Board.
1. Trade Secrets [Web page]. PBS. http://www.pbs.org/tradesecrets/program/program.html. Accessed Sept. 2014.
2. Body burden: the pollution in newborns [online article]. Environmental Working Group. July 14, 2005. http://www.ewg.org/research/body-burden-pollution-newborns. Accessed Sept. 2014.
3. Pollution in People [website]. PlPou http://www.pollutioninpeople.org. Accessed Sept. 2014.
4. National Report on Human Exposure to Environmental Chemicals [website]. CDC. http://www.cdc.gov/exposurereport. Accessed Sept. 2014.
5. Crinnion WJ. The CDC fourth national report on human exposure to environmental chemicals: what it tells us about our toxic burden and how it assist environmental medicine physicians. Altern Med Rev. 2010 Jul;15(2):101–119.
6. National Report on Human Exposure to Environmental Chemicals. Op cit.