About This Study
About This Study section of the Pollution in People report
In 2005, the Toxic-Free Legacy Coalition and the Washington Toxics Coalition invited ten Washingtonians on an unusual journey: to submit their hair, blood, and urine for toxic chemicals testing. We and our participants sought to uncover the chemical secrets in their bodies—to find out whether the computers, cars, and cosmetics they use could in fact be the source of hidden dangers. We submitted their samples to accredited laboratories to test for heavy metals; pesticides; toxic flame retardants; the plasticizers known as phthalates; the “Teflon chemicals” (perfluorinated compounds); and the banned but persistent DDT and PCBs.
Rev. Dr. Ann Holmes Redding, Episcopal priest, St. Mark’s Cathedral
Dr. Patricia Dawson, breast cancer surgeon, Swedish Providence Medical Center
Pam Tazioli, breast cancer survivor and Washington State Coordinator, Breast Cancer Fund
Denis Hayes, Earth Day founder and president, Bullitt Foundation
Senator Lisa Brown, Washington State Senate Majority Leader
Senator Bill Finkbeiner, Washington State Senate
Laurie Valeriano, toxics policy expert, Washington Toxics Coalition
Deb Abrahamson, member, Spokane Tribe and director, Society for Sovereignty, Health, Air, Water, and Land
Allyson Schrier, children’s book author
Karen Bowman, registered nurse; consultant, Washington State Nurses Association; and faculty member, University of Washington Nursing Department
We submitted blood, urine, and hair samples to three laboratories that specialize in highly sensitive chemical analysis. For some chemicals, the laboratories analyzed the samples for the parent compound; for others, such as phthalates and some pesticides, the analysis was for metabolites, or breakdown products. The laboratories reported the results to us in varying units of measurement. For ease of understanding, we have converted the results in most cases to parts per billion (ppb).
We used several methods to determine the implications of the chemical levels found in our participants. Statistician Abbe Rubin analyzed the resulting data. For chemicals that were detected in most or all participants’ samples, medians were calculated.i Where possible, we compared levels in our participants with values for the U.S. population at large obtained by the Centers for Disease Control and Prevention (CDC). For chemicals not studied by the CDC, we used values from independent scientific studies for comparison purposes.
In addition to determining whether levels in our participants were above or below national averages, we examined studies on the chemicals’ toxicity to assess health hazards posed by the levels we found. In some cases, such as with lead, scientists have extensively researched and documented the chemicals’ health effects in humans. As a result, we were able to compare levels found in our study directly to levels known to have caused harm in people. In other cases, such as with toxic flame retardants, most available health effects information comes from laboratory animal experiments, not human studies. In these cases, we used animal testing levels to assess potential impacts in people.
Animals and people can vary significantly in their response to toxic chemicals, and either group can be much more sensitive than the other, depending on the chemical. People can also differ from each other in their ability to detoxify harmful chemicals in the body. For these reasons, regulatory agencies typically apply a safety factor when using data from laboratory animals to set regulatory limits. For example, EPA typically applies a safety factor of ten to account for differences between animals and humans, and an additional factor of ten for differences among people. The agency may also apply a safety factor of up to ten to account for other uncertainties.
For both people and other animals, the most sensitive time of life is generally during development: before birth and in early childhood. In this study, we compared our participants’ results to the lowest levels in human or animal studies where health effects have been seen. In some cases, such levels are those that result in harm to the offspring when the mother is exposed during pregnancy. None of our participants was pregnant at the time of sampling. To protect public health, however, it is necessary to maintain levels in all individuals that are below levels that would harm a developing child. Therefore, we use the levels we detected in our ten participants as a barometer of the degree of danger faced by the rest of the residents of Washington.
Report reviewers included David Cosman, Ph.D., Nancy Dickeman, Philip Dickey, Ph.D., Steve Gilbert, Ph.D., Kim Hooper, Ph.D., Kristin Hyde, Jen Lamson, Sharyle Patton, Ivy Sager-Rosenthal, Abbe Rubin, Ph.D., Dr. Ted Schettler, Margaret Shield, Ivy Sager-Rosenthal, Kristin Schafer, Gregg Small, Pam Tazioli, Heather Trim, and Laurie Valeriano. Elena Conis edited the manuscript.
i In order to be consistent with methods used by the CDC, to calculate medians, values for samples in which the chemical was not detected were set at the detection limit divided by the square root of two.