Blood samples and floor sweepings provide the data for new studies showing that the human body harbors chemicals found in weed killer, rocket fuel, plastic food containers, and fire retardants.
But the hundreds of people who open their homes and bodies to such intense scrutiny have rarely received their personal results from these studies, a trend that's changing as more participants want to know what's inside their bodies and how it might affect their health.
As a result, experts said at the 2011 AAAS Annual Meeting, researchers are searching for ways to report these results that are personally useful but also honest about the uncertainties of chemical exposure.
"People want this information," said Rachel Morello-Frosch, an environmental science researcher at the University of California, Berkeley. " It makes them think about their chemical exposure over the life course."
"We ask a lot of these participants," said Gwen Collman, who studies the relationship of environmental pollution and health at the National Institutes of Health. They give up blood, urine, and breast milk samples and submit to strangers scouring their floors and windowsills, and, says Collman, "we should try to reciprocate."
Sharyle Patton agreed to be tested for one small study, and found that she had traces of 109 potentially harmful chemicals in her body, including PCBs and dioxins. Patton, director of the health and environment program at Commonweal Research Institute, said her first reaction to the results was "absolute outrage."
She had lived for a long time in a small town in the Colorado Rockies, eating beef and vegetables that her family had raised themselves. But her test results made her consider the more mysterious and convoluted history of other foods, she said, like whether her favorite cheese came from California cows that were fed alfalfa grown with irrigated water drawn from a Colorado River source polluted by rocket fuel.
"You get a sense," she said, "that the web of life is also a web of contamination."
Scientists are glad to know that their studies are making people think more carefully about their chemical environment, said Julia Brody, an environmental health researcher and director of the Silent Spring Institute, a nonprofit organization that studies links between pollution and breast cancer. "But we're also faced with the dilemma that we don't always know how to report results in terms of what they mean for human health."
There are no consistent guidelines yet on how researchers should report chemical results to individuals, Collman said.
But it's a practice that's becoming more common and even required in peer-reviewed studies, she said, to the point where "we're grading the grants in a way that encourages more reporting back."
In their study of 75 mothers and their newborn children in California's Bay Area, Morello-Frosch and her colleagues are asking their study participants to help them design better ways of sharing personal results.
The scientists have used the feedback to change many details of the reports: There are now more graphs and pictures, less text on a page, and less scientific jargon. In one report, the word "benchmark" was quickly replaced with "level of health concern," Morello-Frosch said, after it became clear that "benchmark" was meaningless to most of the participants.
The participants liked seeing how their exposures compared to others in the study and individuals around the country, Morello-Frosch noted, even though they soon learned that safe exposure levels are unknown for most chemicals. "They understand that scientific uncertainty and appreciate our honesty about it."
Brody said individual exposure reports can help participants trust researchers, and she said people in these studies often have a "sense of pride in contributing to science."
In some cases, the results may have a wider community influence, she noted. Richmond , California, participants in a toxin study conducted by the Silent Spring Institute brought their test results to public hearings about expanding the area's Chevron Richmond oil refinery. The refinery's expansion was blocked by a court order that is now being appealed by Chevron.
Scientists are also concerned that personal chemical exposure reports might have legal implications for the participants and the researchers. But Harvard Law School lecturer Shaun Goho said legal concerns "are much smaller than we feared they would be."
Goho, who is also staff attorney at the school's Emmett Environmental Law and Policy Clinic, said households are mostly ignored under broad environmental regulations created by the U.S. Food and Drug Administration or the U.S. Environmental Protection Agency, for example. But real estate law in some states, he said, could compel home sellers to disclose household tests on some chemicals.