Household Exposures

For more than a decade, Silent Spring Institute research has found that exposure to harmful chemicals hits too close to home. Since 2000, the Institute’s Household Exposure Study has sought to provide the science-based evidence needed to inform our national conversation on environmental health, and to support precautionary measures to reduce exposures, leading to safer products and widespread health and environmental benefits.

In the program’s initial, groundbreaking study, Silent Spring researchers took indoor air and dust samples from 120 homes on Cape Cod and measured the concentrations of 89 chemicals identified as endocrine disrupting compounds, which mimic or interfere with human hormones, sometimes affecting cell growth and development. The investigators’ selection was based on the chemicals’ wide use in pesticides, detergents, plastics, furniture, and cosmetics.

The researchers detected a total of 67 endocrine disruptors in the air and dust, providing the first reported measurements in indoor environments for more than 30 of the compounds. The number of chemicals detected in the homes averaged 19 for air and 26 for dust.

The researchers found phthalates—which have known effects on sperm quality and the development of baby boys—in all of the homes, while parabens—an estrogenic class of chemicals that have been found in urine samples of almost all people tested—were found in 90 percent of the homes. The researchers also demonstrated, for the first time, that alkylphenols, which are found in detergent and plastics, are abundant in indoor air.

In addition, the study provided the first report of the levels in U.S. household dust of the polybrominated diphenyl ether (PBDE) flame retardants, found in carpets, draperies, electrical appliances, televisions, and computers. In the Cape Cod homes the researchers found PBDE levels to be ten times higher than in European homes, where these chemicals are being phased out because of their suspected toxic effects.

The U.S. Environmental Protection Agency has issued health-based exposure guidelines for only about half of the compounds in the study. For fifteen of those compounds—including ones that are currently banned—the researchers measured levels that exceeded the guidelines.

“Many of the chemicals we detected were banned many years ago, suggesting that they do not break down indoors,” said Ruthann Rudel, now director of research at Silent Spring Institute. “We found DDT in dust in 65 percent of the homes even though it was banned 30 years ago. The fact that so many banned chemicals were still in homes suggests that we need to do more substantial testing before products are put on the market.”

No comprehensive list of endocrine disrupting chemicals exists because most of the nearly 100,000 chemicals in use have not been tested to determine whether they affect hormone systems. “Not enough is known about the potential health risks from exposure to these chemicals,” Rudel said. “Part of the problem is that we tend to study chemicals that are regulated—and we regulate chemicals that are studied. So we end up looking at only a small fraction of the chemicals we should be examining. One of our goals with this study has been to try to expand the universe of chemicals that receive regulatory attention.”

The Household Exposure Study has continued to lay the groundwork for a systematic approach to tracking, evaluating, and reducing everyday exposures to suspect chemicals in homes. In 2006, the program expanded to Northern California.