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Even the Dust Is Toxic in Homes, Scientists Say

Many hormone-altering compounds contained in household products are found in indoor air. The findings suggest that exposure is common.

September 16, 2003|Marla Cone | Times Staff Writer

In the first comprehensive look at contaminants inside households, scientists have found dozens of toxic chemicals in indoor air and dust, suggesting that exposure to hormone-altering compounds is common in American homes.

The study of 120 homes in Cape Cod, Mass., discovered 67 compounds in dust and air, dominated by chemicals found in plastics, detergents and cosmetics such as nail polish, perfumes and hairsprays. Insecticides and flame retardants used in foam furnishings were also commonplace.

The household sampling is part of a decade-long study of 2,100 women that aims to determine why Cape Cod has a high prevalence of breast cancer unexplained by genetic factors.

Nine chemicals were found in every house tested -- six phthalates, found mostly in cosmetics and hard plastics, and three alkylphenols, including one used in detergents and cleaners.

The sampling, conducted by the Silent Spring Institute of Newton, Mass., and Harvard University's School of Public Health, provides new information that should help the government prioritize which compounds may pose a high risk. However, because the compounds are ubiquitous in household products and are rarely listed as ingredients, there is little that people can do to limit their exposure except to avoid indoor pesticides.

The findings suggest that consumer products are a substantial route of exposure to chemicals that have been shown to alter hormones in laboratory tests. But for most of them, including phthalates and alkylphenols, little is known about what effects they have on human health or at what levels they pose a risk.

Tests on animals and on human cells have demonstrated that some of the compounds, called endocrine disruptors, mimic estrogen or block testosterone, which guide development of reproductive organs and sexual characteristics, while others alter thyroid hormones, which control how the brain of a fetus develops.

"This is a wake-up call," said Linda Birnbaum, chief of experimental toxicology at the U.S. Environmental Protection Agency. "These chemicals are all over, and are these things that we really want all over? That's the question we have to address."

Tom McDonald, a scientist with California's Office of Environmental Health Hazard Assessment, said that "this ambitious study demonstrates that we are exposed daily to a wide array of chemicals that affect our hormone systems" and that it "provides new insights into the sources of exposure."

The results, published over the weekend in the online version of the journal Environmental Science & Technology, are considered valuable because the sampling was done in residential neighborhoods, not in areas with smokestack industries or farms where pollutants might be coming from outdoors.

"People spend most of their time indoors, and chemical concentrations build up indoors -- so much so that they typically exceed outdoor concentrations," said Ruthann Rudel, the study's lead investigator and a senior toxicologist at the Silent Spring Institute. "A lot of [the chemicals found] seem to be inescapable."

The researchers said there was no reason to believe that contaminants in Cape Cod homes would be more prevalent than elsewhere in the country.

"It's very clear that these must be very common exposures," said Julia Brody, executive director of the Silent Spring Institute, which specializes in women's environmental health issues.

The research shows that many chemicals break down slowly inside houses. For example, DDT, which was banned 30 years ago, was found in dust in 65% of the homes, and the DDT levels were higher than the levels of many of the pesticides still in use today.

The most prevalent pesticide found was permethrin, an active ingredient in many household insecticide sprays.

The study did not determine whether people within the households were actually ingesting or inhaling the chemicals from the dust and indoor air, but a previous study by the national Centers for Disease Control and Prevention found many of the same chemicals inside the bodies of Americans.

"We're living in a soup," said Susan Teitelbaum, assistant professor of community and preventive medicine at Mount Sinai School of Medicine in New York City. "We're being exposed to all of these chemicals through food, through contact with products, as well as things that settle in our home environment. This study gives one piece of that whole exposure puzzle."

For 15 of the compounds detected, levels violating government health risk guidelines were found in some homes. Among them was chlorpyrifos, a pesticide banned by the EPA three years ago for residential use. But for 28 of the hormone-altering chemicals found, there are no government guidelines for risk.

Women of child-bearing age and children are considered most at risk because exposure might obstruct the sexual and neurological development of fetuses and young children. Some scientists suspect endocrine disruptors may also raise the risk of hormonal diseases including testicular and breast cancer.

Many chemicals bind to dust that penetrates deep into rugs and cannot be removed by ordinary vacuuming. The dust is particularly worrisome for small children, "who crawl around on the floor and put everything in their mouths," said Birnbaum.

Tests show that male reproductive development is sensitive to the phthalates, which are found in building materials, toys and plastic food containers.

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