Chemicals known to cause tumors in animals or disrupt the hormone activity of humans have been found in all of the 120 Cape Cod homes studied by the Silent Spring Institute of Newton and Cape Cod.
In its two-year Household Exposure Study, a review of which was posted on the Journal of Environmental Science and Technology's Web site this weekend, researchers found that 67 of the 89 toxic chemicals they were looking for were present in varying amounts in the Cape women's homes.
The journal is a publication of the American Chemical Society, an association of academic chemists.
Among the chemicals detected were phthalates, which are found in plastics and cosmetics; flame retardants, found in furniture foam; and even DDT, a pesticide banned 30 years ago.
While a large percentage of the 89 chemical compounds were found in the air or dust in the homes, it is too soon to tell whether the levels of many of them pose a health risk, said Julia Brody, executive director of Silent Spring Institute.
Thirty of the chemicals they found have never before been measured indoors, she said.
The finding is one of the most significant in Silent Spring's nine-year investigation into the causes of elevated breast cancer rates on Cape Cod, Brody said.
"This is one of the most important pieces in the entire study," she said. "It is a clear contribution to possibly understanding the connection between breast cancer and the environment."
Breast cancer rates on Cape Cod are about 20 percent higher than the state average. In some towns - such as Dennis, Harwich, Chatham, Orleans and Truro - they are even higher.
Silent Spring Institute was founded in 1994 by the Massachusetts Breast Cancer Coalition and a group of Cape Cod citizens. Its goal is to find preventable causes of breast cancer, the most common cancer in women and the leading cause of cancer deaths among women 35 to 46 years of age.
Close to 250,000 new cases of the disease are diagnosed in the United States each year.
Cheryl Osimo, Silent Spring's Cape Cod coordinator, called the study's discoveries an important step.
"It is not only about Cape Cod. The findings have implications for breast cancer research throughout the country," she said.
Other groups watching
The Breast Cancer Fund, a San Francisco-based research project, was one of the groups watching Silent Spring's household exposure study, said Nancy Evans, health science consultant for the fund. She said the findings have implications for health risks from chemicals in general.
"It is essential for people to know you don't have to be working in a factory or other industrial site in order to be exposed to hazardous chemicals," Evans said. "Those chemicals are pervasive in our environment and when they're found in house dust, that means your family is exposed to them chronically."
While the household exposure study demonstrates that women on the Cape are being exposed through the air and dust in their homes to chemicals found in commonly used household products, it makes no conclusions as to the health risks they pose. But the findings will give researchers more reason to take a closer look to learn whether the lingering presence of these chemical compounds can possibly increase a woman's risk of getting breast cancer, Brody said.
"This is again another step that says not only have we seen laboratory research that says these compounds are important (as known carcinogens and endocrine disrupters), but now we're saying they are present in women's homes."
Silent Spring researchers took the measurements by collecting air, dust and urine samples from 120 women's homes around Cape Cod from 1999 to 2000. About half of the women living in the homes had been diagnosed with breast cancer while living there, Brody said. The rest had not.
They chose the homes from among the 2,100 women interviewed as part of Silent Spring's original Cape breast cancer study, which began in 1994. Funds limited the inclusion of more homes in the exposure study, said Ruthann Rudel, project director and senior scientist at Silent Spring.
Mimicking estrogen
Researchers chose the 89 chemicals in the study because of their toxicity and their ability to mimic estrogen, Rudel said. Chemicals that interfere with the body's natural estrogen activity have been shown to stimulate the growth of breast cancer cells.
Compounds widely used in pesticides, detergents, plastics, furniture and personal care products were detected in the study. Found in the highest concentrations in both dust and air were phthalates and alkylphenols, Brody said. Alkylphenols are found in detergents, plastics and pesticides.
The number of chemicals detected in a given home ranged from 13 to 28 found in the air, and from six to 42 found in dust. The average number of chemicals per home was 19 for air and 26 for dust.
Indoor air concentrations of many of the chemicals were generally similar to levels reported in other studies. But the amounts of certain chemicals were higher, Rudel said. For example, levels of polybrominated diphenyl ethers, which are known endocrine disrupters, were 10 times higher in the Cape homes than were found in two European studies.
There is no comprehensive list of endocrine disrupters, Brody said. Most of the approximately 87,000 chemicals in use today have not been tested to see how they affect hormones. She said that for the Cape study, Silent Spring researchers looked for certain chemicals that are commonly used by consumers or are produced in large quantities.
As far as pesticides, DDT, carbaryl, chlordane and methoxychlor were among the chemicals that tested higher in the Cape homes than in other regions of the country where they have been measured.
Safe levels unknown
Since some of the chemicals they found have never been tested indoors before - and therefore have not been assigned safe levels by the Environmental Protection Agency - it is too early to tell whether the levels would affect human health, Rudel said.
However, one way researchers can evaluate whether the levels are of concern is by looking at the chemicals they found that are already EPA-regulated for their toxicity.
For instance, polycyclic aromatic hydrocarbons, or PAHs, are common air pollutants and carcinogens regulated by the EPA. As controlled compounds, safe levels of exposure have been assigned to them.
PAHs, which are known endocrine disrupters, have been linked to breast cancer in the Long Island Breast Cancer Study, a federally funded study released last year.
On the other hand, safe levels of phthalates, another endocrine disrupter, have not yet been established by the EPA. The levels of phthalates found in Cape Cod homes were generally about 1,000 times higher than the PAHs in the same homes, Rudel said. The alarming difference should be a red flag to researchers about their possible threat to humans, she said.
"Even if the toxicity is 1,000 times less (than PAHs), it's still a potential concern," she said.
Rudel and Brody are now comparing the levels of phthalates and pesticides found in the urine of Cape women with the measurements found in dust and air in their homes, to learn more about the pathways of exposure.
source: http://www.capecodonline.com/cctimes/toxicchemicals15.htm 15sep03
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