Are U.S. Homes a HAVEN for TOXINS?
ART EXPLOSION
K E L LY N B E T TS
The most comprehensive analysis to date shows that people are exposed to a wide variety of potentially toxic compounds in their homes.
© 2003 American Chemical Society
omes in the U.S. are likely to contain dozens of chemicals and pesticides that have been identified as endocrine-disrupting compounds, according to research published in the October 15 issue of ES&T. By showing that many people may be continually exposed to dangerous levels of many toxic substances, including chlorinated pesticides like DDT that have been banned for decades, the researchers hope to inspire more research into the effects of exposure to these chemicals. The vast amount of data amassed through the four-year project also contains a few surprises and highlights concerns about the U.S. EPA’s reliance on industry for exposure data.
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alkylphenols in air was a bit of a surprise. The study, together with other data, shows that U.S. families may have “very widespread exposures” to chemicals that could affect the health of everyone from infants to senior citizens, warns Mary Wolff, of Mount Sinai School of Medicine in New York City. Currently, EPA has no regulatory authority over indoor air or endocrine-disrupting chemicals. The study was led by Ruthann Rudel of the Silent Spring Institute, a nonprofit organization based in Newton, Mass., as part of its ongoing Cape Cod Breast Cancer and Environment Study. The group measured concentrations of 89 suspected endocrine disrupters in air and dust samples taken from 120 homes on Massachusetts’ Cape Cod peninsula, where the state’s Bureau of Environmental Health Assessment has documented elevated incidences of breast, colorectal, lung, and prostate cancers. The Silent Spring study contains the first reports of residential concentrations for 30 of the compounds, including what Rudel believes to be the first report of the levels of the polybrominated diphenyl ether (PBDE) flame retardants in U.S. household dust. It shows that the levels of PBDEs in household dust are 10 times higher than the levels in Europe—where some of the PBDE compounds are being banned— and higher than the levels of PCBs in dust in U.S. homes. “We know that levels of PCBs are going down, and the PBDE flame retardants are still being made and their levels of usage are increasing,” Rudel says. PBDEs are used in upholstery foam, electrical appliances, televisions, and computers. Linda Birnbaum, director of the Experimental Toxicology Division of EPA’s National Health and Environmental Effects Research Laboratory, agrees that this finding is important. Three new animal studies show that BDE-99—the PBDE congener found in most abundance in household dust, according to the study—can have neurotoxic effects and that embryonic exposures can impair sexual development in addition to causing thyroid toxicity, Birnbaum says. In addition, the researchers found bis(2-ethylhexyl)phthalate (DEHP), which is “reasonably anticipated to be a human carcinogen,” according to the National Institutes of Health, in the dust of every home tested, at concentrations ranging from 16.7 to 7700 micrograms per gram (µg/g). DEHP is used in a range of flexible poly(vinyl chloride) products, including children’s toys, shower curtains, raincoats, shoes, and floor tiles. The concentrations of DEHP in the dust of most of the tested homes exceeded EPA’s risk-based safety guidelines of 35 µg/g for residential soil, which are based on the compound’s carcinogenicity. Rudel acknowledges that not all scientists agree that DEHP causes cancer in humans, but she points out that the 408 A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / NOVEMBER 1, 2003
levels in some households exceeded EPA’s guidelines of 1240 µg/g to protect against reproductive toxicity.
4-Nonylphenol in air The Silent Spring study also contains the first reports of residential concentrations for 4-nonylphenol, an alkylphenol that can act like female estrogen hormones, and its ethyoxylates. Nonylphenol or nonylphenol ethoxylates are found in some laundry detergents, disinfecting cleaners, all-purpose cleaners, spot removers, hair-coloring and other hair-care products, and spermicides. The researchers found 4nonylphenol to be one of the most abundant chemicals in the air of the sampled homes. It was discovered in every tested home at concentrations ranging from 21 to 420 nanograms per cubic meter of air (ng/m3). The European Union (EU) Parliament has approved a directive that would restrict the use of 4nonylphenol, but no EPA safety guidelines have been set for human exposure for it or any other chemicals based on their endocrine activity. TANYA SWANN
Finding the
With the aid of researcher Jennifer Kachajian, the Silent Spring Institute collected samples of air and dust from inside 120 homes on Cape Cod, Mass.
“Finding the alkylphenols in air was a bit of a surprise because EPA and some documents from the manufacturers had suggested that you wouldn’t expect it to volatilize at all,” Rudel says. She adds that this is just one example raised by the study showing that reliance on using manufacturers’ claims by EPA and the U.S. Food and Drug Administration (FDA) can be problematic. Wolff points out that “air pollutants don’t have to be volatile” because they can be adsorbed onto particles. People have a limited exposure to nonylphenols through the use of products, and the daily intake is
thought to be very low, according to the Alkylphenols and Ethoxylates Research Council, an industry group. Rudel says that the findings show that the compound’s potential for inhalation toxicity merits further investigation. The researchers also documented the presence of some long-banned substances in the tested samples, including PCBs and the pesticides dieldrin, chlordane, and DDT, at levels that exceed federal risk-based safety guidelines.
DDT not breaking down 4-4´ DDT was one of the most abundant pesticides in the tested household dust. The scientists detected it in 65% of the homes at concentrations of up to 9.61 µg/g. Although they also detected some of DDT’s breakdown products, most of the chemical was in the form of DDT. “Since [DDT] really hasn’t been used in 30 years, it means it’s really not breaking down indoors,” Rudel says. The results could help explain why the Centers for Disease Control (CDC) has reported that DDT’s breakdown product, DDE, is present in the bodies of youth aged 12–19 who were born after the United States banned the pesticide. Another chemical measured for the first time in the study is 2,3-dibromo-1-propanol, a mutagenic and carcinogenic chemical that was found as an impurity in the TRIS flame retardant, which was banned in the late 1970s. Rudel is currently trying to solve the mystery of why the research team detected the chemical in the air of 9% and in the dust of 6% of the tested homes. Other banned pesticides frequently detected in the homes included heptachlor (found in the air of 44% of the tested homes), pentachlorophenol (detected in the dust of 86% and the air of 58% of the homes), methoxychlor (in the dust of 54% of the homes), -chlordane (detected in 51% of the tested air in the homes), -chlordane (found in the air of 53% of the tested homes), and chlorpyrifos (found in the air of 38% and the dust of 18% of the homes). All of these banned pesticides were detected in some of the homes at levels that exceed EPA’s risk-based safety guidelines (see Table 1). The Silent Spring team’s finding of high levels of the recently banned chlorpyrifos in some homes could also provide explanatory fodder for why CDC found that levels of this pesticide are higher in children aged 6–11 than in the rest of the population.
Few toxicity guidelines Although the presence of these compounds in the tested homes should set off alarm bells, Rudel stresses that the risk presented by exposure to the compounds could be much higher. EPA has developed toxicity guidelines for only 39 of the tested compounds, and the agency does not yet consider the impacts of exposure to mixtures of chemicals, she says. The agency does not regulate indoor air. On average, the dust in the tested homes contained 26 different compounds and the air contained 19 different compounds. In a high proportion of the homes, the concentrations of at least one of the compounds
TA B L E 1
Compounds exceeding U.S. EPA guidelines The Silent Spring researchers compared the levels of contaminants they found in air and dust to some of the only risk-based guidelines available in the United States: preliminary remedial goals set by U.S. EPA’s Region 9. This table includes only chemicals that exceeded at least one guideline.
Chemical
Amount EPA Amount EPA found in risk-based found risk-based indoor air guideline for in dust guideline for (range, ambient air (range, residential ng/m3) (ng/m3) µg/g) soil (µg/g)
Benzo[a]anthracene ND Benzo[a]pyrene ND Chlordane
