Water Research
To protect Cape Cod’s coastal marine sanctuary, wastewater is disposed on land, primarily in septic systems that allow pollutants to seep through porous soils, often reaching shallow drinking water wells. Silent Spring Institute is undertaking a number of initiatives aimed at understanding the role that such polluted water may play in the disproportionately high levels of breast cancer on Cape Cod.
Estrogens and Other Hormonally Active Pollutants in Groundwater and Drinking Water
Drinking water for Cape Cod residents comes from a sole-source aquifer. Because the Cape has a shallow water table and sandy, porous soil, the aquifer is particularly vulnerable to land use activity. Silent Spring Institute’s study Tracking Estrogens and Other Hormonally Active Pollutants in Cape Cod Groundwater and Drinking Water focuses on measuring degradation to groundwater quality from wastewater leaching from septic systems and into the aquifer. This research is critical because 85 percent of Cape residences use septic systems. This research has provided some of the first data to quantify the levels of hormonally active compounds introduced into groundwater from septic systems and how these compounds behave as they travel through groundwater systems.
Wastewater from Septic Systems
Clean water is fundamental to life. Yet many septic systems do not rid sewage of pollutants that may be harmful to human health before discharging the sewage to groundwater—and in some cases before it contaminates drinking water wells.
Silent Spring Institute scientists made this discovery after monitoring—for the first time ever—water for hormone-disrupting chemicals such as natural estrogen and alkylphenols, as well as certain pharmaceuticals, as the water passed from the septic system into the ground. The study looked at a typical septic system on Cape Cod, where septic systems serve more than 85 percent of residential and commercial properties. Two other chemicals the researchers detected indicated the presence of sewage fallout: optical brighteners, which are found in laundry detergents, and caffeine.
The presence of hormone-disrupting chemicals in the environment has been associated with the feminization of male fish and reduced fertility in other wildlife. The scientists note that additional research is needed to determine whether the concentrations typically observed in the environment produce similar adverse effects on the human hormone system. Exposures during critical prenatal and childhood stages of reproductive development may be most critical.
Effects on hormonally responsive cancers are an additional concern. Chemicals that mimic natural estrogen, for example, may contribute to a woman’s cumulative lifetime exposure to estrogen, a factor that has been linked to an increased risk of developing breast cancer.
One in every four citizens of the United States relies on septic systems for wastewater treatment. At least a portion of the residents in a number of states—including Delaware, Florida, Maryland, Massachusetts, New Jersey, and New York—also rely on private, shallow groundwater wells for their drinking water. With housing density increasing and lot size shrinking to accommodate population growth, the likelihood is growing that wastewater from a household’s or neighboring household’s septic system will contaminate a drinking water well.
“While septic systems may be effective at preventing bacterial contamination of these water supplies,” says Chris Swartz, lead researcher for the study, “our results suggest that these systems do not remove hormone-disrupting chemicals from septic wastewater before they infiltrate into groundwater.”
And since groundwater feeds many drinking water supplies, Swartz adds, further research is needed to determine the extent and potential effects of drinking water contamination. Previous research on hormone disruptors focused on surface waters receiving discharge from wastewater treatment plants. This study was the first to directly link the infiltration of these hormone disruptors into groundwater—and therefore residential well water—from onsite treatment systems.
“Our findings should encourage communities to consider more restrictive land use policies to protect their public and private drinking water supply wells,” Swartz says. “Communities may also consider replacing onsite septic wastewater treatment systems with improved onsite technologies or centralized wastewater treatment plants, at least in densely populated areas that rely on shallow groundwater as a drinking water source.”
The study appeared in the August 15, 2006, issue of Environmental Science & Technology.
Ponds
In 2006, the researchers discovered that natural and synthetic hormones, as well as many pharmaceuticals, were in test wells down-gradient from a septic system plume on the Cape. The researchers then wanted to know if the chemicals travel into the groundwater to spring-fed ponds.
Silent Spring Institute researchers conducted a study of six Cape Cod ponds to determine whether hormone-disrupting and cancer-inducing chemicals have found their way from septic systems into the water. Ponds studied included three that were located in higher residential density areas (Lewis [Barnstable], Oyster [Falmouth], and Schoolhouse [Brewster]) and three located in lower residential density areas (Joshua [Barnstable], Flax [Dennis], and Flax [Brewster]).
The study found that Cape Cod ponds located near residential septic systems are contaminated by pollutants including human hormones and pharmaceuticals. Levels of estrogenic hormones approached those found to induce physiological changes in male fish. this is the first study to document the presence of pharmaceuticals and hormone disruptors in ponds fed by wastewater contaminated
aquifers.