At a recent meeting in Eastham, MA, Silent Spring Institute researchers presented the results of their study, “Emerging Contaminants in Cape Cod Private Drinking Water Wells.”
In February 2011, Silent Spring Institute tested twenty private drinking water wells in seven towns on Cape Cod for emerging contaminants to learn more about the effect of septic systems and other sources of groundwater pollution on water quality on the Cape. Emerging contaminants include chemicals such as pharmaceuticals and consumer product chemicals that may have health effects but are not currently regulated or routinely studied in drinking water. This study follows Silent Spring Institute’s 2010 study of twenty public wells on Cape Cod, in which three quarters of wells tested contained low levels of consumer product chemicals and pharmaceuticals.
A majority (85%) of samples contained emerging contaminants at parts per trillion levels. As in the public well study, the results show that chemicals in household and commercial wastewater can seep from septic systems into groundwater and make their way into drinking water. In general, results were similar in public and in private wells. Many of the same chemicals were detected in both studies, and maximum concentrations of these chemicals were generally similar. In both private and public Cape Cod drinking water wells, researchers found some compounds present at levels as high or higher than reported elsewhere in the U.S.
Researchers report that the study results demonstrate widespread impact of wastewater, primarily from septic systems, on Cape groundwater and drinking water. While there are no enforceable drinking water standards for emerging contaminants, health-based guideline values have been developed for four of the detected chemicals; levels in all samples were below guideline values. However, guideline values are not available for most of the chemicals detected, and health effects of exposure to low levels of these types of chemicals, especially in complex mixtures, are not yet known.
In the previous study, tests of twenty wells and two distributions systems supplying drinking water on Cape Cod found that 75 percent of the wells and both distribution systems had detectable levels of emerging contaminants such as pharmaceuticals and consumer product chemicals, primarily coming from septic systems. Nine water districts on Cape Cod voluntarily participated in the study. The study provides some of the first information in the U.S. about impacts of septic systems on groundwater used for drinking water.
Septic systems are the most likely source for most of the eighteen chemicals detected, which include nine pharmaceuticals, an insect repellent, halogenated organophosphate flame retardants, and perfluorinated chemicals. The two most frequently detected chemicals were sulfamethoxazole, an antibiotic commonly used to treat urinary tract infections and pneumonia, and PFOS, used in stain-resistant and nonstick coatings, as well as fire-fighting foams. Levels of these compounds were among the highest reported in US drinking water, except in a few cases of industrial contamination. The widespread presence of antibiotics has raised the possibility of promoting development of antibiotic-resistant pathogens. PFOS and the related compound PFOA, which was also detected in this study, are hormone disrupting compounds that have been associated at higher exposure levels with effects on the thyroid, mammary gland, cholesterol metabolism, immune system, cancer, and growth and development.
While septic systems are likely the main source of the contaminants, some detected chemicals may have commercial sources. Two perfluorinated chemicals, PFOS and PFOA, used in fire-fighting foams and aviation hydraulic fluids were found at relatively high levels in Hyannis Water System wells downgradient of the Barnstable Municipal Airport. Additional testing would be required to pinpoint the sources.
A different study published recently by scientists at Boston University reported elevated breast cancer risk for women in the 1980s and early 1990s in Hyannis compared with other Upper Cape areas and associates this increase with contaminants in the Hyannis Water System supply.
To access the complete 2011 report, please visit:
To access the complete 2010 report, please visit:
Silent Spring Institute: Emerging Contaminants in Cape Cod Drinking Water (May 2010)
Media report:
Cape Cod Times: Chemicals found in Cape wells (3 NOV 11)
Background information:
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