Health officials are urging all Connecticut residents with private wells to test their water for contamination after 31 percent of 628 wells in Stamford tested positive for the banned pesticides chlordane and dieldrin.
What was thought three years ago to be an environmental issue related to the polluted Scofieldtown landfill has sparked a statewide effort to examine whether pesticides used for farming and pest control decades ago have leached into private well water.
Testing has proven the contamination is not limited to North Stamford, and health officials say the problem likely exists in other communities across the state.
"We believe that this problem in Stamford could reach much further than Stamford itself and it could exist even beyond Fairfield County," said Sharee Rusnak, epidemiologist for the Connecticut Department of Public Health. "In the past year or so we've been sort of getting the word out to other health departments throughout the state to let them know that this exists and to let residents know they should test their wells."
The response from other municipalities has been tepid so far. The only other community that has reported pesticide contamination in private well water is Wilton, Rusnak said. Stamford, which passed an ordinance creating a city-coordinated well water testing program late last year, has conducted the most extensive testing in the state on pesticide contamination in private drinking water, she said.
"There are no towns that are really actively doing their own sampling as far as I know," Rusnak said.
Since 2009, the Stamford Health Department has collected data from 628 private wells, both through its own testing efforts and from private homeowners who have submitted their results to the city. The city-coordinated well water program tests samples for 25 different pesticides, volatile organic compounds and other contaminants, Health Director Anne Fountain said.
Stamford's testing results have so far only revealed the presence of chlordane and dieldrin. The pesticides, historically used on agricultural crops and for termite control, were banned in the late 1970s and 1980s due to "the adverse environmental and human health effects of these substances, including their probable carcinogenicity," according to the federal Environmental Protection Agency's website.
Of the 628 private wells tested in Stamford, 195 tested positive for some amount of chlordane or dieldrin, according to information provided by Fountain. Of the 195 contaminated wells, 108 -- or 55 percent -- contained pesticides at levels designated as "above action level."
Health officials classify pesticide contamination as either above or below "action level" depending on the concentration of pollutants found in the water sample. Residents with pesticide contamination detected above action level are at a greater risk for adverse health effects over a lifetime exposure, Rusnak said.
The health department has records of 108 Stamford wells that tested above action level for either chlordane or dieldrin. That's 17 percent of the 628 wells tested in Stamford.
"I haven't seen it anywhere else, so to me this is high," Rusnak said. "At least in my experience being here 10 years, I haven't seen any pesticide contamination like this."
The Stamford Health Department maintains a map, available on the city's website, which tracks the locations of known pesticide contamination. Chlordane and dieldrin have been detected in private well water both above and below the Merritt Parkway and in homes near all of the city's borders with neighboring towns.
"There really isn't any rhyme or reason -- we couldn't postulate where it is or where it could be," Fountain said. "As you can see, one house may have it and the one next door may not. This is happening in Stamford and I don't think it stops at the borders."
There are still many wells in Stamford left to test. Fountain believes there are 5,000 private wells in the city, meaning her department only has data on about 13 percent of them. The more information health officials have, the more the public will learn about the scope and magnitude of the contamination, former Health Laboratory Director Bob Murray said.
"The percentage of (contaminated wells) that we're finding below the parkway, North Stamford area, this (downtown) area -- are all about the same," Murray said. "There's still a limited number of samples to make any broad conclusions."
There is no scientifically proven link between the pesticide contamination in Stamford's private well water and cancer. Connecticut's action levels, which are stricter than federal standards but looser than guidelines in other states, were developed with a margin of safety, Rusnak said.
"If there's an exceeding of that action level it doesn't mean that any exposure level will result in adverse effects," Rusnak said. "If you're far enough above that action level you're at an increased risk of getting sick. It's not over a short-term exposure. Your risk goes up if you're exposed to it for a longer time and your risk goes up if you're exposed to higher levels."
Connecticut's action levels are under review, however. Environmental and health officials could potentially raise, or more likely lower, the threshold for acceptable pesticide contamination.
"I believe chlordane and dieldrin are currently under review right now and they are reviewing them with Department of Environmental and Energy Protection over the next year," Rusnak said.
Homeowners with chlordane or dieldrin in their well water are exposed to the pesticides through drinking contaminated water or absorbing the chemicals through their skin during bathing and showering. Rusnak recommended homeowners install whole house filtration systems if their well water tests positive for any amount of pesticides -- above or below action level.
"If you have dieldrin or chlordane contamination, please get a whole house filter," she said. "There's a lot of gray area to this. When you take a sample it's only a shot in time. The levels could go up or they could go down. You don't know, unless you routinely sample the water, what you're drinking."
"This problem is easily resolvable," Lo said. "It's an extra cost and inconvenience and that's it. It's easy to resolve, but it's a potential danger because these are clear carcinogens and they have been associated with different kinds of cancers. I see cancer all of the time and it is just a devastating disease."
Lo, a North Stamford resident, spent two summers with his teenage daughter, Ana Lo, assembling data on cancer rates in Stamford and surrounding communities. The father-daughter team wrote an article about the study, which was published in October's issue of Connecticut Medicine.
The pair's research, which used data from the U.S. Census Report and Connecticut Tumor Registry, revealed North Stamford's overall cancer rate is not statistically different from similar towns in Fairfield County. North Stamford had the second-highest overall cancer rate, with 664 annual cancer incidences reported per 100,000 people in the area from 1998 through 2007. New Canaan had the highest cancer rate at 672 annual incidences, followed by Wilton with 650 and Weston with 620 incidences. Darien had the lowest number of reported cancer cases, with 605 reported each year.
Lo said the results indicated more studies are needed. He and other members of Stamford's Community Advisory Panel, which includes neighborhood activist groups, health and environmental officials, are considering launching a more in-depth study of cancer rates in Stamford.
"That's going to be a very difficult thing to look at and that's a part of the direction that we're heading," Lo said. "One of the things that I have been communicating with the Connecticut DPH about is indeed whether these cancer clusters around the Scofieldtown area are real or not. But it's not going to be a quick answer."
In the meantime, Lo said he is imploring residents and health officials in communities across Connecticut to test their wells and share the results with city and state health officials.
WIDENING THE SCOPE
Health, medical, environmental officials and neighborhood groups all agree pesticide contamination in well water is likely not limited to Stamford. Jay Crutcher, spokesman for the North Stamford Concerned Citizens for the Environment, has advocated for extensive well water testing for years and said he is glad more attention is being paid to the problem.
"The NSCCE has always worried that this is a more geographically widespread problem," Crutcher said in an email. "We're encouraged to see that the issue is now getting more attention and response, regardless of whether that's in North Stamford, Westover, Springdale or Hartford."
Lo said concerns over funding and property values have historically deterred people from testing their well water. But homeowners could be avoiding a serious health concern, he said.
"Stamford's results tell me that this is not a rare event," Lo said. "Seventeen percent of all the wells tested have high levels that require mediation. So it requires installing filters to really clean up the water. This is such a potential hazard. I don't want to scare people. I think what we're going to find is similar types of statistics in other communities."
Lo said the fact that he and his daughter did not find statistically different cancer rates in Stamford compared to surrounding communities begs the question of whether the other towns and cities studied also have pesticide contamination in their well water.
"Then our concern was, is it really valid now to compare surrounding communities, because what if surrounding communities have similar kinds of contamination?" Lo said. "Ethically and morally it would not be the right thing to not pursue this. I'm hoping that surrounding communities will seize on this and just do the testing so we can just learn how extensive this is."
Kate.King@scni.com; 203-964-2263; http://twitter.com/kcarliniking