Groton - The chemical soup of modern life is leaving its stain on the waters of the Thames River.
Over the past three years, Penny Vlahos, assistant professor of marine sciences, has been overseeing student researchers at the University of Connecticut's Avery Point campus in testing the Thames for traces of some of the most widely used man-made compounds, six kinds of pesticides and the polybrominated diphenal ethers, or PBDEs, that are used as flame retardants.
The pesticides are commonly used in many types of agriculture as well as on lawns and home landscaping. The flame retardants, explained Vlahos, are sprayed or imbedded onto everything from computers and electrical equipment to children's clothing. But like the pesticides, they don't stay put.
"They readily diffuse back into the environment," she said.
The PBDEs are just one example of industrial chemicals that are leaching into the air, water and soil, with little or no monitoring, Vlahos said. Some PBDEs are banned in Europe, she noted, and the Environmental Protection Agency is considering placing PBDEs on its list of "priority chemicals" that should be monitored. But the EPA hasn't yet taken that action.
"There are so many compounds we use every day that are not being measured," Vlahos said.
And unlike many older compounds, no "acceptable" level of PBDEs have been set by U.S. governmental regulators, she noted. But lab tests of these chemicals have shown that high levels can cause cancer and disrupt normal development of animals and humans, particularly the very young, so, Vlahos and her students have concluded, ignoring their rapid accumulation in the environment isn't wise.
"We've got to be very careful about the concentrations we expose ourselves to," she said.
To begin documenting the widespread distribution of PBDEs and pesticides, Vlahos and her students developed a sampling device that could be submerged into the Thames to test for these chemicals. Testing was conducted at three sites - offshore from Pfizer's Groton facilities, from Electric Boat and from Dow Chemical in Ledyard.
"It's a relatively small waterway, and it's not in a highly populated area, but it's got a lot of stresses on it," Vlahos said of the Thames.
The sampler consists of a metal frame with plates that passively collect residues of these compounds from the sea water. After the sampler has been submerged for a specific time, the plates are removed and analyzed for traces of several different PBDEs and the pesticides.
Results have found that flame retardants and pesticides are indeed ending up in the Thames River, some at levels as high as those found in San Francisco Bay, a highly industrialized waterway. They are likely to be settling in the bottom muds where they will be taken up by the small creatures that are at the bottom of the marine food chain and bottom feeders like flounder.
Levels were highest at the stations nearest EB and Dow, Vlahos said, but that doesn't mean those industries are the source. Much more research is required, she said, both into what happens to these chemicals after they're used for their intended purpose and their long-term effects. The most prevelant pesticides found were atrazine and metribuzin, both herbicides used on vegetable and field crops, and endosulfan, an insecticide.
"We're trying to come up with a real explanation of how this stuff is moving in the environment," Vlahos said.
One likely pathway for at least some of the PBDEs in the Thames is the air. PBDEs and the pesticides are known to dissipate into the atmosphere, but will eventually settle on the Earth and its waterways.
The Thames also has several characteristics that make it susceptible to accumulations of PBDEs and pesticides, noted Tiffany St. George in her 2008 master's degree thesis. It fits the description of the "highly industrialized" waterway that other research has determined is "most susceptible" to chemical contamination through "atmospheric deposition, watershed runoff and discharge of wastewater from industry and sewage treatment plants," she wrote.
Six treatment plants discharge into the Thames between Norwich and its mouth between Groton and New London, and wastewater empties in from EB, Dow, Pfizer, the Naval Submarine Base, the AES Thames and NRG plants and other sources.
In addition, low dissolved oxygen levels occur each summer from Norwich harbor to Ledyard, a result, experts believe, of pollution problems in the feeder rivers and streams north of Norwich in the sprawling Thames River watershed. These rivers and streams are also carrying in significant amounts of sediments into the Thames that serve as "one of the major sinks" to collect PBDEs and pesticides, St. George wrote.
And while these exposures alone may not be harmful to animals or humans, she added, there is reason to believe that in combination with other chemical exposures, it could cause reproductive, hormonal or other health problems.
In essence, much more research is needed.
The problem, Vlahos said, is that these compounds and many others were created and manufactured in large quantities without forethought or research about what would happen after they were released. Some, she said, "look like compounds our body uses," so our systems readily absorb them.
"What effects are these compounds having?" she asked. "We have to be smart about what we allow in the environment."