Chemical's Traces Spur Concern At 7 Mass. Sites
Perchlorate found in water sourcesAug 24, 2004 | Boston Globe
At the Tewksbury Victory Garden where she tends tomatoes, cantaloupe, and cucumbers, Kim Viens points to a frustrating irony. She goes to great lengths to grow her produce without pesticides, but when she cans pickles, she no longer feels comfortable using her tap water.
"I'm concerned enough that I've been buying bottled water for my kids," she said of sons Alex, 8, and Matthew, 7. "Even when they brush their teeth, I'm telling them to use bottled water."
Tests of Tewksbury water this month have found traces of perchlorate, a chemical used in rocket fuel and missiles and more commonly detected near contaminated military bases. No one knows where the chemical came from or why other towns that draw their water from the Merrimack River aren't affected. But Tewksbury is not alone in facing this uncertain threat. This year, after the state Department of Environmental Protection began requiring water suppliers to test for perchlorate, the substance turned up in drinking water in six other Massachusetts locations as well.
Perchlorate has recently emerged as a focus of debate among environmentalists, regulators, and the US Department of Defense. As more sensitive tests begin to detect the chemical in more places, regulators in Massachusetts and elsewhere are trying to decide what levels of perchlorate in the water can be considered safe.
Once known chiefly as a hazard in the areas surrounding military training areas, perchlorate is turning up in groundwater and crops in towns far from the nearest base. Last year, a national organization, the Environmental Working Group, conducted tests of supermarket produce and found perchlorate in lettuce samples grown in California and southern Arizona. This summer, the group found perchlorate in milk bought at California grocery stores. The US Food and Drug Administration is currently testing items like lettuce, spinach, tomatoes, and carrots, as well as milk and bottled water, to determine what levels of perchlorate are seeping into food.
But there is currently no state or federal standard for perchlorate in drinking water, and no agreement among states or among scientists as to what level marks a threat. Perchlorate is known to impair the function of the thyroid gland, in part by interfering with the uptake of iodide, leading to iodine deficiency. Children born to iodine-deficient mothers can have lower IQ, and iodine deficiency in children is linked to impairment to physical development, vision, and hearing. For adults, the EPA has said the chemical may be connected to thyroid tumors.
Massachusetts is trying to develop one of the nation's first limits for perchlorate in drinking water. In addition, the state is developing a cleanup standard for the hazardous waste site at the Massachusetts Military Reservation, which sits atop the aquifer that provides water for hundreds of thousands of Cape Cod residents and where levels as high as 500 parts per billion have been detected in groundwater. Perchlorate was found last year in a private Bourne well near the base, and traces were found in three public wells in 2002.
Based on a review of all the available studies on perchlorate, the state DEP has suggested that children under 12, pregnant women, and people with thyroid problems should not drink water containing more than 1 part per billion of perchlorate roughly the equivalent of a half-teaspoon in an Olympic-sized swimming pool for more than three or four weeks. For healthy adults, the suggested guideline is 18 parts per billion.
Among the Massachusetts sites that tested positive, only in Millbury, where a private water company provides service, has the perchlorate shown up higher than that proposed adult standard. Millbury is now relying on an uncontaminated well and water from neighboring municipalities, said Ed Coletta, DEP spokesman.
In testing this spring and summer, traces were also found in wells at a Boxborough condominium complex, Mount Greylock Regional and Westport high schools, and the towns of Hadley and Westford. All the sites but Tewksbury and Mount Greylock have alternative wells or sources to tap. Tewksbury, a town of about 30,000, was the only community that found perchlorate in surface water rather than groundwater. A test on Aug. 14 found 3.21 parts per billion.
In California, where perchlorate has been found in more than 300 water sources, regulators recently set the health limit at 6 parts per billion. Like Massachusetts, California is now considering setting an official limit on how much perchlorate should be allowed in drinking water.
On the federal level, the US Environmental Protection Agency's 2002 proposed safe limit of 1 part per billion was sent to the National Academy of Sciences for review after the Department of Defense, which faces billions of dollars in cleanup costs at contaminated military bases across the country, fought against it. The Academy is now scrutinizing the scientific basis for the regulators' decision, and is expected to release findings by the end of the year.
The Pentagon has said it will clean up the Massachusetts Military Reservation to the perchlorate standard that Massachusetts adopts, even if it differs from the ultimate federal limit. However, in meetings with the state Department of Environmental Protection, the Pentagon has been urging adoption of a standard no stricter than California's and has maintained that perchlorate could be safe at levels as high as 300 parts per billion, said Carol Rowan-West, director of DEP's office of research and standards.
The DEP put out an extensive report in May contrasting its work with that of California regulators, who based their perchlorate standard on a human study that examined how perchlorate inhibits iodide uptake by the thyroid gland. That study, however, looked only at healthy adults who ingested perchlorate and were monitored for 14 days; Massachusetts analysts disputed the findings, saying the study might not be applicable for children, who are more vulnerable to perchlorate's effects. The DEP also relied on a study of pregnant rats that showed perchlorate could cause developmental problems in their offspring, born and unborn, at lower levels of exposure than the human study indicated. Perchlorate is passed through the womb and also into breast milk.
As the state took steps to establish a standard for environmental cleanups, it also wanted to determine whether there was a need for a statewide drinking-water standard. DEP ordered water suppliers to begin testing water this year to better understand the level of pollution across the Commonwealth, an effort that has yielded the first full picture of the curious reach of the chemical, which is also left behind by fireworks, dynamite, and some types of fertilizer and rocket fuel.
Perchlorate contamination has been identified in at least 20 states, often on or near military bases. Until the past several years, tests couldn't detect levels of perchlorate below 4 parts per billion; now, more sophisticated tests can detect it at concentrations below 1 part per billion.
Puzzlingly, in Tewksbury, perchlorate had not shown up in testing in the spring, and tests after the Aug. 14 finding showed dropping perchlorate levels, leading the town manager, David Cressman, to speculate that something may have been dumped in the river.
"I really wish I could pinpoint it," said Cressman. "But when you look up and down the river and its tributaries, it's difficult to point a finger at any particular operation."
At the community gardens, Viens was not concerned about perchlorate in her produce; the water comes from a well. But she and others voiced suspicions about their home taps.
"I've been drinking enormous amounts of water, so it was really, really scary," said Diana Carlson, who is 35 weeks pregnant with her first child. "My doctor looked into it for me, but also said there wasn't a whole lot of research. Everybody sort of says the same thing: 'Don't worry about it, it should be fine.' "