The company that has accepted responsibility for cleaning the contaminated drinking water of thousands of residents in Southern New Hampshire allegedly withheld critical information from state regulators about the amount of toxic chemicals its Merrimack plant released, according to state lawmakers and environmental scientists.
Their allegations are based on a raft of court documents from several class-action lawsuits against Saint-Gobain that suggest executives were aware that their plant used substantially more toxic compounds known as “forever chemicals” than they had previously acknowledged. Company officials dispute the allegations.
In a letter to the state’s attorney general, the lawmakers and scientists said Saint-Gobain’s omissions “may have misled” regulators and led the multinational manufacturing company to “substantially underestimate” its pollution.
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If the company used greater amounts of the per- and polyfluoroalkyl chemicals, known as PFAS, they alleged, then significantly more residents are likely to have had their wells polluted in what was already considered the largest source of ground-water contamination in the history of New Hampshire.
PFAS chemicals have been used for years in a range of products to repel water and resist stains, but minute amounts have been linked to cancer, low infant birth weights, and a range of diseases. The compounds are called forever chemicals because they never fully break down in the environment.
In 2018, Saint-Gobain executives acknowledged their responsibility for addressing the pollution in a settlement agreement with the state for most of a 65-square-mile area around their plant in Merrimack.
Since then, however, state officials have found hundreds of wells beyond the boundary with PFAS levels that exceed state limits. They blame that pollution on Saint-Gobain, which makes everything from radar domes to insulation for industrial hoses at its Merrimack plant.
The pollution comes from years of the plant, Saint-Gobain Performance Plastics, spewing a range of toxic chemicals from its stacks.
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The lawmakers and scientists urged regulators to expand the area in which the company is responsible for covering the costs of testing and providing clean drinking water.

“Saint-Gobain continues to play hide the ball from the state,” said Mindi Messmer, a former state representative and environmental scientist, who wrote the letter. “Their obfuscation has misled N.H. regulators and … allowed them to drag out and deny accepting full responsibility for the harm their pollution has caused.”
Company officials said they have been transparent with the state.
“Saint-Gobain vehemently denies any allegation … that it withheld data or misled the New Hampshire Department of Environmental Services,” Peter Clark, a spokesman for Saint-Gobain, said in a statement.
The company should not be held responsible for wells outside the 65-mile area around the plant, or hundreds of wells inside it that may have been contaminated in other ways, he said. Saint-Gobain already has identified more than 3,800 wells in the area that are likely to have been contaminated; about a quarter of those have been found to exceed New Hampshire regulatory limits for drinking water.
“Over the past four years, a robust, science-based sampling program has continued to provide data confirming these boundaries as appropriate,” Clark said. “Our company strongly rejects the notion advanced by some in the community that our facility is the sole source of elevated PFAS levels throughout Southern New Hampshire.”
State regulators in May pressed Saint-Gobain to submit a plan to test 700 wells that the state identified as contaminated within the 65-square-mile zone. They have also said the company is probably responsible for contaminating many wells outside the zone, describing them as “within inferred areas of impact from Saint-Gobain’s releases.”
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Officials at the state Department of Environmental Services declined to comment on the new allegations.
“We’re going to review the materials, and see what they mean,” said Mike Wimsatt, director of waste management at the Department of Environmental Services.
In their letter, the lawmakers and scientists urged the state’s attorney general to review the court documents, which they said show that the company failed to inform the state about the amount of one highly toxic PFAS chemical, known as PFOA, that it used extensively in Merrimack.
“We respectfully request that the attorney general’s office investigate whether [the company] has, and continues to, mislead the state regarding the full extent of historic usage of PFOA,” wrote the lawmakers, including state Representative Rosemarie Rung, who chairs a legislative commission investigating the public health impacts of PFAS, and scientists, including Linda Birnbaum, former director of the National Institute for Environmental Health Sciences.
Their allegations are based on documents produced in legal proceedings involving Saint-Gobain, including class-action lawsuits filed by residents in New Hampshire, Vermont, and New York who have claimed they were affected by pollution from company plants there. The residents in Bennington, Vt., and Hoosick Falls, N.Y., won multimillion-dollar settlements from Saint-Gobain; the litigation in New Hampshire remains unresolved.
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In 2016, Saint-Gobain lawyers sent a letter to state regulators, asserting the company never used pure PFOA as a raw material, according to the court documents. They claimed to have only used diluted versions of that toxic compound, which were less likely to spread as widely as the pure version.
But a salesman from DuPont de Nemours, Inc., which sold products to Saint-Gobain containing PFOA, contradicted those assertions, according to the court documents. “I personally had learned that they were using [pure PFOA] … and adding it to our products, other people’s products, as part of their formulation work,” he testified last year in the lawsuit against the company in New York.
Another allegation came from a consultant for Saint-Gobain, who testified this year in the New Hampshire lawsuit that the use of pure PFOA in Merrimack led the company to create a flawed model that probably underestimated how far its pollution spread.
Separately, an independent chemical engineer hired by plaintiffs in the New York class-action lawsuit testified in 2020 that Saint-Gobain used pure PFOA, which he concluded “unreasonably disregarded public safety.” “The defendants … should have understood what constitutes reasonable practices that prevent harm to others,” he wrote in a report for the plaintiffs.
Christopher Bandazian, who serves as chairman of an environmental subcommittee of a state commission studying the impact of Saint-Gobain’s pollution, said he found the allegations “extremely distressing” and that “there are too many omissions from the company to plausibly accept.”
“There’s a tremendous volume of information concerning the extent of PFOA pollution from the Merrimack facility that wasn’t apparently available to the state when negotiating with Saint-Gobain in 2018,” said Bandazian, who didn’t sign the letter. “It would have materially changed the state’s modeling of the extent of the contamination of the surrounding community. Unfortunately, as a result, the financial burden has fallen on individual residents.”
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Officials in the state attorney general’s office declined to comment on the allegations.
The court documents also revealed a previously unknown program in which Saint-Gobain in 2006 tested the blood of its employees for elevated levels of PFOA, which critics said reflects that the company was aware of the potential dangers of the chemicals.
Clark declined to say what the company learned from those tests.
“Saint-Gobain maintains an industrial hygiene program that periodically includes offering medical exams and blood testing to employees, including those in Merrimack,” he said. “The results of these tests are the protected health information of our employees, and we will not be sharing additional details with the news media.”
Clark called allegations that the company didn’t take its responsibility to protect the environment and public health “unfounded.”
“Our commitment to our environmental, health, and safety responsibilities is unwavering,” he said.
Birnbaum, a toxicologist who spent years studying the health impacts of PFAS at the National Institute for Environmental Health Sciences, urged state officials to hold Saint-Gobain accountable for its actions, calling the company’s use of so many forever chemicals “absolutely irresponsible.”
“It’s clear that Saint-Gobain didn’t do what was necessary to protect the public or their workers,” she said. “Now, regulators and the attorney general need to understand the full extent of the pollution and notify the public of the dangers.”
David Abel can be reached at david.abel@globe.com. Follow him @davabel.