Water Treatment Open House (copy)

The Mansfield-Foxboro-Norton wastewater treatment facility in Norton.

Some communities are dropping state mosquito spraying because a pesticide used for years has been found to contain a chemical that’s been contaminating drinking water supplies across the state and could cause health problems.

North Attleboro, Foxboro and Mansfield water has been shown to have the chemical — per- and polyfluoroalkyl substances known as PFAS and also referred to as the “forever chemical.”

Plainville gets some of its water from North Attleboro, which had trace amounts of PFAS. Foxboro water has had some of the chemical and Mansfield water has exceeded state Department of Environmental Protection-recommended levels.

It’s unclear if pesticide spraying brought the contamination, and the towns are taking steps to address the problem but not opting out of spraying, which is primarily done each spring by county mosquito control programs that are not using the pesticide that had been tainted.

The programs had used the pesticide in the past but it’s uncertain if it was contaminated then.

Aerial state spraying is conducted when state officials declare a mosquito emergency.

DEP only last year established guidelines for PFAS but earlier recommended communities have their water tested for them. Testing became a requirement in October.

PFAS date to the mid-1900s and are primarily used in consumer products to create grease, water and stain resistance for clothing, Teflon cookware, takeout containers, upholstery and carpets, and have also been found in firefighting foam.

Drinking water may become contaminated if PFAS deposited onto the soil seeps into groundwater or surface water.

Most will not naturally degrade in the human body and environment, and PFAS in public water supplies can potentially cause health effects, health officials say. Those most at risk are pregnant women, nursing mothers, and infants.

Studies have shown exposure to high levels of some PFAS may cause developmental problems in fetuses and infants, and effect the thyroid, liver, kidneys, certain hormones and the immune system, according to DEP. Some studies link it to cancer.

North Attleboro, Mansfield and Foxboro water departments in March were among 17 public water supply systems sharing in $3 million in state grants to address elevated levels of the chemical.

The grants were awarded to water systems for expenses related to the design and planning of treatment systems that protect drinking water from PFAS.

North Attleboro received $200,000 for planning and design. Mansfield and Foxboro were allocated $200,000 for reimbursement and planning and design.

The main pesticide the state has used to spray, Anvil 10+10, was found last year to have PFAS concentrations that exceed state allowable amounts in drinking water.

“The information that I have found indicates that the PFAS was in the packaging of the product that was formerly used,” Foxboro Water Superintendent Robert Worthley said.

State and federal regulators had determined PFAS in the packaging leached into Anvil, and PFAS wasn’t found in the pesticide when it came in new packaging.

Foxboro has spraying conducted by Norfolk County Mosquito Control District, which in late April began treating wetlands in the county by helicopter with the aerial application targeting mosquito larvae.

The product is Vectobac GR, a granular chemical the district says it has used for years that it stresses isn’t a liquid.

The county last used Anvil in 2010, said David Lawson, director of the Norfolk County Mosquito Control District, which is based in Walpole.

Local boards of health and public safety officials are notified of the treatment program.

The Foxboro Health Department has received the town's 2020 water sampling report, which doesn't show an exceedance of the state standards, Director of Public Health Matthew Brennan said.

"To my knowledge the Health Department has not received complaints or concerns in regards to PFAS levels in the drinking water," Brennan said.

None of the towns in the district applied for the state opt-out, Lawson added.

North Attleboro and Mansfield have mosquito spraying done by the Attleboro-based Bristol County Mosquito Control Project, which also isn’t using Anvil but did years ago.

North Attleboro’s public works department took two of its wells offline late last year after tests confirmed the presence of trace amounts of PFAS.


In Mansfield, residents at the fall town meeting approved borrowing $13.92 million to improve the quality of town water by reducing PFAS amounts that are above DEP-recommended levels.

The project involves treatment systems and other well improvements, including expanding water production.

The borrowing has been projected to increase customer water rates by an estimated 1% on top of a 5 percent hike approved by the select board. A $200 water bill would only see an additional $2 added for the water project.

Two of Mansfield’s nine wells had tested slightly above recommended levels for PFAS, and were taken out of operation. The wells produced 1.2 million gallons of water per day and the town uses up to 4 million gallons a day during the summer, town officials say, so the work was expedited to meet this summer’s demand.

Of the $13.9 million, $4.18 million was earmarked for a treatment system to remove PFAS at the Cate Springs Well, and $4 million for a treatment system to remove PFAS at the Walsh Well on Gilbert Street in West Mansfield.

Mansfield began testing for PFAS in September 2019.

Bristol County Mosquito Control Project began spraying in early June, having taken residential spray requests.

The pesticide used is Zenivex E4 RTU, an EPA-approved, reduced-risk adulticide.

Bristol County, which sprays from trucks, used Anvil 10+10 from 2003-2013. However the pesticide did not always come in plastic drums. For many years they were in steel containers and then the manufacturer switched to plastic, according to Priscilla Matton, superintendent for Bristol County Mosquito Control Project.

If parts of Massachusetts show more extensive than usual mosquito problems, the state begins spraying.

The decision to forgo state spraying is a difficult choice facing cities and towns with PFAS as it has been clearly demonstrated the pesticides reduce the spread of eastern equine encephalitis, West Nile and other mosquito-borne diseases that can be deadly.

After hearing board of health concerns, selectmen in Pepperell, a town at the New Hampshire border, voted recently to make the community one of at least 13 in Massachusetts, most in the western part of the state, to take advantage of a new law that allows cities and towns to ask state permission to opt out of what had been state-mandated pesticide spraying. Pepperell’s water supply contains elevated levels of PFAS.

Residents and environmental advocates for years have opposed widespread use of pesticides, claiming they harm people, animals and the environment, and activists have been advising cities and towns to forgo spraying after successfully pushing through the new state law.

The concerns have grown as more communities have found elevated levels of PFAS in their drinking water.

Last summer, a year after six people died from EEE in what was the state’s deadliest outbreak since the 1950s, Gov. Charlie Baker signed a law that gave the state more powers to fight mosquito diseases.

It could do spraying without permission from local officials. Previously, the state could only conduct aerial pesticide spraying without local authorization if the governor declared a public health emergency.

State spraying has “historically only been conducted when a EEE emergency is occurring,” said Lawson of the Norfolk County Mosquito Control District.

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