As the state ramps up its response to what officials fear could be another dangerous summer for eastern equine encephalitis, environmental advocates are warning them to avoid relying on aerial spraying to reduce transmission of the deadly, mosquito-borne disease, an approach they say has proven to be ineffective and endangers public health.
In a complaint to be filed this week with the state’s inspector general, the environmental groups argue that state records from aerial spraying last year, when Massachusetts experienced its most deadly outbreak of EEE since the 1950s, suggest that the application of the pesticides had little impact, despite significant expense.
Using chemicals that the US Environmental Protection Agency has found to include “possible human carcinogens,” the state deployed helicopters and airplanes to douse more than 2 million acres over 26 days last year, when six of the 12 people who contracted EEE died.
At a cost of more than $5 million, state officials estimate that the aerial spraying eliminated only about a third of the mosquitoes, according to state records. In half of those applications of the pesticide, known as Anvil 10+10, there was no evidence that it killed any of the targeted mosquitoes.
“The bottom line is we are indiscriminately spraying known poisons over millions of acres, and we don’t know the environmental costs,” said Kyla Bennett, a former EPA scientist who directs Public Employees for Environmental Responsibility in New England, an advocacy group that filed the complaint.
At a news conference in Plymouth on Tuesday, Governor Charlie Baker and other state officials noted that EEE outbreaks usually last for two to three years, raising concerns that the number of infections this year could reach that level again.
“If there’s a big outbreak, it can be a really big deal,” said Baker, who urged residents to protect themselves by using insect-repellent and wearing long pants and long sleeves, especially at dusk. “It’s very dangerous.”
Public health officials defended the state’s use of aerial spraying, which they said they’re likely to resume later this summer as more EEE-carrying mosquitoes are identified. State and local officials began spraying from trucks several weeks ago.
Before last year, the state applied the same pesticide, which has been used by other states, in three previous years. There were no human EEE cases reported in Massachusetts from 2014 to 2018.
“The administration continues to use all available tools to prevent EEE,” said Ann Scales, a spokeswoman for the state Department of Public Health. “Spraying is only one tool — and a rare one — the state uses when risk levels indicate an immediate threat to human life and health.”
In response to concerns that aerial spraying of the pesticides can be toxic to fish and other aquatic species, bees, and other insects, she said: “Every effort is taken to safely deploy aerial application only in those places and times when it can have an impact on that risk without harming insect and fish species.”
State environmental officials said they don’t spray the pesticides over certain areas, such as organic farms, commercial fish hatcheries, and ponds and other sources of drinking water. They also monitor honeybee hives and other surface water for any presence of the pesticides.
“The Commonwealth employs licensed pesticide applicators to ensure the safety of operations, including the handling of the product and pesticide-licensed pilots that fly the aircrafts,” said Katie Gronendyke, a spokeswoman for the state Executive Office of Energy and Environmental Affairs.
At the news conference, Baker said aerial spraying was needed in part because mosquitoes carrying EEE — which were historically limited to Southeastern Massachusetts — have increasingly been found in other parts of the state. Indeed, the first mosquitoes detected with the disease this year were found in Franklin County, the north-central part of the state.
He also said the changing distribution of the disease, which scientists say could become more likely as a result of climate change, underscored the need for the Legislature to pass a controversial bill that would make it easier for the state to conduct aerial spraying and take other steps to combat EEE.
“It’s important that we think a little more about this as a statewide issue,” Baker said.
But environmental advocates, many of whom opposed earlier drafts of the bill, said the state should be far more cautious about spraying.
Not only are there better ways to prevent the proliferation of mosquitoes, they said, but there’s little evidence to show that spraying reduces the likelihood of someone contracting the disease, which often kills half of those infected and leaves as many as 80 percent of survivors with permanent neurological damage.
Instead of spraying, the state should be doing more to remove dams, better manage stormwater, and protect species, such as eels, that feed on mosquitoes, said Pine duBois, executive director of the Jones River Watershed Association in Kingston.
“We cannot poison our way out of this,” said duBois, who signed the complaint. “[Aerial spraying] is a practice that serves only to make people think they are safe, but it’s a waste of precious dollars. Put the money in environmental restoration and infrastructure improvements, and really solve the problem.”
Sylvia Broude, executive director of Community Action Works, and others raised concerns about the use of such pesticides when COVID-19 remains rampant.
“In the midst of the coronavirus pandemic, we should do everything possible to avoid using pesticides that can harm immune function and cause respiratory problems,” Broude said. “We’d like to see the state invest strategically in safer, proven methods of mosquito prevention.”