Massachusetts Concedes Aerial Spraying Largely Ineffective

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For Immediate Release: Wednesday, July 8, 2020
Contact: Kyla Bennett (508) 230-9933; Kirsten Stade


Massachusetts Concedes Aerial Spraying Largely Ineffective


Half of Spray Events Kill Zero Mosquitos; No Proof of Disease Reduction

Boston — State records document the ineffectiveness of aerial spraying as a tactic to combat mosquito-borne diseases, according to a complaint filed today by Public Employees for Environmental Responsibility (PEER) with the Commonwealth Office of Inspector General. This new evidence emerges as Massachusetts considers legislation to enshrine aerial spraying into statute as a disease-control measure.

Governor Charles Baker has embraced aerial spraying as a key tool to stem arboviruses, such as Eastern Equine Encephalitis. EEE occurs in approximately 7-year cycles. The state sprayed in 2010, 2012, then again last year, and plans to do so again this year. Data from the 2019 applications give scant reason for confidence since half the spray events had 0% efficacy (i.e., no reduction in primary mosquito vectors) at a cost to taxpayers of $2.2 million.

An assessment by the Department of Health admits that “it is impossible to measure the reduction in EEE cases based on aerial applications of pesticide,” and that “[r]eduction of risk from EEE relies primarily on the use of personal prevention behaviors by individuals.”

“Based upon the current evidence, aerial spraying is faith-based disease prevention; it is an aspirational tactic without scientific support,” stated PEER Science Policy Director Kyla Bennett, a biologist and attorney formerly with the U.S. Environmental Protection Agency (EPA). “Spraying only targets flying adults, not the eggs, larva or pupae, meaning that many repeat applications are needed to have any hope of controlling emerging adult mosquitoes.”

Other records PEER obtained relate to the pesticide agent the states uses, Anvil 10+10, which has two active ingredients: sumithrin and PBO. EPA classifies PBO is a “possible human carcinogen.” Sumithrin is known to suppress the immune system and interferes with respiratory function. Official concerns about the serious adverse effects from aerial spraying Anvil 10+10 include –

  • The Department of Marine Fisheries points out that it is “very highly toxic to fish and aquatic invertebrates… runoff from treated areas or deposition of spray droplets into a body of water may be hazardous to fish and aquatic invertebrates…”;
  • The Department of Fish and Wildlife notes that “unfortunately, all of these products impact a variety of native insects. Aerial application of these products in certain areas of the state would result in a Take of state-listed species…”; and
  • The Department of Environmental Protection recognizes that the agent is “highly to very highly acutely toxic to fish, aquatic invertebrates and honeybees.”

“In addition to all the other harmful side-effects, spraying carcinogenic immune suppressors over a wide area is not a very smart thing to do during a pandemic,” added Bennett, who is asking the Inspector General to determine if more aerial spraying is so ineffective and counterproductive as to constitute a waste of funds. “Currently, Massachusetts only tries to measure the impact spraying has on mosquitos but collects no data on harm to humans and wildlife in spray areas.”

PEER is part of a coalition containing members of beekeeping and pollinator groups, as well as organic farmers, pushing to amend Governor Baker’s emergency spraying bill to add public health and ecological safeguards, as well as protections for property-owners.

Read the IG complaint

Look at issues with pending legislation

View practical limitations on aerial spraying efficacy

Examine aerially sprayed pesticides contaminating waterbodies

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