OVERKILL: Using pesticides to control West Nile Virus mosquitoes in Maine may do more harm than good, a MEPI report.

Findings and Recommendations from the report

  • The chemicals that are released into the environment in an effort to control mosquitoes are harmful to human health, lobsters, wildlife, and ecosystems. They can cause: cancer, immune and nervous system disruption, vision loss, and reproductive and learning problems. Many are highly toxic to wildlife, particularly fish, bees, birds, and lobsters.

  • Lobstermen in Long Island Sound blame spraying for West Nile Virus (WNV) mosquitoes in New York and Connecticut for the near total destruction of their fishery. They are suing the chemical company manufacturers for $125 million. 150 lobstermen who fished in the Sound have lost their livelihoods.

  • West Nile Virus is expected to show up in Maine this summer. It was found in New Hampshire last summer. 448 positive birds were reported in Massachusetts in 2000, but no human cases.

  • West Nile Virus is not a "deadly epidemic." Approximately 1 in 1000 mosquitoes in areas where WNV is endemic carry the virus, and only 1 in 300 people bitten by a WNV-carrying mosquito show any signs of sickness, and then usually only mild, flu-like symptoms.

  • The eight people who died from WNV in the New York City area in 1999 and 2000 range in age from 68-87. 1 had HIV, 3 were on immuno-suppressive drugs for cancer, and 1 had a "pre-existing condition that probably contributed to his death."

  • Maine state officials have formed a WNV Working Group, and have evaluated ten pesticides for control of WNV mosquitoes. They have not disclosed under which criteria they would allow towns to spray the chemicals. They have yet to hold a public forum to discuss their plans.

  • Many state officials involved in the process are on record as saying they are disinclined to spray. The pressure to spray is expected to come from towns, especially in southern coastal Maine. The DEP will be responsible for issuing permits for spraying of surface waters.

  • Pesticide applicators in New York have been found by the NY Attorney General's Office to be fomenting West Nile Virus hysteria, and fined. A pesticide applicator in Maine is on record as saying WNV "would be good for business."

  • Three organophosphate pesticides: malathion, temephos, and naled, three synthetic pyrethroids: permethrin, sumithrin, and resmethrin, and the larvicides BTi and Altosid are proposed for use to control WNV mosquitoes in Maine.

  • The toxic effect of these chemicals on humans, particularly at risk populations like the elderly, children, and fetuses, has not been thoroughly examined. Studies of the long-term subtle effects on endocrine and immune systems, behavior, intelligence, cancer, etc., have either not done or are inadequate.

  • The larvicide methoprene (Altosid) poses a particular concern as it can kill marine crustaceans like lobsters at very low doses by disrupting their ability to molt. The compound, dumped directly into water bodies, is being put forth as a "safe" alternative to spray programs.

  • All the chemicals are designed to kill insects, many of which are responsible for pollinating wild and cultivated plants in Maine. The future of agriculture depends on pollinators. Insect pollination is a necessary step in the production of most fruits and vegetables we eat.

  • The pesticides are ineffective in that they kill only a limited percentage of mosquitoes in sprayed areas. They could even make the situation worse by creating resistant populations of mosquitoes, and actually increasing the number of mosquitoes by wiping out the predators that keep their numbers in check.

  • The legal ramifications of a pesticide spray program are serious. In New York, lawsuits are being brought by environmentalists, sprayed residents, and lobstermen. These suits could total in the hundreds of millions of dollars.


  • Given available evidence on the low risk of WNV as a public health threat and the low efficacy and potential harm of a chemical response, it does not make sense to spray pesticides to control mosquitoes that may carry WNV -- it may be do more harm than good.

  • Intensive monitoring and surveillance for the virus, combined with on the ground educational efforts aimed at minimizing breeding and biting opportunities for mosquitoes are needed. Personal protection measures like screens, clothing, repellents are important, but do not use DEET, especially on children as it can be harmful to them. Nontoxic alternatives are available.

  • Citizens should also be educated on the minimal risk WNV poses to their health, and understand that the elderly and immune-compromised people are at a greater risk.

  • The state should establish a toll-free 'hotline' for all questions relating to WNV: health, pesticides, dead birds, standing water, etc. The state should hold public fora on WNV.

  • Use natural predators like fish to control larvae, and limit the use of biopesticides like Bti to contained standing water only. Methoprene should not be used anywhere in Maine.

  • Authorities should monitor the activities and ad campaigns of pesticide applicators carefully.

    The 50 page report has 130 references and is available in its entirety on the Institute's web site at http://www.meepi.org. Printed copies can be ordered for $10, includes postage to: MEPI, 126 2nd Street, POB 347, Hallowell, Maine, 04347.