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After the deaths of 200 birds on Marco Island, the EPA proposes curtailing Florida's use of the pesticide fenthion.
By CRAIG PITTMAN
© St. Petersburg Times, published January 28, 2001
For 30 years, ornithologist Ted Below regularly waded out to a sandbar off the public beach at Marco Island to document herons, sandpipers or other birds stopping off there. Occasionally, he ran across a few dead ones, but he didn't pay much attention -- until the day in 1997 he found 80 at once.
Among the dead lay an endangered piping plover. A band on its leg showed the tiny bird had flown south from Michigan only to keel over in sunny Florida.
In the years since, the U.S. Fish and Wildlife Service has blamed the deaths of 200 birds on Marco Island on a pesticide called fenthion, which for decades has been sprayed throughout Florida -- including around Tampa Bay -- to control mosquitoes.
Marco Island's bird deaths have fueled a running feud over fenthion. Conservation groups want to ban it, citing concerns not only for birds but also for humans. Local government officials contend it is vital in warding off mosquito-borne viruses such as encephalitis.
"In 30 years of work in Florida, I have not seen any adverse effects from this product when it is applied properly," said David Dame, president of the American Mosquito Control Association. To ban fenthion now, he said, "would not be prudent."
The U.S. Environmental Protection Agency this month proposed curtailing the use of fenthion. The EPA expressed concern about the effect it might have on birds, golfers, homeowners doing yard work, toddlers playing outdoors and anything else that gets in the way of the spray. Citing the Marco Island deaths, the EPA wants to restrict the use of fenthion to Florida counties that have a plan for avoiding environmentally sensitive areas.
Those proposed EPA restrictions aren't final. In the meantime, Florida officials say they have no qualms about the pesticide. Hillsborough County, for example, plans to use the spray when mosquito season begins this spring.
"We've sprayed it just about anywhere in Hillsborough," said spray operations supervisor Richard Wilkins. "Nothing has keeled over yet."
Two weeks ago, supporters and opponents of fenthion squared off for an eight-hour hearing in Orlando over whether the EPA should allow spraying to continue in Florida.
"We will not stand idle while fenthion continues to be sprayed in one of the most biologically rich and ecologically sensitive regions in the world," Linda Farley of the American Bird Conservancy told the EPA.
Conspicuously absent from the hearing was the Fish and Wildlife Service. Federal wildlife officials say their Marco Island investigation is still going on, so they cannot talk about it.
So mosquito-control officials told the EPA that, in making a decision about fenthion's future, the agency should simply ignore the deaths on Marco Island.
Some mosquito-control officials dismiss fenthion's connection to Marco Island's bird deaths as mere rumor, not worth discussing. Until independent scientists can review the federal records, Dame explained, "it's kind of a dead issue for us."
Fenthion, developed in the 1960s by the company that makes Bayer aspirin, is a yellowish liquid that smells like garlic and disrupts the nervous system. Fenthion is part of the organophosphate family, which includes nerve gas. For more than three decades, mosquito-control officials around the state -- including Pinellas, Pasco and Hillsborough counties -- have dispatched helicopters, airplanes and trucks to spray fenthion at the pesky bloodsuckers that can make life in Florida less than postcard-perfect. It is so effective that California, Georgia, Louisiana and Mississippi want to try it.
Fenthion kills more than just mosquitoes. It was once used in a product called Rid-A-Bird. Starlings and pigeons would land on a fenthion-impregnated perch and absorb it through their skin. They would then foam at the mouth, go into convulsions and die.
But the dead starlings and pigeons were then eaten by hawks, owls and falcons, which also died. Seattle timber company executives pleaded guilty to criminal charges after Rid-A-Bird perches in a paper mill killed federally protected owls and hawks. A bird lovers' campaign to rid the world of Rid-A-Bird succeeded last year when the manufacturer pulled the product off the market.
Bayer recently dropped another fenthion product, ear tags for cattle that warded off pests for five months. The fenthion showed up in cows' fat and milk, raising questions about food safety.
Fenthion used to be available nationwide for mosquito spraying. In 1988, faced with tightening government restrictions, Bayer nearly halted production. Bayer officials say Florida's mosquito-control districts begged them to continue making it for use in this state only, so the company agreed.
Since then, fenthion has taken a toll on Florida wildlife. University researchers spent five years studying the effect of mosquito sprays in the Keys and found fenthion nearly wiped out the nation's rarest butterfly, the Schaus swallowtail.
"It was extremely toxic to butterflies in the Keys, and to 50 percent of other insect species," University of Florida zoologist Thomas Emmel said.
Three years ago, fenthion sprayed north of Marco Island killed fiddler crabs in the pristine Rookery Bay National Estuary Reserve. After a study, Collier County's mosquito control officials created a milewide no-spray buffer around the reserve. The crab deaths occurred about the time Below began finding dead birds. Yet Florida A&M University entomologist James Dukes scoffed at the possibility of a connection.
"If this compound really did what they are accusing us of," he said, "there wouldn't be a bird left."
The federal investigation into Marco Island's bird deaths found that sick or dead birds turned up at least 12 times between October 1998 and August 1999, each time after helicopters sprayed fenthion nearby. "Sprays were made over the beach early in the morning, and sick and dead birds were observed on the beach within 8-10 hours," a terse EPA memo on the wildlife agency's investigation reported last fall. Tests at an Oregon laboratory found fenthion "on legs, feathers, beaks and/or in stomach contents."
To mosquito-control experts, the EPA memo is infuriating. They cannot understand how the Fish and Wildlife Service could allow the slaughter to continue if investigators thought fenthion was to blame. "I do find it somewhat hard to believe we are killing birds," said Collier mosquito-control director Frank Van Essen. "If the Fish and Wildlife Service had told us when they first started investigating, we would've addressed it at the time."
To Below, the delay is perfectly understandable. When he first found the dead birds in 1997, he shipped some off to a Wisconsin laboratory. Tests there found the birds died from a pesticide, but did not determine which one.
"The hard thing is to pin it down to a particular brand," Below, a 76-year-old retiree from the National Audubon Society staff, said. "It took more sampling and more sophisticated chemistry."
At this point, the EPA's proposal to curtail the use of the pesticide isn't satisfying either side. Fenthion's friends and foes both wonder how easy it will be to create no-spray buffers when Florida's mosquitoes are swarming.
"Florida, in general, is covered with water and swamps and marshes," Van Essen said. "What's the target area for mosquitoes? It's the state of Florida."
-- Researcher Caryn Baird contributed to this story.
To comment on the use of fenthion in mosquito spraying, write to:
Office of Pesticide Programs
Docket No. OPP-34145A, Fenthion
U.S. Environmental Protection Agency
1200 Pennsylvania Ave. NW Washington, DC 20460
For more information, click on this Web address:
http://www.epa.gov/pesticides/op/fenthion.htm