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How safe is permethrin?

AMBROSE CLANCY PHOTO Placing permethrin-soaked rollers onto a feeding stand of a 4-poster unit.

AMBROSE CLANCY PHOTO Placing permethrin-soaked rollers onto a feeding stand of a 4-poster unit.

Some Saturdays your neighbors have a professional spray their property to kill ticks. Other neighbors put out small tubes containing cotton soaked in a tickicide with the hope they will keep tick-infested mice from their yard.

Question: Are you thinking of following one example or the other to try and protect your family from tick-borne illnesses? Or are you concerned about the safety of chemicals used and/or their effectiveness?

There’s not a simple answer, according to experts familiar with permethrin, the tickicide used on 4-poster units, the feeding stands that brush deer with the chemical, and also used by some property owners. Its safety is related to the amount used, which raises questions in some quarters about its effectiveness.

The amount used in the Island’s 4-poster units is 10 percent of the total solution compared with 7.4 percent of the active ingredient in the tick tubes.

“By far, the most effective way to address ticks is to utilize an integrated approach,” said Shelter Island Animal Control Officer Beau Payne. “People too often seek a ‘silver bullet’ to solve their issue with a single method and sadly that is rarely the case.”

Tick tubes show some ability to control ticks on white-footed mice, but have “not shown much in the way of long-term tick control” Mr. Payne has said.

Nor have the tick tubes shown ability to control Lone Star ticks that, at all stages of their lives, prefer to feed on deer, he said.

A combination of methods is likely to provide the best protection, Mr. Payne said.

Those would include using chemicals along with using personal protection.

As for spraying, there are a number of factors influencing both its safety and effectiveness, Mr. Payne said. He noted there are several types of sprays used, some with permethrin and others with ingredients like cedar oil. Product ingredient levels are printed on the labels, he said.

Hiring a licensed professional who has the proper equipment is critical, but still only provides “temporary relief due to the transient nature of wildlife and ticks as well as environmental degradation of the application,” Mr. Payne said.

The United States Environmental Protection Agency and the state Department of Environmental Conservation provides guidelines for pesticide use.

Applying pesticides in the manner indicated on the product labels is the best way to ensure their maximum effectiveness and safety, Mr. Payne said.

As for those tick tubes frequently advertised as a means of keeping a property tick-free, Mr. Payne said they’re intended to provide a chemically treated material for white-footed mice to use in building nests. Mice take the material, usually cotton, back to their nests. It does provide a means of eliminating early stage black-legged ticks, the animal control officer said.

The black-legged ticks are responsible for spreading Lyme Disease, according to University of Rhode Island research conducted by  Dr. Tom Mather, director of the school’s Center for Vector-Borne Disease and its TickEncounter Resource Center.

Studies conducted at the University of Rhode Island show the tick tubes can reduce black-legged ticks, but it would take about 24 tubes in a one-acre yard on which half the acre is covered by a building. The tick tubes have to be replaced throughout the season and the homeowner would have to make judgments about the best placement for the mice to be attracted to the tubes.

Mr. Payne outlined a five-year study being launched in Dutchess County dealing with use of two commercially available products that are aimed at ticks on rodents.

One is a bait box that attracts rodents and sprays them with a tickicide while the other is a naturally occurring fungus that kills ticks. The jury is still out on how effective those products are.

But Deer & Tick Committee member Marc Wein recently pointed to another study by Moses Cucura of the Suffolk County Public Works Department Division of Vector Control that may raise questions for property owners about the safest and most effective ways of dealing with ticks.

The Reporter has not yet been able to obtain a copy of Mr. Cucura’s report, but Mr. Wein said the official has determined that those opting for natural products instead of permethrin-based products are fooling themselves because the chemical is known to kill ticks while the natural products appear to have no real effect.

How safe is Permethrin?
The answer is that studies vary.

Cornell Cooperative Extension, which conducted a three-year pilot program  of 4-posters beginning in 2008 included Shelter Island with 60 units deployed here.

While Cornell warned users to avoid the chemical’s contact with eyes, skin and clothing, it maintained that permethrin has a low toxicity for humans. Because it tends to be excreted from the body quickly, permethrin doesn’t appear to significantly affect human body tissues, the Cornell study said at the time.

Cornell scientists found it non-toxic to birds, but toxic to fish and advised it “should be kept out of all bodies of water.”

Town officials are hoping the state Department of Environmental Conservation will update findings on the safety and effectiveness of permethrin since the Island is likely the only community where permethrin has been used continually for 11 seasons. What locals want to know is whether permethrin is safe for long-term use and whether it is still as effective in killing ticks as it appeared to be back in 2011 when the last report was released.

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