Common chemical still requires caution

Sandy Bressner - sbressner@nwherald.com Dr. Adam Conroy applies Frontline flea and tick treatment to Chip, a 5-year-old cairn terrier, as Chip's owner, Hilary Frank of Algonquin, looks on at the Animal Care Clinic in Algonquin. Products like Frontline are recommended as a safer alternative to the chemical pyrethrin, which is used frequently in over-the-counter pet flea and tick treatments and is not recommended by area veterinarians.

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When giving your pet a bath or flea treatment, a local veterinarian says to check the label.

A recent study shows that the number of reported human health problems of a chemical found in many lawn-care and flea treatment products are on the rise, and the local picture presents it as an issue among pets, too.

But the Illinois Poison Center considers pyrethrin safe for humans – when used as directed.

Pyrethrins and the synthetic version called pyrethroids are used widely in lice shampoos, flea and tick killers, and other insecticides, such as roach and ant sprays. The chemicals also are used in some medications, including scabies treatments, said Carol DesLauriers, a pharmacist and clinical service manager for the Illinois Poison Center.

“If you see a lot of reports on pyrethrins, it’s only because they’re everywhere,” DesLauriers said. “The only thing that can possibly happen is it exacerbates asthma or allergies because they are derived from plants.”

The Center for Public Integrity analyzed records from the Environmental Protection Agency filed by pesticide manufacturers and found that pyrethrin and pyrethroids accounted for more than 26 percent of all fatal, major and moderate human incidents in 2007, up from 15 percent in 1998.

The organization’s records revealed that in McHenry County, there were 70 pesticide incidents between 1992 and 2007 reported by chemical manufacturers to the EPA. However, not every exposure is included; it is limited to the those that the companies report.

Of the 70 county incidents, 22 were to humans, 29 affected plants, and 18 involved animals. One was identified as “nontarget.”

At least half of the incidents with animals involved a product that contained pyrethrin.

“They are actually very safe pesticides,”  DesLauriers said. “They are very toxic to insects but minimally toxic to humans.”

DesLauriers said the chemical was safe for humans, but Dr. Dan Markwalder, a veterinarian at Animal Care Clinic in Algonquin, said animals were a different story.

“This is a really old drug that should not be used on animals because nowadays there are so many more safer products out there,” Markwalder said. “Unfortunately, they’re not being taken off the shelf; they’re very prevalent.”

But the number of negative reactions to pyrethrin is decreasing, Markwalder said. He now sees fewer than 10 cases each year, compared with as many as 60 cases a year 10 years ago.

Death from pyrethrin exposure is rare in animals but can happen if left untreated, Markwalder said. Symptoms include excessive drooling, hyperexcitability, diarrhea, and seizures.

“Usually what we do when an animal comes in is give them active charcoal to decrease absorption and control the seizures with anti-seizure medication,” Markwalder said. “General recovery is about 24 hours.”

Most of the cases he sees of pyrethrin poisoning come from inappropriate use, such as using a shampoo for dogs on cats, which are particularly sensitive. Cats are constantly grooming themselves and can easily ingest the chemicals but are unable to metabolize them, Markwalder said.

To get rid of fleas, Markwalder recommends products such as Frontline, which is applied by squeezing a small tube of the liquid between the animal’s shoulders.