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Insecticide Spraying in Loudon County: When Lyme Prevention Raises Cancer Risk.

tick spray lyme disease prevention with bifenthrin

If you go down to the woods today...

Loudon County, ever at the forefront of Lyme disease prevention, angered residents last week by giving them less than 24 hours notice of a plan to spray local parks with a carcinogenic insecticide. While they may be applauded for being so on the ball about infectious disease, residents were less than happy to find out that the insecticide they would be using is a Category C carcinogen-based spray, with research published just this month showing that it can have serious effects on health even at sublethal doses.

Preventing Lyme disease, it seems, could simply lead to a whole raft of other health issues, so what’s the deal with Talstar insecticide and what are the alternatives?

Carcinogenic Insecticide

Talstar is a bifenthrin-based insecticide that was used initially on six of Loudon county’s parks, followed by another three parks on June 10th, as part of their Lyme disease prevention strategy. Parks that were sprayed last Thursday include Claude Moore Park, Franklin Park and Philip A. Bolen Memorial Park and, yesterday, Banshee Reeks Nature Preserve, Conklin Park and Brambleton West Fields.

Dangers of Bifenthrin

The Environmental Protection Agency (EPA) has classified bifenthrin as a class C carcinogen, or “a possible human carcinogen,” based on evidence from animal research exposing mice to the chemical. These mice had an increased risk of developing specific types of tumors but the research has not been reproduced in human studies and so may not be translatable. A paper published just last week found that the antioxidant status of rats exposed to sublethal doses of bifenthrin was severely impaired, with signs of significantly increased lipid peroxidation (a sign of serious oxidative stress that can affect the health of cell membranes and cellular function). The rats’ glutathione levels decreased as did the activity of catalase and glutathione peroxidase and antioxidants superoxide dismutase and glutathione S-transferase after repeated exposure to bifenthrin (20-30 days).

Long-Term Effects of Bifenthrin Exposure

As such, those who were unaware of the spraying of the parks may have been unnecessarily exposed to high levels of a potential carcinogen that can also cause damage of a more subtle kind. It, therefore, becomes extremely difficult, if not impossible, to tie the use of these kinds of sprays to chronic health conditions that arise months or even years later. Other research published earlier this year found that bifenthrin actually has the potential to bind to DNA, although what effect, if any, this has on health remains unknown.

Limiting Risks of Lyme Disease Prevention Strategies

With so little notice given it is possible that families frequenting the parks simply did not have time to find out about the spraying which was to take place strictly on weekdays, according to the public information office. This schedule seems wise to limit the number of people exposed to the chemical but those who would be in the park at such a time are likely to be parents and childcare workers with small children, as well as people playing with their dog(s) who could be even more vulnerable to the effects of the carcinogens due to smaller body size.

Symptoms of Bifenthrin Toxicity

The parks did display signs before, during, and after spraying to alert the public. Despite widespread use of these types of insecticides there have been relatively few reports of deaths connected to the chemicals. Toxic exposure is possible, however, and the following may be signs of insecticide poisoning:

  • Paraesthesia (especially in the face), with symptoms exacerbated by heat, sunlight, scratching, sweating and the application of water
  • Sore throat
  • Nausea and vomiting
  • Abdominal pain
  • Ulceration of the mouth
  • Dizziness
  • Headaches
  • Fatigue
  • Dysphagia
  • Increased salivation
  • Palpitations
  • Blurred vision
  • Chest tightness
  • Convulsions and coma.

Those experiencing any such symptoms should seek medical attention immediately, especially if they believe they may have been exposed to high levels of insecticide. Unfortunately, many of these mirror the symptoms of Lyme disease which could cause a delay in diagnosis in areas endemic for the tick-borne infection.

Combined Exposure to Multiple Insecticides

Combined exposure to insecticides also increases the risk of adverse effects on health, which is a consideration for those using insecticide sprays and sunscreens containing insect repellents and for those using tick and flea control medication on their dog(s). One study found that the following chemicals had the potential to increase the toxicity of bifenthrin: chlorpyrifos, profenofos, emamectin and fipronil.

Why Loudon County Sprays their Parks

So, if there are so many potential safety concerns with the use of insecticides such as bifenthrin, why would Loudon County decide to go ahead and spray the parks? The simple answer is that local health officials collected data on the number of ticks in the county’s 27 parks and were sufficiently concerned over the risk of Lyme disease for their residents that the spraying seemed necessary. Considering that black legged (‘deer’) ticks may not be the only pests carrying Lyme disease bacteria this may be even more justified than local officials already consider it to be.

Preventing Lyme Disease and Staying Safe

There are, of course, other Lyme disease prevention strategies, many of which can be implemented at home to help protect your family against Lyme disease. In the meantime, perhaps it is wise to find out if your local authority has any intention of spraying potential carcinogens in the park you take the kids to every day and give it a wide berth for a little while.


Dar MA, Khan AM, Raina R, Verma PK, Sultana M., Effect of Repeated Oral Administration of Bifenthrin on Lipid Peroxidation and Antioxidant Parameters in Wistar Rats. Bull Environ Contam Toxicol. 2013 Jun 2.

Zhu P, Zhang G, Ma Y, Zhang Y, Miao H, Wu Y., Study of DNA interactions with bifenthrin by spectroscopic techniques and molecular modeling. Spectrochim Acta A Mol Biomol Spectrosc. 2013 Apr 11;112C:7-14.

Bradberry SM, Cage SA, Proudfoot AT, Vale JA., Poisoning due to pyrethroids. Toxicol Rev. 2005;24(2):93-106.

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