Permethrin Fast Facts

Many public health officials and many news organizations are cautioning that this will be an epic year for tick borne diseases. This is especially so in endemic areas like New York’s Hudson Valley. While it is important to take steps against these devastating diseases, it also important to use caution that we take sensible, safe measures. We are often told to use permethrin on our clothing, but are rarely warned of the alarming risks associated with it. Here’s the quick run-down of the evidence I have found to support my warning so that people can make informed choices regarding the risk vs benefit of these chemicals.


Male American Dog Tick crawling on a flower
  • The Endocrine Disruption Exchange reports that it is most concerned with the fact that permethrin acts as an endocrine disruptor. Disorders that have increased in prevalence in recent years such as unusual male gonad development, infertility, ADHD, autism, intellectual impairment, diabetes, thyroid disorders, and childhood and or adult cancers are now being linked to prenatal exposure to endocrine disruptors.” (Endocrine, 2007)
    Alarmingly, “Endocrine disruptors exert their effects at extremely low doses, even when higher doses exhibit no adverse effects.” (Endocrine, 2007).

    American Dog Tick on a leaf
  • Studies at the University of California Davis found that:“Mothers who lived in close proximity to agricultural sites during pregnancy were two thirds more likely to have children with autism or other developmental delays than mother’s who lived far away from these sites.” (Whiteman, 2014). Specifically, they found that “pyrethoids significantly increased autism risk for children whose mothers were exposed to the chemicals prior to conception and during the third trimester.”They explain that in utero exposures during early development may distort the complex processes of structural development and neuronal signaling, producing alterations to the excitation and inhibition mechanisms that govern mood, learning, and social interaction and behavior.” (University, 2014). This matches the Endocrine Disruption Exchange’s warning that “behavioral studies of rats and mice showed reductions in learned behavior, as well as impairments in balance, strength, and speed. One study found changes in motor activity and social behavior in the offspring of mice who were given permethrin prior to mating.” (Endocrine, 2007).
    A Black Copper Maran showing a couple of chicks how to search for Ticks and other bugs


  • The Endocrine Disruption Exchange also reports on other areas of concern when using permethrin: “Permethrin is highly toxic to bees, fish, and other aquatic organisms.” They also report that while very few studies have been done on the cancer causing potential of permethrin, a 1994 review by the US Army concluded that, “Permethrin is a possible human carcinogen” based on mouse studies showing evidence of lung and liver tumors related to permethrin.” Without bees, we would have no food.

    Permethrin is toxic to bees
  • We are often told to apply permethrin to clothing and shoes, and DEET to skin for complete protection. Yet the research shows that:
    Permethrin, used in conjunction with Deet, poses even more risk: “combined exposure to permethrin and DEET produced greater bio-chemical behavioral and metabolic alterations in animals compared to each individual compound.” (Aquesl, 2012). In another study, the “toxicity of permethrin was shown to be greatly enhanced when used in combination with DEET.” (Endocrine, 2007).A third study notes that “a pesticide mixture of permethrin and DEET can promote epigenic transgenerational inheritance of adult onset disease and potential sperm epigenetic biomarkers for ancestral environmental exposures.” (Mannikam, 2012). (That means it can damage the dna we give to our offspring).

    Adult Male American Dog Tick

    For these reasons, I won’t be using permethrin at my house. I don’t believe the risk outweighs the benefit. Instead, I will keep battling to be allowed to keep enough tick eating chickens to control the tick plague around my home. I will be vigilant in checking myself and my family and pets often (while outside, morning, evening, and whenever you return to the house from outdoors). People can’t live indoors or in a bubble. But the risk is so great that soon you may see me around town in my daily life wearing chest high gore-tex waders at all times. Because then you have at least a better chance of finding the ticks before they can get to you. 

    You can also see my slightly longer winded post, or check my references regarding permethrin by looking at my earlier post:

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