Permethrin is Problematic

In February, we had a warm spell and people started to see ticks again. At the time, I had a large enough flock of chickens that I no longer had to worry about ticks in my own house and yard. But when I left my house I worried about them. And my children even had to worry about them at recess at school.
I was going to break down and try chemical control for the clothing my family wore when we left the house. I had read so often how safe and effective it was, if properly applied. I purchased a large bottle of permethrin and a spray bottle to apply it to my family’s shoes and clothing.
Luckily, the little instinctive alarm bells inside my head began to ring that I had seen some pretty incriminating evidence about this particular chemical. I began researching and quickly found that there is no way I will ever use this product under a misinformed ruse of protecting my family. In fact, the evidence was so easy to find and so prevalent that I became very confused. Everywhere a person looks, newspapers, television, physicians, health departments, everyone is suggesting that people apply permethrin to clothing and DEET to skin to protect against the very real tick epidemic. I have even seen people recommend spraying the entire yard with permethrin. From the small amount of research I myself have managed to do on these chemical repellents, my horror is immense. I don’t know why the use of permethrin is being recommended far and wide. The science does not support this position at all.
Permethrin kills bees. Bees are required to pollinate our food.
Permethrin can cause neurotoxicity, and in children, exposure to permethrin has been linked to developmental delays and autism. In babies, toxicity is shown to be caused by not just exposure during pregnancy, but even from a mother’s exposure to the pesticide long before conception. Please read the rest of this post before deciding to use this repellent for your family. I know it is widely recommended. But I also know the facts support the fact that it is potentially a very dangerous chemical.

Permethrin is part of a class of chemicals known as pyrethoids. They are described by the Agency for Toxic Substances and Disease Registry (US Dept. of Health and Human Services) as “manufactured chemicals that are similar in structure to the naturally occurring pyrethins, but are often more toxic to insects as well as mammals, and last longer in the environment.” (ATSDR Public Health Statement pg1). I have even heard people refer to permethrin as “natural” tick control due to the fact that there are naturally occurring pyrethins. However, this proves that it is not “natural”, “green” or “organic” and is, in fact, known to be more toxic and longer lasting in the environment than the naturally occurring pyrethins it is based on.
The Endocrine Disruption Exchange reports that it is most concerned with the fact that permethrin acts as an endocrine disruptor. They state that “endocrine disruptors exert their effects at extremely low doses, even when higher doses exhibit no adverse effects.” (Endocrine, 2007). They go on to clarify that “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.”

A new study by the MIND institute at UC Davis wanted to measure the effects of pesticide use on expectant mothers who lived near fields and farms where chemical pesticides were applied. They then compared the data to data showing the incidence of developmental delays and autism and compared the results.  Alarmingly, they 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 in the third trimester.”
The researchers believe exposure may pose a greater risk to the developing fetus because the developing brain is more vulnerable to the toxins than adults. This is the stage where all the “electrical wiring” in the brain is being formed. The synapses between the nerves are all hard at work forming new pathways to communicate with each other. Researchers suggest 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).  As a certified Early Childhood Educator, I have spent countless hours learning about brain development and how best to foster that development in the early years of development. That last quote actually makes the hair stand up on the back of my neck. Because it sounds an awful lot like a description of autistic behavior and some common developmental delays in young children. Could these chemicals we were applying to our children in order to try and protect them from insect bites and disease be inhibiting their development and causing the rise in developmental delays and autism? Could we be hurting them, at the advice of all public health authorities, when we were just trying to protect them?
To further this horrific line of thought, the Endocrine Disruption Exchange warns 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). Wouldn’t changes in motor activity and social behavior also fit into the picture above? To someone with my child development background, these sound like very important facts in the search for the cause of the increased incidence of developmental delays and autism. The endocrine disruption exchange thinks pyrethoids can “penetrate the skin of infants and young children more easily than the skin of adults. Pyrethoids that penetrate skin may become more concentrated in internal tissues of the young.” (Endocrine, 2007).
Permethrin, when applied to the environment doesn’t just affect pregnant woman and young children. The endocrine exchange states that “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.” It is interesting the Army found this. Their pest control standards include permethrin impregnated or sprayed clothing, and DEET applications on skin. This is similar to frequent recommendations from various sources regarding control of ticks for everyone.   During the Persian Gulf War, battle dress uniforms were impregnated with permethrin, and DEET repellent was applied to skin. Since the war, there has been much research on the effects of these pesticides on the soldiers. In fact, the “toxicity of permethrin was shown to be greatly enhanced when used in combination with DEET.” (Endocrine, 2007). Another 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). I’ll admit this quote is slighlt over my head. But it seems to mean that exposure to permethrin and DEET can actually cause us to pass genetically modified material onto our offspring. Furthermore, another study found “combined exposure to permethrin and DEET produced greater bio-chemical behavioral and metabolic alterations in animals compared to each individual compound.” (Aquesl, 2012). And another indicates that “combinations of DEET and Permethrin produced greater neurotoxicity than that caused by individual agents.” (Abou-Donia, 2010). I find it very disturbing that the evidence suggests combining these two pesticides is the most dangerous when that’s what we are advised to do to prevent ticks.
One of the researchers from UC Davis, Hertz-Picciotto, said that “finding ways to reduce exposure to chemical pesticides, particularly for the very young, is important.” (University, 2014). The Endocrine Disruption Exchange summarizes that “given the specific evidence reported here, we urge people to weigh the risks and benefits of permethrin exposure carefully to employ the precautionary measures recommended by the Department of Health and Human Services, as the real effects of permethrin on human health may not be recognized for many years.” I find that to be very good advice.
I am quite aware of the risks of Lyme disease. I have been suffering from several for many years now. I got all of them in my own home and yard. I eventually found a perfect green method of tick control. For several years, I did not have to worry at home due to the chicken’s voracious tick appetites.  But I was still reluctant to turn to chemicals. Now, I am no longer allowed to keep a large enough population of chickens to prevent ticks. I am well aware of the ever increasing risks the ticks pose. I am also all too aware of the effects of neuro toxicity. I suffer from Neurological Lyme disease, which demyelinates my nerves (takes off the covering of my nerves)  and when trying to treat the infection, the spirochetes release toxins into my  brain. I know about neurotoxins. Still I choose to wear light colored clothing, tall boots and do frequent tick checks while trying to fight to once again be allowed to keep enough chickens to keep my family safe.
Now that I understand all the research I’ve collected and presented above, Despite the risks, I will not be applying any chemical repellents to my children. I might begin to only go outside wearing chest high gortex waders, but I will not expose my children, or the greater natural world, to these poisonous chemicals. The risk is too great for me.

Permethrin Resources: (the Proof)


Abu Qare, Aqel W, Abou Donia, Mohamed. Combined Exposure to Deet (N,NDiethylmToluamide) and Permethrin: Pharmacokinetics and Toxicological Effects. Journal of Toxicology and Environmental Health. 25 May 2012.

Endocrine Disruption Exchange. Citizen’s guide to permethrin. 7 2007. Retrieved from

Manikkam, Mohan, et al. Pesticide and insect repellent mixture (permethrin and DEET) induces epigenetic transgenerational inheritance of disease and sperm epimutations. Reproductive Toxicology. Vol 4 Iss 4. December 2012.

Mohammed B. Abou-Donia, Larry B. Goldstein, Katherine H. Jones, Ali A. Abdel-Rahman, Tirupapuliyur V. Damodaran, Anjelika M. Dechkovskaia, Sarah L. Bullman, Belal E. Amir, Wasiuddin A. Khan; Locomotor and Sensorimotor Performance Deficit in Rats following Exposure to Pyridostigmine Bromide, DEET, and Permethrin, Alone and in Combination. Toxicol Sci 2001; 60 (2): 305-314. doi: 10.1093/toxsci/60.2.305

University of California – Davis Health System. “Association found between maternal exposure to agricultural pesticides and autism.” ScienceDaily. ScienceDaily, 23 June 2014. <>.

Whiteman, Honor. Offspring autism risk linked to pesticide exposure during pregnancy. Medical News Today. 23 June 2014. Retrieved from


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