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Avoiding Insecticides That Could Harm the Heart

Pyrethroid pesticides may increase cardiovascular risk, although these compounds work to repel ticks. People want help on avoiding insecticides.
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We get excited about sharing new research that could have an impact on health. And we really appreciate it when our readers raise practical questions about the implications of the study. A recent report in JAMA Internal Medicine showed that people who had been exposed to high levels of pyrethroid pesticides were at higher risk for heart problems and early death. Consequently, we were pleased when an astute visitor asked about avoiding insecticides in tick-resistant clothing. We only wish our answer could be more definitive.

Avoiding Insecticides in Treated Clothing: 

Q. I read a news story on your website about pyrethroid insecticides harming the heart. I use permethrin-treated clothing to keep ticks off when I work outside to reduce my risk of Lyme disease.

Do you know if people absorb such chemicals through their skin? These clothes work great to keep ticks off, but my heart is important too!

Pesticides and Heart Disease:

A. The research you refer to was published in JAMA Internal Medicine (Dec. 30, 2019). People exposed to such insecticides were at greater risk of dying from cardiovascular disease. In a comparison of people with the highest levels of pyrethroid metabolites in the urine to those with the lowest levels, death rates in 14 years were 11.9 percent and 8.5 percent respectively. Most of the difference was due to heart disease and strokes. There was no difference in the risk of cancer.

Is Permethrin-Treated Clothing Hazardous?

Unfortunately, there is not much research on whether or not permethrin-treated clothing poses a problem. Some studies show marginal absorption. A study of the German military, however, showed that soldiers wearing permethrin-impregnated uniforms had high levels of permethrin metabolites in their urine (Occupational and Environmental Medicine, Feb. 2014). In another study, scientists issued ordinary work pants or permethrin-treated pants to German forestry workers (Journal of Exposure Science & Environmental Epidemiology, Jan-Feb. 2016). Those wearing the treated pants had significantly higher levels of permethrin metabolites. Nonetheless, these were below the proposed WHO threshold for acceptable daily exposure. 

On the other hand, North Carolina state and county park employees volunteered for a different trial (Parasites & Vectors, Jan. 23, 2019). For three months, they wore long-lasting permethrin-impregnated clothing to work. The scientists monitored urinary levels of three different permethrin metabolites. In addition, they tested the ability of the socks and pants to kill ticks at the end of the time. That remained high. 

In summary, the investigators concluded:

“The estimated absorbed dosage of permethrin was well below the U.S. EPA level of concern, suggesting that LLPI clothing can be used safely by outdoor workers for tick bite prevention.”

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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Citations
  • Bao W et al, "Association between exposure to pyrethroid insecticides and risk of all-cause and cause-specific mortality in the general US adult population." JAMA Internal Medicine, Dec. 30, 2019. doi:10.1001/jamainternmed.2019.6019
  • Kegel P et al, "Biomonitoring in wearers of permethrin impregnated battle dress uniforms in Afghanistan and Germany." Occupational and Environmental Medicine, Feb. 2014. DOI: 10.1136/oemed-2012-101279
  • Rossbach B et al, "Biomonitoring and evaluation of permethrin uptake in forestry workers using permethrin-treated tick-proof pants." Journal of Exposure Science & Environmental Epidemiology, Jan-Feb. 2016. DOI: 10.1038/jes.2015.34
  • Sullivan KM et al, "Bioabsorption and effectiveness of long-lasting permethrin-treated uniforms over three months among North Carolina outdoor workers." Parasites & Vectors, Jan. 23, 2019. DOI: 10.1186/s13071-019-3314-1
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If you understand the behavior of ticks you can use pesticides safely. Ticks only live in the lower area of plants, only as high as your knee, where their chances of getting on an animal are very good. So, if you wear pants and socks over your pants and spray your cloths from the knee down your chances of getting a tick or chiggers are almost nil, and your exposure to pesticides is greatly reduced.

In my past research regarding causes of Parkinson diseases, Pyrethrin compounds, synthetic and organic, were discussed as causal. Before using Pyrethrin I would investigate again this research.

I have been spraying my outside work pants and boots with permethrin for nine years in an effort to keep ticks and chiggers off me. I re-treat about every six weeks or so and try not to launder any more than necessary in between treatments. I also sometimes spray street shoes, jeans, carpeting in my vehicle, and also occasionally around house entry points. It has been my understanding that once dried it will not be harmful. Permethrin is deadly to cats until surfaces have dried.

Not a fan of pyrethroid metabolites in my urine, but, I wonder if the root cause of the 50% increase in relative-risk of (vascular related) death were the myriad of infectious tick-vectored microbes that just happen to correlate to pyrethrin use?

Getting to the bottom of this would be a Two-fer…since we learned, on your show, from Dr. Dale Bredesen that infections play a crucial role in AD.

I think one will need to dig into the numbers on this issue. I wonder if, in the original study, pyrethrum urine metabolite values were above or below the EPA approved levels. We thought it was relatively safe until this recent study.

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