The People's Perspective on Medicine

Are Insecticides Bad for Your Heart?

Greater exposure to pyrethroid insecticides was linked to higher mortality from heart disease in a new study published in JAMA Internal Medicine.
Tractor sprays insecticide in apple orchard fields image

Insecticides are designed to be bad for bugs, but are they also bad for humans? Often, people assume that if insecticides applied to their homes don’t make them sick right away, they are safe. However, a new study calls that into question. People with high levels of common pest control chemicals known as pyrethroids were more likely to die over the decade (JAMA Internal Medicine, online Dec. 30, 2019). 

Studying Exposure to Insecticides:

The scientists used data collected at the turn of the 21st century from participants in the National Health and Examination Survey (NHANES, 1999-2002). In addition to answering comprehensive questionnaires, the volunteers provided urine samples. The researchers analyzed these for evidence of 3-phenoxybenzoic acid (3-PBA), a metabolite of pyrethroids. They also collected mortality data on these adults through the end of 2015.

What they found is somewhat alarming. People with the highest levels of 3-PBA in their urine were more likely to die during the follow-up period. Although the investigators found no association with death from any form of cancer, participants with the highest urinary levels of 3-PBA were three times more likely to die of heart disease.

Why This Study Matters:

In an editorial that accompanies the report, public health experts Stellman and Stellman point out why this is troubling (JAMA Internal Medicine, online Dec. 30, 2019). Pyrethroid pesticides are very widely used around the world as well as in the US. Public health programs rely on this family of chemicals to control dangerous disease-bearing insects such as mosquitoes carrying West Nile virus or dengue. Experts have assumed that these pyrethroids are safe for humans. Previous research hinted that pyrethroids may disrupt hormones and puberty. This evidence that insecticides could harm cardiovascular health means that researchers need to examine this problem more closely. 

What Should You Do?

In the meantime, you might wish to avoid such insecticides when possible. For most people, eating vegetables and fruits that were sprayed with pyrethroids provides the greatest exposure. People who do agricultural work and those who use pyrethroids in their gardens or homes expose themselves to additional risks.

This study established a correlation, and we need to remember that correlation is not causation. Still, concerned individuals could minimize their use of insecticides in their homes and gardens. To limit pyrethroid exposure, they might avoid the EWG “Dirty Dozen” and eat organically grown alternatives when possible. This could be prudent until we have more information on the exact nature of the link between these compounds and cardiovascular health.

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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, online Dec. 30, 2019. doi:10.1001/jamainternmed.2019.6019
  • Stellman SD et al, "Pyrethroid insecticides—Time for a closer look." JAMA Internal Medicine, online Dec. 30, 2019. doi:https://doi.org/10.1001/jamainternmed.2019.6093
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Terry, is this the class of chemical that comes from marigold flowers and was supposed to be less harmful to use in the garden? If so, this is worrisome. Thanks!

I did a little research on pyrethroid pesticides after reading your article. I found the article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174339/
to be of concern. Curious, I called our exterminator to ask what their technician uses in our home and received a reply email saying he uses a product called Cyzmic. The active ingredient in Cyzmic is is Lambda-Cyhalothrin, a pyrethroid pesticide.

While I LIKE having a home free of vermin, I also like having healthy cardiovascular, neurological, etc. systems. I was particularly concerned by the above article’s statement (it appears this product) crosses the blood/brain barrier.

I’d love input from chemists, pharmacists and medical professionals regarding how to find “safer” products and, if there is such a thing, should I request a different product?

Does washing with a vinegar solution remove the residue?

I use Permethrin treated clothing to keep ticks off when working outside. Although the name is not the same, is it in the same class? Do you know if this could be absorbed through my skin? It works great to keep ticks off! But my heart is important too!

It is in the same class. Since the clothing is pre-treated, we don’t think that the insecticide penetrates the skin to a significant extent. A pilot study in North Carolina found that permethrin-impregnated clothing retained its ability to repel and/or kill ticks for at least three months, with absorption into the bloodstream “well below the EPA level of concern.” Here’s the link:
https://www.ncbi.nlm.nih.gov/pubmed/30674346

On the other hand, German military personnel wearing permethrin-impregnated battle gear in Afghanistan had body levels 200 times higher than the average German person. Link to this one:
https://www.ncbi.nlm.nih.gov/pubmed/24343973

An earlier study, also by the military, concluded that while DEET on the skin enters the bloodstream readily, permethrin on clothing does not. Link: https://www.ncbi.nlm.nih.gov/pubmed/16578980

We’ll keep looking for more data on this. Of course, it is also important to prevent Lyme disease, which has a deleterious effect on the heart as well.

Can you clarify whether this study was strictly about synthetic pyrethroids, or also included the organic pyrethrins allowed in organic production?

The biomarker they used, 3-PBA, might not discriminate between synthetic and organic pyrethroids. They did not specify in the article.

Synthetic pyrethroids for this study.

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