A recent study looked at more than 2,000 US adults who had their urine tested once for pyrethroid metabolites (permethrin is the most common kind of pyrethroid), then roughly 14 years later looked at heart attacks, cancer, and all causes of death. The subjects with the highest levels of pyrethroid were 3 times more likely to die of heart disease.
HOWEVER – the study had many limitations, including a relatively small number of people who died from heart attacks, and it didn’t prove causation. Pending more research, limiting your exposure to permethrin might be a good idea, or maybe switching to DEET (which has its own problems). On the other hand, getting Lyme Disease or any of the dozens of other insect-carried diseases is a known and serious hazard to your health.
Personally, I’ll continue to apply permethrin to hiking clothes, packs, and tents following Sawyer’s directions, or use factory-treated clothing. Don’t spray it on your body!
JAMA Internal Medicine study, with some interesting comments:
https://dx.doi.org/10.1001/jamainternmed.2019.6019
Consumer Reports readable summary with background plus advice on limiting your exposure:
https://www.consumerreports.org/pesticides-herbicides/common-pesticides-linked-to-heart-disease-risks-in-new-study/
— Rex
