Years ago, a pest problem required a visit from an exterminator to deal with flying wood roaches that had made their way into a Midwestern home. With young children in the house, there was concern about using harsh chemical sprays indoors. The exterminator assured that the spray being used contained pyrethrins—a substance “naturally derived” from chrysanthemums—and claimed it was completely safe.
That wasn’t entirely accurate.
While pyrethrins and their synthetic counterparts, pyrethroids, are considered safer than older pesticides like organophosphates (which originated as nerve agents during wartime), they are far from harmless. Pyrethroids are now widely used and found in everything from lawn treatments and mosquito sprays to pet shampoos, lice treatments, and household insect repellents.
Though derived from a natural plant source, the versions used in commercial products are typically synthetic, designed to be more potent and fast-acting. These chemicals target the nervous system of insects, overstimulating them before ultimately killing them.
The rise in popularity has been significant. As of 2009, the U.S. Environmental Protection Agency (EPA) identified over 3,500 commercial products containing pyrethrins or pyrethroids. These substances are sprayed in homes, on school grounds, in restaurants, hotels, and on food crops. Suburban lawns and public spaces are frequently treated with them. And exposure is nearly impossible to avoid.
A study from the University of California found pyrethroid residues in the urine of over two-thirds of adults and children from 90 families tested. Another long-term study published in JAMA observed over 2,100 adults for 14 years. Those with detectable pyrethroid levels in their systems had significantly higher risks of death from all causes—particularly cardiovascular disease. The risk of early death was found to be up to 56% higher.
In short, the so-called “safe” insecticide isn’t quite so harmless. And those at highest risk include young children and breastfeeding mothers. Pyrethroids can accumulate in the body, and research suggests they can be passed to infants through breast milk.
Acute exposure to pyrethroids may cause symptoms like coughing, wheezing, nasal irritation, chest discomfort, rashes, or blistering skin. Long-term exposure is more serious. These chemicals are known to disrupt the endocrine system, mimic estrogen, and contribute to hormonal imbalances. In women, this may increase the risk of hormone-related cancers. In men, exposure has been linked to reduced testosterone, lower sperm counts, and hormonal shifts.
Pyrethroids have also been classified as neurotoxins. There is evidence of their connection to learning issues, behavioral changes, tremors, and even an increased risk of conditions like Parkinson’s and dementia.
So, while marketed as safe and derived from nature, the reality is much more complicated.
Reducing exposure starts with awareness. Avoiding the use of chemical insect repellents, questioning community-wide mosquito spraying, and steering clear of synthetic pest treatments on lawns and in homes are all steps in the right direction. Natural alternatives, like essential oils, can offer an effective and safer approach. And sometimes, simply dealing with a bug the old-fashioned way—without chemicals—is the best choice for long-term health.
