What has been my experience with DEET?I write this as someone who has had a long intellectual and personal involvement with DEET as an insect repellent. Growing up in the Upper Midwest in the 1960s my family spent much of the time during our relatively short summers outside enjoying the many wonderful lakes in the region. My memories of summer are those of long sunny days, picnic lunches and fishing. Oddly enough, the smell of DEET repellents also is part of that memory. Those days were years before Lyme disease and West Nile virus were ever heard of. We used DEET simply because it prevented the annoying harassment and bites from what in Minnesota was often referred to as “the Minnesota State Bird,” the mosquito.
Being the child of Great Depression-era parents from immigrant families, we were taught a very important lesson that happened to pertain to insect repellents as well as so many other aspects of life: use only what is necessary and not any more. So, we did, as did my friends. My parents knew nothing of the complex chemical feeding triggers that are picked up by mosquitoes triggering them to seek a host and feed. But my parents had common sense: when the mosquito pressure was intense and we were getting bitten, like on calm days at dawn and dusk, we told to carefully reapply the repellent.
From a professional perspective
I have a doctorate in toxicology (the study of toxicity of chemicals) and am certified in toxicology by the American Board of Toxicology. I have been practicing toxicology for over 25 years in industry and consulting and have spent a significant amount of time studying DEET. Often referred to by experts as “the gold standard” for repellents, DEET has been a most effective repellent, and has a reliable safety record when used according to label directions. As Dr. Mark Fradin says in a landmark medical journal article (
http://www.annals.org/cgi/content/full/128/11/931), DEET has a “remarkable safety profile.” I agree.
The proof of DEET’s reliability is in the data, and there’s more scientific data on DEET than just about any other ingredient used by consumers in any kind of product. Much of the data comes from well-designed, properly executed, and appropriately interpreted studies. I played a leadership role in a major study (The DEET Registry of Adverse Events) that included a team of physicians, nurses and scientists that collected reports on “adverse events,” or health incidents, reported over a seven-year period in some way associated with the use of DEET.
We thoroughly reviewed each report to determine if DEET might have caused any of the more serious health issues. Over seven years, we logged 242 cases that warranted further analysis. Our team determined that just one case of major severity was probably related to DEET. It was likely an allergic reaction (non-neurologic) to the product. We found 12 cases of neurological effects of major severity that we categorized as possibly related to DEET. The “Possibly Related” category means that the individuals had used DEET prior to the reaction and we could find no other reasons why they experienced the adverse events. Even if we assume that DEET had played a role in these reports, 13 cases is amazingly few, given the millions of users and billions of applications of DEET-based repellents over the seven years of the Registry.
It also is noteworthy that our data showed no indication that use of DEET in combination with common medicines or other compounds resulted in adverse effects in humans. Recognizing the extensive use of DEET by Americans, and considering the relatively few adverse events described in the Registry, I believe that the risk of serious health effects in humans following use of DEET repellents according to label directions is quite low.
Despite the overwhelmingly positive data on DEET, exceptions exist. These include laboratory studies that some critics of DEET inappropriately cite to make inferences about toxicity to humans. In many cases, it has been my job to carefully review these studies and determine their relevance and applicability to humans. Without exception, I have done so with an abundance of caution, because—as mentioned above—I too am a DEET user. None of these studies have caused me to change my view of DEET. Moreover, you can rely on the recommendations from the CDC, the AAP and the EPA for guidance as their physicians and scientists have combed the data as well.
So how do I approach the use of DEET now?When I consider the use of DEET either on myself or on my family, I consider the risk versus the benefit. If we lived in an ideal world, no consumer product would ever cause adverse events in anyone, under any conditions. But most do. Consider the valuable pain-reliever acetaminophen. The FDA reports that it causes more than 400 deaths annually in the United States. A 2009 study by a CDC team found that overdoses in children account for more than 7,200 emergency room visits annually. We find acetaminophen valuable, so we all still have it in our homes. We’re just reminded each time we use it to read the label instructions.
Some things have changed since I was growing up. Mosquitoes are more than just annoyances—some carry diseases that can be debilitating and even fatal. Ticks, which were very uncommon when I was a child, are far more prevalent now and Lyme Disease is a serious public health issue. I personally know several people who have had the disease in Virginia over the past year. A good change: new DEET repellent formulations have improved scents and skin feel, and are barely reminiscent of the formulations used when I was a child.
As much as we can lament the emergence of mosquito- and tick-borne disease, happily some things have not changed. The warm summer days and long daylight hours are just as delightful as ever and must be savored to the fullest. I still take pleasure personally in those, but now also get the joy of seeing my children enjoy the outdoors. Mosquitoes are just as annoying as before. And DEET repellents are just as effective as when I was a child. Moreover, what my parents taught me when I was a child is just as true and prudent today as it was then: use only what is necessary and not any more.
Regulatory Toxicology and Pharmacology, Feb 2010
