Last week, Broward Country Florida recorded the first two Zika cases transmitted by mosquitos in the United States. The Centers for Disease Control and Prevention (CDC) is urging pregnant women to assemble and deploy a “Zika Prevention Kit,” which is a good idea.
CDC’s suggested kit includes: bed nets; insect repellent; mosquito dunks, which are added to standing water to prevent development of mosquito larvae; permethrin spray for clothing; and condoms to prevent transmission of Zika through intercourse.
The fact that four out of five of these items use pesticides is illustrative of the importance of these chemical technologies. Bed nets are usually treated with pesticides to keep insects away; the mosquito dunks are a registered pesticide as well, even though their key active ingredient is a bacteria rather than a synthetic chemical, and the repellents are also pesticides.
Used properly, these products pose little risk, but can be effective in preventing mosquito and tick transmitted diseases like Zika, West Nile virus, Lyme disease, and many others. Unfortunately, many people may be afraid to use these products because of unsupported hype about their alleged risks.
For example, the website Mercola.com maintains: “Most insect repellants out there are loaded with toxic chemicals, including the pesticide DEET, which is so poisonous that even the Environmental Protection Agency says you should wash it off your skin when you return indoors, avoid breathing it in and not spray it directly on your face.”
Yet pretty much any product—manmade or “natural”—requires care in how it’s used. In fact, the U.S. Environmental Protection Agency’s (EPA) guidelines on repellents that Mercola apparently cites applies to all repellents—including botanical products that Mercola recommends. And while the EPA recommends DEET as safe for children, it points out: “According to the label, oil of lemon eucalyptus products should not be used on children under the age of three [emphasis original]. Other ingredients do not have an age restriction.” This indicates that this allegedly more “natural” product may pose greater risks than DEET.
In fact, there are no documented cases of anyone dying or suffering serious long-term health effects from the proper use of DEET. There have been concerns that excessive application of DEET on children caused seizures, but these claims were based on a handful of inconclusive cases.
In 2003, Researchers published a review of these cases in the Canadian Medical Association Journal. They could only find ten case reports of children suffering from seizures possibly related to DEET, and none were conclusive. Given that 3 to 5 percent of children suffer from such seizures for a variety of reasons and that 23 to 29 percent of children are exposed to DEET, it is possible that the cases were incorrectly attributed to DEET. “Nonetheless, these case reports have been widely quoted and have led regulatory agencies and pediatric societies to limit use of DEET in young children,” the researchers note.
In contrast, the insect-borne diseases that DEET applications can prevent levy a heavy toll on public health. For example, the CDC reports that last year alone there were 2,060 reported West Nile virus cases, 119 deaths, and 1,360 cases of neuro-invasive illnesses that can have long-term debilitating effects. In 2014, there were more than 25,000 cases of Lyme disease, which CDC says is “the most commonly reported vectorborne illness in the United States.” And now we must also be concerned about Zika and the birth defects it may produce.
The EPA has long maintained that DEET is very low risk, while providing important health benefits. Its most recent evaluation in 2014 explained: We continue to believe that the normal use of DEET does not present a health concern to the general population, including children.”
Regarding the benefits of DEET, the EPA notes:
DEET’s most significant benefit is its ability to repel potentially disease-carrying insects and ticks. The Centers for Disease Control and Prevention (CDC) receives more than 30,000 reports of Lyme disease (transmitted by deer ticks) and 80-100 reports of La Crosse encephalitis virus (transmitted by mosquitoes) annually. A total of 48 states and the District of Columbia have reported West Nile virus infections in people, birds or mosquitoes to CDC.
Each of these diseases can cause serious health problems or even death in the case of encephalitis. Where these diseases are prevalent, the CDC recommends use of insect repellents when out-of-doors. Studies in EPA’s database indicate that DEET repels ticks for about two to ten hours, and mosquitoes from two to twelve hours depending on the percentage of DEET in the product.
Insect repellents containing DEET have the longest record of demonstrated safety and effectiveness, which explains why both CDC and EPA recommend it. In fact, a 2002 study published in the New England Journal of Medicine that evaluated the effectiveness of various insect repellents on the market found that: “DEET-based products provided complete protection for the longest duration.” In fact, DEET effectiveness lasted 15 times longer than so-called “natural” botanical products. The study also noted that DEET has been in use for decades with few health repercussions. Accordingly, researchers dubbed DEET as the “gold standard for protection” against dangerous insect-borne diseases.
Zika, West Nile, Lyme, and other insect-transmitted illnesses pose serious risks, and DEET is among the best tools available to prevent their transmission. Expecting mothers—or anyone else—should not fear DEET and other EPA-approved pesticides as long as they follow the directions on the label. The real danger lies in remaining inadequately protected because of misinformation about DEET and other pesticide risks.