IS DEET safe?
The ingredient DEET ((N,N-diethyl-m-toluamide) in insect repellents is safe when used according to directions on the container, according to the U.S. Environmental Protection Agency (EPA). For approval, the EPA requires manufacturers seeking registration of a product to present laboratory data showing safety and efficacy supported by extensive testing on both the short-term and the long-term health effects of the chemical. DEET passed this stringent test, and has been extensively used all over the world. Very few incidents of toxicity have been reported over its long history.
Why use insect repellent?
Insect repellents greatly minimize people’s exposure to tick bites and mosquito bites which may transmit potentially serious illnesses, such as West Nile viral infection, dengue fever, malaria, etc. The use of such repellent also allows individuals to indulge in outdoor activities, recreational or labor-related.
When should the repellent be applied?
It should be used before going outdoors, especially in known endemic areas for mosquito-borne illnesses. While the West Nile virus-carrying mosquitoes usually bite around dusk and dawn, some have been reported to bite during the day. The prudent thing to do is to use insect repellent whenever going outdoors, where mosquitoes abound.
Should it be reapplied?
Since perspiration, washing or rain may render the first application useless, the repellent should be reapplied accordingly, following the instructions on the container. Those preparations with higher concentration of DEET are not any superior or more effective, but will provide longer lasting protection.
How about indoors?
Not really, unless you see or feel mosquitoes indoors. In this situation, the use of repellent is necessary. More importantly, check on all window and screen doors which may have holes in them, and making sure the doors and windows are always properly shut. Getting rid of stagnant waters (in potholes and containers) near the house also helps eliminate mosquito breeding places.
How does DEET work?
The reason why female mosquitoes bite people and animals is to suck the blood that contains the protein to help develop their eggs. The skin odors (even perfume, cologne or skin lotion) and carbon dioxide from our breath attract mosquitoes. Like other mosquito repellents, DEET repels mosquitoes, making the wearer unattractive for feeding. It makes mosquitoes unable to “find” the person. If you wear DEET and you are not being bitten my mosquitoes flying around, you know the repellent is working. If you still get a bite, then you have to reapply the chemical.
Which one works best?
The repellent that contains DEET has been proven to be the most effective. The higher the concentration (up to 50 percent only) of DEET, the longer the action is. Studies done in 2002 have shown that at 23.8 percent DEET, it provides almost 5 hours of protection; at 20 percent, 4 hours; at 6.65 percent, 2 hours; and, at 4.75 percent and 2 percent soybean oil were both (each) about 1 ½ hours. The rule of thumb is: choose the concentration that you could use for the various lengths of time you will be outdoors, since you can always reapply if needed for a longer period.
Are non-DEET repellents equally effective?
Plant-based repellents that are applied to the skin also provide some protection, but DEET appears to provide longer lasting protection. Product labels usually states on them the duration of protection. Individuals concerned about using DEET should consult their physician. You could also access the National Pesticide Information Center (NPIC) over the Internet at www.npic.orst.edu. Those repellents with DEET are labeled accordingly.
How should repellent be used?
(1) Read and follow the instructions on the label of the container; (2) Apply repellent on the skin that is exposed, not the skin under the clothing; (3) Do not over-apply; (4) Do not apply to wounds, irritated skin or cuts and bruises; (5) Upon return indoor, was the treated skin with soap and water; (6) Apply the spray aerosol or pump outdoors and not in an enclosed area or room; (7) Do not spray directly to the face, spray the hands and then rub them gently to the face, avoiding the eyes and mouth; and (8) The adult should apply the repellent on young children, excluding the children’s hands to prevent eye or mouth contamination.
Is DEET safe for children?
There are no specific studies done on the use of DEET in children. However, the American Academy of Pediatrics (AAP) Committee on Environmental Health has this report: “Insect repellents containing DEET (N,N-diethyl-m-toluamide, also known as N,N-diethyl-3-methylbenzamide), with a concentration of 10% appear to be as safe as products with a concentration of 30% when used according to the directions on the product labels.” The AAP and other experts say it is acceptable to apply repellent with low concentrations of DEET to infants over 2 months old. Other guidelines cite that it is acceptable to use repellents containing DEET on children over 2 years of age. Check with your pediatrician for more details.
Is allergy to DEET possible?
Yes. As a matter of facts, there are occasional reports of skin allergy to some DEET preparations. If this happens, wash the areas with soap and water and consult your physician. As far as conclusive studies on pregnant women or data on its effects on the fetus, we are unable to find any, so we recommend against its use by them.
Can DEET be used with sunscreen lotion?
Yes, this is recommended during daytime. Apply sunscreen first and then DEET containing repellent. Some preparations have both, but the use of these combination products is discouraged, because sunscreen may need to be applied more often than DEET repellent. Applying DEET preparation to clothing also helps.
How about non-chemical strategies?
The less chemicals or drugs we use, the better, and the lesser expensive, as long as we have equally effective and safer alternatives. If wearing long sleeve shirts, head nets and gloves (or, mosquito tent or net) will not interfere with the outdoor activities, and is effective, this is the best choice. However, realistically and logistically, this strategy may be cumbersome and impractical. In this situation, insect repellent may be resorted to. Always remember to take a shower or wash the areas with repellent thoroughly with soap and water after the outdoor activities.
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Philip S. Chua, MD, FACS, FPCS, Cardiac Surgeon Emeritus in Northwest Indiana and chairman of cardiac surgery from 1997 to 2010 at Cebu Doctors University Hospital, where he holds the title of Physician Emeritus in Surgery, is based in Las Vegas, Nevada. He is a Fellow of the American College of Surgeons, the Philippine College of Surgeons, and the Denton A. Cooley Cardiovascular Surgical Society. He is the chairman of the Filipino United Network – USA, a 501(c)(3) humanitarian foundation in the United States. Email: [email protected]
