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EWG’s 2018 Guide to Bug Repellents
July 17, 2018

EWG’s 2018 Guide to Bug Repellents : Frequently Asked Questions

BUYING AND USING REPELLENTS

INGREDIENT SAFETY

BUG-BORNE ILLNESSES

ALTERNATIVE TECHOLOGIES

BUYING AND USING REPELLENTS

Q. When should I use tick/insect repellent?
Bug bites can be irritating and pose serious risks if the bugs in your area can transmit diseases such as Lyme disease or West Nile virus. Use repellents sparingly when needed. Higher concentrations of chemical repellents are generally not more effective, but may provide longer lasting protection. Use the right concentration for the amount of time you will be outdoors. There is no need to use a product with more than 30 percent DEET.

Q. How do I prevent tick bites?
Make sure the repellent you are using is rated for tick protection. Tuck your pants into your socks and apply repellent around your ankles. Consider permethrin-treated clothing since other repellents may be less effective at deterring ticks. Always check your body and your children’s bodies for ticks after returning indoors. Remember to check your dogs too!

Q. How do I apply repellents safely?
Always read product labels and follow all instructions. Take basic precautions to minimize your exposure. Start by applying a small amount to exposed skin. Do not apply to skin covered by clothing. Apply directly to clothes if mosquitoes are landing on or biting through clothing. Wash hands after applying. Do not let children apply their own repellent. When you return home, change out of treated clothes, and wash all treated clothing or body parts.

Q. How many hours of protection do I need?
As a general strategy, we recommend choosing a product based on how long you plan to be outside. Choose a short protection time product with a 5 to 10 percent concentration of picaridin, DEET, PMD or 2-undecanone, unless you are concerned about ticks or you know you will be outside for an extended period of time. Avoid products with high concentrations of chemical repellents that pose an unnecessary risk of over-exposure. Reapply repellent when you notice signs that it is wearing off.

Q. Where can I find out more about bug repellents and their active ingredients?
The EPA’s website allows people to search for registered bug repellents by active ingredient, mosquito and/or tick protection, and the number of hours of protection they offer.

Q. How does mosquito repellent work?
Mosquito repellents that are applied to the skin give off an odor that mosquitoes want to avoid. The repellent odor may confuse or discourage ticks and other bugs from landing or crawling on the treated item. The odor of DEET has been shown to stimulate receptors on the antennae of mosquitoes, and it blocks the skin’s release of mosquito-attracting compounds such as octanol, nonanal, decanol and geranyl acetone.1

Permethrin used to treat clothing is an insecticide and, according to the EPA, it targets the nervous systems of insects, “causing muscle spasms, paralysis and death.”2

Q. Are some people more attractive to mosquitoes than others?
Yes. Mosquitoes can smell natural chemicals that evaporate off skin. Some people smell better to mosquitoes than others. Perfume can bring unwanted mosquito attention. Studies show that DEET can reduce or block the release of many compounds that attract mosquitoes.3

Q: What should I do if I have an adverse reaction to a bug repellent?
Wash the repellent off skin and launder any clothing it touched. Monitor the reaction and contact your local Poison Control Center to report any potentially serious symptoms. Keep the product container for medical professionals to examine, and avoid products with that active ingredient in the future. Remember to test new repellents on a small patch of skin the day before you plan to use them all over the body.

Q. Can repellents be used on children?
Generally yes, but it is important to pick the least toxic option and take basic precautions to minimize any risk of overexposure. Do not use bug repellents on infants under 6 months old. Limit the amount of repellent used on a child, and avoid using repellents on children daily for an extended time. When using repellent on a child, apply it to your own hands and then rub them on your child. Avoid children's eyes and mouths and use it sparingly around their ears. Do not apply repellent to children's hands, as children tend to put their hands in their mouths. Make sure to wash repellent-coated skin when your kids come indoors or at the end of the day. The EPA suggests avoiding use of Oil of Lemon Eucalyptus or PMD on children. Health agencies offer conflicting advice about the DEET concentration safe for children. In 2016, the CDC recommended DEET with maximum concentrations of 20 to 30 percent for protection from Lyme disease borne by ticks. Health Canada recommends DEET at concentrations no greater than 5 to 10 percent for children. But this weaker concentration may not offer a strong defense against ticks with Lyme disease.

Q. How else can I protect young children from mosquito bites?
Dress young children in light-colored long-sleeve shirts and pants. Cover baby carriers and strollers with mosquito netting. Try a bed or crib tent. A ceiling fan may also dispel mosquitoes.

Q. Can pregnant and nursing women use bug repellents?
Yes, all licensed repellent products are registered for use during pregnancy and breastfeeding. Human studies haven't found any specific problems in babies born to mothers who use DEET during pregnancy. However, it is wise to take precautions to avoid both bug and tick bites, and excessive use of repellent during pregnancy. As a first line of defense, try to avoid tick bites by covering up with pants, socks, shoes and long-sleeve shirts.

Q. Why not use products that combine repellent with sunscreen?
We recommend that you avoid all products that combine repellent with sunscreen. Sunscreen must be reapplied every two hours, but reapplying combined products this frequently may overexpose you to repellent chemicals. And in at least one study, DEET was shown to decrease the SPF of sunscreens, which could increase your susceptibility to sunburns.4 As of 2016, the CDC recommended applying sunscreen first and then an insect repellent after the sunscreen dries.5

Q. Do all bug repellents work against ticks?    
No! You must look for a product that specifically claims to protect from tick bites. Repellents are not nearly as effective against ticks as against mosquitoes. Read the product label to ensure the product provides some protection from ticks or check the EPA’s repellent database.

REPELLENT CHEMICAL SAFETY

Q. Which products are safest?      
Repellent chemicals generally fall in the classification of "low" or "very low" toxicity, but unlike agricultural pesticides, they are designed to be applied directly to skin, sometimes repeatedly over the course of weeks or months. Bug repellents can generally be used safely, but minimize your risks by tailoring the product you use to the intensity of bug and disease risks. Some approved repellents have a better safety profile than DEET and can be as effective at preventing bites. There are also numerous products sold as natural repellents that offer some degree of protection. The downside? Plant-based repellents may not work against all species of mosquitoes and will probably need to be reapplied more frequently. Many botanical repellents are potential skin allergens. The EPA has less data on unusual adverse effects for ingredients and botanicals that are newer on the market. Take precautions when applying any repellent. Try new repellents on a small patch of skin the day before you plan to use them all over the body.

Q. What does EPA registration entail? Is it necessary to buy an EPA-registered product?
Nine bug repellent active ingredients have been registered with the EPA, which requires a standard list of safety tests and proof that these chemicals effectively ward off pests. A number of botanical ingredients are exempted from registration because EPA has determined they pose “minimal risks” to human health. These include citronella oil, mint oil, geranium oil, lemongrass oil and soybean oil. The safety and effectiveness data for these products are spotty, and most do not offer more than two hours of protection against mosquitoes.

Q. Do botanical repellents work?
Botanical ingredients may prevent bites, but vary in terms of effectiveness and duration. Read labels and try them out to see how long they last against the bugs you encounter. In general, products with Oil of Lemon Eucalyptus/PMD and Bite Blocker with soybean oil and geranium oil are the most effective.

Q. Are botanical repellents safer than synthetic ingredients?
Botanical ingredients are naturally derived, but can cause allergic reactions. Take precautions to limit excessive exposures. Citronella, geraniol and other botanical repellents can cause allergic skin reactions. Oil of Lemon Eucalyptus/PMD should not be used on children ages 3 and younger.

BUG-BORNE ILLNESSES

Q. Am I at high risk for Lyme disease?
In 2015, most Lyme disease cases were reported in 14 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia and Wisconsin. If you live in one of these states, you should take special precautions to prevent tick bites. Take extra care in the summer, since more than half of all new cases are confirmed in June and July. Read the CDC’s tips on preventing and diagnosing Lyme disease. And check out CDC’s Lyme disease map to find out if you are in a high-risk place.

Q. What is the risk of getting Lyme disease when bitten by a tick?
The answer depends on the type of tick, the deer population in your location and how long the tick was attached to the skin. Lyme disease is caused primarily by bites from the nymph stage of Ixodes scapularis, commonly known as the blacklegged tick or deer tick. Peak tick activity occurs during late June and early July. In high-risk areas of Connecticut, 10 to 30 percent of nymph deer ticks are infected. Infected ticks do not transmit the disease in the first 24 hours, and only a small fraction transmits the disease within 48 hours. It is critical to conduct thorough tick checks after returning indoors.6

Q. What should I know about West Nile virus?
West Nile virus is a mosquito-borne illness that has recently spread to nearly every state in the U.S. Cases peak in the summer and linger through early fall. About 80 percent of people who are infected with the virus do not show symptoms. Most of the rest have flu-like illness for days or weeks, and about one in 150 become seriously ill.7 People older than 60 are at greatest risk of serious infections. The only way to avoid West Nile virus is to prevent mosquito bites. If cases are reported in your area, make an extra effort to rid your yard of standing water, fix window screens, and cover up or use repellent when mosquitoes are out. 

Check out the CDC’s West Nile Virus map of cases diagnosed in 2018.

Q. I am traveling abroad. What precautions should I take to avoid bug-borne illness?
The five repellents the CDC recommends for protection from mosquito-borne diseases are DEET, picaridin, Oil of Lemon Eucalyptus/PMD, 2-undecanone, and IR3535. Products with these ingredients are all EPA-registered to provide protection from a wide range of biting insects and ticks. The risks vary by country, so consult your physician or the CDC's traveler information site for details about risks in the regions you plan to visit. 

ALTERNATIVE TECHNOLOGIES

Q. What bug repellent technologies should I avoid?       
EWG recommends that you avoid all aerosol repellents, all products that mix repellent and sunscreen, all products with more than 30 percent DEET, wristbands, repellent candles, bug zappers, yard insecticides and clip-on fans with repellent in them. These products are either ineffective or subject you to greater risk than lotion-based skin treatments.

Q. Are repellent candles worth it?
Repellent candles release botanical ingredients into the candle smoke and your breathing zone. They are an inhalation hazard for people near them. We recommend using other measures to keep bugs away.

Q. What about treated wristbands?
The data generally show that wristbands are not very effective. Try applying repellent on the cuffs of clothing to protect hands and wrists from bites.

Q. When should I consider repellent clothing?
Permethrin is the only chemical registered for use on clothing, shoes, nets and camping gear. It is an insecticide that is toxic to mosquitoes, ticks and other insects, and is more toxic than repellents approved for direct skin application. Pre-treated products are designed to withstand multiple uses and washing cycles. These products should be limited to use in extreme situations in locations with dense bug populations or high disease risks. As a precaution, do not launder these clothes with other clothing. Store in sealed containers out of the reach of children.

Q. What about clip-on repellent fans?
The two ingredients registered for use in clip-on repellent fans are more toxic than ingredients in lotions. We recommend you avoid these products and choose less toxic options.


References:

1 Zainulabeuddin Syed and Walter S. Leal, Mosquitoes Smell and Avoid the Insect Repellent DEET. Proceedings of the National Academy of Sciences, 2008, 105(36):13598-13603. Available at doi.org/10.1073/pnas.0805312105

2 Permethrin Facts. Environmental Protection Agency, 2009. Available at www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-109701_1-Aug-09.pdf

3 Zainulabeuddin Syed and Walter S. Leal, Mosquitoes Smell and Avoid the Insect Repellent DEET. Proceedings of the National Academy of Sciences, 2008, 105(36):13598-1360 Available at doi.org/10.1073/pnas.0805312105

4 Jocelyn Rodriguez and Howard I. Maibach, Percutaneous Penetration and Pharmacodynamics: Wash-In and Wash-Off of Sunscreen and Insect Repellent. Journal of Dermatological Treatment, 2016, 27(1):11-18, Available at doi.org/10.3109/09546632015.1050350

5 Travelers’ Health: Prevent Bug Bites. Centers for Disease Control and Prevention. 2016. Available at wwwnc.cdc.gov/travel/page/avoid-bug-bites

6 Kirby C. Stafford III, Tick Bite Prevention & the Use of Insect Repellents. Connecticut Agricultural Experiment Station, 2005. Available at www.compassionatecareveterinaryhospital.com/documents/5_5_RESOURCES_PHL_2_tickbiteprevention05.pdf

7 West Nile Virus Symptoms, Diagnosis, & Treatment. Centers for Disease Control and Prevention, 201 Available at www.cdc.gov/westnile/symptoms/index.html