Insect Repellents

Avoiding insect bites requires multiple strategies, such as wearing long-sleeved pants and shirts when outdoors. However, insect repellents are essential, too. 

 

To find the most effective mosquito repellents, Consumer Reports tested products containing deet or a chemical called IR3535, as well as those containing three plantlike, but chemically synthesized, ingredients: lemon eucalyptus, picaridin, and 2-undecanone. They also looked at repellents made with natural plant oils, such as geraniol, castor oil, soybean oil, citronella, and rosemary.

 

The most effective products against mosquitoes and other insects were: 

  • Sawyer Picaridin and Natrapel 8 Hour, each containing 20% picaridin kept mosquitoes from biting for 8 hours.

  • Off! Deepwoods VIII, which contains 25% DEET kept mosquitoes from biting for about 8 hours

  • Ben's 30% DEET Tick & Insect Wilderness Formula kept mosquitoes away for 7.5 hours

  • Repel Lemon Eucalyptus, containing 30 percent lemon eucalyptus, stopped them for 7 hours

  • The IR3535 products didn’t make their list of recommended sprays

  • Products that contained 5 percent picaridin or 7 percent deet also did not make the list.

 

NOTE: The Sawyer 20% Picaridin product (a synthetic plantlike pepper) was more effective at repelling mosquitoes and ticks than the deet products tested, making it the top insect repellent overall. The Sawyer product can be found at REI and on Amazon.

 

Insect repellents that use deet come in varying concentrations, ranging from 4 percent to 100 percent. Previous tests by Consumer Reports show that concentrations of 30 percent provide the same protection against mosquitoes as higher percentages for up to 8 hours. But higher concentrations of deet have been linked to rashes, disorientation, and seizures. That’s why Consumer Reports says you should avoid mosquito repellents with more than 30 percent deet and not use it at all on infants younger than 2 months.

 

Consumer Reports also advises skipping products made with natural plant oils, such as:

  • California Baby Natural Bug Blend (a blend of citronella, lemongrass oil, cedar oil, and other ingredients)

  • EcoSmart Organic, (which includes geraniol, rosemary oil, cinnamon oil, and lemongrass oil).

None lasted for more than 1 hour against Aedes mosquitoes, and some failed almost immediately. In addition, these products are not registered by the Environmental Protection Agency, which regulates skin-applied repellents and evaluates them for safety and effectiveness. Most plant-oil products are exempt from scrutiny by the EPA because the agency considers them to be a minimum risk to human health.  

  

For those of you who would like to see the Consumer Reports rating chart, please click on the following link:

www.consumerreports.org/cro/health/beauty-personal-care/insect-repellent/insect-repellent-ratings/ratings-overview.htm

 

Women who are pregnant or breast feeding can safely use deet, picaridin, lemon eucalyptus, and IR3535, according to the EPA, if they are applied properly.

 

Here are tips from the EPA on how to use insect repellent:

  • Apply repellents only to exposed skin or clothing—never put it on under clothing. Use just enough to cover and only for as long as needed; heavy doses don’t work better.

  • Don’t apply mosquito repellents over cuts, wounds, or irritated skin or immediately after shaving.

  • When applying to your face, spray first on your hands, then rub in, avoiding your eyes and mouth, and using sparingly around ears.

  • Don’t let young children apply. Instead, put it on your own hands, then rub it on. Limit use on children’s hands, because they often put their hands in their eyes and mouths.

  • Don’t use near food, and wash hands after application and before eating or drinking.

  • At the end of the day, wash treated skin with soap and water, and wash treated clothing in a separate wash before wearing again.

 

Additional commentary from Dr. Whitney Edwards MD:

  • Picaridin is CHMA’s preferred repellant.

  •  It doesn’t melt plastic (like camera bodies, which matters to her). 

  •  It does however sting like the dickens when you get it in your eye since it’s essentially a pepper. Of course DEET doesn’t feel too great either.  

  • Please note: the toxicity from DEET is related to the frequency of application, not the concentration.  Also duration of action is related to concentration, so that high percentage DEET products (ie 30%, not higher), applied less often, are actually safer. 

  • DEET-Sunblock combos should definitely be avoided since the frequency with which the sunscreen should be reapplied is much greater than you would want for the DEET component.

  • Consumer Reports did not comment at all about permethrin treatment for clothing. Whitney is under the impression that the treatment of clothing with permethrin is also an effective deterrent, used in conjunction with picaridin on the skin.  See: https://www.epa.gov/insect-repellents/repellent-treated-clothing

     

     

     

     

     

     

     

     

     

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