James R. Roberts, MD, MPH, FAAP;
William B. Weil, Jr, MD, FAAP; and
Michael W. Shannon, MD, MPH, FAAP

AAP News - June, 2005

- Reprinted with permission of AAP News -

In April, the Centers for Disease Control and Prevention (CDC) revised its recommendations for mosquito control to include compounds that contain picaridin (1-methylpropyl 2-(2-hydroxyethyl)-1-piperidinecarboxylate, also known as KBR 3023).

The repellent has been in use in Europe, Australia, Latin America and Asia for years and originally was registered by the Food and Drug Administration in 2000 but has just been recommended by CDC in terms of efficacy and safety when used as directed. The mechanism of action appears to be the same as for DEET. Picaridin currently is available in 5% to 10% solutions.

In addition, CDC has indicated that oil of lemon eucalyptus (P-menthane diol; PMD) also is registered with the Environmental Protection Agency and is comparable in its duration of effectiveness to lower concentrations of DEET. Earlier studies also indicate that 2% soybean oil has similar levels of effectiveness. The range of DEET concentrations that have been shown to be similar in duration of action to these other products generally are in the 6.65% to 15% range. The mechanisms of action for oil of lemon eucalyptus and for soybean oil have not been determined.

Although all of these products are considered safe when used appropriately, long-term follow-up studies are not available, with the exception of DEET. There are insufficient data to determine the efficacy of these newly recommended repellents against ticks.

It should be noted that the methods used to measure duration of efficacy vary from field tests to laboratory "arm-in-cage" experiments, and within each method there are other variables that lead to somewhat different results.

It appears, however, that picaridin and DEET have similar effectiveness at comparable concentrations. Estimated protection time varies by study and type of mosquito being tested, but the range for both has been between 3 and 7 hours in most studies. Some studies have required DEET concentrations of 25% to meet the longer protection time. Oil of lemon eucalyptus is close behind DEET and picaridin, followed by 2% soybean oil; all other substances are less effective than these.

Using DEET and sunscreen products at the same time is an acceptable practice. However, the use of combination products is not recommended because the sunscreen needs to be reapplied after swimming, whereas the mosquito repellent generally does not need to be reapplied. There is no reason to use more than one repellent at a time and no data exist about the safety of such an action.

Although little information is available on the combined use of repellents other than DEET with sunscreen, it is likely that similar recommendations will be forthcoming.

Both the Academy and the EPA recommend the following precautions when using insect repellents:

• Apply repellents only to exposed skin and/or clothing (as directed on the product label). Do not use repellents under clothing.
  
  
• Never use repellents over cuts, wounds or irritated skin.
  
  
• Do not apply to eyes or mouth, and apply sparingly around ears. When using sprays, do not spray directly on face — spray on hands first and then apply to face.
  
  
• Do not allow children to handle the product. When using on children, apply to your own hands first and then put it on the child. Do not apply to children's hands.
  
  
• Use just enough repellent to cover exposed skin and/or clothing. Heavy application and saturation generally are unnecessary for effectiveness.
  
  
• After returning indoors, wash treated skin with soap and water or bathe. This is particularly important when repellents are used repeatedly in a day or on consecutive days. Also, wash treated clothing before wearing it again. (This precaution may vary with different repellents — check the product label.)
  
  
• If a child develops a rash or other apparent allergic reaction from an insect repellent, stop using the repellent, wash it off with mild soap and water and call a local poison control center for further guidance.

As indicated in the AAP handbook, repellents are not recommended for children younger than 2 months of age ( AAP Committee on Environmental Health. Pesticides. In Etzel RA, ed. Pediatric Environmental Health. 2nd edition. Elk Grove Village, IL. American Academy of Pediatrics; 2003:350).

Other than recommendations listed here, EPA does not suggest any additional precautions for using registered repellents on pregnant or lactating women, or on children.

Dr. Roberts and Dr. Weil are members of the AAP Committee on Environmental Health. Dr. Shannon chairs the committee.