Calming West Nile fears - more advice from the American Academy of Pediatrics, Sept. 2002
Studies show insect repellents with a DEET concentration of 30% are more protective than lower concentrations, but that concentrations higher than 30% do not provide more protection. They simply last longer. In response to these findings, the Academy says a 30% concentration is safe for adults and children, but that 10% can be used for children if parents are concerned about the potential risks or if the threat of disease-carrying mosquitoes is small.
Update - June, 2003
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. DEET is not recommended for use on children under 2 months of age.
DEET-containing products are the most effective mosquito repellents available. DEET also is effective as a repellent against a variety of other insects, including ticks. It should be used when there is a need to prevent insect-borne disease. The concentration of DEET in products may range from less than 10% to over 30%. The efficacy of DEET plateaus at a concentration of 30%, the maximum concentration currently recommended for infants and children. The major difference in the efficacy of products relates to their duration of action. Products with concentrations around 10% are effective for periods of approximately two hours. As the concentration of DEET increases, the duration of activity increases; for example, a concentration of about 24% has been shown to provide an average of 5 hours of protection.