NCPA - National Center for Policy Analysis


June 24, 2004

Worries about West Nile virus and other bug-borne diseases have raised new questions about the risks and benefits of insect repellent.

The biggest debate is whether to use the chemical known as DEET, found in many commercial insect repellents like Deep Woods OFF! or to turn to "natural" bug fighters like citronella or soybean oil. A "Fight the Bite" publicity campaign from the Centers for Disease Control and Prevention calls for more people to use DEET to battle mosquitoes.

But while DEET does scare away mosquitoes, it scares many people too. Products with DEET -- which shows up as N,N-diethyl-meta-toluamide on the label -- have been safely used since the 1940s, however:

  • In nearly 60 years of use, there have been fewer than 50 cases of significant side effects attributable to DEET.
  • Even in cases of accidental overexposure in children, 85 percent of cases resulted in no symptoms.
  • A product with a 23.8 percent DEET concentration kept mosquitoes away for an average of 301.5 minutes.
  • Oil of eucalyptus repelled bites for about 120.1 minutes, while a product with 10 percent citronella worked for only 19.7 minutes.

Fears about DEET have been fueled in the past by reports of neurological reactions like confusion or seizures, but those rare cases involved DEET products that were overused or applied to broken skin. The skin can absorb from 6 to 17 percent of the DEET from a mosquito-repellant, but the body will eliminate the chemicals within 12 to 24 hours.

Source: Tara Parker-Pope, "Backyard Dilemma: Which Is Worse--Using DEET or Possibility of West Nile?" Wall Street Journal, June 22, 2004.

For text (subscription required),,SB108784874929743171,00.html


Browse more articles on Environment Issues