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 away 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. Still, many consumers are wary of putting a chemical on their skin that can also dissolve fishing wire, fabrics and glasses frames. In rare cases, mostly due to improper use, DEET products have been linked with skin reactions, breathing problems and even seizures.

With a growing number of cases of West Nile and other bug-related illnesses, many DEET-wary families are wondering if they should rethink their stance. Here's a look at what we know about DEET and West Nile.

How do the risks of becoming sick from a bug-borne illness compare with the known risks of DEET? There have been far more cases of West Nile virus from mosquitoes and Lyme Disease from ticks than cases of health problems associated with DEET, notes Kimberly Thompson, associate professor of risk analysis at Harvard School of Public Health. Last year, there were more than 9,800 U.S. cases of West Nile virus and 264 deaths. In 2002, there were 23,000 cases of Lyme Disease, which is treatable and rarely fatal but can cause long-term problems. In nearly 60 years of use, there are fewer than 50 cases of significant side effects attributable to DEET reported in medical journals, notes Mark S. Fradin, clinical associate professor of dermatology at University of North Carolina at Chapel Hill.

Your real risk for contracting a bug-borne illness depends on a variety of factors, including where you live. You can find out about West Nile in your state by going to www.cdc.gov/ncidod/dvbid/westnile/ or to learn about Lyme Disease go to www.cdc.gov/ncidod/dvbid/lyme/. [CLICK ON THE LINK BELOW TO GO TO THE CDC WEBSITE]

Although the risk of West Nile is real, keep things in perspective. Most people who develop the virus don't even know it or experience only mild flu-like symptoms. The people at the highest risk for getting severely ill are the elderly or people with compromised immune systems. Serious cases involving children also are rare.

What do we know about the safety of DEET products? Last year, the Journal of Toxicology published an extensive review of the scientific literature assessing the safety of DEET-containing products. The conclusion was that adverse effects from DEET use are rare. Even in cases of accidental overexposure in children, 85% of cases haven't resulted in symptoms, says lead author Daniel L. Sudakin, assistant professor in the department of environmental and molecular toxicology at Oregon State University.

Dr. Sudakin notes that fears about DEET have been fueled by a few reports describing neurological reactions such as confusion or even seizures. Those cases typically happened after DEET products were overused or put on broken skin. That's why experts warn against using sunscreen and DEET combination products because DEET shouldn't be reapplied often. The National Pesticide Information Center also has more information at www.npic.orst.edu/.

If studies show DEET is safe, why are some people worried? The concern is that we simply don't have enough research looking at long-term health effects, particularly in children. The Toxicology review showed that the skin may absorb from 6% to 17% of the dose applied, but the body eliminates the chemicals through the urine within 12 to 24 hours. There's no real evidence that absorbing small amounts of DEET from occasional use of bug repellents will have any harmful effects. While many studies have shown no neurological link, rat studies from Duke University did show an effect.

How effective are repellents that don't contain DEET? Other products do work to repel bugs; just not as long. In a July 2002 New England Journal of Medicine study, researchers placed their repellent-covered arms into a cage of mosquitoes. A DEET product with 23.8% concentration (Deep Woods Off!) kept mosquitoes away the longest- 301.5 minutes. Oil of eucalyptus at 30% concentration staved a bite off for 120.1 minutes, while Bite Blocker, with 2% soybean oil, kept bites away for 94.6 minutes. Citronella, a commonly used alternative to DEET performed poorly, keeping bugs away for less than 20 minutes.

The American Academy of Pediatrics says DEET products shouldn't be used on infants younger than two months, but it's safe to use concentrations up to 30% on kids.

Still, some doctors say too much is still unknown about health effects on kids. Robert Nevin, a father of three and a family physician in Toronto, says questions remain about the impact of chemical exposure on a child's brain development, so he urges caution with DEET, particularly since kids are at such low risk for serous problems from West Nile anyway. "For me it's not a dilemma," says Dr. Nevin, who buys a soybean-oil-based product for his kids.

For the latest information on West Nile, Lyme Disease, and other disease outbreaks, click on the link below to visit the Centers for Disease Control website, where you will find the most up-to-date information.

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