Time to choose mosquito repellent

By on August 2, 2009

As outdoor activities increase for the summer, and with concerns about West Nile Virus, many people will choose from various methods to reduce the potential for mosquito bites, such as wearing protective clothing and using repellents. If they choose to use repellents, the most effective ones contain DEET (N,N-diethyl-m-toluamide). DEET has been tested against a variety of biting insects and has been shown to be very effective. It is recommended by the Center for Disease Control.

“The question of which DEET formulation to use often comes up,” John Church, University of Illinois Extension Educator, Natural Resources, said.

The more DEET that a repellent contains, the longer the time of protection provided from mosquito bites. A higher percentage of DEET in a repellent does not mean that the protection is better, just that it will last longer. Based on studies, a product containing 23.8 percent DEET provided an average of five hours of protection from mosquito bites. A product containing 20 percent DEET provided almost four hours of protection. A product with 6.65 percent DEET provided almost two hours of protection.

Products with 4.75 percent DEET and 2 percent soybean oil were both able to provide roughly one and a half hour of protection.

A higher percentage of DEET might be the best choice for a person who will be outdoors for several hours, while a lower percentage of DEET can be used if time outdoors will be limited. It can be re-applied if you are outdoors for a longer time than expected and start to be bitten by mosquitoes. Choose a repellent that will likely be used consistently and that will provide sufficient protection for the amount of time that will be spent outdoors. Product labels often indicate the length of time that protection can be expected from a product.

Use enough repellent to cover exposed skin or clothing. Do not apply repellent to skin that is under clothing. Heavy application is not necessary to achieve protection. Do not apply repellent to cuts, wounds, or irritated skin. After returning indoors, wash treated skin with soap and water. Do not apply aerosol or pump products directly to your face. Spray hands and then rub them carefully over the face, avoiding eyes and mouth.

Always follow all label directions when using a chemical product, especially if using on children. If there are questions about a product’s safety, consult a physician or pharmacist prior to use. Persons choosing not to use a chemical repellent can wear more protective clothing such as long-sleeved shirts, long pants and socks. Non-chemical formulations of repellents are also available and some have been shown to be effective, but again vary in length of time of protection as compared to DEET products.

More information on West Nile Virus in humans and pets and the use of mosquito repellents, chemical and non-chemical, can be found at U. of I. websites, www.urbanext.uiuc .edu/westnile/repellent.html and www.urbanext.uiuc.edu/ westnile/about.html.