Is Bug Spray Dangerous?

A summer necessity, bug spray keeps insects away – but is it also bad for our health? Researchers are debating whether the anti-pest sprays with which we douse ourselves are putting our health in danger.

One chemical found in many repellents is DEET (N,N-diethyl-m-toluamide). Developed and tested in the 1940s and 1950s by the U.S. Army for use in jungle warfare during World War II, DEET is extremely efficient at repelling mosquitoes, ticks, fleas, chiggers and blood-feeding flies such as black flies and deer flies.

In addition to popular forms such as aerosols and pump sprays, DEET is also found in towelettes, lotions, creams and gels. The chemical keeps insects away for hours after application and can be applied over sunscreen.

But as long as DEET has been around, it has raised questions over its safety from citizens and scientists alike. Some are bothered by the smell, while others worry that it may irritate skin; many have felt the burning sting of accidentally spraying bug repellent over a minor cut.

Although the Environmental Protection Agency re-approved the use of DEET in 1998 after an extensive safety review, new data suggests that the substance may affect our cells in unintended ways.

A 2009 study found that DEET can interfere with the activity of enzymes that are vital for the nervous system to function properly. In the study, the researchers found that DEET blocked the enzyme cholinesterase, which is essential for transmitting messages from the brain to the muscles in insects. The researchers noted that DEET may also affect the nervous systems of mammals, and that more research in this area is needed.

The study, conducted by the Institute of Development Research in France, and published in the journal BMC Biology, found that chemicals that interfere with the action of cholinesterase can cause excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death.

However, based on a 1998 review, EPA officials determined that DEET, if used as directed, does not pose significant health risks to consumers.

While the recent DEET study may deter some people from using bug spray altogether, other scientists have suggested that people keep in mind that the purpose of bug repellents is to prevent being pricked by biting insects that may transmit disease, including Lyme disease, malaria and encephalitis.

So what are some alternatives to DEET?

One of the newest arrivals on store shelves is picaridin, a substance derived from pepper that is popular in Europe and Australia. Studies by its manufacturer suggest that picaridin lasts for two to eight hours and is just as effective as DEET, but is less oily and completely odorless. Independent studies by the EPA are underway.

Another bug repellent on the market is the chemical IR3535, which has also been growing in popularity since its approval in the U. S. about adecade ago. Available in Europe for 20 years, numerous studies have confirmed the effectiveness of IR3535, which can offer protection for up to 10 hours.

A formulation that consists of 20 percent IR3535 is "very effective," entomologist Daniel Strickman of the U.S. Department of Agriculture told LiveScience, a sister site of Life's Little Mysteries. "It's the only repellent active ingredient that has never caused an adverse effect."

The EPA strongly recommends that consumers carefully read the instructions on bug spray products before applying them in order to ensure that they are applied safely, particularly on children.

The Centers for Disease Control (CDC) advises that DEET be sprayed over clothing, rather than directly onto the skin. Other steps to ensure that you're applying bug spray in the safest way possible include:

  • Never apply bug sprays over cuts, wounds or irritated skin.
  • Do not apply on hands or near the eyes and mouth, especially of young children.
  • Do not allow young children to apply DEET products themselves.
  • After returning indoors, wash bug spray-treated skin with soap and water.
  • Heavy application is not necessary to achieve protection, so apply it sparingly.
  • Do not spray in enclosed areas.
  • Some bug spray products cannot be used on children under three years old, so always check the label to make sure.

This article was provided by Life's Little Mysteries, a sister site to LiveScience.

Remy Melina was a staff writer for Live Science from 2010 to 2012. She holds a bachelor’s degree in Communication from Hofstra University where she graduated with honors.