The skin-applied bug repellents approved by or registered with the EPA have all been evaluated for safety, and their presence on either list means that the EPA has determined that they pose minimal risk to human health [source: EPA]. In fact, with tick-borne illnesses like Lyme disease infecting as many as 300,000 people in the U.S. each year and the mosquito-borne West Nile Virus reported in at least 30 states as of July 2014, there is some level of health risk involved in notusing bug spray if you're in an area populated by mosquitoes and ticks [sources: CDC, CDC].
Of the conventional skin-applied repellents on the EPA-registered list, DEET is not only the most common and most effective, but also the most controversial for consumers concerned about exposure to chemicals. DEET has been in use since 1946, and the EPA reviewed its safety in 1998 and again in 2014, both times concluding that the insect repellents containing DEET do not present a health concern to people [source: EPA].
The American Academy of Pediatrics (AAP) recommends that parents use products containing DEET concentrations between 10 and 30 percent for children older than two months of age, and not at all for children under two months of age. But the EPA has approved DEET for use on children with no age restriction. Of the EPA-registered repellents on their list, only oil of lemon eucalyptus is age-restricted: It should not be used on children younger than three years of age.
Household bug sprays are formulated for use on insects and floors -- not skin -- but their safety to humans, pets, and the environment is still a concern. Bug sprays formulated for inside use may contain fragrances that mask their chemical smells, but the labels make it clear that they shouldn't come into contact with skin, and they should never be used around food, children or pets. Exposure to the pyrethroid insecticide cypermethrin, for example, has been shown to cause tremors, writhing and convulsions in mice and rats and burning, dizziness and itching in humans [source: NPIC].
Inside pests such as ants and roaches may be more effectively controlled with traps, gels, baits or granules that the insects carry back to their colonies and that humans are less likely to inhale [source: Consumer Reports].