This is one of those 'it depends on who you ask' questions.
If you visit deet.com, their section on 'DEET and Children' states that 'the US EPA has determined that when label instructions are followed, all concentrations of DEET repellents can be used by people of all ages.' As this site is maintained by one of the 'world's largest supplier of DEET', it is easy to question their claim.
Most people are more aware of the general recommendations of the American Academy of Pediatrics to limit the use of DEET containing products on kids to those that contain 10% or less DEET.
So who is right?
The EPA did state that 'from the toxicological date reviewed by the Agency for DEET, and from DEET incident data, there appears to be no correlation between the percent active ingredient in the product and its safety. Therefore, the Agency does not believe that certain DEET formulations are inherently safer for children.'
Now I think it is a bit of a stretch to go from saying that some concentrations of DEET aren't safer than others to saying that 'all concentrations of DEET repellents can be used by people of all ages'.
Still, DEET is thought to be safe and has been in use for over 50 years, with few reports of adverse effects, even in children.
And with the worry over West Nile Virus and its spread by mosquitos, parents want to do their best to protect their kids.
Choosing an Insect RepellentWhen picking an insect repellent for your family, it can help to understand what the concentration of DEET actually means. Although some people report that a higher concentration, up to 30% provides more protection, the CDC states that 'a higher concentration of DEET in a repellent does not mean that your protection is better - just that it will last longer.' And they give examples of a repellent with 20% DEET lasting 4 hours and one with 6.65% DEET only lasting 2 hours.
So if you can regularly reapply the insect repellent when you are out for long periods of time, or if your child will only be outside for a few hours, a repellent with 10% or less DEET should be enough. If your child is going to be out all day and usually gets 'eaten alive', then you might look into using a repellent with a higher concentration of DEET.