DEET is a toxic compound, partially absorbed into the bloodstream, and associated with dermal and neurological reactions. Several cases of toxic encephalopathy (brain damage) associated with the use of DEET in children have been reported in the medical literature. Generalized seizures have also been temporally associated with the use of DEET.
The Environmental Protection Agency (EPA) made a Reregistration Eligibility Decision (RED) for DEET in late 1998, but with this decision, the EPA will not reregister DEET products marketed specifically at children, claiming them to be misleading. Due to their alcohol base, these low percentage DEET formulas may actually increase absorption into the bloodstream, especially when reapplied frequently to increase effectiveness. The EPA expressed concern about the fact that DEET is widely used, is one of the few registered pesticides applied directly to human skin and is potentially related to seizure incidents. As a result, the RED calls for stronger label warnings and restrictions that are protective of children and others who are sensitive to chemical substances.
Permethrin is a synthetic contact insecticide, causing nervous system toxicity that leads to the death of the insect. It is said to have low toxicity in mammals, and is poorly absorbed through the skin. However, it's wise to stay away from any synthetic pesticide, especially when there are safe alternatives to do the job.
Plants whose essential oils have been reported to have repellent activity include citronella, cedar, verbena, geranium, lavender, pine, cajeput, cinnamon, rosemary, basil, thyme, allspice, garlic, and peppermint. Calendula ointment is also an excellent insect repellent. Unfortunately, plant-derived repellents have been relatively poorly studied. When tested, most of these essential oils tended to give short-lasting protection, usually less than 2 hours. But reapplying the essential oils is a small price to pay for keeping a child protected from insects while free from potentially harmful insecticides.
Neem oil is a highly effective, non-toxic, child safe bug repellent that can also be used on open sores and wounds. Neem heals wounds, cuts, sores, poison oak or ivy, and has anti-bacterial, anti-fungal, and anti-viral properties. The National Research Council found that Neem is known to repel more than 200 species of insects. A compound (salannin) found in neem leaves, seeds and seed oil is a safer but more effective insect repellent than DEET. Neem provides protection from not only mosquitoes but also from biting flies, sand fleas and ticks.