Deet does have side effects as a 'chemical'. It IS a "pesticide". The explicit warnings about NOT using it on children under a certain age is a definite heads up to be concerned about this product.
DEET was released because it proved to keep bugs away NOT because it was safer than others. Marketing/Advertising is who has promoted it as safer not the USDA/FDA. And sadly they have done a great job at promoting that is safe.
Read this and then rethink about how 100% safe DEET is 'supposed' to be and using it anywhere's near children. We are talking seizures, coma, and death here.
So NO, DEET is not 100% safe and chemical free.
For those that don't want to read the entire lengthy scientific link provided. Albiet you should.
Here's an excerpt.
""Products containing N,N-diethyl-m-toluamide and isomers (Deet) are beneficial as insect repellents, but have also been associated with dermal and neurological reactions in humans...""
""Several cases of toxic encephalopathy associated with the use of Deet in children have been reported in the medical literature. The first reported case involved a 3.5 year old girl whose body, bedclothes and bedding were sprayed each night for two weeks with an insect repellent containing 15 percent Deet (12). Since then, five additional cases of toxic encephalopathy have been temporally associated with the use of Deet products in children, all of whom were females (Edwards and Johnson, 1987; de Garbino et al., 1983; Heick et al., 1980; Roland et al., 1985; Zadikoff, 1979). The toxic encephalopathy was characterized by agitation, weakness, disorientation, ataxia, seizures, coma and in three cases resulted in death. Autopsies conducted on two fatalities (Heick et al., 1980; Zadikoff, 1979) indicated edema of the brain, with one case presenting necrotic lesions in the cerebellum and spinal cord and an enlarged liver accompanied by microscopic changes (Heick et al., 1980). One child was reported to be heterozygous for ornithine carbamoyl transferase deficiency (a sex linked enzyme deficiency which may produce effects similar to those reported above) and it has been hypothesized that children with this enzyme disorder may be at greater risk of adverse reactions to Deet (Heick et al., 1980). This enzyme deficiency which usually causes infant death in males is of variable severity in females (Stanbury et al., 1983). Accidental and deliberate ingestion of Deet-containing products has produced neurotoxic effects similar to those described following dermal exposure (Tenenbein 1987, Zadikoff, 1979) (3).
Generalized seizures have also been temporally associated with the use of Deet-containing insect repellent on skin (Oransky et al 1989). These cases differ from those described above in that they involved males (four boys aged 3-7 years and one 29-year-old adult), had few associated neurotoxic effects and resolved rapidly. Lower exposure to Deet in these males (four of five males had either one or two dermal applications) may have accounted for the effects being less severe than in females. That the majority of identified neurotoxic cases involved children raises concerns that this subpopulation is at greater risk of adverse reaction following exposure to Deet than are adults (3).
http://pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/deet-ext.html