Children's immature and developing organs, brains, and detoxification and immune systems, plus their larger intake of food per kilo of body weight, combine to make them even more susceptible to toxins than adults. American toddlers eating mostly organic food have been found to have less than one sixth the pesticide residues in their urine compared to children eating conventional foods, lowering their exposure from above to below recognized safety levels.

Elizabeth Gillette's landmark 1998 paper in the journal Environmental Health Perspectives showed how a combination of low-level environmental, household and dietary exposures caused subtle yet measurable developmental deficits in children. Gillette compared children in two nearby isolated villages in Mexico, one in which pesticides were routinely used in their farming, and one in which they were not. Everything else was the same between these two villages—genes, diet, lifestyle, climate, culture, etc. The study found significant differences between the two groups in both mental and motor abilities (with the children who were exposed to pesticides scoring at a much lower level), as well as an increase in aggressive behavior.

In many Western countries, children and adults are similarly exposed to multiple sources of pesticides, and in 1995 an Australian study of breast milk found that infants are regularly exposed to several pesticides at levels greater than maximum recommended exposures. In Canada, a direct correlation has been observed between pesticide contamination of breast milk and increased risk of otitis media in Inuit infants.