It's Up to Parents to Decide What's Safe
Even trace amounts of chemicals used in conventional farming can be potentially harmful to a developing baby. Keep in mind that the studies recommending "safe" levels of toxin exposure for humans are not conducted on infants - but on older children and adults. In the absence of adequate data parents must choose what they feel is right.
Eating non-organic foods can expose your baby to more pesticide residue per pound of bodyweight than for a typical adult. Where dealing with a small amount of toxins may be manageable for an adult's body, a baby's digestive system and organs may be unable to process these foreign substances. The presence of toxins may interfere with your baby's rapid development.
A 1995 study by the Environmental Working Group (EWG) tested eight conventionally-grown and prepared baby foods produced by three main companies that accounted for 96% of the baby food market at the time. According to the EWG report, "sixteen pesticides were detected in the 8 baby foods tested, including three probable human carcinogens, five possible human carcinogens, eight neurotoxins, five pesticides that disrupt the normal functioning of the hormone system, and five pesticides that are categorized as oral toxicity category one, the most toxic designation."
In 2007 the EWG tested conventionally-grown fruits and vegetables for pesticide residue and rated them accordingly. The EWG found that the following "dirty dozen" foods tested highest in pesticide residue: peaches, apples, sweet bell peppers, celery, nectarines, strawberries, cherries, pears, imported grapes, spinach, lettuce and potatoes. Whether you buy prepared baby food or make your own, feed your baby organically-grown versions of these foods.