In conventional food production systems, not all pesticides remain on a plant’s exterior. Systemic pesticides are chemicals that are actually absorbed by a plant when applied to seeds, soil or leaves. The chemicals then circulate through the plant’s tissues, killing the insects that feed on them. Use of these pesticides on food crops began in 1998, and has steadily increased during the past 10 years. Unlike with traditional insecticides, you can’t wash or peel off systemic pesticide residues because they’re in the plant’s tissues, not on their exteriors.
Yikes! That just makes me more convinced than ever that we are killing ourselves. I'm glad I have a garden. The article goes on to state that they don't really know the effect yet and that there are studies being done. It also lists some of the pesticides and what plants they use them on.