Pesticides have been linked to cancer, developmental disabilities, endocrine disruption, and many other serious problems.
This infographic from Juicing with G gives critical information about which are the most, and the least, pesticide contaminated fruits and vegetables.
This chart does not address GMOs. So sweet corn shows up as being less contaminated with pesticides, mainly because the husk catches most of them. But if the corn is genetically modified, then it is itself literally registered with the EPA as a pesticide. Watch out for that!
For more information about pesticides and food, check out these sources:
http://www.ewg.org/foodnews/
http://www.ewg.org/foodnews/summary.php
http://www.naturalnews.com/030005_GMOs_foods.html#
http://www.alternate-energy.net/Gvid/index.php