The Environmental Working Group has a nifty Shoppers Guide to Pesticides, a wallet size card you can download for free, print and carry with you when you are shopping. Get it here . It shows the 12 worst supermarket veggies in terms of pesticide residues, and the 15 cleanest. The rankings are based on tens of thousands of tests on supermarket produce, from 2000-2008, conducted by the USDA and FDA. Their data shows that people who consume foods from the "Dirty Dozen" every day, eat an average of 10 pesticides every day. Those who eat primarily from the "Clean Fifteen", consume an average of 2 or less pesticides a day.
The best choice of course is organic or all natural, where you get ZERO pesticides, but there remain problems of supply, access, and price. So if you have no other choices, avoid the "Dirty Dozen" like the chemicalized plague they are, and dine on the Clean Fifteen. In the meantime, start your own garden so you have convenient access to clean organic foods in your own back yard (or front yard, for that matter).
The Dirty Dozen
The worst polluted are at the top of the list.
The Clean Fifteen
The least polluted are at the top of the list.