Below is a quick, concise overview from an article at runnersworld.com of the recommended foods that should be consumed organically and a list of foods that aren’t as critical.
I recommend reading the entire article: "The Organic Question"
Organic Shopping GuideWhat does the label mean?
The USDA National Organic Program regulates how the word organic can be used for both domestic and imported foods. The official "USDA Organic" seal signifies a product is at least 95 percent organic. Here's what the other labels mean:
*100% Organic All ingredients must be organic
*Organic Guarantees 95% of the ingredients are organic
*Made with organic ingredients At least 70% of the contents are organic
These 12 fruits and vegetables contain the highest levels of pesticides; buy organic to reduce your exposure.
Apples, Bell peppers, Celery, Cherries, Imported grapes , Nectarines, Peaches, Pears, Potatoes, Raspberries, Spinach, Strawberries
Also buy organic meats, poultry, eggs, and dairy to limit your exposure to antibiotics and growth hormones.
Don't Worry (as much)
The pesticide levels of these 12 fruits and vegetables are low to undetectable; okay to buy conventional.
Asparagus, Avocados, Bananas, Broccoli, Cauliflower, Kiwi, Mangoes, Onions, Papaya, Pineapples, Sweet corn, Sweet peas
Choose organic breads, pastas, cereals, and other processed foods when cost and availability allow it.