Certainly helpful to your decision about which vegetables should be purchased organic and which conventional veggies may be safe, is the measured pesticide loads found on conventionally farmed fruits and vegetables.
Of the 43 different fruit and vegetable categories tested by the Environmental Working Group and included in their Shoppers' Guide to Pesticides in Produce, these 12 fruits and vegetables had the highest pesticide load, making them the most important to buy or grow organic:
Sweet bell peppers
In contrast, these foods were found to have the lowest residual pesticide load, making them the safest bet among conventionally grown vegetables:
Sweet peas (frozen)
Sweet corn (frozen)
So if you need to work within a certain budget, use this information to help guide you to the best choices when it comes to lowering your overall pesticide exposure.