Biological vs non (organic vs non)

Reference: Paleo Effect

Red Means Stop – Avoid these at all cost unless they are organic
Peaches, Apples, Sweet Bell Peppers, Celery, Nectarines, Strawberries, Cherries, Carrots, Pears, Frozen Winter Squash

Orange Also Means Stop – Not quite as horrible as the Reds, but still, go organic.
Spinach, Grapes, Lettuce, Green Beans, Hot Peppers, Cucumbers, Mushrooms, Cantaloupe, Oranges, Fresh Winter Squash

Yellow, Proceed with Caution – These foods are much better, but not perfect.
Apple Sauce, Raspberries, Plums, Grapefruit, Tangerines, Apple Juice, Honeydew Melon, Tomatoes, Sweet Potatoes, Watermelon, Cauliflower

Green Light – These foods contain very low amounts of contaminants.
Broccoli, Orange Juice, Blueberries, Papaya, Cabbage, Bananas, Kiwi, Canned Tomatoes, Sweet Peas, Asparagus, Mango, Canned Pears, Pineapple, Avocado, Onions.