Fruits and Pesticides, Carbide etc.
Guava - Not much pesticides are used (to the best of my knowledge). Comparatively safer bet. But watch out for maggots of fruitflies in guava, which may lead to diarrhoea in kids. Buy a clean looking fruit, wash it and consume. Preferably buy them when they are little green to get more Vit C.
Apples - No harm as far as know (Apples are stored for longer duration before reaching us). Sometimes they may have a mild wax coating, to preserve it. Just wash well and consume.
Mangoes: Not much direct treatment with pesticides. But they are artificially ripened, which is not good for our digestive system. Don't pick Mangoes from a vendor, where all mangoes look uniformly ripe. more