strawberry

strawberry is one of my favourite fruit.i know it is very good for health, gives lots of vitamins and cleans the blood and everything. now a days i am little worried, i heard from many of my friends and doctors too that sellers inject some sort of chemicals which makes them dark redish and more sweeter to attract the buyers now how can i prevent my self from this? as my friends daughter get skin alergic from it, which has been discovered after investigated by his family doctor. can someone guide me???