Always when you buy grapes, do you notice some white color stuff outside the skin? In fact, those are poisonous chemical "malathion" that is sprayed on grapes to get rid of insects. This is a very simple tips on how to remove those chemical from grapes. It is simple, washe the grapes with tooth paste, as demonstrate below.
A very simple and useful tips. So do remember wash your grapes with tooth paste before eating.