Wash, wash and wash. Like the way you wash your hands. Just running them under tap water does little to remove oily grime. Agricultural pesticides do not come off in water. Petrochemical companies make pesticides with chemical “stickers” that are insoluble in water.
Soap, or detergent is effective in removing pesticide residues. Take a squirt of dishwashing detergent, in a large bowl of water. Mix the detergent in thoroughly, and swish the apples around for a minute. Carefully watch the water. You will see evidence that detergent works.
Rinse until the water is clear. The detergent-washed fruit, you will also notice feels different, too. (We are so used to fruit with chemical coatings on it that when we touch truly clean fruit, it’s a new tactile experience).
Many fruits and vegetables are not merely sprayed, but are waxed as well. So-called “food grade” waxes improve shelf life, appearance, coat over and lock in any previously applied pesticides. This poses a problem, for waxes do not readily dissolve in detergent solution. Simply peel them. Frequently waxed fruits include apples, brinjals and tomatoes. The lack of a high gloss is not proof positive that a fruit is unwaxed: many waxes, like many types of floor polyurethane or spray varnish, are not at all shiny. One way to tell if a fruit or vegetable is waxed is to run your fingernail over it and see if you can scrape anything off.