After harvesting, most citrus fruits are washed before being packed. As the washing process removes some of the fruits' natural protective coating, they are given a thin coating of wax to help prevent hydration, extend storage life and improve their appearance. The waxes used for fruits are made from natural products and are also used to coat jelly beans. They must conform to food standards.
The washed fruit is also treated with preservatives and pesticides to prevent the fruit decaying and protect it against insect damage. These substances are controlled by state and territory legislation and safety assessment, taking account of the fact that the peel may be used for cooking.
If these additives make you uneasy, buy organic fruit which is neither waxed nor treated with fungicides. Seville oranges, used for marmalade, are usually free of wax and fungicide, but unwaxed lemons (unless they are organic) will have been treated with fungicides. It is best to scrub citrus fruit under a warm tap with a clean nailbrush before use, as the various substances can come off on your fingers and be eaten with the fruit.
** Asian Recipes