In 2012, Americans consumed well over 79 billion servings of tea, which is just over 3.60 billion gallons. If you factor in the rest of the world it makes tea the most consumed traditional beverage worldwide. Black, green, oolong and white teas all come from the same plant, but the differences among the types come from a diverse degree of processing and level of oxidization.
As with any plant based commodity, it has the potential to be vulnerable to pests and diseases. In which these pests and diseases are controlled by applying pesticides to the tea crop. Thus, meaning a potential for having pesticide residues in the final product.