Explain Pro-Oxidants

Transition metals, particularly those possessing two or more valency states and a suitable oxidation - reduction potential between them (e.g., cobalt, copper, iron, manganese and nickel), are effective pro-oxidants. If present, even at concentrations as low as 0.1 ppm, they can decrease the induction period and increase the rate of oxidation. Trace  amounts of heavy metals are commonly encountered in edible oils and they originate from the soil in which the oil - bearing plant was grown, from the animal, or from metallic equipment used in processing or storage. Trace metals are also naturally occurring components of all food tissues and of all fluid foods of biological origin (eggs, milk, and fruit juices) and are present in both free and bound forms.