POPs are primarily products and by-products of human industry that are of relatively recent origin.
POPs released to the environment can travel through air and water to regions far distant from their original sources. Persistent substances with this property tend to enter the air, travel long distances on air currents, and then return to earth. Persistent substances with these properties bioaccumulate in fatty tissues of living organisms. Some POPs in extraordinarily small amounts can disrupt normal biological functions, including the activity of natural hormones and other chemical messengers, triggering a cascade of potentially harmful effects. B. Injury from POPs 3.