It has not been easy to draw up an initial list of POPs for inclusion in a protocol, because so many interests are at stake. Moreover, while POPs may be harmful to human beings, some are useful for agriculture and even for human health. Short-chain chlorinated paraffins, lindane and pentachlorophenol will require further examination before a decision can be taken about their possible inclusion. POP stands for P ersistent O rganic P ollutant.
POPs break down very slowly.
As a result they are easily taken in by plants, fish and other animals but are difficult to eliminate. As POPs are semi-volatile, they can move long distances in the atmosphere before deposition. They also 'bioaccumulate', which means that their concentrations increase in fatty tissues. They gradually build up in the food chain. For example, although the concentrations of a substance such as PCBs or DDT deposited into a lake may be very low, they will be concentrated in the fatty tissues of plankton living in the lake.