Managing POPs in Sweden Dr . Bo Wahlstr m , Assoc. Swedish National Chemicals Inspectorate 1. Introduction Substances that are persistent, i.e. do not easily degrade, have a potential for widespread exposure through winds and streams and through trade in chemicals and products. When problems are identified exposure cannot be easily reduced by discontinuing production.
Problems caused by persistent chemicals are therefore long lasting.
Many fat-soluble organic substances show extreme accumulation in organisms and concentrate more than several orders of magnitude. They may also biomagnify, i.e. concentrations increase for each step in the food chain, from algae to small crustaceans through fish to seals, eagles or man. Sooner or later they reach concentrations where adverse effects occur. When such chemicals are released to the environment they will redistribute themselves to end up in organisms at the top of the food chain, e.g. man. Discontinuation of their production and use will not alleviate the situation for a long time for those already exposed.