Persistent, ecotoxic, and bioaccumulative compounds and their possible environmental effects

Abstract

The relationship between physico-chemical properties, environmental distribution and effects of organochlorine compounds as a major class of persistent organic pollutants (POPs) are discussed. The environmental fate of a compound includes its transport and dispersion in the environment as well as its accumulation and transformation in defined environmental compartments. Accumulation and transformation as the result of environmental distribution may have long-term consequences; this is indicated by the ultimate accumulation and long-term bioactivity of several widely spread organochlorines, and is clearly evident in the decomposition of chlorofluorocarbons in the stratosphere. Depending on the order of trophic levels biomagnifiaction factors of 10 000 up to 100 000 are encountered for persistent semivolatile organochlorines like 4,4′-DDE, PCB congeners or some Toxaphene constituents. Mammals show intra-species pollutant transfer during the lactation period. While the mother animal is partly depleting its body burden the calve accumulates in a critical period of its life via the milk a concentrated input of persistent organochlorines. A similar depletion phenomenon is also found for fish and crustacean which enrich in the eggs a substantial part of the accumulated body burden of the female. The air skimming of semivolatiles by plant surfaces leads to surprisingly high levels of pollutants in the upper soil layers of forests that otherwise would be considered pristine in terms of human activities.