Long-term Effects of Bioaccumulation in Ecosystems

Extensive damage to organisms and declines in wildlife populations have been observed together with long-term bioaccumulation and biomagnification of persistent xenobiotic chemicals. Heavy metals, especially organic or biomethylated mercury, lead, cadmium and organic tin compounds have caused environmental damage through bioaccumulation on a local scale. Effects on wildife caused by bioaccumulation of persistent organochlorine compounds are more widespread. However, the causal relationship between a biomagnified compound and the long-term effects have been established in only a few cases. Metabolic transformations, and occurrence of several toxic contaminants together in many cases, complicate evaluations of the sources of long-term effects. Environmental fate, exposure of biota and biomagnification of a chemical can be predicted by modelling from its properties and from ecological, geological and climatic conditions of the recipient environment. Model predictions can be refined by experimental factors obtained from results of the field studies. Empirical estimates of hazardous bioaccumulation or biomagnification are obtained from field analyses of different trophic levels. Trend analyses of biomagnified contaminants and their effects can be utilized in prognosis of future development and in evaluation of the need for further action to protect the environment and human health.