Predicting the Fate of Chemicals in the Aquatic Environment from Laboratory Data

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Abstract
Reasonable predictions of the fate of chemicals in the aquatic environment can be made from laboratory data. Some of the important data include evaporation, degradation, bioconcentration, and particulate adsorption. One of the more promising approaches for predicting fate is called “environmental rates approach” and requires that the laboratory data be expressed as rates. Suitable material balance models can then incorporate the environmental rates and predict exposure concentrations from a given rate of entry. The “model ecosystem approach” is another way to predict fate. To evaluate model ecosystem data, the biodegradability index and ecological magnification values are compared with the biochemical oxygen demands and bioconcentration factors for a few benzene derivatives. Both types of data identify aniline and benzoic acid as the most susceptible to biodegradation in the series. Both also identify chlorobenzene and pentachlorophenol as the most accumulative in the series. Neither compound is as accumulative as DDT. The main advantages of the environmental rates approach are the predictability of environmental concentrations at several points in time and the fundamental understanding of what happened to the chemical. The main advantages of the model ecosystem approach are the existing large data base and the identification of stable breakdown products as part of the test method.