Models that predict the environmental fate of toxic chemicals can be used as guides for data acquisition for currently used chemicals and as tools for calculating expected environmental concentrations or new chemicals introduced into commerce. These models are based on a set of mathematical descriptions of rate processes of chemical transformations and equilibria, both written as functions of environmental factors. To test the model, it must be used to make predictions that can be observed experimentally. For the tests, experimental environmental environments should be employed that can be controlled to provide conditions for which the predictions were made. Applications of the models requires that a file of environmental descriptions be available. Several applications have been made.