In an effort to lessen the environmental impact of chemicals discharged by industry, some countries rank chemicals according to mass released each year and then set environmental protection policy based upon this ranking. These rankings have driven industries and companies to change their process configurations and their chemical releases to reduce the release of higher ranking chemicals. But, chemicals that are higher ranked due to mass release may not be particularly toxic nor persistent in the environment; conversely, lower ranked chemicals may be substantially more toxic and persistent in the environment.

The physical/chemical properties of forty five organic chemicals from the EPA's Toxic Release Inventory were used as inputs to a Level III fugacity model to estimate fate, transport, and steady state concentrations of chemicals in the environment. The resulting concentrations in the air and water, for each chemical, were determined using the fugacity model and were then compared with toxicity data, the ratio was used as an indication of the environmental impact of the release of each chemical. The chemicals were then ranked according to the degree of environmental impact and the results were compared to other ranking systems reported in the literature.