The paper shows how EPA's Environmental Assessment (EA) methodology can be used to: (1) screen gaseous, liquid, and solid waste streams for potentially harmful health and ecological effects (Level 1); (2) prioritize the waste streams and their components for detailed analyses (Level 2); and (3) apply these data to the selection and evaluation of control technologies. To do this, chemical and biological data, collected during an environmental test program at a commercial-size Chapman low-Btu gasifier were used. The paper concludes that: (1) results of the SAM/IA analysis and bioassay screening tests compared favorably in most cases (exceptions included the gasifier ash and separator liquor); (2) results of the SAM/IA analysis and bioassay screening tests can be used to prioritize waste streams and their components for detailed analyses (Level 2); and (3) results of the detailed analyses can be applied to the selection and evaluation of control technologies and to chemical parameters that need to be monitored in the control technology's waste streams for long-term health and ecological impact studies. Existing standards determine when a control technology is required and what pollutants need to be controlled.