The report gives results of an evaluation of relative environmental hazards from a laboratory-scale coal gasifier. Detailed chemical analyses of four effluent streams (gas, aqueous condensate, tar, and ash) were performed for more than 30 gasification runs on a variety of coals, from lignite to bituminous. It briefly describes the gasification reactor, the associated sampling and analysis system, problems encountered with analyses, and special techniques for analyzing complex samples. Relative environmental hazards were determined using the Multimedia Environmental Goals methodology. Toxicity and mutagenicity were assessed using bioassay data. More than 400 effluent stream constituents were identified. Environmentally, the most significant effluent stream is aqueous condensate, followed by tar, product gas, and ash. However, on an equivalent weight basis, the tar stream is more toxic and mutagenic than aqueous condensate. Polycyclic aromatic hydrocarbons and organic bases are the most mutagenic fractions of the tar. Coal pyrolysis and gasification at higher temperatures leads to reduced tar mutagenicity. The most environmental significant constituents (by stream) are: (1) product gas--CO, benzene, H2S, and carbonyl sulfide; (2) aqueous condensate--phenol/cresols/xylenols (PCX), NH3, sulfides, thiocyanates, CN, As, and chlorides; and (3) ash--As, Ni, Be, and Se.