Argonne National Laboratory is studying health and environmental issues related to coal gasification, using data and samples from the oxygen-blown slagging fixed-bed gasifier at the University of North Dakota Energy Research Center (UNDERC). The pilot study reported here developed preliminary chemical and toxicological data needed to evaluate the health and environmental, as well as the process, implications of using partially treated gasifier wastewater in cooling towers. This minimal-treatment process removes organic compounds by solvent extraction and removes ammonia and acid gas by steam stripping; then, without intermediate biological treatment, the wastewater is reused in a cooling tower. Samples were collected of both the influent wastewater to the cooling tower and the effluent in the tower's blowdown pipeline. These samples were analyzed for the presence of organic chemicals and trace metals and tested for mutagenic and teratologic activity. Results indicate that the UNDERC solvent-extracted and steam-stripped coal gasification wastewaters doe not contain any easily observed mutagenic or cytotoxic activity. The blowdown water sampled was not cytotoxic or mutagenic after phenol removal and ten-fold concentration. Initial indications are that UNDEREC cooling tower blowdown water may contain teratogenically active compounds. Phenolic material is volatilized in the cooling tower and 85 to 90% is lost as a vapor effluent. Probably less than 10% oxidative degradation of phenols occurs in the UNDERC cooling tower. Hydantoins and most inorganic elements are concentrated in the blowdown water approximately ten-fold, as expected. Trace element distributions of zinc and lead in the blowdown water are not as predicted and are unexplained. The aerodynamic size of the drift aerosol may be 12 ..mu..m or greater, depending on the characteristics of the cooling tower's eliminators. 26 references, 2 figures, 13 tables.