The results of animal studies of the carcinogenic and fibrogenic potentials of three smelter slags used in abrasive blasting and three other particulate materials were presented. The smelter slags tested included secondary copper slag, primary copper slag, and nickel slag; and the nonslag materials were feldspar, novaculite, and Min-U-Sil (14808607). Fischer-344-rats were exposed to the dusts by a single 20 milligram intratracheal instillation followed by a 22 month observation period. Body weights were significantly reduced by inhalation of Min-U-Sil, and significant reductions of the survival rates were observed for animals treated with either Min-U- Sil or novaculite relative to the controls or the other treatment groups. All treatments resulted in significant increases in lung weight. Treatment related lesions were observed in the lungs, trachea, and tracheobronchial lymph nodes after inhalation of all dust samples. The copper slags produced lung adenomas, chronic bronchitis, and chronic tracheitis without secondary inflammation of the pulmonary lymph nodes. Nickel slag treatment produced bronchitis and tracheitis and alveolar foci consisting of variable aggregates of pigmented macrophages. No pulmonary tumors were evident after nickel slag treatment. The feldspar, Min-U-Sil, and novaculite treatments were associated with granulomatous inflammation and pulmonary neoplastic changes. The authors conclude that copper slag exposure is carcinogenic in rats and that the changes induced by nickel slag exposure are consistent with foreign body reaction.