INTRODUCTION The purpose of this study was twofold: (1) to assess the potential chronic inhalation toxicity of raw and spent shale dusts@ with emphasis on potential pulmonary toxicity@ and (2) to assess the inhalation carcinogenic potential of micronized raw and spent Anvil Points shale dusts. This study was initiated on April 12@ 1977 and exposures were terminated on April 16@ 1979 for the monkeys and on April 26@ 1979 for the rats.