This monograph evaluates the evidence for carcinogenicity of ionizing radiation from internally deposited radionuclides. The radionuclides considered in this monograph belong to two broad categories: those that emit a-particles (helium nuclei) and those that emit b-particles (electrons) during their primary radioactive decay. For purposes of this monograph 'internally deposited' refers to radionuclides in dispersed forms (e.g. dusts suspensions...