An assessment of the behavioral toxicity of high-energy iron particles compared to other qualities of radiation.

Conditioned taste aversion was used to evaluate the behavioral toxicity of exposure to high-energy iron particles (56Fe, 600 MeV/amu) in comparison to that of gamma photons (60Co), high-energy electrons, or fission neutrons. Exposure to high-energy iron particles (5-500 cGy) produced a dose-dependent taste aversion with a maximal effect achieved with a dose of 30 cGy. Gamma photons and electrons were the least effective stimuli for producing a conditioned taste aversion, with a maximal aversion obtained only after exposure to 500 cGy, while the effectiveness of fission neutrons was intermediate to that of photons and iron particles, and a maximal aversion was obtained with a dose of 100 cGy. In the second experiment, rats with lesions of the area postrema were exposed to iron particles (30 cGy), but failed to acquire a taste aversion. The results indicate that (1) high-energy iron particles are more toxic than other qualities of radiation and (2) similar mechanisms mediate the behavioral toxicity of gamma photons and high-energy iron particles.