Effects of inhalation of cadmium on the rat olfactory system: behavior and morphology.

To investigate the effects of cadmium on olfaction, two separate studies were conducted in which male adult rats were exposed to CdO, via inhalation, for 5 h per day, 5 days a week for 20 weeks. Target exposure values of 250 and 500 micrograms/m3 were measured at 200 and 325 micrograms/m3 for the low concentration in two experiments, and 550 and 660 micrograms/m3 for the high concentration. Prior to exposure, olfactory thresholds were obtained using a conditioned suppression technique. After 20 weeks of cadmium exposure, there was no evidence of anosmia in any of the rats nor were there any significant changes observed in olfactory thresholds. Although olfaction was not impaired, cadmium levels in the olfactory bulbs of exposed rats were significantly elevated compared to controls. Cardiac and respiratory histopathology were observed at all exposure levels, but there was no evidence of nasal pathology related to exposure to cadmium. Failure of cadmium to produce olfactory dysfunction may be due to the protective effects of metallothionein and/or to the highly resilient nature of the rodent olfactory system.