Toxicology of Inhaled NiO and CoO in Syrian Golden Hamsters

Abstract

Syrian golden hamsters exposed in several manners to the inhalation of nickelous oxide (NiO) and cobaltous oxide (CoO) showed completely different behavior in response to these two compounds. Exposures ranged from 3 to 7 hours per day for up to 60 days. The NiO concentrations were from 10 to 190 µg/liter, and CoO concentrations were from 2 to 160 µg/liter. Nearly 20% of the inhaled NiO was retained in the lungs after initial clearance, and 45% of this was still present after 45 days. Comparable figures for CoO were less than 1% after initial clearance and none after 6 days. No hamster exposed to NiO at any concentration died before scheduled sacrifice within 6 months postexposure. All the hamsters exposed to CoO at 106 µg/liter died by the fourth of the 3-hour exposures.