The Biologic Effect From Long-Term Exposure of Primates to Carbon Monoxide

Abstract

This study gives the results of exposing cynomolgus monkeys—22 hr/day, 7 days/week, for two years—to 19.86 and 65.46 ppm of carbon monoxide (CO) on the average. Nine monkeys were exposed to each level of CO and nine were used as controls maintained under identical conditions with the exception of CO exposures. The only observed dose-related difference between the exposed and control animals was in the blood earhoxyhemoglobïn values which were 1.0% to 1.5% higher in the animals exposed to 19.86 ppm CO and 6% to 8% higher in the animals exposed to 65.46 ppm CO. These elevated carboxyhemoglobin levels did not lead to compensatory increases ïn hematocrit, hemoglobin, or erythrocyte count determinations, nor to cardiac fibrosis or brain pathology. The conclusion is reached that these levels of carboxyhemoglobin for two years did not lead to any biologically significant changes In the cynomolgus monkey.