Abstract
The currently accepted “no effect” Threshold Limit Value (TLV) for carbon monoxide is 50 ppm. Rats were chronically exposed to this level for 5 hours per day, 5 days per week. Approximately 9 exposed and 6 control rats were sacrificed every 3 weeks until the 12 week exposure period was terminated. The concentrations of zinc, copper, cobalt, iron, and magnesium were determined in liver nuclear, mitochondrial, and supernatant fractions by atomic absorption spectroscopy. Statistically significant changes in the 5 metal species were observed. This investigation indicates that carbon monoxide exerts a trace metal effect at the current TLV level.