Carboxyhemoglobin values in swine relative to carbon monoxide exposure: guidelines for monitoring animal and human health hazards in swine-confinement buildings.

Miniature pigs were exposed, in an environmental chamber, to 55 mg of CO/m3 of air, 110 mg/m3, 220 mg/m3, or 330 mg/m3. Blood samples were taken from the swine every hour over an exposure period of 6 or 8 hours. After the pigs were removed from the chamber, blood samples were taken every 30 minutes for an additional 3 hours. The blood samples were measured by spectrophotometry for the amount of carboxyhemoglobin (COHb). On exposure to CO, the COHb values in the pigs increased in a linear fashion during the first 2 hours, then began to level off, reaching a peak concentration at 6 to 8 hours. The percentage of COHb in the blood after 6 hours' exposure to the different amounts of CO were as follows: 55 mg/m3 - 5%, 110 mg/m3 - 10.5%, 220 mg/m3 - 20%, and 330 mg/m3 - 27.2%. There was a linear relationship between the amount of CO exposure and the peak blood value of COHb. The present data provide guidelines for the use of COHb measurement in swine as a means to monitor the environment in swine-confinement buildings for potentially dangerous amounts of CO for swine and persons and to aid in the diagnosis of CO-induced perinatal disease in swine.