Journal of Clinical Toxicology
Open Access

Absolute Lethal Concentration

Absolute lethal concentration is the lowest concentration of a substance in an environmental medium which kills 100% of test organisms or species under defined conditions. This value is dependent on the number of organisms used in its assessment. It is denoted with LC100.

Lethal concentrations of carbon monoxide can be achieved within 10 minutes from an automobile running in the confines of a closed one-car garage. An ambient CO concentration of 100 ppm (0.01%) produces no clinical signs during an 8-hour exposure. Dogs can tolerate 200 ppm (0.02% CO concentrations) for 90 days with no clinical signs. However, CO concentrations more than 1000 ppm (0.1%) cause unconsciousness, respiratory failure, and death if exposure is continued for 1 hour. Chronic poisoning in the sense of accumulation of carbon monoxide with repeated exposure does not occur.