Evaluation of lethality estimates for combustion gases in military scenarios.
To meet the military objective of determining criteria for incapacitation and lethality from toxic gas exposures, a series of small animal tests and data analyses were conducted. Carbon monoxide (CO), a narcotic gas and nitrogen dioxide (NO2), an irritant gas, along with carbon dioxide (CO2) were tested individually and in the following mixtures: (CO + CO2), (NO2 + CO2) and (NO2 + CO + CO2). A group of six animals was exposed to each of the gases and their combinations, lethality and biophysical data were collected. We conclude that our observations of lethality from single toxic gases can be correlated with a fractional effective dose (FED) description, in which external concentrations are corrected for minute volume changes. Multiple gas exposures clearly demonstrate synergistic effects because lethality rates greatly exceed those expected from statistically independent causes. Simple addition of the FED values, however, overstates the effect and implies a competition between the narcotic and irritant gas effects. The N-Gas model, while being an additive FED model, does not appear to be in a form that could guide the setting of military exposure standards.
Smith
S M
SM
Applied Science and Engineering Technology Group, JAYCOR, San Diego, CA 92121, USA.
Stuhmiller
J H
JH
Januszkiewicz
A J
AJ
D000818:Animals; D001273:Atmosphere Exposure Chambers; D002245:Carbon Dioxide / Q000633:toxicity*; D002248:Carbon Monoxide / Q000633:toxicity*; D004867:Equipment Design; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015208:Smoke Inhalation Injury / Q000139:chemically induced* / Q000401:mortality; D015996:Survival Rate; D018675:Toxicity Tests / Q000379:methods*
D002245:Carbon Dioxide; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide