Downloaded from https://www.everyspec.com MIL-STD-2031 (SH) where the term m equals minus 18 and b equals 122,000 when the C02 concentration is S percent or less. If the COZ concentration is above 5 percent, m and b equal 23 and minus 38,~, respectively. Other values are the same as equation (l). (3) For CO, HCN, C02 and low 02: m[CO]/([COJ-b) + [HCNJ/LC50HCN + 21 - [0. J(21-5.4) = 1 k 0.2 where 5.4 is the percent 02 that causes 50 percent of the animals to die in 30 minutes Other values are the same as for equations (1) and (2). NOTE The values used in the above equations are dependent on the test protocol, the source of test animais, and the strain of rat selected.
These equations represent the best data concerning the toximlogical interaction of these gases as of the spring of 1989. 40.7 Animnl exposu~ tests. For each decomposition mode, a single animal experiment shall be performed using 80 percent of the predicted IA250 In each animal exposure experiment, six rats shall be exposed. The animals shall be plaud in restrainers, then inserted into the SK portholes located along the front of the exposure chamber such that only the heads of the animals are exposed. In the non-flaming or flaming experiments, the animals in their restrained shall be placed in the portholes before the test sample is dropped into the eup furnace.
In the now Raminglflaming transition experiments, the portholes shali ba Mocked front the hide of the chamber with rubber stoppers during the first phase. Fn minutes into the second phase of decompition, the animals in their restrainers shall be inserted into the portholca so that the stoppers are pushed into the chamber while simultaneously exposing the anirnais’ heads to the combustion atmospheres. The animals shall remain in place for 30 minutes. Because all of the combustion products shall be kept in the chamber, these exposures shall consist of both the initial generation of the test atmosphere, which usually lasts about 5 minutes, as well as the later steady- state cmditions.
The toxicological endpoint shall be death which occurs during the 30 minute exposure or the post-exposure 24 hour observation period. In all experiments, the ~, Coz 02, and HCN shall be measured throughout the exposures. The gas concentrations used in the N- Gas Mode! shall be the time-weighted average values which shall be calculated for the exposure period. 40.8 Animal post-test procedure.
Although this protocol shall be limited to animal lethality up to 24 hours after the termination of an exposure, observation of the animals’ condition post- exposure, and up to 14 days following the exposure shall be important to ensure that toxicological syndromes are consistent w“th the gases included in the equations specified in 40.6. Animals shall be removed while still in the restrainer and examined for the following responses: animal’s eyes shall k examined for reflexes, redness, tearing, and cornea] opacity and, animal’s nose and mouth shall be examined for any discharge and respiratory difficulties such as gasping, wheezing, and rapid or slow breathing.
After removal of the animal from the restrainer, the investigator shall examine 4s