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VIII. CONCLUSIONS 1. The criteria for a valid test were satisfied in that no sham exposed animals died or showed signs of toxicity and the COHb 11 levels for the survivors in smoke exposed groups were sig- l h h d " group. y greater than t am-expose nificant e s The results of this comparative toxicity study showed that mice respond very similarly to exposure to smoke from the Reference cigarette and the two test cigarettes, D13 and D17. Survival was 100% for all groups and the mean number of puffs received was exactly the same. { I As described in Protocol Amendment (1601.003-3), lung, liver, and kidney tissues were removed from up to 3 mice/group in Groups 1-4 at 6 hours after smoke exposure initiation. Aryl hydrocarbon hydroxylase (AHH) levels will be determined and ex- pressed as nmoles 3-hydroxy-benzo(a)pyrene (3-OH-BaP) for- med/min/g wet weight tissue or nmoles 3-OH-BaP formed/min/mg protein. These data will be reported in a Final Report Amendment. In comparison to the historical data base accumulated for studies of this type, COHb levels are within the expected range. TPM levels, however, are slightly higher than expected for 8 puffs/cigarette. Indeed, the higher TPM values observed for 7 puffs are closer to the historical values (p. 6, Cigarette Characterization). Since a change to a 7 puff regimen for repeated-dose studies has been recommended for rats (see Report 1-2130.004), it is recommended that the dosing regimen for longer term studies in mice also be changed from 8 to 7 puffs per ex- posure to allow comparison between species. .