Inhalation experiments with 14C-labelled cigarette smoke. II. The distribution of cigarette smoke particles in the hamster respiratory tract after exposure in two different smoking systems.

Male and female Syrian golden hamsters were exposed to the smoke of [14C]dotriacontane-16,17 ([14C]DOT)-labelled cigarettes in 2 different exposure systems. These 2 systems differed in terms of the smoke concentration drawn into the exposure chamber. To compare the effectiveness of the exposure systems, the inhaled dose of 14C-labelled cigarette smoke was determined in the different parts of the hamster respiratory tract by liquid scintillation counting. About 6 times more smoke particles were deposited in the respiratory tract after exposure to high smoke concentration with intermittent puffs of fresh air (closed system) than after exposure to smoke diluted with air (open system). About 80% of the diluted smoke reached the bronchi and lung compared to approximately 60% of the concentrated smoke. The remainder of the dose was trapped in the upper respiratory tract, mainly by the nose and larynx. Additionally, in the open system the total dose of inhaled smoke was dependent upon the position in the exposure chamber. The results are discussed with respect to the use of the exposure systems for chronic cigarette smoke inhalation studies in experimental respiratory tract carcinogenesis.