Chronic inhalation study in rats, using cigarettes containing different amounts of Cytrel tobacco supplement

The paper describes a chronic (18-month) inhalation study in rats, comparing respiratory tract lesions produced by exposures to cigarettes with different inclusions of Cytrel, a tobacco supplement. Histopathological examinations indicated lower responses in animals exposed to Cytrel-containing cigarettes than in those exposed to all-tobacco cigarettes, despite similar total deliveries of smoke. The decrease in response was approximately proportional to the level of Cytrel inclusion.