LONG-TERM EFFECTS OF INHALED NICOTINE

Tobacco smoking has been reported to be associated with increased risk of cardiovascular disease and cancer, particularly of the lungs. In s pite of extensive research on the health effects of tobacco smoking, t he substances in tobacco smoke exerting these negative health effects are not completely known. Nicotine is the substance giving the subject ive pleasure of smoking as well as inducing addiction. For the first t ime we report the effect on the rat of long-term (two years) inhalatio n of nicotine. The rats breathed in a chamber with nicotine at concent ration giving twice the plasma concentration found in heavy smokers. N icotine was given for 20 h a day, five days a week during a two-year p eriod. We could not find any increase in mortality, in atherosclerosis or frequency of tumors in these rats compared with controls. Particul arly, there was no microscopic or macroscopic lung tumors nor any incr ease in pulmonary neuroendocrine cells. Throughout the study, however, the body weight of the nicotine exposed rats was reduced as compared with controls. In conclusion, our study does not indicate any harmful effect of nicotine when given in its pure form by inhalation.