Ninety-day inhalation study in rats, comparing smoke from cigarettes that heat tobacco with those that burn tobacco*1

Abstract

Eight groups of 30 male and 30 female rats were exposed 1 hr per day, 5 days per week for 13 weeks, to smoke from reference (tobacco burned) or test (tobacco only heated) cigarettes, at nicotine concentrations of 5, 15, or 30 micrograms/liter of air. Similar smoke concentrations of wet total particulate matter and carbon monoxide were produced in each of the test/reference comparisons. There was a pronounced depression of minute ventilation of animals in the reference groups, but not in the test animals. Blood carboxyhemoglobin concentrations were similar in animals exposed to smoke from test and reference cigarettes. Plasma concentrations of nicotine and cotinine in the test groups were higher than in the reference groups. There were no differences between the smoke-exposed groups in terms of body weight or feed consumption. At necropsy, an increase in heart weight was noted in both high exposure groups. There were notable differences in histopathology, with fewer and less-pronounced changes in the test groups than in the reference groups. Many of the histopathological responses induced in the reference groups were absent in the test groups. Overall, the study demonstrated a substantial reduction in the biological activity of smoke from the test cigarette when compared with the reference.

An online survey of users of tobacco vaporizers, reasons and modes of utilization, perceived advantages and perceived risks

“…For more than 25 years, studies have tended to show that the aerosol produced by tobacco that is heated but not burned is less toxic than cigarette smoke [6–8]. Biomarker analysis in humans [9–11], animals [12, 13] and on human cultured cells [14, 15] also showed reduced toxicity from the aerosol produced by heated tobacco products compared to cigarette smoke.…”