Comparison of Fresh and Room-Aged Cigarette Sidestream Smoke in a Subchronic Inhalation Study on Rats

Abstract

Two experimental types of cigarette sidestream smoke (SS) were compared in a subchronic inhalation study on rats. Fresh SS (FSS) was generated continuously from the reference cigarette 2R1. Room-aged SS (RASS) was generated by aging FSS for 1.5 h in a room with noninert surfaces with materials typically found in residences or offices. Male Sprague-Dawley rats were head-only exposed to three dose levels of each SS type and to filtered, conditioned fresh air (sham-exposure) for 6 h/day, 7 days/week, for 90 days. Room-aging resulted in decreased concentrations of various SS components, e.g., total particulate matter (TPM) and nicotine, while other components, such as carbon monoxide (CO), were not affected. The CO concentrations were 6, 13, and 28 ppm for both SS types. TPM concentrations were between 0.6 and 8.7 micrograms/liter and thus up to 100-fold above the maximum of average concentrations of respiratory suspended particles reported for environmental tobacco smoke. Slight reserve cell hyperplasia in the anterior part of the nose as well as hyperplastic and metaplastic epithelial changes in the larynx were the only observed dose-dependent findings. The metabolism of benzo(a)-pyrene--as a proxy for polycyclic aromatic hydrocarbon metabolism--was induced in the nasal respiratory epithelium and in the lungs while no effect was seen in the nasal olfactory epithelium. The lowest-observed effect level was 6 ppm CO or 0.6 microgram TPM/liter. Most of the effects seen were less expressed in RASS-than in FSS-exposed rats when compared on the basis of the CO concentrations. When compared on the basis of TPM, these effects were equally pronounced for both SS types, suggesting a major role of particulate matter-associated compounds. All findings reverted to sham control levels following a 42-day postinhalation period.

Concentrations of the Carcinogen 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone in Sidestream Cigarette Smoke Increase after Release into Indoor Air: Results from Unpublished Tobacco Industry Research

“…The precedent established in previous toxicologic experiments on sidestream cigarette smoke, by the tobacco industry (39,40,(51)(52)(53) and by independent scientists (54-61), of aging smoke in a controlled manner before testing biological effects is sound. It would be useful for these researchers to validate their experimental proxies for SHS by comparing proxy NNK concentrations to those found in the real world.…”

Cigarette Mainstream Smoke: The Evolution of Methods and Devices for Generation, Exposure and Collection

“…Using the 30-port reverse smoking machine described by REININGHAUS and HACKENBERG (363) cigarette sidestream smoke was collected by HAUSSMANN et al (365) with the help of a circular hood made of glass and stainless steel placed on top of the apparatus; mainstream smoke was exhausted. A subchronic inhalation study with rats examined both fresh side stream smoke (three concentrations) and room-aged sidestream smoke (generated during 1.5 hours in a mock-up living room).…”

“…At this point, 30-40% of particle mass were typically lost due to the redistribution of initially condensed volatiles into the gas/vapor phase of the diluted smoke. Animals were exposed nose-only in the exposure chambers described by HAUSSMANN et al (365). Smoking machines of the SM85 type were used by CARMINES et al (367) and GAWORSKI et al (368) for the production of mainstream smoke from 1R4F Kentucky reference cigarettes in inhalation studies, which examined effects on prenatal and postnatal development in rats.…”

Efeitos da inalação passiva da fumaça de cigarro sobre as pregas vocais de ratos

“…In a study carried out by Haussmann et al (1998) 15 , the larynx was considered the organ most sensitive to histopathological changes after exposure to cigarette smoke. There is dosedependent diffuse squamous metaplasia of the pseudostratified epithelium and squamous hyperplasia on the base of the epiglottis.…”