Arnold T. Mosberg

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

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 μg/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.

SUBCHRONIC INHALATION STUDY IN RATS USING AGED AND DILUTED SIDESTREAM SMOKE FROM A REFERENCE CIGARETTE

AbstractMale Sprague-Dawley rats were exposed 6 hr/day, 5 days/week for up to 13 weeks to aged and diluted sidestream smoke (ADSS), used as a surrogate for environmental tobacco smoke (ETS), at concentrations of 0.1 (“typical”), 1 (“extreme”), or 10 (“exaggerated”) mg of particulates/m3. Subgroups of animals were killed after 1 and 4 weeks of exposure. Animals were exposed nose-only, inside whole-body chambers, to ADSS from the 1R4F reference cigarette. End points included histopathology, CO oximetry, plasma nicotine and cotinine, clinical pathology, and organ and body weights. The target particulate concentrations were achieved; at the exaggerated exposure they resulted in CO concentrations in excess of 50 ppm. Particle size distributions showed that the aerosols were completely respirable: the mass median diameter values were less than 1 μm. The only pathological response observed was slight to mild epithelial hyperplasia in the rostral nasal cavity, in the exaggerated exposure group only. No effects we...

2-Week and 13-Week Inhalation Studies of Aerosolized Glycerol in Rats

AbstractThe potential toxicity of aerosolized glycerol was studied by 2-wk and 13-wk nose-only inhalation exposures in Sprague-Dawley-derived (Cr1:CD) rats. In the first study, 10 ratslsedgroup received 10 nose-only exposures of 6 h/day for 2 wk over a 14-day period to mean aerosol concentrations of 0, 7.00 ± 0.08, 1.93 ± 0.123, or 3.91 ± 0.458 mg glycerol/l of filtered room air: Animals were observed for signs of toxicity twice daily, were weighed at 2– to 3-day intervals, and diet consumption was recorded at weekly intervals. All rats underwent complete necropsy, and designated tissues were weighed and examined histopathologically Blood was collected and analyzed for specific hematological and clinical chemistry parameters. The results of this study showed that rats exposed to 6-h nose-only inhalation for 70 days at all three concentrations of glycerol exhibited minimal to mild squamous metaplasia of the epithelium lining the base of the epiglottis. In a second study, 75 ratslsedgroup were exposed 6 h/d...

Comparative Inhalation Study in Rats, Using a Second Prototype of a Cigarette that Heats Rather than Burns Tobacco

AbstractSprague-Dawley rats were exposed nose-only for 1 h/day on weekdays for 13 weeks to the smoke from test and reference cigarettes. The test cigarette was a new prototype: the tobacco is heated rather than burned. The University of Kentucky 1R4F cigarette was used as a reference. The exposures used were around 25% higher than those used in earlier studies, and for the test cigarette the resulting blood carboxy-hemoglobin concentrations approached those associated with death (62+%). The smoke from the reference cigarette produced substantial reductions in breathing frequency, whereas the smoke from the test cigarette did not. The availability of nicotine from test and reference cigarettes was very similar. The histopathology seen (mucus-secreting cells; nasal, laryngeal, and bronchial hyperplasia and squa-mous metaplasia, pulmonary macrophages) indicated that most of the changes observed in the reference animals were absent in the test animals. When changes were seen in the test groups (primarily in t...

Fourteen-Day Inhalation Study in Rats, Using Aged and Diluted Sidestream Smoke from a Reference Cigarette I. Inhalation Toxicology and Histopathology

Abstract Sprague-Dawley rats were exposed 6 hr per day for 14 consecutive days to aged and diluted sidestream smoke (ADSS), used as a surrogate for Environmental Tobacco Smoke (ETS), at concentrations of 0.1 (typical), 1 (extreme), or 10 (exaggerated) mg of particulates per cubic meter. Animals were exposed nose-only, inside whole-body chambers, to ADSS from the 1R4F reference cigarette. End-points included histopathology, CO-oximetry, plasma nicotine and cotinine, clinical pathology, and organ and body weights. The only pathological response observed was slight to mild epithelial hyperplasia and inflammation in the most rostral part of the nasal cavity, in the high-exposure group only. No effects were noted at medium or low exposures. The minimal changes noted were reversible, using a subgroup of animals kept without further treatment for an additional 14 days. Overall, the end-points used in the study demonstrated that there was no detectable biological activity of ADSS at typical or even 10-fold ETS concentrations and that the activity was only minimal at very exaggerated concentrations (particle concentrations 100 times higher than typical real-world concentrations).

Subchronic inhalation by rats of mainstream smoke from a cigarette that primarily heats tobacco compared to a cigarette that burns tobacco.

A subchronic, nose-only inhalation study comparing the potential biological activity of mainstream smoke from a cigarette that primarily heats tobacco (Eclipse) to mainstream smoke from a 1R4F reference cigarette was conducted using Sprague-Dawley rats of each gender. Smoke exposures were for 1 h/day, 5 days/wk for 13 wk, at concentrations of 0, 0.16, 0.32, or 0.64 mg wet total particulate matter (WTPM)/L air. Smoke was generated at the Federal Trade Commission standard of a 2-s puff of 35 ml, taken once per minute. Clinical signs, body and organ weights, clinical chemistry, hematology, carboxyhemoglobin, serum nicotine, plethysmography, gross pathology, and histopathology were determined. Plethysmography indicated that respiratory rate was decreased at all concentrations of 1R4F smoke, but only at the high concentration of Eclipse smoke. Tidal volume was depressed and minute volume was lower for all smoke-exposed rats. Rats exposed to Eclipse smoke inhaled more smoke at the low and mid-concentration exposures than rats exposed to equivalent concentrations 1R4F smoke. Carboxyhemoglobin and serum nicotine were directly related to the exposure concentrations of carbon monoxide (CO) and nicotine in an exposure-dependent manner. Body weights were slightly lower in smoke-exposed rats, while no treatment-related effects were seen in clinical signs, clinical chemistry, hematology, or gross changes at necropsy. The only treatment-related effect seen in organ weights was an increase in heart weight in females in the Eclipse high-concentration exposure group, attributed to higher CO in the Eclipse exposure atmosphere. Higher CO resulted from the lower dilution of Eclipse smoke required to maintain WTPM concentrations equal to those of the 1R4F smoke, and not from a higher CO yield from Eclipse cigarettes. Nasal epithelial hyperplasia and ventral laryngeal squamous metaplasia were noted after exposure to either the 1R4F or Eclipse smoke. The degree of change was less in Eclipse smoke-exposed rats. Lung macrophages were increased to a similar extent in the Eclipse and 1R4F smoke-exposed groups. Brown/gold pigmented macrophages were detected in the lungs of rats exposed to 1R4F smoke, but not those exposed to Eclipse smoke. Subsets of rats from each group were maintained for an additional 13 wk without smoke exposures. Most of the changes noted at the end of the smoke exposures had disappeared, while those that remained were regressing toward normal. Evaluation of these findings indicated the overall biological activity of Eclipse smoke was less than 1R4F smoke at comparable exposure concentrations.A subchronic, nose-only inhalation study comparing the potential biological activity of mainstream smoke from a cigarette that primarily heats tobacco (Eclipse) to mainstream smoke from a 1R4F reference cigarette was conducted using Sprague-Dawley rats of each gender. Smoke exposures were for 1 h/day, 5 days/wk for 13 wk, at concentrations of 0, 0.16, 0.32, or 0.64 mg wet total particulate matter (WTPM)/L air. Smoke was generated at the Federal Trade Commission standard of a 2-s puff of 35 ml, taken once per minute. Clinical signs, body and organ weights, clinical chemistry, hematology, carboxyhemoglobin, serum nicotine, plethysmography, gross pathology, and histopathology were determined. Plethysmography indicated that respiratory rate was decreased at all concentrations of 1R4F smoke, but only at the high concentration of Eclipse smoke. Tidal volume was depressed and minute volume was lower for all smoke-exposed rats. Rats exposed to Eclipse smoke inhaled more smoke at the low and mid-concentration exposures than rats exposed to equivalent concentrations 1R4F smoke. Carboxyhemoglobin and serum nicotine were directly related to the exposure concentrations of carbon monoxide (CO) and nicotine in an exposure-dependent manner. Body weights were slightly lower in smokeexposed rats, while no treatment-related effects were seen in clinical signs, clinical chemistry, hematology, or gross changes at necropsy. The only treatment-related effect seen in organ weights was an increase in heart weight in females in the Eclipse high-concentration exposure group, attributed to higher CO in the Eclipse exposure atmosphere. Higher CO resulted from the lower dilution of Eclipse smoke required to maintain WTPM concentrations equal to those of the 1R4F smoke, and not from a higher CO yield from Eclipse cigarettes. Nasal epithelial hyperplasia and ventral laryngeal squamous metaplasia were noted after exposure to either the 1R4F or Eclipse smoke. The degree of change was less in Eclipse smoke-exposed rats. Lung macrophages were increased to a similar extent in the Eclipse and 1R4F smoke-exposed groups. Brown/gold pigmented macrophages were detected in the lungs of rats exposed to 1R4F smoke, but not those exposed to Eclipse smoke. Subsets of rats from each group were maintained for an additional 13 wk without smoke exposures. Most of the changes noted at the end of the smoke exposures had disappeared, while those that remained were regressing toward normal. Evaluation of these findings indicated the overall biological activity of Eclipse smoke was less than 1R4F smoke at comparable exposure concentrations.

Modernization of Nose-Only Smoking Machines for Use in Animal Inhalation Studies

Several modifications to a continuous-smoking inhalation machine for exposing animals to cigarette smoke are described. The improvements to the original machine provide a much more efficient method of exposing animals to cigarette smoke, and improve substantially the simplicity of operation and maintenance. The changes include a simplified pump for extracting puffs from the cigarettes, computerized control and display of exposure conditions, improved structure of the cigarette holders, and addition of a second puffing port to allow preignition of the cigarettes. The modifications were part of an overall modernization of the original design, as well as to allow the use of cigarettes which do not decrease in length as they are smoked (cigarettes which heat rather than burn tobacco).

Toxicological Evaluation of Honey as an Ingredient Added to Cigarette Tobacco

A tiered testing strategy has been developed to evaluate the potential for new ingredients, tobacco processes, and technological developments to increase or reduce the biological activity that results from burning tobacco. In the manufacture of cigarettes, honey is used as a casing ingredient to impart both aroma and taste. The primary objective of this document is to summarize and interpret chemical and toxicological studies that have been conducted to evaluate the potential impact of honey on the biological activity of either mainstream cigarette smoke or cigarette smoke condensate. As part of ongoing stewardship efforts, cigarettes produced with honey (5% wet weight) as an alternative to invert sugar in tobacco casing material were subjected to extensive evaluation. Principal components of this evaluation were a determination of selected mainstream smoke constituent yields, Ames assay, sister chromatid exchange assay in Chinese hamster ovary cells, a 30-wk dermal tumor promotion evaluation of cigarette smoke condensate in SENCAR mice, and a 13-wk inhalation study of cigarette smoke in Sprague-Dawley rats. Comparative analytical evaluations demonstrated that the substitution of honey for invert sugar as a casing material in cigarettes had no significant impact on mainstream smoke chemistry. In addition, in vitro and in vivo studies demonstrated that cigarettes containing tobacco cased with honey had comparable biological activity to cigarettes containing invert sugar. Collectively, these data demonstrate that the use of honey as an alternative casing material in the manufacture of cigarettes does not alter the potential toxicity of cigarette smoke condensate (CSC) or cigarette smoke; therefore the use of honey as an ingredient added to cigarette tobacco is acceptable from a toxicological perspective.

Nose-Only Exposure of Rats to Carbon Monoxide

AbstractAnimals were exposed nose-only to 0, 527, 1091, or 1800 parts per million (ppm) carbon monoxide for 1 h/day, for 74 consecutive days. Blood carboxyhemoglobin (COHb) concentrations in the 1800 ppm group approached those concentrations associated with lethality (62+%). Respiratory minute volume was reduced to 73% of preexposure values in animals exposed to 1800 ppm CO, through changes in respiratory rate. Most of the erythrocyte parameters showed increases that were proportional to the CO concentration. Accumulation half-lives for COHb in the low, medium, and high exposure groups were 17.2, 12.6, and 9.0 min, respectively; the elimination half-lives were 42.3, 32.6, and 29.7 min, respectively Heart weights were increased by up to 32% in males and 47% in females as a result of this very high exposure to 1800 ppm CO. Chronic inflammation was observed in the cardiac muscle of animals exposed to 1800 ppm CO. The inflammation consisted of scattered interstitial aggregates of lymphohistiocytic cells, foun...

Comparative study of DNA adduct formation in mice following inhalation of smoke from cigarettes that burn or primarily heat tobacco

The genotoxic potential of mainstream smoke from a test cigarette (TOB‐HT) that primarily heats tobacco and a representative tobacco‐burning cigarette (Kentucky reference 1R4F) was compared in male B6C3/F1 mice after nose‐only inhalation exposure. Mice were exposed 1 hr per day, 5 days/week for a 4 week period to mainstream smoke at concentrations of 0, 0.16, 0.32, and 0.64 mg total particulate matter/liter of air. Micronuclei formation in bone marrow and peripheral blood polychromatic erythrocytes (PCE) of animals exposed to either the TOB‐HT or 1R4F cigarette was not significantly different compared with control animals exposed nose‐only to filtered and humidified air (sham controls). DNA adduct measurement by the 32P‐postlabeling method indicated an exposure‐dependent increase in lung adducts of animals exposed to 1R4F cigarette smoke at all three concentrations with the mid and high exposure groups exhibitingstatistically significant increases (P < 0.05) in adduct formation compared to sham‐exposed animals. The concentration of DNA adducts in the lungs of animals exposed to the TOB‐HT cigarette was not significantly increased (P < 0.05) at any concentration compared to sham‐exposed controls. A statistically significant (P < 0.05) concentration‐dependent formation of DNA adducts was also observed in the heart tissues of animals exposed to smoke from the 1R4F cigarette at all three concentrations, but no significant increase in adduct formation was observed in heart DNA of the animals exposed to the TOB‐HT cigarette (P < 0.05). Under the conditions of this experiment, the mainstream smoke from the TOB‐HT cigarette was demonstrated to be less genotoxic in mice than mainstream smoke from the 1R4F cigarette, which is representative of cigarettes in the current U.S. market. Environ. Mol. Mutagen. 29:303‐311, 1997