Correspondence to: James E. Swauger, Ph.D., Director, Scientific & Regulatory Affairs, R. J. Reynolds Tobacco Co., P. O. Box 1487, Winston-Salem, NC 27102-1487.
David Holzman's news article, "Safe Cigarette Alternatives? Industry Critics Say `Not Yet"' (1), challenges the merits of lower risk cigarettes and questions whether the public should have access to them. Although the R. J. Reynolds Tobacco Co. (RJR) disagrees with several of the opinions and conclusions in the article, it is important to have a forum for constructive discussion and establishment of a framework in which cigarettes that have the potential to reduce health risks can be evaluated.
It is impossible in a brief letter to either fully describe the scientific data characterizing Eclipse or to address all of the issues raised in Holzman's article. However, RJR has conducted an extensive comparative evaluation of Eclipse. In an effort to encourage informed debate, we encourage interested parties to independently evaluate the published studies (2-4).
The article substantially mischaracterizes the potential toxicologic concern associated with the use of continuous-filament glass in Eclipse. The article asserts that ". . . thousands of microscopic glass fibers contaminate the [Eclipse] mouthpiece. . . ." This assertion, attributed to Dr. John L. Pauly, is inaccurate. Studies of Eclipse indicate that the number of continuous glass filaments that might be found on the outside mouthpiece of the product are as much as an order of magnitude lower than the Pauly estimate. Further, glass filaments are ubiquitous and survey data demonstrate that consumers are exposed to literally thousands of glass filaments daily.
The article states, again referencing Dr. Pauly, that " . . . smoking would draw them [these microscopic glass fibers] into the lung." This statement is also inaccurate. The potential transfer of continuous-filament glass to Eclipse mainstream smoke has been evaluated and the studies have consistently demonstrated that, relative to background, biologically significant transfer of continuous-filament glass to Eclipse mainstream smoke does not occur. Furthermore, the continuous-filament glass used in Eclipse was specifically designed to be nonrespirable. The continuous-filament glass-mat insulator is made from continuous glass filaments that have an average diameter of 8.5 µm (range, 5.5-12 µm) and a specified length of 9500 µm. The calculated aerodynamic diameter (parallel) of these filaments would be approximately 53 µm (range, 35-73 µm). It is overwhelmingly accepted by the scientific community that structures with aerodynamic diameters greater than 7 µm are unlikely to reach the pulmonary region of the respiratory tract.
In 1994, glass wool (respirable) was listed by the National Toxicology Program in the Annual Report on Carcinogens (ARC). However, the listing of respirable glass wool in the ARC is not relevant to the continuous-filament glass used in Eclipse, since the physical characteristics of these filaments render them nonrespirable. Furthermore, chronic inhalation studies have been conducted with rat respirable fractions of representative glass fibers and no statistically significant increase in fibrosis or lung tumors was observed (5).
Any assertion that the use of continuous-filament glass in Eclipse represents a potential toxicologic concern to smokers is simply not supported by the relevant facts. In brief, transfer data and the unique physical characteristics of the filaments (e.g., controlled physical dimensions, chemical composition, and dissolution characteristics [biologic solubility]), demonstrate that biologically significant exposure to the smoker will not occur.
REFERENCES
1
Holzman D. Safe cigarette alternatives? Industry critics say
`not yet' [news]. J Natl Cancer Inst 1999;91:502-4.
2 Bombick BR, Murli H, Avalos JT, Bombick DW, Morgan WT, Putnam KP, et al. Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 2. In vitro toxicology of mainstream smoke condensate. Food Chem Toxicol 1998;36:183-90.[Medline]
3 Borgerding MF, Bodnar JA, Chung HL, Mangan PP, Morrison CC, Risner CH, et al. Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke. Food Chem Toxicol 1998;36: 169-82.
4 Bombick DW, Ayres PH, Putnam K, Bombick BR, Doolittle DJ. Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 3. In vitro toxicity of whole smoke. Food Chem Toxicol 1998;36: 191-7.[Medline]
5 Hesterberg TW, Miller WC, McConnell EE, Chevalier J, Hadley JG, Bernstein DM, et al. Chronic inhalation toxicity of size-separated glass fibers in Fisher 344 rats. Fundam Appl Toxicol 1993;20:464-76.[Medline]
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