Research Accomplishment Reports 2008

Formation and Reduction of Tobacco-specific N-nitrosamines (TSNA) in Dark Tobaccos

W. A. Bailey
Department of Plant and Soil Sciences

 

Non-Technical Summary

Tobacco specific N-Nitrosamines (TSNA) are carcinogenic substances that have been identified in tobacco products. This project evaluates current levels of TSNA in dark tobaccos as well as the effects of common dark tobacco production practices such as nitrogen fertility, topping, harvesting, and housing methods on TSNA formation. This project also evaluates the effect of preharvest antioxidant applications on TSNA formation in dark tobacco.

2008 Project Description

EXPERIMENTS: Ten field experiments were conducted in 2007 and repeated in 2008 to address the formation of TSNA in dark fire-cured and dark air-cured tobaccos. One experiment compares standard practices for conditioning, taking down, and stripping dark fire-cured tobacco in a typical double-crop curing system relative to TSNA formation. A second experiment addresses the effect of market preparation method and time of storage prior to marketing on TSNA formation in dark fire-cured tobacco. A third experiment addresses the effect of variety, nitrogen use rate, and housing density on TSNA formation in dark fire-cured tobacco. A fourth experiment addresses the effect of variety and curing structure (standard curing barn or low-cost shed) on TSNA formation in dark air-cured tobacco. A fifth experiment addresses the effect of high moisture at harvest on TSNA formation in dark fire-cured tobacco while a sixth experiment addresses the effect of dirt at harvest and possible microbial growth on TSNA levels in dark air-cured tobacco. A seventh experiment addresses the effect of preharvest applications of ferulic acid (known antioxidant) on TNSA levels in dark fire-cured tobacco. Three other experiments were conducted in 2007 and 2008 to evaluate TSNA formation in tobacco cultivars having a silenced nicotine demethylase gene. Data for these seven experiments are currently being analyzed.

EVENTS: Two field days were conducted in 2008 (Springfield and Greeneville, TN) that included topics related to TSNA formation in dark tobacco and information was presented from project experiments. Six grower meetings that specifically addressed TSNA formation in dark tobaccos from information obtained from this project were also conducted in 2008. Two extension agent trainings (1 for Kentucky agents and 1 for Tennessee agents) were also conducted in 2008 and addressed TSNA formation in dark tobaccos and included information obtained from this project. Three professional scientific meetings were attended where TSNA information for dark tobacco was presented from data collected from this project.

PRODUCTS: The following patent application related to this project has also been filed: Terry Thomas, John Brandon, William A. Bailey, and Thomas A. Losty. Method for reducing nitrosamines in tobacco. U.S. Provisional Patent Application (No. 60/753,683) filed with U.S. Patent and Trademark Office. Joint applicants were University of Kentucky Research Foundation and Swisher International, Inc. Patent publication number 20070149408/US-A1. NDN 041-0642-0000-3

2008 Impact

Results and dissemination of information thus far from this project has resulted in a change in knowledge and changes in action for the dark tobacco industry, particularly dark tobacco growers but also dark tobacco buying companies and manufacturers. Information levels on TSNA formation in dark tobaccos have been increased dramatically due to this project. Changes in grower production practices regarding selection, nitrogen use patterns, housing density, and fire-curing methods and market preparation methods have occured due to results and information gained from this project. Dark tobacco buying companies have also used a portion of this information in their own educational programs for growers and methods of handling tobacco upon delivery to buying stations.

2008 Publications

Bailey, A., J. Brandon, T. Thomas, and T. Losty. 2008. Influence of ferulic acid on TSNA accumulation in dark fire-cured tobacco. Proceedings of 43rd Tobacco Workers Conference, Savannah, GA, January 14-17, 2008.

Pitt, W. and A. Bailey. 2008. Influence of double-crop curing practices on leaf chemistry of dark fire-cured tobacco. Proceedings of 43rd Tobacco Workers Conference, Savannah, GA, January 14-17, 2008.

Lusso, M., D. Xu, A. Bailey, F. Hart, D. Norman, G. Davis, and M. Nielsen. 2008. Agronomic performance and tobacco chemistry evaluation of transgenic dark and burley lines with silenced nicotine dimethylase gene. Proceedings of 43rd Tobacco Workers Conference, Savannah, GA, January 14-17, 2008.

Bailey, A., B. Pitt, and B. Sims. 2008. Influence of curing practices on TSNA production in dark fire-cured tobacco. Proceedings of 62nd Tobacco Science Research Conference, Nashville, TN, September 21-24, 2008.

Nielsen, M., D. Xu, M. Lusso, G. Davis, Y. Shen, A. Bailey, F. Hart, M. Cui, and D. Norman. 2008. Down-regulating the nicotine demethylase gene lowers NNN content levels with little or no effect on field performance of burley and dark tobaccos. 2008 Coresta Congress, Shanghai, China.

Xu, D., Y. Shen, M. Lusso, A. Bailey, D. Norman, G. Davis, F. Hart, M. Cui, and M. Nielsen. 2008. Reducing nicotine conversion: stability of RNAi-mediated and mutant down-regulation of nicotine demethylase. 2008 Coresta Congress, Shanghai, China.

Bailey, A. 2008. Double crop curing dark tobacco. AGR 196. Cooperative Extension Service publication. Joint publication of Univ. of KY and Univ. of TN.

G. Duncan, G. Palmer, and A. Bailey. 2008. Stripping and Preparation of Tobacco for Market. Pp. 53-55 in K. Seebold (ed.) 2008 Kentucky Tobacco Production Guide. ID 160. Cooperative Extension Service publication.

Bailey, A. 2008. Tobacco curing considerations. MidAmerica Farmer/Grower. 28(45):7. Weekly periodical published by MidAmerica Farm Publications, Inc., Perryville, MO.