- FAMRI Center
Gideon St.Helen, PhD
Assistant Professor of Medicine, Division of Clinical Pharmacology, Dept. of Medicine
The focus of my research program in the Division of Clinical Pharmacology, as shown in the image below, is the utility and evaluation of biological markers (biomarkers) of tobacco use and exposure for epidemiology, risk assessment, product regulation, and identification of susceptibility factors.
1. Epidemiology: We identify traditional and novel tobacco biomarkers that may better predict tobacco-related health outcomes. These include breakdown products of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), tobacco-specific nitrosamines, and nicotelline, a tobacco-specific compound found in the particulate phase of tobacco smoke.
2. Risk assessment: We assess exposure to toxic and carcinogenic tobacco compounds by measuring their biomarkers in nonsmoking children and adults, and users of various tobacco products such as cigarettes, hookahs, e-cigarettes, and smokeless tobacco products. The levels of biomarkers of toxic and carinogenic compounds can be used to quantify risk of diseases such as cancer.
3. Product regulation: An important component of my research is providing the Food and Drug Administration with critical data to inform its tobacco product regulatory function. The research in this area involves primarily clinical studies to assess intake of tobacco-related compounds and toxicants from various tobacco products. A priority area is the clinical pharmacology of electronic cigarettes and new technologies under development by the tobacco industry. We investigate the addictive potential of e-cigarettes through assessment of nicotine pharmacokinetic parameters, intake of toxic compounds such as carbonyls, and e-cigarette features that affect nicotine delivery and dependence.
4. Susceptibility factors: An exciting part of my research program entails using tobacco biomarkers to assess factors that increase susceptibility to nicotine dependence and disease outcomes. Part of this effort focuses on understanding racial disparities in tobacco-related disease outcomes, with emphasis on the question, why do African Americans account for more lung cancer incidence than most other racial groups although >50% of them are light smokers? We focus on the role of genetic variation and nicotine metabolism on toxicant intake and smoking behavior among racial groups and sexes.
- Livingstone College, 2006, BS - Biology
- University of Georgia, 2011, PhD - Toxicology
- Center for Tobacco Control Research and Education, UCSF, 2014, Postdoc
- Hall JC, Bernert JT, Hall DB, St.Helen G, Kudon LH, Naeher LP. Assessment of exposure to secondhand smoke at outdoor bars and family restaurants in Athens, Georgia, using salivary cotinine. J Occup Environ Hyg. 2009;6(11):698-704.
- St.Helen G, Hall DB, Kudon LH, Pearce J, Baptiste S, Ferguson S, et al. Particulate matter (PM2.5) and carbon monoxide from secondhand smoke outside bars and restaurants in downtown Athens, Georgia. J Environ Health. 2011;74(3):8-11.
- St.Helen G, Goniewicz M, Dempsey D, Wilson M, Jacob III P, Benowitz NL. Exposure and kinetics of polycyclic aromatic hydrocarbons (PAHs) in cigarette smokers. Chem Res Toxicol. 2012;25(4):952-64. PMCID: PMC3330130.
- St.Helen G, Bernert JT, Hall DB, Sosnoff CS, Xia Y, Balmes JR, Vena JE, Wang JS, Holland NT, Naeher LP. Exposure to secondhand smoke outside of a bar and a restaurant leads to increases in tobacco exposure biomarkers in non-smokers. Environ Health Perspect. 2012;120(7):1010-1016. PMCID: PMC3404659
- St.Helen G, Novalen M, Heitjan DF, Dempsey D, Jacob III P, Aziziyeh A, Wing VC, George TP, Tyndale RF, Benowitz NL. Reproducibility of the Nicotine Metabolite Ratio in Cigarette Smokers. Cancer Epidemiol Biomarkers Prev. 2012;21(7):1105-1114. PMCID: PMC3392523
- St.Helen G, Holland NT, Balmes JR, Hall DB, Bernert JT, Vena JE, Wang JS, Naeher LP. Utility of urinary Clara cell protein (CC16) as a biomarker of increased lung epithelial permeability following outdoor secondhand smoke exposure. J Expo Sci Env Epidemiol. 2013;23(2):183-9. PMCID: PMC3507333.
- Benowitz NL, Dempsey D, Tyndale RF, St.Helen G, Jacob III P. Dose-Independent Kinetics with Low Level Exposure to Nicotine and Cotinine. Br J Clin Pharmacol. 2013;75(1):277-9. PMCID: PMC3555070.
- St.Helen G, Dempsey D, Wilson M, Jacob III P, Benowitz NL. Racial differences in the relationship between tobacco dependence and nicotine and carcinogen exposure. Addiction. 2013;108(3):607-17. PMCID: PMC3553231
- Jones IA, St.Helen G, Meyers MJ, Dempsey DA, Havel C, Jacob P, Northcross A, Hammond SK, Benowitz NL. Biomarkers of secondhand smoke exposure in automobiles. Tob Control. 2014;23(1):51-7 PMCID: PMC3670969.
- St.Helen G, Jacob III P, Benowitz NL. Stability of the nicotine metabolite ratio in smokers of progressively reduced nicotine content cigarettes. Nicotine Tob Res. 2013;15(11):1939-42. PMCID: PMC3790625.
- Dempsey DA, St.Helen G, Jacob P, Tyndale RF, Benowitz NL. Genetic and Pharmacokinetic Determinants of Response to Transdermal Nicotine in White, Black and Asian Non- Smokers. Clin Pharmacol Ther. 2013;94(6):687-94. PMCID: PMC3834081.
- St.Helen G, Aguilar-Villalobos M, Adetona O, Cassidy B, Bayer CW, Hendry R, Hall DB, Naeher LP. Exposure of Pregnant women to cook stove related household air pollution in urban and peri-urban Trujillo, Peru. Arch of Environ Occup Health. 2013. Epub 2013/11/13. doi: 10.1080/19338244.2013.807761. PMID: 24215174.
- St.Helen G, Benowitz NL, Dains K, Havel C, Peng M, Jacob III, P. Nicotine and carcinogen exposure after water pipe smoking in hookah bars. Cancer Epidemiol Biomarkers Prev. 2014;23(6):1055-66. NIHMS583416.
- St.Helen G, Jacob P, Peng M, Dempsey DA, Hammond SK, Benowitz NL. Intake of toxic and carcinogenic volatile organic compounds from secondhand smoke in motor vehicles. Cancer Epidemiol Biomarkers Prev. 2014;23(12):2774-82