Gideon St Helen, PhD

Assistant Professor
Medicine
+1 628 206-2687

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.

Research Themes Visual- information below

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. 

Studies of cannabis pharmacology have recently been added to my research program. These include studies to understand the safety of various forms of cannabis administration, such as novel electronic delivery systems, as well as studies on short-term cardiovascular effects of smoking and vaping cannabis compared to smoking tobacco cigarettes. Other research interests include understanding the pharmacologic interactions of various forms of co-administration of cannabis and tobacco, such as blunts and spliffs.

Publications: 

Comparison of systemic exposure to toxic and/or carcinogenic volatile organic compounds (VOCs) during vaping, smoking, and abstention.

Cancer prevention research (Philadelphia, Pa.)

St Helen G, Liakoni E, Nardone N, Addo N, Jacob P, Benowitz NL

Differences in exposure to toxic and/or carcinogenic volatile organic compounds between Black and White cigarette smokers.

Journal of exposure science & environmental epidemiology

St Helen G, Benowitz NL, Ko J, Jacob P, Gregorich SE, Pérez-Stable EJ, Murphy SE, Hecht SS, Hatsukami DK, Donny EC

Black Light Smokers: How Nicotine Intake and Carcinogen Exposure Differ Across Various Biobehavioral Factors.

Journal of the National Medical Association

St Helen G, Benowitz NL, Ahluwalia JS, Tyndale RF, Addo N, Gregorich SE, Pérez-Stable EJ, Cox LS

Effects of Nicotine Metabolic Rate on withdrawal symptoms and response to cigarette smoking following abstinence.

Clinical pharmacology and therapeutics

Liakoni E, Edwards KC, St Helen G, Nardone N, Dempsey DA, Tyndale RF, Benowitz NL

Revolution or redux? Assessing IQOS through a precursor product.

Tobacco control

Elias J, Dutra LM, St Helen G, Ling PM

IQOS: examination of Philip Morris International's claim of reduced exposure.

Tobacco control

St Helen G, Jacob Iii P, Nardone N, Benowitz NL

Public Health Consequences of e-Cigarette Use.

JAMA internal medicine

St Helen G, Eaton DL

Impact of e-liquid flavors on e-cigarette vaping behavior.

Drug and alcohol dependence

St Helen G, Shahid M, Chu S, Benowitz NL

Comparison of Urine 4-(Methylnitrosamino)-1-(3)Pyridyl-1-Butanol and Cotinine for Assessment of Active and Passive Smoke Exposure in Urban Adolescents.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

Benowitz NL, Nardone N, Jain S, Dempsey DA, Addo N, St Helen G, Jacob P

Tobacco papers and tobacco industry ties in regulatory toxicology and pharmacology.

Journal of public health policy

Velicer C, St Helen G, Glantz SA

An Electronic Cigarette Vaping Machine for the Characterization of Aerosol Delivery and Composition.

Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco

Havel CM, Benowitz NL, Jacob P, St Helen G

Urine Cotinine Screening Detects Nearly Ubiquitous Tobacco Smoke Exposure in Urban Adolescents.

Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco

Benowitz NL, Jain S, Dempsey DA, Nardone N, Helen GS, Jacob P

Impact of e-liquid flavors on nicotine intake and pharmacology of e-cigarettes.

Drug and alcohol dependence

St Helen G, Dempsey DA, Havel CM, Jacob P, Benowitz NL

Biomarkers of exposure to new and emerging tobacco delivery products.

American journal of physiology. Lung cellular and molecular physiology

Schick SF, Blount BC, Jacob P, Saliba NA, Bernert JT, El Hellani A, Jatlow P, Pappas RS, Wang L, Foulds J, Ghosh A, Hecht SS, Gomez JC, Martin JR, Mesaros C, Srivastava S, St Helen G, Tarran R, Lorkiewicz PK, Blair IA, Kimmel HL, Doerschuk CM, Benowitz NL, Bhatnagar A

Nicotine Delivery and Vaping Behavior During ad Libitum E-cigarette Access.

Tobacco regulatory science

St Helen G, Ross KC, Dempsey DA, Havel CM, Jacob P, Benowitz NL

The Influence of Puff Characteristics, Nicotine Dependence, and Rate of Nicotine Metabolism on Daily Nicotine Exposure in African American Smokers.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

Ross KC, Dempsey DA, St Helen G, Delucchi K, Benowitz NL

Nicotine delivery, retention and pharmacokinetics from various electronic cigarettes.

Addiction (Abingdon, England)

St Helen G, Havel C, Dempsey DA, Jacob P, Benowitz NL

Exposure of pregnant women to cookstove-related household air pollution in urban and periurban Trujillo, Peru.

Archives of environmental & occupational health

St Helen G, Aguilar-Villalobos M, Adetona O, Cassidy B, Bayer CW, Hendry R, Hall DB, Naeher LP

Intake of toxic and carcinogenic volatile organic compounds from secondhand smoke in motor vehicles.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

St Helen G, Jacob P, Peng M, Dempsey DA, Hammond SK, Benowitz NL

Nicotine and carcinogen exposure after water pipe smoking in hookah bars.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

St Helen G, Benowitz NL, Dains KM, Havel C, Peng M, Jacob P

Genetic and pharmacokinetic determinants of response to transdermal nicotine in white, black, and Asian nonsmokers.

Clinical pharmacology and therapeutics

Dempsey DA, St Helen G, Jacob P, Tyndale RF, Benowitz NL

Stability of the nicotine metabolite ratio in smokers of progressively reduced nicotine content cigarettes.

Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco

St Helen G, Jacob P, Benowitz NL

Biomarkers of secondhand smoke exposure in automobiles.

Tobacco control

Jones IA, St Helen G, Meyers MJ, Dempsey DA, Havel C, Jacob P, Northcross A, Hammond SK, Benowitz NL

Dose-independent kinetics with low level exposure to nicotine and cotinine.

British journal of clinical pharmacology

Benowitz NL, Dempsey D, Tyndale RF, St Helen G, Jacob P

Racial differences in the relationship between tobacco dependence and nicotine and carcinogen exposure.

Addiction (Abingdon, England)

St Helen G, Dempsey D, Wilson M, Jacob P, Benowitz NL

Utility of urinary Clara cell protein (CC16) to demonstrate increased lung epithelial permeability in non-smokers exposed to outdoor secondhand smoke.

Journal of exposure science & environmental epidemiology

St Helen G, Holland NT, Balmes JR, Hall DB, Bernert JT, Vena JE, Wang JS, Naeher LP

Reproducibility of the nicotine metabolite ratio in cigarette smokers.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

St Helen G, Novalen M, Heitjan DF, Dempsey D, Jacob P, Aziziyeh A, Wing VC, George TP, Tyndale RF, Benowitz NL

Exposure to secondhand smoke outside of a bar and a restaurant and tobacco exposure biomarkers in nonsmokers.

Environmental health perspectives

St Helen G, Bernert JT, Hall DB, Sosnoff CS, Xia Y, Balmes JR, Vena JE, Wang JS, Holland NT, Naeher LP

Exposure and kinetics of polycyclic aromatic hydrocarbons (PAHs) in cigarette smokers.

Chemical research in toxicology

St Helen G, Goniewicz ML, Dempsey D, Wilson M, Jacob P, Benowitz NL

Particulate matter (PM2.5) and carbon monoxide from secondhand smoke outside bars and restaurants in downtown Athens, Georgia.

Journal of environmental health

St Helen G, Hall DB, Kudon LH, Pearce J, Baptiste S, Ferguson S, Green T, Naeher LP

Assessment of exposure to secondhand smoke at outdoor bars and family restaurants in Athens, Georgia, using salivary cotinine.

Journal of Occupational and Environmental Hygiene

Hall JC, Bernert JT, Hall DB, St Helen G, Kudon LH, Naeher LP