Dr Ed Stephens
Senior Research Fellow
Smoke efficiently delivers to the lungs of smokers and bystanders significant quantities of environmental metals that have accumulated in the tobacco plant or adhered to its leaves. My research focuses on the transfer mechanisms and the speciation of metals in the pathway “from seedbed to sickbed”. In this research I am applying the toolbox of geochemistry including ICPMS, XRF, XRD, EPMA, IRMS (all available in house) and XANES (Diamond synchrotron). This research involves characterising the valence and molecular species of metals in tobacco that may change slowly (e.g. curing process) or rapidly (combustion). Species determines the human bioavailability and detoxification pathways of the metal and is thus a key factor in toxicity and health risk.
As well as modelling pathways I have compiled global-scale datasets of compositional characteristics in the tobacco products of both trans-national and local producers. Somewhat fortuitously we found that application of chemometrics to these datasets revealed provincial patterns that we have since used to authenticate and provenance tobacco products in ways that are useful in controlling the distribution of illicit tobacco products. The illicit tobacco problem is colossal with about $50 billion lost in tax revenues each year while the availability of cheap illicit products discourages many smokers from quitting and facilitates many under age in taking up the habit. If there is no substantial reduction in current smoking prevalence then the WHO estimates that the tobacco epidemic will claim one billion lives in the 21st century.
Vaping is widely considered a helpful alternative for smokers who wish to quit and avoid exposure to the high levels of toxins associated with tobacco smoke. Metals are included among a small number of toxins in e-vapour for which there is still some concern over their safety. My research is directed at understanding the chemical processes involved in the creation of these toxins and their transport by vapour, the overall aim being to identify and quantify the risks to vapers' health. A methodology for comparing the cancer potency of aerosols generated by vapourising nicotine from non-tobacco sources with tobacco smoke was recently published (Stephens 2017b).
Stephens, W.E. (2017b) Comparing the cancer potencies of emissions from vapourised nicotine product sincluding e-cigarettes with those of tobacco smoke. Tobacco Control (on-line first)http://hdl.handle.net/10023/11421)
Stephens, W.E. (2017a) Chemometric and trace element profiling methodologies for authenticating, crossmatching and constraining the provenance of illicit tobacco products. Tobacco Control 26: 502-508
Yang J, Barling J, Siebert C, Fietzke J, Stephens WE, Halliday AN (2017). The molybdenum isotopic compositions of I-, S- and A-type granitic suites. Geochimica et Cosmochimica Acta. 2017;205:168-86.
Caruso RV, Fix BV, Thrasher JF, Cummings KM, Fong GT, Stephens WE, et al. (2016) Differences in Cigarette Design and Metal Content across Five Countries: Results from the International Tobacco Control (ITC) Project. Tobacco Regulatory Science. 2016;2:166-75.
Visser W, Geraets L, Klerx W, Hernandez L, Stephens WE, Croes E, et al. (2015) The health risks of using e-cigarettes. RIVM Letters: 2015-0144:47pp.
O’Connor RJ, Schneller LM, Caruso RV, Stephens WE, Li Q, Yuan J, et al.(2015) Toxic metal and nicotine content of cigarettes sold in China, 2009 and 2012. Tobacco Control. 24:iv55-iv9.
Campbell, R.J.C., Klerx, W., Talhout, R. and Stephens, W.E. (2015) Speciation of Metals and Metalloids in Tobacco and Tobacco Smoke Implications for Health and Regulation. RIVM Letters 2015-0026 (http://rivm.openrepository.com/rivm/handle/10029/557149)
Caruso RV, O’Connor RJ, Travers MJ, Delnevo CD, Stephens WE. (2015) Design Characteristics and Tobacco Metal Concentrations in Filtered Cigars. Nicotine & Tobacco Research. 2015;17(11):1331-6.
Campbell, R.C.J., Stephens, W.E. and Meharg, A.A. (2014) Consistency of arsenic speciation in global tobacco products with implications for health and regulation. Tobacco Induced Diseases 12:24 (doi:10.1186/s12971-014-0024-5)
Campbell, R.C.J. Stephens, W.E. and Finch, A.A. (2014) Controls on the Valence Species of Arsenic in Tobacco Smoke: XANES Investigation with Implications for Health and Regulation. Environmental Science and Technology 48, 3449−3456. (dx.doi.org/10.1021/es4039243)
Caruso, R.V., Connor, R.J., Stephens, W.E., Cummings, K.M. and Fong, G.T. (2014). Toxic Metal Concentrations in Cigarettes Obtained from U.S. Smokers in 2009: Results from the International Tobacco Control (ITC) United States Survey Cohort. Int. J. Environ. Res. Public Health 11, 202-217; (doi:10.3390/ijerph110100202)
50 (of 80 published available)
for wes (source: University of St Andrews PURE)
Please click title of any item for full details
Tobacco Control 2017 vol.26 pp.502-508
Tobacco Control 2017 vol.21 pp.10-17
Geochimica et Cosmochimica Acta 2017 vol.205 pp.168-186
Tobacco Regulatory Science 2016 vol.2 pp.166-175
Nicotine & Tobacco Research 2015 vol.17 pp.1331-1336
Tobacco Control 2015 vol.24 pp.iv55-iv59
Tobacco Induced Diseases 2014 vol.12
Environmental Science and Technology 2014 vol.48 pp.3449-3456
International Journal of Environmental Research and Public Health 2013 vol.11 pp.202-217
Tobacco Control 2010 vol.19 pp.-
JOURNAL OF FORENSIC SCIENCES 2010 vol.55 pp.738-741
Eos, Transactions, American Geophysical Union 2009 vol.90 pp.1885
Scottish Journal of Geology 2009 vol.45 pp.117-130
Earth and Environmental Science Transactions Of The Royal Society Of Edinburgh 2008 vol.99 pp.225-250
Earth and Environmental Science Transactions Of The Royal Society Of Edinburgh 2007 vol.98 pp.59-69
Scottish Journal of Geology 2006 vol.42 pp.137-148
Geological Society Special Publication 2005 vol.248 pp.133-151
Geological Society of America: Special Papers 2004 vol.389 pp.1-390
Teaching Earth Sciences 2004 vol.29 pp.26-27
Transactions of the Royal Society of Edinburgh: Earth Sciences 2004 vol.95 pp.1-390
Transactions of the Royal Society of Edinburgh: Earth Sciences 2004 vol.95 pp.5-6
Geological Society of America: Special Papers 2004 vol.389 pp.5-6
La Medicina de Lavaro 2003 pp.64-65
Geochimica et Cosmochimica Acta 2003 vol.67 pp.A448
Geochimica et Cosmochimica Acta 2003 vol.47 pp.A448
Geochimica et Cosmochimica Acta 2003 vol.68 pp.A530
Geophysical Research Abstracts 2003 pp.2834
Eos, Transactions, American Geophysical Union 2003 vol.86 pp.314
Transactions of the Institution of Mining and Metallurgy, Section B-Applied Earth Science 2003 vol.112
Transactions of the Royal Society of Edinburgh: Earth Sciences 2001 vol.91 pp.1-321
Transactions of the Royal Society of Edinburgh: Earth Sciences 2001 vol.91 pp.v-vi
Geological Society of America: Special Papers 2001 vol.350 pp.v-vi
Journal of the Geological Society 2000 vol.157 pp.601-613
1999 vol.17 pp.409-412
Lithos 1999 vol.46 pp.331-626
1999 vol.46 pp.331
Anais da Academia Brasileira de Ciencias 1999 vol.71
1999 vol.17 pp.444-468
Acta Universitatis Carolinae - Geologica 1998 pp.83-85
Chemical Geology 1997 vol.143 pp.127-144
Chemical Geology 1997 vol.136 pp.55-70
Journal of Petrology 1997 vol.38 pp.169
Transactions of the Institution of Mining and Metallurgy, Section B-Applied Earth Science 1997 vol.106