Tackling the global tobacco epidemic with geochemistry

One in two smokers will succumb to a smoking-related disease and one billion deaths in the 21st century will be attributable to smoking. The World Health Organisation (WHO) is responding to this global epidemic with a variety of strategies within the Framework Convention on Tobacco Control (FCTC) to which 176 countries are signatories. Geochemical research at the University of St Andrews has contributed to FCTC policies and supports their implementation by chemically characterising and monitoring potentially toxic environmental metals such as arsenic and cadmium in tobacco. The group’s research has been helping to combat the global trade in illicit tobacco and its major consequences for health and for government revenues through taxation and criminal activity.

The science 

Approximately 5% of tobacco (dry weight) is inorganic with its origins in soils, atmospheric particles (natural and anthropogenic pollutants) and agrochemicals. Some of this is taken up through the plant roots while particles tend to adhere to the sticky and hairy surface of the leaf. Among this diversity of material are several “heavy metals”. Fundamental to determining whether these metals or metalloids might be toxic to humans is their chemical form (valence and molecular speciation). The contribution each metal makes to the harmful effects of tobacco smoke is determined by a combination of concentration and speciation. As a result of research conducted in the Department of Earth and Environmental Sciences (e.g. Analysis of non-organic elements in plant foliage using polarised X-ray fluorescence spectrometry, DOI: 10.1016/j.aca.2004.08.015 and Source and health implications of high toxic metal concentrations in illicit tobacco products, DOI: 10.1021/es049038s), it became clear that toxic metal concentrations, determined primarily by geographical location and legal status, varied by an order of magnitude. The speciation of arsenic in tobacco has now been determined and combustion (i.e. smoking) has been shown to generate the most toxic form (inorganic trivalent arsenic) in respirable smoke (e.g. Controls on the Valence Species of Arsenic in Tobacco Smoke: XANES Investigation with Implications for Health and Regulation, DOI: 10.1021/es4039243).

Principal components analysis of inorganic elements in tobacco
from global sources demonstrating provincial variability.

Using an archive of tobaccos collected over more than a decade from most parts of the world, it proved possible for the first time to identify provinciality among tobaccos products. The figure illustrates that significant differences exist at the continental scale at least. This feature can be used to constrain the geographical origins of illicit products. The same dataset helps to identify regions on a global scale where tobacco smoking represents a major source of exposure to toxic metals.

Health and economic benefits 
Since 2004 FCTC has been the main driver of national and global policy on tobacco control. It is predicted that full implementation of FCTC will prevent over seven million premature deaths by 2050. The unexpected discovery by the University of St Andrews group of high toxic metal concentrations, including carcinogens such as cadmium and arsenic, in most counterfeit tobacco products prompted HMCE (now HMRC) to run a nationwide information campaign in 2004 ("Counterfeit Cigarettes") sponsored by HM Treasury. The illicit share of the UK cigarette market at that time was 18% but was halved to 9% by 2012-13. Evidence presented in Treasury revenue reports indicates that revenues recovered due to the range of UK policies for reducing the supply and demand for illicit tobacco since 2006 may exceed £1 billion. Evidence of the harmful nature of illicit products from the St Andrews laboratories was used to support this effort. Globally over $31 billion is lost in tax revenue. It has been suggested that 164,000 premature deaths might be avoided annually if illicit tobacco was eliminated.

The University of St Andrews research into toxic metals in commercial cigarettes also highlighted legal Chinese tobacco products as among the most heavily contaminated so far analysed (Cigarettes sold in China: design, emissions and metals, DOI: 10.1136/tc.2009.030163). China is the world’s largest tobacco-growing nation with the largest number of smokers. The adverse impact on health of habitual use of contaminated products by the Chinese population is not yet quantifiable but could be considerable. Currently, it accounts for one million deaths annually from tobacco use.