Polycyclic aromatic hydrocarbons in smokeless tobacco products
A new study shows that the concentration of polycyclic aromatic hydrocarbons (PAHs) in smokeless tobacco products (STPs) can differ by as much as 60 fold, with the highest levels in moist snuff, and dry snuff and soft pellets; the lowest levels were in snus. Higher levels can be explained by the use of of fire-cured tobaccos in the products. The source of the trace amounts of PAHs in snus and other products using non-fire-cured tobaccos was previously unknown. The results of this study indicate the source to be environmental pollution, such as car exhausts and agricultural and wood fires.
Scientists at British American Tobacco and the University of Louisville analyzed 70 contemporary STPs, representing 80-90% of market share in Sweden and the USA, including chewing tobacco, dry and moist snuff (dipping tobacco), hard and soft pellets, plug, and loose and portion snus, for 21 PAHs.
PAHs are produced during the incomplete burning of organic material such as coal, oil, gas, wood, and tobacco. They do not occur naturally in plants such as tobacco, but can be created during the drying (curing) process, for example, if the tobacco leaf is exposed to exhaust gases from heat sources that rely on burning wood, this can increase PAH level. Fire-cured tobaccos, whose production involves direct contact of the tobacco leaf with wood smoke, contain particularly high concentrations of PAHs.
The US Food and Drug Administration, has identified 15 PAHs as harmful or potentially harmful constituents in tobacco, and one, benzo(a)pyrene (B[a]P), is a known human carcinogen. This comprehensive analysis did not find seven of the FDA-specified PAHs in any of the STPs tested. However, it provided benchmark quantitative information on the PAHs in contemporary STPs used in Sweden and the USA.
In this study, PAHs were found in all STPs tested, but there were significant differences in the total and individual PAH concentrations in the different product styles. Substantially higher levels of total PAHs (10-60 fold) were found in moist and dry snuff and soft pellets than in the other STPs.