Hazardous chemicals from cigarette flavourings identified in tobacco smoke


A new study in the United States shows that smokers inhale hazardous chemicals that originate from compounds used to flavour cigarettes from tobacco smoke (Journal of Agricultural Chemistry, 2000, 48:1298 –1306). Flavourings are used in certain brands of cigarettes to enhance the taste experienced by smokers. The tobacco industry declares that most of the additives it uses are ‘‘generally recognized as safe’’. However, most flavour additives tested are classified as safe when they enter the human body through the ingestion of food and not through inhalation. Moreover, flavour-related compounds present in cigarette tobacco are transformed by burning cigarette coal to alkenylbenzenes. Combustion products of additives are not safe simply because the original materials are classified as being without risk.

For the first time, scientists have now measured flavour-related alkenylbenzenes in tobacco smoke particulate by a very sensitive method (selected ion monitoring gas chromatography – mass spectrometry). In the past, the measurement of flavour- derived alkenylbenzenes required as much as 1kg of smoke condensate, which is equivalent to the smoke from 50 000 cigarettes. Stephen B. Stanfill and David L. Ashley from the Centers for Disease Control and Prevention, Atlanta, Georgia, USA have developed a method than can detect alkenylbenzenes in the mainstream smoke particulate of a single cigarette in the low nanogram range. The findings are not only important in understanding the composition of tobacco smoke, but will also be useful in showing if these compounds have a role in smoking-related pathology after repetitive long-term inhalation.

Five alkenylbenzene compounds were identified and quantified in the smoke particulate from eight brands of cigarettes currently on the market in the United States. The brands had mean levels of alkenylben- zenes in the range 6.6–4210 ng per cigarette. The complete blocking of ventilation holes in the cigarette filter increased the transfer of alkenylbenzenes from tobacco to the particulate fraction of mainstream smoke 2–7-fold. Over a 30-year period, a two-pack-a-day smoker who is exposed to a seemingly small amount of alkenylbenzenes on a per cigarette basis, could inhale up to milligram amounts of alkenylbenzenes from smoke particulate alone.

Research data on the acute toxic properties of alkenylbenzenes are available. For methyleugenol, carcinogenic and mutagenic effects have been demonstrated in rodents; for myristicin and elemicin, genototoxic and halucinogenic effects have also been established.

Dr John Slade, Head of the Program in Addictions at the University of Medicine and Dentistry of New Jersey, New Brunswick, NJ, said that these results ‘‘point to some of the information that regulatory agencies should require cigarette makers to disgorge: what are all the desired functions that each additive and its combustion products play in manufactured cigarettes and what is known about adverse effects or potential toxicities of each additive and its combustion products in manufactured cigarettes? He added: ‘‘Regulatory agencies need to understand these products well enough to regulate them intelligently.’’§


Tudor Toma, London

World Health Organization Genebra - Genebra - Switzerland