5.1 How could additives affect addictiveness of tobacco products?
The SCENIHR opinion states:
Possibilities to make tobacco more addictive or attractive
Tobacco products are manipulated by tobacco companies by the addition of chemical compounds, most of which are flavours. Obviously, the flavours are added to the natural tobacco to give the product a better taste thereby increasing the attractiveness of these products. This includes the addition of humectants which keep the humidity of the tobacco product at a desired level; dry tobacco generates an unpleasant harsh smoke.
“Light” cigarettes were introduced on the market in the 1970s. Typical for light cigarettes is their high grade of ventilation. Due to the delivery of less tar, the impact and taste of the “diluted” smoke is also decreased. It is therefore probable that the light cigarettes were “enriched” by adding more substances, and in higher amounts, to compensate for reduced taste and impact.
An important reason for using additives is to give the product a specific and standardised taste. A specific taste is important for the company to be competitive on the consumer market in view of the large variety of brands available. A unique product binds the customer/consumer to this specific product. The specific taste of a certain product must be preserved (standardised) to compensate for the yearly variation of the natural tobacco, because consumers do not like to smoke a product that changes from year to year. To circumvent this, some 40 or more substances per product are added to the majority of the brands in order to mask the variation. Additives with direct or indirect addictive potency
In the following two sections, various approaches to increase the addictive and attractive potency of tobacco products have been briefly described. Details of these additives and further information about their effectiveness can be found in later sections.
The addictive potency of tobacco products may in theory be increased by:
Direct enhancement of the nicotine content;
Addition of substances which increase the bioavailability of nicotine;
Addition of substances which facilitate the inhalation of tobacco smoke;
Addition of substances which generate compounds in the mainstream smoke which increase the addictiveness of nicotine;
Changing the physical properties of tobacco smoke, e.g. particle size.
The five approaches are briefly described below.
Direct enhancement of the nicotine content
No examples of increasing the content of nicotine in tobacco are known. Moreover, in cigarettes sold (or produced) in the EU nicotine yield has to remain below a maximal level of 1 mg per cigarette. Some Member States also have upper limits for roll your own (RYO) tobacco. Genetic techniques or classical selection of variants are available to produce tobacco with relatively high nicotine content. From public sources it cannot be deduced or concluded that such approaches are indeed used by tobacco growers or tobacco companies.
Addition of substances which increase the bioavailability of nicotine
Increase the bioavailability of nicotine by adding alkalising ingredients which increase the pH of tobacco (such as ammonium compounds). At higher pH (pH >8.0) more nicotine is in its free uncharged form, which would therefore more easily pass the (lung) membrane i.e. higher absorption leading to higher blood and brain nicotine levels. For details see section 3.8.3.2 on ammonia and other compounds affecting smoke pH.
Increase the bioavailability of nicotine by adding ingredients which serve as a carrier for nicotine.
Increase the effect of nicotine by inhibiting its metabolism.
Addition of substances which facilitate the inhalation of tobacco smoke Certain ingredients have local anaesthetic effects. As a result coughing due to inhalation of irritating smoke is dampened and the smoker can inhale the smoke deeper (and more frequently). Examples are etheric oils, such as menthol and thymol. For details see later sections e.g. section 3.8.1.
Compounds which have bronchodilating properties (opening/broadening the airways) would enable the smoker to inhale deeper (a larger volume of) tobacco smoke implying an increase in the bioavailability of nicotine. It has been proposed that theobromine, generated from cocoa, caffeine and glycyrrhizine, serves such a function.
Addition of substances which generate compounds in the mainstream smoke which increase the addictiveness of nicotine
It has been suggested that certain natural components in tobacco promote the addictiveness of nicotine. Examples are components like sugars, which when pyrolysed generate aldehydes. The combination of acetaldehyde and nicotine appears to be more addictive than nicotine alone. The addition of sugars may thus increase the addictive nature of tobacco products. In tobacco smoke or in vivo, tryptophan may react with aldehydes to form beta-carbolines, like harman and norharman. Both beta-carbolines are inhibitors of monoamine oxidases (MAO). Monoamine oxidases are enzymes that degrade neurotransmitters involved in addiction such as dopamine, serotonin and noradrenaline. As such, tryptophan as an ingredient may potentiate nicotine addiction.
Acetaldehyde and other aldehydes can react in vivo with biogenic amines to yield carbolines or isoquinolines, which have affinity for the opiate receptor. These ligands are, however, formed in very low amounts.
Changing the physical properties of tobacco smoke, e.g. particle size
It is possible to change the physical properties of tobacco smoke, for example the particle size of the tobacco smoke aerosol. Considering the entry of particles to deeper lung levels, there is probably an optimum in size. Cigarette paper and/or filters can be modified in a technological way to attain an optimal particle size (see section 3.5). The size and its distribution of smoke particles can be changed to obtain an optimum so that particles enter deeper levels of the lungs. As a result, a more efficient absorption of nicotine from the particles and higher blood nicotine levels can be attained. Examples of such applications are the use of cigarette paper with a higher porosity and filters with higher ventilation (see section 3.5).
Source:
https://ec.europa.eu/health/scientific_committees/opinions_layman/tobacco/en/l-3/5.htmDon't smoke! It's as simple as that!
Peter
