Additives

Nearly all commercial tobacco products contain chemical additives. As long ago as the sixteenth century, Spanish sailors applied licorice water to tobacco as a preservative (Browne, p. 55). Today, both cigarette and smokeless tobacco manufacturers publicly acknowledge the use of hundreds of additives in their products. The modern U.S.-style cigarette contains about 10 percent additives by weight, mostly in the form of sugars, humectants, ammonia compounds, cocoa, and licorice. Smokeless tobacco likewise incorporates moisteners, sweeteners, and flavors such as cherry juice. These additives may affect the flavor of the product, sensory properties such as smoothness and impact, and other important product characteristics. Additives can also be used to enhance or alter nicotine delivery, a practice denied by manufacturers.

Role of Additives in Product Design

The flavor of a tobacco product is primarily determined by the tobacco leaf blend, while additives are used to modify or enhance tobacco flavor characteristics. Menthol is the only commonly recognized tobacco flavor category, although vanilla, cherry, orange, and other product flavors have been introduced commercially. Most additives are used in very small amounts—less than .01 percent of total weight. As a result, although the cumulative effect of additives on tobacco flavor may be significant, it is often difficult or impossible to assess the impact of specific flavorants.

Additives perform a number of roles in addition to altering product flavor. For example, additives may also control cigarette burn rates, properties of tobacco such as moisture and consistency, and delivery of specific smoke constituents. Not surprisingly, the most widely used additives—including sugars, cocoa, and licorice—demonstrate important sensory, physiological , and respiratory effects. Both theobromine, the principal alkaloid of the cocoa bean, and glycyrrhizin, the active component in licorice, act as bronchodilators, relaxing the bronchial muscle and therefore enhancing respiratory inhalation. Likewise, the addition of sugars helps to offset bitterness, improve smoothness, and reduce irritation caused by tobacco smoke. Highly aromatic compounds, such as vanillin, may also be used to alter the aroma of side-stream smoke (the smoke produced from the lit end of the cigarette between puffs).

Some additives demonstrate properties that significantly alter product chemistry. A number of additives in both cigarettes and smokeless tobacco products are used for modification of "smoke pH," which is a measure of its acid/base chemistry. Increased "smoke pH" allows more nicotine to be present in the chemical freebase form, which is more readily available for absorption and use in the body (much as crack cocaine is a more potent freebase form of cocaine). Other additives increase or alter the effects of nicotine, or produce their own effects on the central nervous system and brain. For example, pyridine, a cigarette additive, acts as a depressant in much the same way that nicotine does, although it is less potent.

Manufacturers have used modified forms of tobacco, in combination with other design changes, to reduce the amount of tar produced per cigarette and to cut production costs. Modified tobaccos, such as reconstituted tobacco (combined from stems, leaves, and other tobacco scraps), rely on additives to maintain their physical integrity, to promote consistency, and to control resulting tobacco and smoke chemistry. Additional flavorants or enhancing agents may also be used to counteract the loss of sensory or other subjective response in these reduced delivery products.

Many products today are marketed with the claim "no additives." However, a true evaluation of additives must include not only the flavors applied directly to the tobacco but also other chemicals used during stages throughout the production and manufacturing process. Additives are used as tobacco processing agents, as treatment for cigarette papers or filters, or even applied to product packaging (which then allows transfer to the finished product). The hundreds of pesticides and other chemicals used in the growing or harvesting of tobacco may also be present as residues in manufactured tobacco products.

Physiological and Behavioral Effects

Additives may produce important changes to the effects of tobacco, altering dependence, toxicity, or use behaviors. For example, additives may increase the addictive character of tobacco smoke by altering the effects of nicotine or by exerting other pharmacologic effects on the user. Changes to the physiological properties of nicotine could also radically alter the character of tobacco dependence. Additives that enhance the body's interaction with nicotine or other constituents may increase their addictive or toxicological effects. For example, menthol has been shown to enhance drug absorption and demonstrates effects on metabolism that could alter the pharmacological action of other substances in tobacco smoke. Moreover, industry research has demonstrated a 50 percent increase in the binding of nicotine to brain receptors in the presence of the additive levulinic acid. These and other additives could significantly alter the effects of nicotine and other constituents, again without noticeably changing the amount of nicotine delivered.

Changes in chemical composition of tobacco products could alter the site and rate of uptake of nicotine and other constituents. For example, a greater percentage of nicotine delivered in freebase form may result in increased rates of absorption in the mouth (in the case of smokeless tobacco) as well as faster absorption from the lower respiratory tract to the brain (in the case of cigarettes). These changes could alter the intensity of response and increase dependence. The addition of bronchodilators to cigarettes may have similar effects by allowing deeper inhalation and deposition of smoke constituents in areas of the respiratory tract where they are more likely to be absorbed.

One primary use of additives in cigarettes is to counteract the irritation of tobacco smoke and its active component, nicotine. The perception of smoother smoke may facilitate increased or deeper inhalation of tobacco smoke by removing physical barriers. Similarly, reduced irritation may encourage or support increased frequency of use. Published research suggests that increasing ease of inhalation may be linked to increased rates of initiation among youth. Candy-like flavors, such as cherry, may also be used to target youth.

Health Risks and Regulation

No systematic assessment has been conducted of the hundreds of additives used in tobacco products. However, a number of these additives are known to pose direct health risks. Deer tongue extract, once a widely used tobacco flavorant, was banned in some countries and ultimately phased from use due to its high concentration of coumarin, a known animal carcinogen . The combustion products of cigarette additives may pose additional health risks even though the additive from which they were generated is considered safe. For example, cocoa, although harmless on its own, produces carcinogenic compounds when burned. Another significant health issue is exposure to environmental tobacco smoke (ETS). Research suggests that additives may be used to reduce the visibility, irritation, or odor of ETS, possibly increasing nonsmokers' exposure, without rendering the smoke less harmful.

Tobacco manufacturers emphasize in public statements that the majority of additives have been shown to be safe when eaten in foods. However, compounds are significantly more toxic when inhaled or absorbed directly into the bloodstream rather than ingested. In the digestive system, additives and other complex molecules are broken down by enzymes into simpler chemical structures and/or transformed into other compounds. These processes render most substances less toxic to the body. In contrast, tobacco additives escape the metabolic pathways that would help make them less toxic. Although a number of additives are present in commercial products only in small concentrations, it does not follow that these can be considered harmless. Since people often use tobacco products for decades, their long-term exposure must be taken into account.

Even though the use of additives raises significant concerns regarding increased health risks, the tobacco industry has largely been left to police itself. Many countries regulate tar and nicotine levels of tobacco products and require that this information be reported to the public. In most cases, however, legislative authority does not extend to disclosure of additives. Only a handful of countries (Thailand, Canada, Ireland) have enacted meaningful additive disclosure laws, and in each case the availability of information to the public has been severely limited. Some countries have limited or banned use of particular additives, or specify additives that may be permitted for use. In Canada, the list of permitted additives for use in cigarettes is quite small; as a result, Canadian cigarettes differ significantly from cigarettes sold elsewhere.

Increased Addictiveness: Ammonia and Acetaldehyde

T he use of ammonia in Marlboro cigarettes has been widely publicized. Ammonia compounds, especially ammonium hydroxide and diammonium phosphate (DAP), are used in the ammoniation of reconstituted tobacco. The ammonia compounds are reacted with sugars at a high temperature to produce pyrazines and other flavors through a chemical process known as Maillard browning. These flavors demonstrate unique sensory and pharmacological effects. The ammoniated tobacco produces a characteristic mild smoke, increased "smoke pH," and a more efficient transfer of nicotine, all of which combine to make the cigarette more addictive. Early adoption of DAP in tobacco processing in the 1950s is widely believed to be responsible for the unique flavor of Marlboro cigarettes and, ultimately, their success worldwide.

In the early 1980s, the research scientist Victor DeNoble and coworkers at Philip Morris studied the behavioral effects of nicotine and acetaldehyde (a byproduct of sugar) in rats. The results of this research showed that the two compounds work together to produce greater addictive effects. DeNoble later claimed in public testimony that based on this information, Philip Morris increased the level of acetaldehyde in Marlboro cigarettes by 40 percent between 1982 and 1992 through the addition of sugars (Bates 1999).

In 1994 in the United States, major cigarette manufacturers voluntarily released to the public a list of 599 potential additives for use in their products. A similar list was produced by smokeless tobacco manufacturers. Both lists were composite and did not provide brand-specific information. Some tobacco manufacturer websites provide an updated summary of additives used in their products, including maximum levels, although again this information is composite rather than brand-specific. Overall, the information provided by tobacco manufacturers is not sufficient to provide a reliable assessment of the effects of additives on addiction and toxicity.

See Also Addiction; "Light" and Filtered Cigarettes; Menthol Cigarettes; Nicotine; Processing; Product Design; Regulation of Tobacco Products in the United States; "Safer" Cigarettes; Toxins; Youth Marketing.

? GEOFFREY FERRIS WAYNE

BIBLIOGRAPHY

Bates, Clive, Gregory Connolly, and Martin Jarvis. "Tobacco Additives: Cigarette Engineering and Nicotine Addiction." Action on Smoking and Health (July 1999). Available: <http://www.ash.org.uk/html/regulation/html/additives.html>. An accessible summary analysis of use of additives through study of internal industry documents.

Browne, C. L. The Design of Cigarettes, 3rd ed. Charlotte, N.C.: Hoechst Celanese Corporation, 1990. A widely accepted industry reference on basic cigarette design.

Doull, J., J. P. Frawley, and W. George. List of Ingredients Added to Tobacco in the Manufacture of Cigarettes by Six Major American Cigarette Companies. Washington, D.C.: Covington & Burling, April 12, 1994. A commonly cited list of cigarette additives released by U.S. manufacturers. The list is widely available online; see <http://www.tobacco.org/Resources/599ingredients.html>.

Ferris Wayne, G., and G. N. Connolly. "How Cigarette Design Can Affect Youth Initiation into Smoking: Camel Cigarettes, 1983–1993." Tobacco Control 11 (2002): 32–39. Links the use of additives to an increase in youth initiation.

Hoffmann, D., and I. Hoffmann. "The Changing Cigarette, 1950–1995." Journal of Toxicology and Environmental Health 50, no. 4 (March 1997): 307–364. Describes the use of additives in the context of other product changes.

Leffingwell, John C., Harvey J. Young, and Edward Bernasek. Tobacco Flavoring for Smoking Products. Winston-Salem, N.C.: R.J. Reynolds Tobacco Company, 1972. The definitive industry review of additive flavorants.

Wells, John Kendrick, III. "Subject: Technology Handbook" (22 August 1995). Available: <http://tobaccodocuments.org/product_design/945335.html>. Internal industry study of ammoniation, its use and importance historically.

menthol a form of alcohol imparting a mint flavor to some cigarettes.

physiology the study of the functions and processes of the body.

depressant a substance that depresses the central nervous system. The most common depressant is alcohol.

tar a residue of tobacco smoke, composed of many chemical substances that are collectively known by this term.

carcinogen a substance or activity that can cause cancer. Cigarette smoking has been proven to be carcinogenic, that is, cancer causing.