Concentrations of nine alkenylbenzenes, coumarin, piperonal and pulegone in Indian bidi cigarette tobacco

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Abstract

Indian-made bidi cigarettes sold in the United States are available in a variety of exotic (e.g. clove, mango) and candy-like (e.g. chocolate, raspberry) flavors. Because certain tobacco flavorings contain alkenylbenzenes and other toxic or carcinogenic chemicals, we measured the concentration of flavor-related compounds in bidi tobacco using a previously developed method. Twenty-three brands of bidis were sampled using automated headspace solid-phase microextraction and subsequently analyzed for 12 compounds by gas chromatography–mass spectrometry. Two alkenylbenzene compounds, trans-anethole and eugenol, were found in greater than 90% of the brands analyzed. Methyleugenol, pulegone and estragole were each detected in 30% or more of the brands, whereas safrole and elemicin were not detected in any of the brands. The flavor-related compounds with the highest tobacco concentrations were eugenol (12,000 μg/g tobacco) and trans-anethole (2200 μg/g tobacco). The highest eugenol and trans-anethole concentrations found in bidi tobacco were about 70,000 and 7500 times greater, respectively, than the highest levels previously found in US cigarette brands. Measurement of these compounds is crucial to evaluation of potential risks associated with inhaling highly concentrated flavor-related compounds from bidis or other tobacco products.

Introduction

Indian bidi cigarettes simply consist of a small amount (approx. 0.2 g, 40% by weight) of sun-dried Indian tobacco that is hand-rolled in dried tendu leaves from trees such as Diospyros melanoxylon or Diospyros ebenum (Malson et al., 2001), which are members of the Ebony family (Hardin et al., 2000). Intact and cutaway views of a bidi cigarette are shown in Plate 1. Interestingly, Indian-made bidis, sold in the United States, are available in exotic (e.g. mango, clove) and candy-like (e.g. chocolate, strawberry) flavors that are packaged in colorful boxes or wrappers. Anecdotal evidence suggests that bidi smoking has been gaining popularity among adolescents since the mid-1990s (CDC, 1999). In a 1999 survey of 642 high-school students from Massachusetts, conducted by the Centers for Disease Control and Prevention (CDC), it was found that 24% of the students were current bidi smokers (one or more bidi within the last 30 days) or heavy bidi smokers (more than 100 bidis in their lifetime). An additional 16% of the students reported that they had tried at least one bidi in their lifetime. When the student smokers were asked why they smoked bidis, most often they responded that bidis taste better than cigarettes (23%), or that bidis are cheaper (18%) or safer (13%) than cigarettes. These results seem to indicate that factors such as appealing taste, affordable cost, and a perception of bidis as being a “safer” smoking alternative appear to contribute to the seductive appeal of bidis (CDC, 1999). Another CDC survey conducted in 2000 found a high incidence of bidi use among adolescents across the United States (CDC, 2000). Because bidi use is becoming more common, an in-depth analysis of flavor additives present in bidis is prudent.

Studies have shown that bidis are quite different from traditional US cigarettes. Chemically, bidi tobacco contains nicotine at concentrations more than double (37.7 mg/g) the levels found in US cigarette tobacco (16.2 mg/g) (Pakhale and Maru, 1998). Because of the low combustibility of the tendu leaf wrapper, bidis must be smoked more rapidly than US cigarettes to keep the cigarette rod ignited, although the smoke is generally inhaled less deeply than smoke from US cigarettes (Shirname et al., 1984). When comparing US cigarettes smoked under standard Federal Trade Commission conditions (NCI Expert Committee, 1996) with bidis smoked twice as fast, bidis yielded five times more “tar” and three times more nicotine and carbon monoxide (CO) than regular cigarettes (Rickert, 1999). The elevated levels of nicotine, CO and “tar” in bidi smoke are especially surprising because bidis contain less than one-third of the tobacco in US cigarette brands (about 0.7 g) (Stanfill and Ashley, 1999). In addition to these findings, earlier chemical studies have shown that bidi smoke condensate, a solvent extract of mainstream smoke particulate (i.e. smoke particles drawn directly through the cigarette mouthpiece by the smoker), contained higher levels of toxic compounds, including phenols, cresols, ammonia, hydrogen cyanide (Hoffmann et al., 1974), and polyaromatic hydrocarbons (Bhide et al., 1984), than found in cigarette smoke condensate.

Over the past two decades, studies have addressed both the direct effects of bidi smoke on laboratory animals, as well as the incidence of disease among populations in India where bidi use is prevalent (Gupta et al., 1996). Using laboratory animals, researchers found that 47% of Swiss albino mice exposed to bidi smoke condensate developed cancerous tumors, whereas those exposed to the same level of cigarette smoke condensate had a much lower incidence of tumor formation (Pakhale et al., 1988). On the other hand, epidemiological studies in India, where 34% of the 400 million adults smoke bidis (Gupta et al., 1996), showed that bidi use is associated with increased incidence of oral cavity, pharynx, larynx, lung, esophagus (Shirname et al., 1984), stomach, and liver cancers (Gupta et al., 1996), and that overall cancer risks are higher for bidi smokers than for cigarette smokers (Sanghvi, 1981).

Generally, flavoring agents are added to tobacco products to enhance the taste or aroma of tobacco or mask undesirable odors (Penn, 1997). Common tobacco flavoring sources such as anise, cinnamon, and nutmeg (Tobacco Reporter Staff, 1994), contain alkenylbenzenes, which are allyl- and propenyl-benzenes with methoxy- or methylenedioxy-ring substitutions (Leung, 1980). Unfortunately, some alkenylbenzenes, such as safrole, estragole, methyleugenol (Miller, Miller, and Phillips, 1982, Enomoto, 1987), eugenol (Leleng et al., 1982), and trans-anethole (Truhaut et al., 1989) have exhibited genotoxic, mutagenic or carcinogenic properties in laboratory animals or biological assays (e.g. Ames Salmonella assay). Other alkenylbenzenes, such as myristicin and elemicin, are thought to have hallucinogenic (Braun and Kalbhen, 1973) and genotoxic (Hasheminejad and Caldwell, 1994) properties. Unfortunately, very little is known about the toxic effects of inhaling many of these compounds.

Eugenol, one of the most widely studied alkenylbenzenes, was 250 times more toxic when inhaled than when ingested by laboratory animals (LaVoie et al., 1985), which suggests that flavor-related compounds deemed safe for ingestion may not necessarily be considered safe when inhaled in cigarette smoke (Hoffmann and Hoffmann, 1997). US cigarette makers do not report using eugenol as a direct additive, or ingredients such as clove buds or clove bud oil (Tobacco Reporter Staff, 1994), which contain a high percentage of eugenol (Burdock, 1995). Some unburned cigarettes, however, contain small amounts of eugenol (Stanfill and Ashley, 1999), which may be derived from other eugenol-containing flavor ingredients, such as nutmeg (Masada, 1976), which are added to some cigarette tobaccos (Tobacco Reporter Staff, 1994).

Surprisingly, when some US cigarettes, which contain no detectable levels of eugenol (>0.01 μg/g tobacco) (Stanfill and Ashley, 1999) are burned, they actually produce smoke that contains eugenol (0.08–0.50 μg/cig) (Stanfill and Ashley, 2000). The production of eugenol in the smoke from these cigarettes may result from the pyrolysis of naturally-occurring tobacco constituents (Rodgman, and Cook, 1964, Schlotzhauer, and Chortyk, 1987). Nevertheless, inhalation of extremely high concentrations of eugenol probably is rare, but can occur when clove cigarettes, which consist of tobacco and eugenol-laden clove buds, are smoked (Council of Scientific Affairs, 1988).

Other flavor-related compounds, including piperonal, pulegone and coumarin, also exhibit potentially harmful effects. In rodents, the metabolism of pulegone, a mono-terpene ketone, causes irreversible destruction of cytochrome P450, a critical liver detoxifying enzyme (Moorthy et al., 1991); depletes glutathione, a necessary component for toxicant elimination (Thomassen et al., 1990), and causes death of liver and lung cells (Gordon et al., 1982). Piperonal, a substituted benzaldehyde, causes central nervous system depression in rodents (Enomoto, 1987), and coumarin, a benzopyrone compound, was shown to cause liver toxicity in rats and dogs as early as the mid-1950s (Lake, 1999). Pulegone, coumarin and the alkenylbenzene safrole are banned as individual flavorants in all US products (Code of Federal Regulations, 2001), but are present as minor constituents of some flavor additives (Masada, 1976, Burdock, 1995) used in certain US tobacco products (Tobacco Reporter Staff, 1994). The analysis of alkenylbenzenes and other flavor-related compounds in bidis is important because of their potential health risks and because of their presence in both US cigarette tobacco (Stanfill and Ashley, 1999) and tobacco smoke (Stanfill and Ashley, 2000).

The present study contains the concentration ranges of coumarin, elemicin, estragole, eugenol, methyleugenol, myristicin, piperonal, pulegone, safrole, anethole, isoeugenol and methylisoeugenol (Fig. 1) found in 23 brands of bidis using a modified version of a previously reported method (Stanfill and Ashley, 1999). The IUPAC names and CAS numbers associated with each analyte quantified in this study are listed in the Appendix. Eugenol concentrations were measured in five clove cigarette brands for comparison with eugenol-containing bidis. To our knowledge, the concentrations of these 12 flavor compounds in bidis have not been previously reported for bidi tobacco, but such measurements are crucial to the assessment of potential health risks that these additives may pose to bidi smokers.

Section snippets

Acquisition and storage of samples

Bidi and clove cigarette packs were purchased at convenience stores in the metropolitan Atlanta area between autumn 1999 and spring 2001 and were processed and stored as previously described (Stanfill and Ashley, 1999). The results presented in the present study may not be representative of all of the bidi or clove cigarette brands sold in the United States, nor are the results inclusive of all bidi or clove cigarette brands available within the United States. These brands were convenience

Quantification of flavor compounds in bidis

In this study, concentrations of 12 flavor compounds, found in 23 brands of bidis made by four manufacturers: Darshan, ShivSagar, Kailas and Mangalore Ganesh, were measured. The samples were analyzed at least in triplicate, and in one case, 10 times. Owing to ion interferences and repeated QC failures for some analytes, some brands required repeat analysis to produce at least three valid results for each analyte. In three cases, an analyte had only two reportable results: estragole (Darshan

Conclusion

In this study, 12 flavor-related compounds with demonstrated toxic properties in laboratory animals and, in the case of eugenol, in humans, were selected for measurement in bidi cigarettes. The concentrations of these compounds were measured in the cigarette filler from 23 brands of bidis, whereas eugenol levels were measured in the filler from five brands of clove cigarettes. Seven alkenylbenzenes and three related flavor compounds, piperonal, pulegone and coumarin, were detected in bidi

Acknowledgements

We acknowledge the support received for this research from the Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention. Use of trade name is for identification only and does not imply endorsement by the US Department of Health and Human Services or the Centers for Disease Control and Prevention. We appreciate the helpful discussion with Dr. George A. Burdock of the Burdock Group (Toxicology and Risk

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