This is the second part of a two part article that the authors prepared for Burning Issues. The addictive practices of people world wide often do and don’t include tobacco products. With the steady growth of peoples from the Indian sub-continent and other parts of the world, it behooves tobacco control researchers and advocates to familiarize themselves with their tobacco and other addictive practices. (PG) part #1

By Kamlesh Asotra, Ph.D and Rajesh N. Sharan, Ph.D.

The Bad…
Habitual and regular chewing of betel nut produces several adverse effects on the oral and upper digestive tract, including inflammation and development of white or gray patch on the tongue and inside of cheeks (leukoplakia), fibrosis, and oral cancers. Frequent use turns the lips red and the mouth and teeth black. Betel leaf contains large proportion of a carcinogen Safrole, which is readily metabolized and excreted in urine as dihydroxychavicol and eugenol (17). Safrole used to be the ingredient in original root beer; because of its cancer-causing properties, the formula for root beer was later reformulated without this key flavor ingredient.

Areca nut contains cancer-causing alkaloids (0.25% of sun-dried Areca nut by weight), predominantly arecoline (0.15%) and Arecaidine (0.10%) and trace amounts of guvacine, guvacoline, and arecolinidine. Arecaidine is reportedly more toxic than arecoline, but both have similar pharmacokinetic properties (17). When oxidized in the presence of lime, the compounds extracted by chewing of Areca nut give a characteristic red coloration to saliva, teeth, tongue, and lips. Gallotannic acid is the predominant tannin in betel nut, with minor components as gallic acid, D-catechol, and phiobatannin. The Areca alkaloids are cholinergic agonists, which affect the nervous system’s functions via acetylcholine and result in a stimulant action that increases capacity to work and has euphoric effects with heightened alertness. Arecoline, a mildly toxic agent, interacts preferentially with the muscarinic receptors, rather than the nicotinic receptors that mediate the action of nicotine. If excessive amounts of betel nut are used, the symptoms of Amanita poisoning occur such as intense discharges, including production of saliva, tears, sweat, diarrhea, vomiting, and stomach cramps. Urinary incontinence, fever, flushing, confusion, difficulty in walking, memory lapse, and anxiety may also result from intake of large quantities of Areca nut. Metabolomic technologies have recently been developed to identify the metabolic products of Areca nut alkaloids Arecaidine and arecoline in urine samples of animals, and soon this technology may be useful in human studies (18).

Heavy use of Areca nut produces a wide spectrum of adverse health effects including cardiovascular disease (19, 20), heart attacks (21), arrhythmia (22), metabolic syndrome (23), and diabetes (24, 25).

…and the Ugly
Areca nut and betel-quid chewing leads to oral submucous fibrosis (OSF)— a painful, disabling and potentially precancerous condition of the oral mucosa (Figure 4). The elasticity of the inner lining of the cheeks and mouth becomes reduced, and fibrous bands develop in people who chew Areca nut, betel-quid, paan masala, gutkha, and tobacco (26, 27). If not diagnosed and treated early, OSF can lead to dysplasia and oral squamous cell carcinoma. Oral cancer represents only 2–4% of the malignancies in the Western world, but accounts for nearly 40% of all cancers in the Indian subcontinent (28, 29).

The carcinogenic agents in the betel quid are thought to be at least three of the constituents: arecoline, Arecaidine, and safrole. Arecoline and Arecaidine from the Areca nut may be promoters for other carcinogens (especially the N-nitroso compounds with which they can combine); the Areca alkaloids also contribute to changes in the oral mucosa that lead to the detrimental oral effects, including oral cancer.

Figure 4. Left panel: Oral submucous fibrosis of the lower lip in a patient. Notice the white coloration of the affected area. Right panel: Toluidine blue stained area showing dysplasia of the lower lip and dark-stained teeth because of betel-quid chewing. (Courtesy, Mehrotra et al., 2006; reference 29).

Some studies suggest that the combined use of betel-quid with tobacco and tobacco-containing gutkha is much more damaging to the chewer’s health, perhaps because of greater combinatorial dose of nitrosamines from Areca nut and tobacco. However, the absence of tobacco in the Taiwanese quids helps avoid the objection that it is inclusion of tobacco in the chewing material that is causing oral cancers. In addition, it is suspected, though not proven, that regular chewing of betel nut also increases the occurrence of other cancers besides those of the mouth.
Cytotoxic, Genotoxic, Mutagenic, and Teratogenic Effects

Sufficient and compelling evidence shows that constituents of Areca nut, betel leaf, betel-quid, and catechu cause, both independently and synergistically, several cytotoxic, genotoxic, and mutagenic effects on mammals. For example, these products enhance chromatid breaks and exchanges in the range of 12–37% in human cells in vitro (30) and in DNA strand breaks in mouse kidney cells or human buccal epithelial cells (31-34). Shirname and colleagues (35) were the first group to show that betel-quid caused gene mutations. Their findings have been confirmed and replicated in other human and mammalian cell types by others (2, 36). Cytotoxic, genotoxic, and mutagenic effects of Areca nut saliva extract due to nitrosamines derived from alkaloids, are widely implicated in oral cancers (37, 38).

Teratogenic effects of Areca nut and arecoline have been reported in mice and rats including death, enhanced resorption, and reduced weight of the fetus (39). A study on six babies of Asian women who habitually chewed Areca nut reported abnormalities of the fetoplacental circulation such as those seen with nicotine or cocaine addiction, but the authors could not make a definitive conclusion regarding the correlation between prenatal exposure to arecoline and birth outcomes (40). Perhaps, a larger study would shed more light on the possible teratogenic effects of Areca nut in humans.

Induction of Carcinogenesis by Areca Nut Alkaloids
It is believed that Areca-nut-specific N-nitroso compounds converted from alkaloids are the causal agents in oral and esophageal cancer (reviewed in 2, 3). The major cancer-causing agents from tobacco are also N-nitroso compounds. Recent studies have demonstrated the molecular mechanisms by which Areca nut and betel-quid cause esopharangeal cancer (41-43). Induction of esophageal cancer in Areca nut and betel-quid chewers in India was found to be associated with up-regulation of genes of four different molecular pathways and down-regulation of genes of six different molecular pathways (43). The significantly over-expressed pathways included the genes for mitogen-activated protein kinase signaling cascade, G-protein coupled receptor, and cation transporter. The down-regulated pathways included the cytoskeletal genes, the ribosomal genes, and genes that regulate the antioxidant activity. The ribosomal proteins may function as cell-cycle checkpoints and play a role in cellular transformation, tumor growth, and metastasis. Thus, Areca nut alkaloids cause cancer at molecular level by modulating the expression of a number of genes (Chattopadhyay et al., 2007). An important step in Areca nut-induced carcinogenesis is catalyzed by the process of poly-ADP-ribosylation of chromosomal proteins, which alters chromosomal superstructure and, consequently, the functional status of chromosomes (44, 45).

Efforts to Control Use of Areca nut, Betel-quid, and Gutkha
In recognition of the health hazards due to chewing Areca nut, betel-quid, and the tobacco-containing gutkha preparation, policy makers in many countries have enacted laws banning the chewing of these masticatories in public places, with threat of stiff fines for violators. Since 2001, India and Taiwan have been particularly aggressive in such control measures. Several states and cities in India such as Pune and Mumbai in Maharashtra State, Lucknow in Uttar Pradesh and the city of Hyderabad, among others have embraced these policies to discourage the use of gutkha and paan masala. The most effective implementation of control efforts was observed in the state of Tamil Nadu. However, enforcement of ban on the sale of these masticatories in the Indian states of Goa, Gujrat, Andhra Pradesh, and Kerala has not met with much success (46). Interestingly, when the ban on sale and use of gutkha and paan masala was enforced in the city of Hyderabad in India, the sales of fresh betel-quid increased by 50% (47). Even after the imposition of a ban on open sale of gutkha and paan masala in Patna city of Bihar, these were available “under the counter” in almost every betel shop in the city (48). The restrictions imposed on gutkha and paan masala in India have been challenged by the manufacturers in the State High Courts and The Supreme Court of India (49). The battle between the health policy makers and the suppliers of Areca nut, betel-quid, and gutkha continues. One can only hope that by educating general public about the health hazards of these masticatories, the younger generations can be dissuaded from taking up the habit and help the current users quit. Enforcement of ban, the will of governments, and cooperation of courts must be in place to combat the public health hazards due to the practice of Areca nut, betel-quid, and gutkha chewing in the Asian and Pacific Rim countries.

Future Research Needs
California has a large population of immigrant Asians and Pacific Islanders, who may have traditionally practiced chewing Areca nut and betel-quid, with or without tobacco. Since paan masala is freely available in Asian stores, one would assume that it is consumed by Californians. Although Areca nut and betel-quid are on the State of California’s list of materials that cause cancer, there is no information available about the use of these harmful masticatories. TRDRP encourages and welcomes research grant applications from investigators in California proposing to investigate the statewide use and health effects of Areca nut, betel-quid, and gutkha.

Acknowledgement: Kamlesh Asotra would like to thank the Flight Attendant Medical Research Institute, the National Institute of Environmental Health Sciences, and the National Heart, Lung and Blood Institute, for grants to organize the 5th World Assembly on Tobacco Counters Health Conference in New Delhi during December 2–-5, 2007.This conference provided the ideas, interactions with colleagues, and opportunities for gathering information on Areca nut and betel-quid. Rajesh Sharan thanks India’s Department of Science & Technology, Council of Scientific & Industrial Research, Department of Energy, and the University Grants Commission (India) for research grants supporting the work reported here.

*Dedication: This article is dedicated to the loving memory of Mrs. Kamini Grover, who passed away on February 16, 2008 in Winnipeg, Canada, after a battle with stomach cancer diagnosed at a very advanced stage. Kamini was best known for her remarkable cheer, grit, and helping nature. All family members and friends will dearly miss Kamini.

References
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