pp41-80.qxd 21/09/2004 14:38 Page 41 BETEL-QUID AND ARECA-NUT CHEWING 1. Exposure Data 1.1 Composition of betel quid Areca-nut/betel-leaf/tobacco chewing habits are widely prevalent in many parts of Asia and in migrant communities arising therefrom. Many betel-quid products in different parts of the world are not actually chewed; rather, they are placed in the mouth or applied to the oral cavity and remain in contact with the oral mucosa. Nevertheless, it is recom- mended that they all be considered as part of the betel-quid chewing habit. Given the varied ingredients and combinations used in different parts of the world, an accurate description of terms is essential (see Glossary A for definitions and synonyms). 1.1.1 Betel quid The term ‘betel quid’ is often used with insufficient attention given to its varied contents and practices in different parts of the world. A ‘betel quid’ (synonymous with ‘pan’ or ‘paan’) generally contains betel leaf, areca nut and slaked lime, and may contain tobacco. Other substances, particularly spices, including cardamom, saffron, cloves, aniseed, turmeric, mustard or sweeteners, are added according to local preferences. In addition, some of the main ingredients (tobacco, areca nut) can be used by themselves or in various combinations without the use of betel leaf. Numerous commercially produced mixtures containing some or all of these ingredients are also available in various parts of the world. A consensus workshop held in 1996 (Zain et al., 1999) recommended that the term ‘quid’ should be defined as ‘a substance, or mixture of substances, placed in the mouth […], usually containing at least one of the two basic ingredients, tobacco or areca nut, in raw or any manufactured or processed form.’ A chewing substance may primarily consist of (Table 1): • areca nut alone, without any betel leaf, slaked lime or tobacco • chewing tobacco without any areca nut • areca nut with components of betel vine and any other ingredients except tobacco (betel quid without tobacco) • areca nut with components of betel vine and any other ingredients including tobacco (betel quid with tobacco). –41– pp41-80.qxd 21/09/2004 14:38 Page 42 42 IARC MONOGRAPHS VOLUME 85 Table 1. Composition of the different types of chewing substances Areca Betelb Catechud Tobaccoe Slaked nuta lime Leaf Inflo- Stemc rescence Areca X Betel quid without tobacco X X (X)f X Betel quid with tobacco X X (X)f X X Gutka X X X X Pan masalag X X X Khaini X X Mawa X X X Mainpuri tobacco X X X Lao-hwa (Taiwan) Xg X X Betel quid (Taiwan) Xg X X Stem quid (Taiwan) Xg X X Naswar X X Zarda X X a May be used unripe, raw or processed by baking, roasting or baking with sweetening, flavouring and decorative agents (see Table 2). b In place of the leaf, the inflorescence or its stem may also be used (see Table 2). c Stem of inflorescence d In powdered or paste form (see Table 2) e In flaked, powdered or paste form, with or without processing, with or without sweetening (see Table 2) f ( ) means optional g Used in unripe form It is recommended that, when the term ‘betel quid’ is used, other ingredients used to make up the quid be specified. A betel quid is often formulated to an individual’s wishes with selected ingredients. In many countries, ready-made, mass-produced packets of the above products are now available as proprietary mixtures known as pan masala or gutka (see Section 1.2). The major constituents of a betel quid are listed in Table 2 and are outlined below. 1.1.2 Areca nut Areca nut is the seed of the fruit of the oriental palm Areca catechu. It is the basic ingredient of a variety of widely used chewed products. Use of the term ‘betel nut’ is not botanically correct; it has caused considerable confusion in the scientific literature and should be avoided. Areca nut is an important agricultural product in many regions of the world. The world’s largest producers of areca nut, as estimated by the Food and Agriculture Organiza- pp41-80.qxd 21/09/2004 14:38 Page 43 BETEL-QUID AND ARECA-NUT CHEWING 43 Table 2. Constituents of betel quid Constituent Origin/preparation Areca nut Unripe/ripe Whole/sliced Raw/roasted/sun dried Boiled/soaked in water Fermented (under mud) Piper betle L. Fresh leaf Inflorescence Stem Slaked lime From coral From shell fish From quarried lime stone Tobacco Sun dried Fermented Boiled with molasses Perfumed Concentrated extract (kiwam) Catechu (extracted from) • Heartwood of Acacia catechu or A. suma • Leaves of Uncaria gambier • Bark of Lithocarpus polystachya (nang ko) Spices Cloves Cardamom Aniseed (± sugar coat) Sweeteners Coconut Dried dates Essences Rose essence Menthol Mint Rose petals Updated from Gupta & Warnakulasuriya (2002) tion (FAO), are listed in Table 3. The FAO has estimated that world production of areca nut is increasing (FAO, 2003). In most South Asian countries where information is available, the production of areca nut has increased several fold over the past four decades. In India, production of the nut has risen nearly threefold and may reflect the commercialization of areca products since the early 1980s. Notably, Bangladesh is a significant contributor to the agricultural base of areca-nut production, but its use by the Bangladeshi population is not well documented (see Section 1.3.3). There are several palms under the genus Areca that are native to South and South-East Asia and the Pacific islands. An annotated list of the Areca species according to their geo- pp41-80.qxd 21/09/2004 14:38 Page 44 44 IARC MONOGRAPHS VOLUME 85 Table 3. Production of areca nut by country since 1961 (in millions of tonnes) Country 1961 1971 1981 1991 2001 Bangladesh 62 995 23 369 25 051 24 120 47 000 India 120 000 141 000 195 900 238 500 330 000 Indonesia 13 000 15 000 18 000 22 812 36 200 Kenya NA NA NA 100 90 Malaysia 6 500 3000 2 500 4000 2500 Maldives 1 1 5 16 37 Myanmar 8000 19 203 25 807 32 270 51 463 Taiwan, Chinaa 3718 10 075 24 358 111 090 165 076 Thailand NA NA NA 13 250 20 500 World 428 428 423 296 583 242 892 316 1 305 732 From FAO (2003) NA, not available a From Council of Agriculture, ROC (2003) graphical cultivation in South and South-East Asia and in the Pacific basin was given by Furatado (1933). Areca nut for chewing is obtained exclusively from Areca catechu, which is believed to be native to Sri Lanka, West Malaysia and Melanesia (IARC, 1985a). This tropical palm tree bears fruit all year, which are ovoid or oblong with a pointed apex, measuring 3–5 cm in length and 2–4 cm in diameter. The outer surface is green when unripe and orange-yellow when ripe. The seed (endosperm) is separated from a fibrous pericarp, is rounded with a truncated base and is opaque and buff-coloured with dark wavy lines. It has a characteristic astringent and slightly bitter taste and is consumed at different stages of maturity according to preference. An individual may consume the whole nut or thin slices of the nut, in its natural state or after processing in many forms. The nut may be used fresh or it may be dried and cured before use, by sun-drying, baking or roasting (Table 2). Areca fruit may also be boiled and fermented (in eastern parts of India, Sri Lanka) by covering it with mud to soften the nut for consumption. These treatments change the flavour of the nut and its astringency. In Taiwan, China, areca nut is most often used in the unripe stage when it is green, like a small olive. Areca nut is known colloquially in Hindi and other languages in India as supari; it is called puwak in Sri Lanka, gua in Sylheti (Bangladesh), mak in Thailand, pinang in Malaysia, daka in Papua New Guinea, pugua in Guam and Kun-ywet in Myanmar (IARC, 1985a). Chemical constituents Comprehensive analyses of the chemical composition of areca nut have been reported and reviewed (Raghavan & Baruah, 1958; Shivashankar et al., 1969; Arjungi, 1976; Jayalakshmi & Mathew, 1982). The major constituents of the nut are carbohydrates, fats, pp41-80.qxd 21/09/2004 14:38 Page 45 BETEL-QUID AND ARECA-NUT CHEWING 45 proteins, crude fibre, polyphenols (flavonols and tannins), alkaloids and mineral matter. The ranges in concentration of the chemical constituents of areca nut are given in Tables 4 and 5. Variations in the concentrations of the various constituents may occur in nuts from different geographical locations and according to the degree of maturity of the nut. Of the chemical ingredients, tannins, alkaloids and some minerals that may have biological acti- vity and adverse effects on tissues have been subjected to detailed study. Polyphenols (flavonols, tannins) constitute a large proportion of the dry weight of the nut. The ranges in concentration of polyphenols in unprocessed and processed nuts are shown in Tables 4 and 5. The polyphenol content of a nut may vary depending on the region where Areca catechu is grown, its degree of maturity and its processing method. The tannin content is highest in unripe areca nuts and decreases substantially with increasing maturity (Raghavan & Baruah, 1958). The roasted nut possesses the highest average content of tannins, ranging from 5 to 41% (mean, 21.4%); the average tannin content of sun-dried nuts is 25%; and the lowest levels are seen in boiled nuts, which contain 17% (Awang, 1987).