genicity of betel quid without tobacco for oral cancer and for betel quid with tobacco for cancers of the oral cavity, pharynx and oesophagus. Oral cancer

Areca nut is one of the most widely used psychoactive substances with several hundred million users worldwide, predominantly in southern Asia. Areca nut can be chewed alone or in a variety of ways that differ by region. The habit of chewing betel quid, containing fresh, dried or cured areca nut, catechu, slaked lime and flavouring ingredients wrapped in betel leaf, is widespread in India, Pakistan, Bangladesh and Sri Lanka and in migrant populations coming from these regions. Tobacco is often added. Many people in these regions chew areca nut, with a somewhat higher usage among women. Since the 1980s, the use of industrially manufactured products, often containing tobacco, has increased, especially among children and adolescents. In Taiwan, China, the unripe areca nut is chewed with slaked lime and betel inflores-cence, sometimes wrapped in betel leaf. Tobacco is not added. About 10% of the population , including adolescents, chew areca nut, with highest usage among men (90% of users) and in certain rural ethnic groups. In parts of southern China (Hainan Island, Xiangtan), areca nut is chewed after treatment with maltose and slaked lime and is wrapped in betel leaf. Tobacco is never added. About one third of the population, both men and women, use areca nut. In other SouthEast Asian countries such as Myanmar, Thailand, The Lao People's Republic, Cambodia and the Philippines, the betel quid contains areca nut, slaked lime, catechu and betel leaf. Tobacco is often added. In some of these countries, especially Thailand and Cambodia, the habit is only common among elderly women and usage is declining. In Papua New Guinea, unripe or uncured ripe areca nut is chewed, sometimes with betel leaf, betel inflorescence or wild ginger. A stick is dipped in slaked lime and applied IARC MONOGRAPHS VOLUME 85 230