Betel-quid and areca-nut chewing - a traditional habit widely practiced in many parts of Asia - is also popular among immigrants resident in the United Kingdom, other parts of Europe, North America and Australia. An international working group of scientific experts convened by the Monographs Programme of the International Agency for Research on Cancer (IARC), part of the World Health Organization, has reviewed the published studies related to cancer and chewing betel quid and areca nut. A previous evaluation in 1985 had found that chewing betel quid with tobacco is carcinogenic to humans. The new evaluation goes further to conclude that chewing betel quid without tobacco is also carcinogenic to humans. The working group also concluded that the areca nut, a common component of many different chewing habits, is carcinogenic to humans.
A WIDESPREAD HABIT
Betel quid generally consists of betel leaf (from the Piper betle vine), areca nut (from the Areca catechu tree), and slaked lime (predominantly calcium hydroxide), to which tobacco is often added. Other ingredients and flavouring agents can be included according to local preferences and practices.
Betel-quid and areca-nut chewing are widely practiced in many parts of Asia and in Asian-migrant communities elsewhere in the world, with hundreds of millions of users worldwide. Betel quid is chewed for many reasons, including for its stimulant effects, to satisfy hunger, to sweeten the breath, and as a social and cultural practice. Traditional as well as commercially packaged products are now freely available in "pan shops" in many cities outside Asia. The United Kingdom is the number one importing country outside of Asia, with imports having doubled since the early 80s. In some immigrant communities a large majority is using these products. Young children start using sweetened areca-nut products, often adding tobacco later in their adolescence.
A CANCER-CAUSING HABIT
The expert working group has determined that betel quid with tobacco causes oral cancer, cancer of the pharynx, and cancer of the oesophagus in humans. Betel quid without tobacco is now known to cause oral cancer in humans. Areca nut, a common component of all betel quid preparations, has been observed to cause oral submucous fibrosis (a pre-cancerous condition that can progress to malignant oral cancer), leading to the determination that areca nut itself is carcinogenic to humans. Studies among Asian migrant communities have demonstrated a significantly higher risk for oral cancer compared with natives of countries where they have settled.
The new evaluation of betel quid without tobacco was made possible by recent epidemiologic studies from parts of the world where tobacco generally is not added to the betel quid. In addition, recent epidemiologic studies in South Asia have been able to separate the effects of betel quid use with and without tobacco.
Oral cancers are more common in parts of the world where betel quid is chewed. Of the 390,000 oral and oro-pharyngeal cancers estimated to occur annually in the world, 228,000 (58%) occur in South and South-East Asia. In some parts of India, oral cancer is the most common cancer. Striking evidence has emerged from Taiwan, China, where the incidence of oral cancer in men has tripled since the early 1980s, coinciding with a steep rise since the early 1970s and predominantly among men, in the practice of chewing betel quid. Tobacco generally is not added to the betel quid in that region.
A NEW CAUSE FOR CONCERN
In recent years, a variety of mass-produced, pre-packaged areca-nut products have become available in many countries around the world. Aggressive advertising, targeted at the middle class and at children, has enhanced the sales and use of these products. In some parts of India, almost one out of three children and teenagers regularly or occasionally chew these products. Some have viewed such products without tobacco (for example, pan masala) as a safe alternative to betel quid with tobacco. The evidence shows that these products have led to oral disease, even among children, and that use of these products cannot be considered safe. Several states in India have begun to regulate these products, and reductions in oral disease and oral cancer can be expected to follow from reductions in their use.
THE IARC MONOGRAPHS
The IARC Monographs Programme publishes authoritative, independent evaluations of carcinogenic risks to humans caused by a variety of agents, mixtures and exposures. Each evaluation is the product of deliberations by an international working group of scientific experts. Since its inception in 1971, the series has evaluated nearly 900 agents, and the IARC Monographs have become known for their thoroughness, accuracy, and integrity.