A new cause for concern is aggressive advertising, targeted at the middle class and at children, that has enhanced sales and use of mass-produced, pre-packaged areca-nut products now available in many countries around the world, WHO said in a news release in Geneva. In some parts of India, almost one out of three children and teenagers regularly or occasionally chew these products.A previous evaluation in 1985 had found only that chewing betel quid with tobacco was carcinogenic to humans. The habit is popular not only in Asia but among immigrants resident in the United Kingdom, other parts of Europe, North America and Australia.The new findings are the work of an international group of scientific experts convened by the Monographs Programme of the International Agency for Research on Cancer (IARC), part of WHO.The experts 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. 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. 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 – or 58 per cent – occur in South and Southeast Asia.In some parts of India, oral cancer is the most common cancer. Striking evidence has emerged from Taiwan Province of 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, WHO said. Tobacco generally is not added to the betel quid in that region.