Toombak: a major risk factor for cancer of the oral cavity in Sudan.

BACKGROUND

Snuff dipping as practiced in North America and Western Europe is causally associated with cancer of the oral cavity and pharynx. In the Sudan, natives use local Nicotiana rustica, a tobacco species with high levels of nicotine and nornicotine, to prepare their own snuff which they call toombak. The finely ground tobacco leaves are mixed with sodium bicarbonate, water is added, and a paste is made. The resulting "saffa" is placed in the oral vestibule where it remains up to several hours. In general, a saffa is replaced 10-30 times per day.

METHODS

A cross-sectional survey was initiated for establishing the extent of toombak dipping in the Northern Sudan. Using earlier published methods, toombak and the saliva of toombak dippers were analyzed for the major carcinogens, the nicotine- and nornicotine-derived tobacco-specific N-nitrosamines.

RESULTS

Survey data on the use of toombak in the Nile Province in the Northern Sudan encompass 2,000 households with 5,500 adults. About 40% of the males dip toombak, including 9% who are also cigarette smokers. The toombak habit is especially prevalent (> 45%) among males ages 40 years or older. Among women, toombak use is popular only in the older age groups, where up to 10% engage in the habit, whereas cigarette smoking is uncommon (< 1.5%). So far, only one descriptive study has dealt with toombak dipping and oral cancer. Among 62 patients with oral cancer 50 were toombak users; the majority of these had tumors at the site of contact with the tobacco, or in adjacent areas. Chemical analytical studies revealed that toombak contains at least 100-fold higher concentrations of the tobacco-specific N-nitrosamines (TSNA) than US and Swedish commercial snuff brands. The TSNA are by far the most powerful and most abundant carcinogens in snuff. Their concentrations in the saliva of toombak dippers are about the same as those in a solution that had been assayed in rats by twice daily swabbing of the oral cavity and had induced tumors of the cheek and palate.

CONCLUSIONS

The need for in-depth epidemiological studies and further laboratory research to prove that toombak chewing causes cancer is discussed. The data at hand point to the urgent need for educational programs and preventive measures against the use of toombak.