1.   Initially, worries were expressed regarding a possible carcinogenic effect of cimetidine, when case reports of gastric carcinoma in cimetidine treated patients appeared.

2.   Other hypotheses relate to the potentially carcinogenic effects of coal dust alone, or after conversion of aromatic coal derivatives to mutagenic nitroso-compounds in the stomach.

3.   There have also been studies to suggest that unburned tobacco in the form of snuff or chewing tobacco has a carcinogenic effect on gastric mucosa.

4.   The Denmark study released Thursday confirmed previous research showing the carcinogenic effects of alcohol generally.