Primary biliary cirrhosis: an epidemiological study.

A three-year study (1977-9) of primary biliary cirrhosis in the city of Sheffield disclosed 34 cases, a point prevalence of 54 per million population. Closer inspection showed an apparent clustering of cases, and the prevalence in relation to one water reservoir appeared to be more than ten times that of the other reservoirs. Nevertheless, analyses of the water showed no significant relevant differences between the reservoir serving areas with a high prevalence of cirrhosis and other reservoirs. Despite the inconclusive results of the water analyses, these findings do suggest that an environmental agent may be a cause of primary biliary cirrhosis and that further epidemiological studies may help to elucidate the cause.