Geographic clustering of myeloma in Tokushima.

: Between 1978-1988, seven cases of multiple myeloma were found in T Town (population 9,000), which is located at the mouth of a large river within the boundaries of Tokushima City, Japan. This is a significantly high incidence, 7.06 per 100,000 as compared with an incidence of 1.20 in Tokushima City itself and 1.53 in Japan as a whole. The clinical and laboratory features of these patients were typical of myeloma. Although the causes of this small but apparent cluster of multiple myeloma remain obscure, the fact that five of the seven patients had been working for long periods as fishermen was notable.