Epidemiological study of chromium platers in Japan.

A cohort study on platers in Tokyo was carried out using the records of the Tokyo Health Insurance Society of Plating Industry. The type of work and chromium-exposure history of each member of this society was investigated by a questionnaire sent to the manager of each factory. The recovery rate of the questionnaire was 70.5%. Survival information on retired subjects was obtained from the offices of Japanese family registration system ("koseki").As the result, among 889 male chromium platers who were followed up from April 1, 1970 to September 30, 1976, 19 deaths were observed, but there were no cases of lung cancer. The observed number of deaths was only 50% of the expected number, which had been calculated using the annual male mortality by age of Tokyo. In contrast, a slightly higher number of deaths than expected (107%) was observed in the control group consisting of workers selected from the same factories as the chromium platers. Two types of possible error were considered in this study: the first is that deaths from the chromium-exposed group had been incorrectly assigned to the control group, and the second is that the 30% of nonresponders included a significant number of factories where chromium-related deaths had occurred.However, the response for surviving cases on the history of chromium handling is considered to be reliable. Thus it was decided to conduct a further study focusing on those workers alive on October 1, 1976.