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On the basis of the 1990 Chinese death notice data and 1990 Japanese populations vital statistical materials, the mortality patterns and proportions of individual causes of death in the two countries were compared. In both sexes, the mortality rates were the highest in almost all age groups in Chinese rural areas followed by urban areas and Japan. In Japan and in Chinese urban areas, malignant neoplasms cardiovascular diseases and cerebrovascular diseases were the major causes of death, with these three making up about 60% of the total. In Chinese rural areas, these three conditions were responsible for 43% of all deaths, a considerably lower figure as compared to those in the other two areas, and the mortality rates for infectious diseases and accident/suicide were higher than those in the other two areas. Of the three major adult diseases, cerebrovascular diseases were found to be especially frequent in both Chinese urban and rural areas. On the other hand, ischemic heart disease was found at comparable levels in Japan and China and the rate was lower than in other developed countries. Site-specific mortality rates for malignant neoplasms were characterized by high rates for lung, liver and esophageal cancers in China. The mortality rates for bronchitis in both Chinese urban and rural areas were markedly higher than those in Japan These differences in mortality rates and proportions of individual causes of death between China and Japan are thought to be attributable to the differences in medical services and the level of risk factors for each disease.

A follow-up study was carried out from January 1967 to December 1986 on 148 patients with Itai-itai disease, 130 suspected patients (persons requiring observation), and 212 controls who were living in the same community as patients with Itai-itai disease. The relative survival rates for the three groups were calculated from a life expectancy table. Except for 1973 data, comparison of the annual data from 1968 to 1986 showed that the relative survival rates in the patient group were significantly lower than those in the control group. The relative survival rates in the suspected patient group were significantly lower than those in the control group between 1981 and 1986. Recently the differences of the relative survival rates between the patient group and the suspected patient group have become smaller and are not significant. These results show the long-lasting influence of Itai-itai disease on the prognoses of patients and suspected patients.

The eastern part of Toyama prefecture is well known as being one of the areas where many migrant workers* live who have been exposed to dust and suffer from silicosis. The purpose of this study is to investigate the mortality rates of migrant workers exposed to dust through jobs such as tunnelling. Questionaires on occupational careers were sent to all male inhabitants aged 30 or over in the selected area between 1977 and 1978. Two thousand and seventy-seven of the respondents were followed-up until the end of 1983. For those who died, the causes and dates of death were confirmed by death certificates. The mean person-years of observation per a person was 5.9. The subjects were divided into three groups. One group included 644 migrant workers who had worked in jobs with exposure to dust, 275 migrant workers whose jobs did not expose them to dust and 1158 persons who were not migrant workers and whose jobs did not also expose them to dust. Mortality rates compared among the three groups. The mortality rate per 1, 000 person-years of migrant workers who had worked in jobs with exposure to dust was 22.3. The mortality rate was significantly higher than that of migrant workers who had not worked in jobs with exposure to dust (11.4) and those who were not migrant workers (9.1). Especially significant is the excess mortality rates of migrant workers whose jobs exposed them to dust in ages 40 to 69. There was no significant difference in mortalities between non-migrant workers and migrant workers who had not worked in jobs with exposure to dust. Among migrant workers who had worked in jobs with exposure to dust, the highest mortality rates per 1, 000 person-years were found in malignant neoplasms (4.3) and also in pulmonary tuberculosis (4.3) followed by heart diseases (3.8), pneumonia & bronchitis (3.0), cerebrovascular diseases (2.7) and pneumoconiosis (2.1). The mortality rates for pulmonary tuberculosis, pneumonia & bronchitis and pneumoconiosis among migrant workers whose jobs exposed them to dust were higher than those among non-migrant workers. There were no significant differences among all cause-specific mortalities between migrant workers who had not worked in jobs with exposure to dust and non-migrant workers.