Studying the causes of death among inhabitants in mountain villages located alongside the middle stream of the Tenryu River, and farming-fishing villages located along Tokyo Bay, we found that the death rate from lung cancer was high in the former, and that from stomach cancer was high in the latter. So, in those two districts, we carried out case-control studies about both kinds of cancer. Investigation was made into the dead cases from lung cancer, 84 male cases and 168 male controls, and the dead cases from stomach cancer, 83 male and 39 female cases and the same number of controls. We selected these controls, matching district, sex, age, and year of death, and studied occupation and smoking in lung cancer cases ; occupation, eating habits, kinds of food, drinking and smoking in stomach cancer cases. The odds ratio concerning to lung cancer was as low as 0.40 among people engaged in agriculture, forestry or fishery. But that was as high as 3.25 among people exposed to metal dust, and also as high as 3.10 among those exposed to wood dust. The multiplier effect could be suggested between smoking and metal or wood dust exposure. The odds ratio concerning to stomach cancer was as low as 0.69 among males engaged in agriculture, forestry or fishery. Regarding eating habits, ‘rapid eating’ was as high as 2.57 in males, 3.00 in females. Concerning the kinds of food, ‘salted fish’ was as high as 1.90 in males, and ‘white vegetables’ was as low as 0.36 in females. No assocciation was found between stomach cancer and smoking or drinking.

It is to be noted that in rural districts where they live and work in fresh and clean air the incidence of chronic obstructive pulmonary diseases is as high as in the districts of air-pollution. Besides, there are a variety of respiratory diseases particularly incidental to life-environment and farm work. To be more informed of their actual conditions, the Japanese Association of Rural Medicine organized a special study group and has carried out various studies for four consecutive years with grants from the Ministry of Health and Welfare. The major results obtained are as follows:
(1) There were a variety of farm operations which produced or increased respiratory symptoms, including thrashing and scatteringof agricultural chemicals;
(2) It became clear that there existed in an advanced age group certain cases of “agricultural pneumoconiosis” which could be regarded as the terminal of the so-called “thrash-bronchitis”
(3) Among the cultivators of rush, raw material for Tatami, there existed cases of pneumoconiosis;
(4) There were a variety of agents to produce bronchial asthma, such as rice straw, chaff, tea-leaves and chrysanthemum-leaves;
(5) In Japan only two cases of farmer's lung were reported prior to this study. One more case was added to the list by this study group. Besides, cases positive to fungous agents were found among farmers in considerably high percentage.

It is to be noted that in rural districts where they live and work in fresh and clean air the incidence of chronic obstructive pulmonary diseases is as high as in the districts of air-pollution. Besides, there are a variety of respiratory diseases particularly incidental to life-environment and farm work. To be more informed of their actual conditions, the Japanese Association of Rural Medicine organized a special study group and has carried out various studies for four consecutive years with grants from the Ministry of Health and Welfare. The major results obtained are as follows
(1) There were a variety of farm operations which produced or increased respiratory symptoms, including thrashing and scattering of agricultural chemicals;
(2) It became clear that there existed in an advanced age group certain cases of “agricultural pneumoconiosis” which could be regarded as the terminal of the so-called “thrash-bronchitis”
(3) Among the cultivators of rush, raw material for Tatami, There existed cases of pneumoconiosis;
(4) There were a variety of agents to produce bronchial asthma, such as rice straw, chaff, tea-leaves and chrysanthemum-leaves;
(5) In Japan only two cases of farmer's lung were reported prior to this study. One more case was added to the list by this study group. Besides, cases positive to fungous agents were found among farmers in considerably high percentage.

One is inclined to imagine that the incidence of respiratory diseases will be negligible among rural people who live and work in fresh and clean air. On the contrary, however, we have reports on the high incidence of chronic obstructive pulmonary diseases and on the existence of a variety of specific respiratory diseases which are incidental to farm work. To clarify this situation, the Japanese Association of Rural Medicine organized a special study group and carried out various studies with grants from the Ministry of Health and Welfare. This is the study group's summary report of the four year research project prepared in conclusion of the project.
The actual state of respiratory diseases among rural people, as investigated by the present study group, can be summarized as follows:
1) In rural districts, in spite of its freedom air-pollution, there exist in high percentages people suffering from respiratory symptoms and patients of obstructive pulmonary diseases. As the important cause of this phenomenon, farm operations, especially thrashing, rice-hulling, compost preparation, scattering of agricultural chemicals can bementioned, which invite the development of symptoms and their aggravation.
2) Pathologically, farmer's pneumoconiosis attributable to farm operation dust was evidenced, crying for the necessity of dust prevention measure during farm operations.
3) In connection with atopic asthma the study group proved the antigenicity of rice-straw, wheat-straw, celiae of tea-sprout, young leaves, and chrysanthemum leaves. There are also anumber of already known antigens. It is necessary to establish measures for its prevention and treatment.
4) In rural districts of Japan, esp. in stock-raising farm houses, there are in comparatively high percentages those who react positive to fungous antigens which are the causes of farmer's lung. However, there have hitherto been reported only two cases, and the study group added one more. In the future, more extensive practice of immunological tests and clinical follow-ups of the positive cases will be necessary.
5) In view of the results reported above, it is considered that there are numerous questions concerning respiratory troubles and diseases in rural districts which are awaiting further study.