About 7, 000 workers migrated from Kochi Prefecture in 1965. Recently the number of patients with pneumoconiosis and vibration syndrome has increased among these persons who worked on constructing tunnels. To investigate the health status of these workers, we interviewed 73 of these workers with regard to history of migration, work situations, health condition and so on in Niyodo Village in Kochi Prefecture. Thirty workers were examined for pneumoconiosis and vibration syndrome. Geographical distribution of the areas from which these workers had migrated were also analysed by using the statistical data of Kochi Prefecture in 1965.
The results were as follows:
1) Numerous migrant workers come from the mountain villages along the Shikoku Mountains. In the middle-northern areas, included Niyodo Village, the number of migrant workers was large.
2) Their working conditions in the tunnel were poor and measures for prevention of pneumoconiosis, such as wearing of a dust respirator and drilling the rock with water, were poorly carried out. Vibrating tools were also used for long periods of time.
3) Of 73 workers, 40 have been given the compensation follwing a diagnosis of pneumoconiosis or vibration syndrome.
4) In 23 examinees, silicosis was detected in the chest X-ray examination. Classifications included 13 of type 1, 7 of type 2, and 3 of type 4. Also examinees had subjective symptoms and/or objective findings of vibration syndrome. Eighty seven percent were classified as Grade III according to the criteria of Andreeva-Galanina. Thus, most of migrant workers involved in tunnel construction work had complications of pneumoconsosis and vibration syndrome.