[Investigations of the pathogenesis of lung cancer observed among chromate factory workers].

In order to clarify the relationship between the chromate compound and occurrence of lung cancer, the author studied the characteristics of patients with lung cancer among workers of chromate factory and measured the chromium contents of each tissues obtained from 14 patients at surgery and autopsy. The incidence of the chromate lung cancer was 413 per 100,000 population, which was 16 times that of the general population. All were male. The age ranged from 26 to 74 year old (average 53). The histological type was mostly squamous and small cell carcinoma. Location of carcinoma occurrence was mainly limited to the large bronchi. The average total labor period of patients with lung cancer was 258 months and the latent period was 305 months. The working history of the patients in hexavalent-chromium producing process was longer than that of the control group. Patients with small cell carcinoma was mainly engaged in the monochromate producing process. The labor and latent period of patients with squamous cell carcinoma was longer than those of small cell carcinoma. Measurement of chromium contents in the respiratory system of chromate workers revealed much higher chromium content than in control group. The chromium content of tissues in the non-respiratory system was a little higher than that of the control group. High chromium content itself did not have any relation with the occurrence of lung cancer because the primary location of chromate lung cancer was limited to the large bronchi, not to the peripheral lungs which contained the highest chromium content. The longer was the exposure period, the higher was chromium content in the lung. Chromium content in the upper lobe was higher than that in the lower lobe. From these studies, the author concluded that hexavalent-chromate compound might be the compound responsible for lung cancer occurrence.