Abstract
ABSTRACT This study is an analysis of the occurrence of lung cancer in nickel workers, particularly with regard to development time, histological types and tobacco smoking, in addition to specific exposure to nickel dust and fumes. It is a continuation of previous work in this field (Kreyberg, 1954a, b; 1962, 1969). The series consists of 44 cases of lung cancer occurring during the years 1948-74 in people currently or previously employed at Falconbridge nickel refinery. A seven-year period of reduced activity during the war enables lung cancer in workers who took up employment in 1927-39 to be compared with that in workers who started in or after 1946. It is confirmed that exposure to nickel dust and fumes increases the risk of developing lung cancer. However, all subjects with small cell anaplastic carcinoma and at least 25 out of 28 subjects with epidermoid carcinoma had been tobacco smokers. Four smokers and four non-smokers had Group II tumours. The mean age at diagnosis of lung cancer in the nickel workers corresponds closely with that of male subjects with lung cancer in general, in spite of the very wide differences in the development time, if this is related to the employment time in the refinery alone. The mean age at diagnosis is, however, consistent if the development time is related to the length of tobacco smoking. Tobacco smoking is an important factor in the development of lung cancer in nickel workers, and under the conditions described in this study the reduced carcinogenic influence may be attributable to reduced exposure to nickel and possibly also to tobacco.