Preliminary study of lung cancer mortality among Western Australian gold miners exposed to silica.

Gold miners from Western Australia were surveyed in 1961. Data were collected on respiratory symptoms, smoking habits, employment history, and chest X-ray signs. Eighty-four percent of the men had smoked at some time, and 66% were current smokers. The prevalence of chronic bronchitis was over 20% at the time of the survey. A follow-up to the end of 1991 has been started which showed that, from 1969 to 1991, 999 miners died. Because vital status has not been ascertained for the whole cohort, a proportional mortality analysis was undertaken as a case-referent study. A strong effect of smoking on the risk of lung cancer was found, along with a slight, but nonsignificant increase in the lung cancer risk for the subjects employed underground for > or = 40 years after adjustment for smoking. A complete follow-up and a full cohort analysis will enable these effects to be estimated more precisely.