Effects of asbestos in dockyard workers.

The prevalence of pleural and pulmonary abnormalities attributed to asbestos among 15,000 workers in a naval dockyard has been studied by means of a one-in-ten sample. Ninety-four per cent. of the men in the sample were examined. Of these, 3% had experienced continuous occupational exposure to asbestos and half of the remainder (representing approximately 6,800 men) had been exposed intermittently. The prevalence of pleural fibrosis ranged from 28% in continuously exposed workers to 1.9% in those with least exposure.Most cases of pulmonary fibrosis occurred in laggers and sprayers who had been continuously exposed for between 15 and 20 years. Pulmonary fibrosis was also seen in a variety of intermittently exposed trades, and had been preceded by extensive pleural thickening in some cases. Ten cases of pleural mesothelioma have occurred in the last three years and a large number of men appear to be potentially at risk.