The epidemiology and clinical features of asbestosis and related diseases

DURING the last 100 years many materials have been used by industry for a while and then found to have unexpected harmful effects. Usually the risk ceases when safety measures are adopted but sometimes these measures are found to be inadequate and new ones must be introduced. This has happened recently after the re-investigation of flax byssinosis (Carey, Elwood, McAulay, Merrett and Pemberton, 1965). But with asbestos the situation is not so simple. Following the report in 1930 (Merewether and Price) on the dangers of exposure to asbestos dust safety measures were adopted in factories and certain workers kept under medical surveillance. Since then a series of other risks have been recognised which indicate that the measures were either inadequate or did not cover a sufficiently wide variety of asbestos workers. Both cancer of the lung and mesothelioma are now recognised as resulting from levels of exposure to asbestos which still occur in spite of these measures. The summary of present knowledge about the epidemiology of asbestosis and related diseases which follows is necessarily brief and emphasises those points at which our knowledge is as yet incomplete.