Possible effects of the introduction of the 1969 Asbestos Regulations

This paper describes a study of a sample of the chest radiographs collected between 1971 and 1978 in the course of the Health and Safety Executive’s survey of asbestos workers. Each radiograph was read by three doctors from a panel of 18. Despite a wide disparity in readers’ assessments of the radiographs, three radiological signs were consistently observed: (1) profusion of small opacities; (2) diffuse pleural thickening, and (3) obliteration of the costophrenic angle.

Of these, the first showed a relationship both with age and with smoking, the second with age and the third with neither. The risk of showing any one of these signs in those whose exposure began before 1971 was estimated to be at least twice that of those whose exposure started only after the introduction of the regulations.