Patterns of mortality in asbestos factory workers in London.

’ This paper reports the results of a mortality study of workers employed at an East London asbestos factory. The factory opened in 1913, at first producing chiefly asbestos textiles, but later, producing also insulation materials, particularly asbestos pipe sections and a variety of other products. Crocidolite asbestos was used until the late 1950s but also chrysotile and amosite. Both men and women were employed. The factory closed in 1968. The male cohort of 4600 men consists of all males who began work between April I , 1933, the date of implementation of the Asbestos Regulations of 1931, and March 31, 1964; the female cohort consists of 922 women, all of whom were first employed between January 1, 1936 and December 31, 1942, a period when wartime identity records facilitated followup. Identification details of these workers were sent to the Central Registers of the National Health Service and to the National Insurance Scheme, now administered by the Department of Health and Social Security. These registers identified the vital status of the workers and subsequently sent to us copies of death certificates for the deceased and for those who died during the study period. Previous reports on this study have been published.’-’ The present study was continued to December 31, 1975 and thus includes 5 additional years of data. Jobs have been classified into six grades of exposure.’ There was little difference in experience between grades 1-3 and grades 5 and 6, and these two groups are classified as “low-moderate” and “severe” exposure, respectively. The experience of laggers is considered separately. The levels of dust exposure have recently been reviewed and suggest that before 1945, the dust levels in such processes as opening, carding, and sectional pipe making and in most other production jobs averaged 20 fibers/ml or higher. In jobs classified by the authors as “low-moderate,” asbestos levels in the air were probably 5-10 fibers/ml. Only in nonproduction jobs and, possibly, brake-lining departments and departments that make rubber jointings were these levels below 5 fibers/ml. In 1946. dust suppression improved, and dust levels were probably reduced by 50%. In 1955, the textile departments moved to another location, and factory hygiene further improved, but many areas in the factory may have contained levels above the current industrial standard of 2 fibers/ml.