Mortality of British steel workers over an extended follow-up period

Background: An earlier study of mortality in 81,253 steel workers found higher lung cancer death rates in blastfurnace and sinter operators compared with other occupations. There was also some evidence of higher than expected death rates from heart disease in younger men. Death rates from chronic bronchitis were not high. The study period was short and there had been flaws in the basic data so the findings were preliminary ones only.Objectives: The purpose of the present study was to follow up the most important subgroups from the earlier research and where possible to improve the core data for these men; and so to re-examine the earlier findings for blastfurnace and sinter men and for other occupations.Men studied and methods: The latest study followed up 17,718 steelworkers employed for 10 years or more in the early 1970s. The men worked at that time in a wide range of production and maintenance functions, principally in the South Wales, Sheffield and Teesside areas. The study group was based on the core occupations considered to be most important for study and on the areas where data from the original study were most reliable. Extensive checks confirmed the basic soundness of the data studied, though work histories were limited to broad occupation in the early 1970s.The new study looked into deaths from 1974 to 1993 in these men, especially heart and respiratory disease, chronic bronchitis and emphysema, and several types of cancer. Mortality follow-up, via Government agencies, continued whether or not the men remained employed in the industry. Deaths in the study group were compared with those expected based on death rates among men in the general population, of the same age, in the same regions of Britain, over the same time-period.Overall mortality: There were 6,006 deaths; giving overall death rates of about 79 per cent of the general population death rates. (Occupational studies almost always show lower death rates overall than the general population because workers need to be relatively fit to get and to keep a job.)Overall, deaths due to heart disease, non-malignant respiratory disease (including bronchitis and emphysema) and all cancers considered together were also not raised compared with men generally; the all-cancer rates being 92% of the general population. There was no evidence of higher death rates from heart disease in younger workers.There were noticeable regional variations. In particular, for most causes studied, workers in North East England had slightly higher mortality compared with the other steel workers, even after taking account of different regional death rates in the general population.Blastfurnace and sinter.operators: had somewhat higher death rates than other steelworkers. This was seen across the spectrum of causes of death which were studied, and especially respiratory causes. It is unclear to what extent this is due to work, though excess respiratory deaths suggest a role of exposure by inhalation. This general pattern varied importantly by region and by cause of death. For most causes of death, the excess relative to other steel workers was found among blastfurnace and sinter men in the North East works but not in Wales. For lung cancer, the opposite pattern occurred. This geographical pattern is puzzling and we do not know of any process differences which might explain it. It may partly reflect historical differences: some of those studied may have worked in the industry up to 50 years ago or more. For example, the highest lung cancer death rates among blastfurnace and sinter men were found in a small group of men at Electric Arc plants, where blast furnaces were closed in the 1970s.Other occupations: Bricklayers, masons and bricklayers’ labourers had higher than average mortality from non-malignant chest disease; as had crane drivers and slingers. Both results may reflect past exposure to dust.There were five deaths from stomach cancer, compared with 1.3 expected, in a very small group of men employed in 1971-73 in one of the early continuous casting operations. The men studied would have worked in other occupations in earlier years, so it is difficult to judge the relevance of this finding to the modern steel industry.Higher death rates than expected from genito-urinary cancer were found among electricians (18 deaths observed, 11.2 expected). There is no known mechanism of action. However, two recent studies of electricians (not specific to the steel industry) had also discovered excess genito-urinary cancer; and so a possible occupational problem should not be dismissed.Higher non-malignant respiratory disease (but not chronic bronchitis) was found among crane driver and slingers, especially in older men. This may reflect higher occupational exposures in the past. Lung cancer was not increased.Conclusions: In conclusion, then, the present study showed, as expected, lower death rates among steel workers and ex-workers than in the general population. Against this favourable background there were examples of higher death rates from particular causes in some occupations. Principally, these concerned blastfurnace and sinter men, especially in the Northern plants; and non-malignant lung disease in some other occupations. These findings may at least in part reflect an effect of past conditions at work.