The respiratory and cardiovascular health of iron and steel process workers. Part II: results of the field studies and of the analyses of the data

Study design: This study was designed to examine the respiratory and cardiovascular health of workers in the modern British steel industry, and to identify and quantify any risks associated with work in that industry. A total of 3617 current workers took part in a cross-sectional health survey, with wide coverage of occupations, but with selection weighted more heavily in the occupations at the ‘heavy’ end, i.e. in the production of iron and steel. Continuous casting, hot and cold rolling mills, traffic and maintenance were all included, but some plants solely involved in downstream processes such as coating, and the manufacture of tubes and pipes, were not, and so those processes were not represented. Coke workers, who have been widely studied as a group, were excluded.Methods: Field work was carried out by British Steel nursing staff at the works medical centres. Respiratory health was characterised by measurements of basic lung function, and responses to a questionnaire on respiratory symptoms such as those of chronic bronchitis and breathlessness. Cardiovascular responses were measurements of blood pressure and blood cholesterol, and questions on angina, history of heart problems, and pain in the legs caused by poor circulation. Other factors recorded included height, weight, smoking habits and complete occupational history. The methods developed for this study may be useful to steel or other heavy industries in other countries. Data from the seven works included are presented in summary, but organisational changes at one of the works (producing stainless steel) led to poor recruitment and an incomplete data set, and the works was omitted from the formal statistical analyses.Respiratory results: In the men studied, 28% were smokers. Lung function varied, as expected, with age, height and smoking habits, and was generally close to standard predictions. Lung function was decreased in men with higher Body Mass Index, illustrating the damaging effects of obesity. There was no evidence of loss associated with any particular occupation, but there was a small difference between the average values for production and maintenance workers, over a range of working areas with very different exposures. This may reflect differences between the two types of worker. Respiratory symptoms showed expected relationships with smoking habits, but no evidence of occupational relationships.Cardiovascular results: Men in ore and sinter plants showed a small increase in systolic blood pressure, but not in diastolic, which is considered more indicative of cardiovascular disease. There was weak evidence of a very small effect on diastolic blood pressure from work in blast furnaces. Prevalences of cardiovascular symptoms were low. There was no evidence of occupational effects on angina or history of heart attack, nor on hypertension. For episodes of severe chest pain and for leg pain (intermittent claudication) there was evidence of a small effect of work in ore and sinter plants. There was no evidence of occupational effects on the level of total cholesterol hi the blood, but high density lipoprotein cholesterol, believed to protect against cardiovascular disease, was slightly reduced in some engineering and maintenance occupations.Implications: None of the occupational effects found had magnitudes which, on average, were likely to be clinically significant. Many responses showed differences between works, but the only apparent consistency in the patterns was that health tended to be slightly worse, overall, at a works in the north-east of England. The results suggest the need for continuing vigilance to minimise exposure in ore and suiter plants and blast furnaces. “”