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BACKGROUND: Findings from experimental studies on rodents and from epidemiological studies suggest that diesel exhaust may cause lung cancer. There is evidence that in several occupations, e.g., truck drivers and railway workers, the risk of lung cancer increases with duration of employment, and exposure to diesel exhaust provides the most likely explanation for these elevations of risk. METHODS: We investigated the association between lung cancer mortality and exposure to diesel exhaust in a cohort study. The cohort comprised 5, 536 male potash miners who were followed from 1970 to 1994. Exposure was assessed from concentration measurements of the total carbon (i. e., elemental and organic carbon in total) in personal dust samples. The concentration values were multiplied by years of exposure to give a quantitative exposure measure. The concentration levels ranged from 0.12 to 0.39 mg/m(3) total carbon in fine dust. Work histories and smoking habit data were obtained from medical company records. Causes of death were ascertained from death certificates. RESULTS: During the follow-up period, 424 deaths were recorded, including 133 of cancer, 38 of lung cancer. The relative risk of lung cancer between two groups with high and low exposure was 2.2 (95% confidence interval 0.8-6.0). With Cox regression, we found a lung cancer relative risk 1.7 (0.5-5.8) after twenty years of exposure. Extensive scrutiny proved smoking not to be a confounder in this study. CONCLUSIONS: The principal finding of the study is a doubling of relative lung cancer risk after twenty years of exposure in the workplaces with highest exposure. However, the observed elevation is nonsignificant even at a 90% level. Further follow-up is intended to enhance the study power.

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Logistic regression is the fundamental procedure to analyze the dependence of the frequency of a binary disease indicator from exposure and other factors. Disease indicators with ranked levels contain a larger amount of information and permit a more precise prediction. For that, the cumulative logistic model was developed. Its application, demonstrated with an epidemiologic study for the dependence of arthritic changes in the knee-joint from intensity of kneeling stress and age, is very recommendable for the evaluation of well-designed epidemiologic studies concerning the prevalence of chronic diseases.

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With a view of clearing up certain influence of the working and living conditions on health, some results of control examinations in occupational medicine from the years 1985 to 1988 of women employed in the health service (n = 86,769) were analyzed and compared with those of the investigations carried out on all women in the GDR (n = 662,578). The tracking down of significant deviations in the age-standardized prevalence rates for chronic health disturbances was performed by means of a specialized computer programme for the health of women and for 7 occupations. Among other things, it was possible to prove permanently increased prevalence rates for chronic diseases of the kidneys/urinary passages in the overall population and in the personnel for laboratory diagnostics, as well as an increased prevalence of hypertension in day nursery educators. The elaborated strategy for tracking down work-related diseases and chronic diseases proved effective and can also be used for issues in other economic sectors.

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Methodical aspects of designing and evaluation of epidemiological studies in occupational health research concerning chronical damages were discussed and illustrated by a study, which shows an essential dependence of arthrotical changes in the knee-joint from age and the intensity of kneeling stress. It is important for both design and evaluation, to regard relevantly the period of exposure. Dose-response relations can be simple proved and well described by regression analysis. Methods like score regression and cumulative logistic regression are very suitable for medical findings with rank categorial levels.

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In a cross-sectional study of 181 male workers of a rotogravure printing plant, most of whom were exposed to toluene levels well above the GDR threshold limit values, 55 subjects revealed pathological liver screening values (activities of serum aspartate aminotransferase, alanine aminotransferase, gamma glutamyltransferase; liver size). The differential diagnostic examination showed in 51 out of these 55 subjects an association with competing factors such as alcohol abuse (78%) and overweight (40%), to a slight extent disorders of fat and carbohydrate metabolism and of the gallbladder. Drug intake did not play any role. The variance and regression analyses of the biochemical data have shown that alcohol significantly and considerably increases the activities of all three enzymes tested. Bodyweight had a similar, but less pronounced, significant effect. On the other hand, in subjects with a higher alcohol intake the activities of liver enzymes in highly toluene exposed subgroups were significantly and clearly lower than among slightly toluene exposed workers.

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Reaction-time measurements were used to demonstrate the application of change-over designs, known as Berenblut schedules. They are especially useful when improving trial accuracy is merely possible by raising the number of test entities rather than using greater numbers of healthy subjects, which normally are not readily available.

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