Excessive physical demands in modern worklife and characteristics of work and living conditions of persons at risk.

OBJECTIVES: This study attempted to identify work and leisure-time conditions and life-style factors associated with excess metabolic levels (metabolic demands exceeding one-third of a person's aerobic capacity) at work among men and women. METHODS: The study focused upon psychological, ergonomic, and physically loading factors and chemical and physical environmental conditions. Data were obtained through self-reports, interviews, workplace analyses, technical measurements, and observations. Gender-specific calculations were used in univariate analyses and in stepwise logistic regression models for excess metabolic level. RESULTS: Twenty-seven percent of the men and twenty-two percent of the women worked at an excess metabolic level during their workday. Awkward work postures, heavy manual materials handling, high circulatory strain, chemical exposures, noise levels, much routine work, and many obstacles to job performance characterized their work conditions. The women had low skill discretion and more often atypical workhours, while the men showed high circulatory strain during leisure-time activities. Important negative life-style factors were a high consumption of alcohol for the men and a high body mass index and no or little regular physical exercise for the women. CONCLUSIONS: Metabolic demands in worklife today remain high. The women who exceeded the recommended metabolic level at work in this study were characterized by low pay, poor health, and children at home, in addition to high physical load and psychosocial strain at work. These characteristics indicate a group with few possibilities to leave a hazardous job for a less physically demanding one. The men who worked at an excess metabolic level seemed to be characterized more by a life-style common in some male-dominated work cultures with monotonous work.

Calculation of fractions of lung cancer incidence attributable to occupational exposure to asbestos and combustion products in Stockholm, Sweden.

In a population-based case-referent study of lung cancer we wanted to estimate the over-all influence on the lung cancer incidence from several occupational exposures. Standard methods to do this are based on addition of separately estimated attributable fractions (AFs) by rather complex formulas. Although a simple and valid method for direct estimation of summary effects was published in 1990, it is not well known and has rarely been used. We here describe the method and apply it to the data from the case-referent study. The AF for withdrawal of occupational exposure to both asbestos and combustion products were nearly identical regardless of if it was calculated by an algorithm for summation of AF for the exposure factors separately (6.90%), by a bootstrap method (6.89%, 95% confidence interval, CI: 3.69, 10.04), or by the simple 'dichotomization'-method (6.88%, 95%CI: 3.81, 9.84). The method is very easy to apply to population-based case-referent studies analyzed by logistic regression.

Low-dose exposure to asbestos and lung cancer: dose-response relations and interaction with smoking in a population-based case-referent study in Stockholm, Sweden.

This population-based case-referent study investigated the lung cancer risk associated with occupational exposure to asbestos, focusing on dose-response relations and the interaction with tobacco smoking. Incident cases of lung cancer among males aged 40-75 years in Stockholm County, Sweden, were identified from 1985 to 1990. Referents were selected randomly within strata (age, inclusion year) of the study base. Questionnaires administered to subjects or their next of kin gave information on occupations, tobacco smoking habits, and residences. Response rates of 87% and 85% resulted in 1,038 cases and 2,359 referents, respectively. Occupational exposures were assessed by an industrial hygienist. Lung cancer risk increased almost linearly with cumulative dose of asbestos. The risk at a cumulative dose of 4 fiber-years was 1.90 (95% confidence interval (CI): 1.32, 2.74), higher than that predicted by downward linear extrapolation from highly exposed occupational cohorts. The relative risk (exp(beta)) for a transformed dose variable ln(fiber-years + 1) was 1.494 (95% CI: 1.193, 1.871) per unit of exposure. The joint effect of asbestos and smoking was estimated to be 1.15 (95% CI: 0.77, 1.72) times that predicted from the sum of their individual effects and 0.31 (95% CI: 0.11, 0.86) times that predicted from their product, indicating a joint effect between additivity and multiplicativity.

Myocardial infarction among professional drivers.

BACKGROUND: Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain. METHODS: We identified all first events of myocardial infarction among men age 45-70 years in Stockholm County for 1992 and 1993. We selected controls randomly from the population. Response rates of 72% and 71% resulted in 1067 cases and 1482 controls, respectively. We obtained exposure information from questionnaires. We calculated odds ratios (ORs), with and without adjustment for socioeconomic status, tobacco smoking, alcohol drinking, physical inactivity at leisure time, overweight status, diabetes and hypertension. RESULTS: The crude OR among bus drivers was 2.14 (95% confidence interval = 1.34-3.41), among taxi drivers 1.88 (1.19-2.98) and among truck drivers 1.66 (1.22-2.26). Adjustment for potential confounders gave lower ORs: 1.49 (0.90-2.45), 1.34 (0.82-2.19) and 1.10 (0.79-1.53), respectively. Additional adjustment for job strain lowered the ORs only slightly. An exposure-response pattern (by duration of work) was found for bus and taxi drivers. CONCLUSIONS: The high risk among bus and taxi drivers was partly explained by unfavorable life-style factors and social factors. The work environment may contribute to their increased risk. Among truck drivers, individual risk factors seemed to explain most of the elevated risk.