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Objectives This register-based population study determined incidence rates of clinically verified asthma among woodworkers, other blue-collar workers, and administrative personnel employed in wood-processing industries in Finland. Exposure to wood dust was under special scrutiny. Methods All Finns employed in wood-processing industries were followed for asthma incidence via record linkage in the years 1986–1998. Incident cases included people with asthma reimbursed for medication by the national health insurance or registered as having occupational asthma. Age-adjusted incidence rates and relative risks (RR) by gender were estimated for wood workers, other blue-collar workers, and administrative employees (referents) in wood industries. Results The relative risk of asthma was increased for all woodworkers among both genders [men: RR 1.5, 95% confidence interval (95% CI) 1.2–1.8; women: RR 1.5, 95% Cl 1.2–1.7]; a similarly elevated risk was also found for other blue-collar workers (men: RR 1.5, 95% Cl 1.2–1.8; women: RR 1.4, 95% Cl 1.2–1.6) in the same wood industries. Statistically increased relative risks were found for low and medium exposure to wood dust, but not for high exposure. Altogether 217 of the 4074 clinically verified asthma cases were reported as occupational asthma in the Finnish Register on Occupational Diseases. Conclusions The incidence rates for asthma were significantly increased both among the woodworkers and the other blue-collar workers in wood industries but without a clear dose–response. Cases recognized as occupational asthma accounted for only a small part of the total asthma excess, indicating that much of the work-related asthma excess remains unrecognized in these industries.

Objectives The objective of the study was to determine asthma risks at the most-detailed level of occupational classification in a previously described nationwide follow-up study that included the entire employed workforce of Finland. Methods In Finland, persons with clinically verified persistent asthma are registered for medication reimbursement within the national health insurance scheme. Data were combined from three national registers, and all 25- to 59-year-old employed Finns were followed for asthma incidence in 1986-1998. Altogether 49 575 cases were detected. A log-linear model was used to estimate the relative risks of asthma for 275 nonadministrative occupations in comparison with administrative work (33 occupations). Results A significantly increased risk was found for either men or women in 125 occupations. For the men, the risk was highest among bakers, laundry workers, shoemakers and repairers, tanners, fell mongers and pelt dressers, and metal plating and coating workers. For the women, the risk was highest among shoemakers and repairers, railway and station personnel, jewelry engravers, engineroom crew, molders, round-timber workers, and bakers. Conclusions The results suggest that the work-related excess of asthma incidence is much more widely spread across the labor force than has been previously thought. A great number of occupations deserves to be targeted for in-depth studies focusing on the determinants of asthma excess and on possibilities for better asthma control among asthmatics working in these occupations. The large work-relatedness of asthma incidence should also raise public health interest because of the economic losses incurred and the potential for prevention.

This study attempts to estimate the proportion of annual deaths related to occupational factors in Finland and considers related methodological issues and associated uncertainties.Statistics on causes of death, numbers of subjects exposed, and risk ratios obtained from the epidemiologic literature were used to estimate the population attributable fraction and disease burden for causes of death from work-related diseases. Gender-, age- and disease-specific numbers of deaths were provided by Statistics Finland for 1996. Information on the size of the population, broken down by gender, age, occupation, and industry, was acquired from population censuses. A Finnish job-exposure matrix supplied data on the prevalence of exposure for specific agents and the level of exposure among exposed workers.The attributable fraction of work-related mortality in the relevant disease and age categories was estimated to be 7% (10% for men and 2% for women), and for all diseases and ages the fraction was 4%. For the main cause-of-death categories, the attributable fraction became 12% for circulatory system diseases, 8% for malignant neoplasms, 4% for respiratory system diseases, 4% for mental disorders, 3% for nervous system diseases, and 3% for accidents and violence. The following estimates were obtained for specific important diseases: 24% for lung cancer, 17% for ischemic heart disease, 12% for chronic obstructive pulmonary disease, and 11% for stroke. Based on these fractions, the total number of work-related deaths that occurred in Finland in 1996 was calculated to be on the order of 1800 (employed work force of 2.1 million); 86% involved men.High-quality epidemiologic studies and national survey data are essential for obtaining reliable estimates of the proportion of deaths attributable to occupational factors. The magnitude of work-related mortality is an insufficiently recognized contributor to total mortality in Finland, especially from circulatory diseases and other diseases caused by exposure to agents other than asbestos.

Objective The aim of this study was to verify a clinical impression that patients with coronary heart disease disproportionately frequently have calcified pleural plaques. Methods Chest X-rays were collected from 148 patients referred consecutively to the Helsinki University Central Hospital for coronary angiography and from 100 consecutive lung cancer patients seen at the same hospital. The radiographs were analyzed for the presence of calcified pleural plaques according to the classification the International Labour Office. A generalized linear model with binomial distribution and log link was used to estimate the relative risks and their 95% confidence intervals (95% CI). Results The prevalence of calcified pleural plaques was 35% for the coronary patients and 19% for the lung cancer patients. Calcified pleural plaques were more common among the men than the women, and the risk increased with age. The relative risk of calcified pleural plaques, adjusted for age and gender, was 2.19 (95% CI 1.44-3.32) for the coronary patients as compared with the lung cancer patients. Conclusions Further studies with better information on past exposure to asbestos and other potential risk factors are warranted to confirm the observations and to examine whether the association between coronary heart disease and calcified pleural plaques is related to an etiologic or an individual susceptibility factor common to both of these conditions.

The aim of the study was to analyze the correlation between pulmonary concentrations of asbestos bodies and asbestos fibers and to characterize asbestos body counts from lung tissue of Finnish patients occupationally exposed and unexposed to asbestos.Ninety-nine surgically treated lung cancer patients were investigated. The number of asbestos bodies in iron-stained 5-micrometers histological lung tissue sections was determined by optical microscopy, and the pulmonary concentration of asbestos fibers was assessed by scanning electron microscopy. The correlation between asbestos body and asbestos fiber counts was calculated with linear regression. The asbestos body and asbestos fiber concentrations were also compared with exposure history according to a personal interview of the patients.The average number of asbestos bodies ranged from0.1 to 750 asbestos bodies per tissue section. All the cases with definite exposure showed an average of at least one asbestos body per tissue section. An average of at least one asbestos body per section was, however, detected in 34% of the patients with unlikely exposure. The regression equation log (AF) = -0.429 + 0.600.log (AB) was found to predict the concentration of asbestos fibers (AF, 10(6) fibers.g-1) corresponding to a given number of asbestos bodies (AB) in a section of lung tissue.The background level of asbestos bodies in the lungs of patients with no specific asbestos exposure seems to be higher in Finland than in other countries. In medicolegal cases, the methodological variation involved in asbestos fiber and asbestos body counting must be recognized and all available exposure data should be used to produce the best possible estimate of the exposure.

Objectives The purpose of this study was to estimate the role of past asbestos exposure as a cause of radiographic small lung opacities and pleural abnormalities in the Finnish adult population. Methods The study was conducted in 1978--1981 and was based on a population sample (N = 8000) representative of the Finnish population aged 30 years or over. Full-size chest radiographs and a complete job title history were available for 3811 women and 3274 men. The radiographs were classified according to the 1980 classification of radiographs of pneumoconioses published by the International Labour Office and the work histories according to the probability of occupational asbestos exposure. Age- and smoking-adjusted relative risks of radiographic parenchymal and pleural abnormalities were calculated with the analysis of covariance according to the probability of asbestos exposure. Results About 13% of the men and 0.8% of the women were classified as probably exposed to asbestos. There was more than 90% agreement in the repeated work history evaluations. The risk of small lung opacities was significantly increased among the probably exposed men [risk ratio (RR) 1.7 for ILO profusion category 1/1 or more and RR 1.6 for profusion category l/0]. The risk of pleural plaques was increased both among the men (RR 3.0) and the women (RR 4.8) with probable exposure. The risk of thickened horizontal interlobar fissure was also increased among the probably exposed men (RR 1.7). Among the men, the etiologic fraction attributable to occupational asbestos exposure was about 30% for small lung opacities, about 40% for pleural plaques, and about 20% for thickened horizontal fissure. Among the women the etiologic fractions for asbestos were similar for pleural abnormalities, but much lower for parenchymal ones. Conclusion Occupational asbestos exposure has been common among Finnish men, and it plays a significant role in the etiology of both pleural and parenchymal abnormalities also at the level of the general population.

OBJECTIVES--The aim of the study was to determine the pulmonary concentrations of mineral fibers in the Finnish male urban population and to evaluate the analysis of pulmonary fiber burden by scanning electron microscopy (SEM) as an indicator of past fiber exposure. METHODS--The pulmonary concentration of mineral fibers was determined by SEM and compared with occupational history for a series of 300 autopsies of urban men aged 33 to 69 years. RESULTS--The concentration of fibers (f) longer than 1 micron ranged from < 0.3 to 163.10(6) per gram of dry tissue (f.g-1). Asbestos fiber concentrations exceeding 1.10(6) f.g-1 were observed in 33% of the cases with probable occupational exposure to asbestos and 1% of the cases with unlikely occupational exposure. Even asbestos fiber concentrations of 0.3 to 1.10(6) f.g-1, especially of crocidolite-amosite fibers, were rare among the men with unlikely occupational exposure. Fiber concentrations exceeding or equaling 1.10(6) f.g-1 were 10 times more frequent among the men more than 60 years of age as compared with those less than 40 years of age. Inorganic fibers other than asbestos had a weaker correlation with occupational history and age. Smoking habits had no significant effect on the pulmonary fiber counts. CONCLUSIONS--Asbestos fiber concentrations exceeding 1.10(6) f.g-1 are highly indicative of past occupational exposure to asbestos. The distribution of fiber concentrations in the different age groups of this study indicated decreasing asbestos exposure in Finland since the 1970s.