Exposure to Particles and Nitrogen Dioxide Among Workers in the Stockholm Underground Train System.

OBJECTIVES: Exposure to fine particles in urban air has been associated with a number of negative health effects. High levels of fine particles have been detected at underground stations in big cities. We investigated the exposure conditions in four occupational groups in the Stockholm underground train system to identify high-exposed groups and study variations in exposure. METHODS: PM1 and PM2.5 were measured during three full work shifts on 44 underground workers. Fluctuations in exposure were monitored by a real-time particle monitoring instrument, pDR, DataRAM. Qualitative analysis of particle content was performed using inductively coupled plasma mass spectrometry. Nitrogen dioxide was measured using passive monitors. RESULTS: For all underground workers, the geometric mean (GM) of PM1 was 18 µg/m3 and of PM2.5 was 37 µg/m3. The particle exposure was highest for cleaners/platform workers, and the GM of PM1 was 31.6 µg/m3 [geometric standard deviation (GSD), 1.6] and of PM2.5 was 76.5 µg/m3 (GSD, 1.3); the particle exposure was lowest for ticket sellers, and the GM of PM1  was 4.9 µg/m3 (GSD, 2.1) and of PM2.5 was 9.3 µg/m3 (GSD, 1.5). The PM1 and PM2.5 levels were five times higher in the underground system than at the street level, and the particles in the underground had high iron content. The train driver's nitrogen dioxide exposure level was 64.1 µg/m3 (GSD, 1.5). CONCLUSIONS: Cleaners and other platform workers were statistically significantly more exposed to particles than train drivers or ticket sellers. Particle concentrations (PM2.5) in the Stockholm underground system were within the same range as in the New York underground system but were much lower than in several older underground systems around the world.

Blood markers of inflammation and coagulation and exposure to airborne particles in employees in the Stockholm underground.

OBJECTIVES: Although associations have been found between levels of ambient airborne particles and cardiovascular disease (CVD) in the general population, little is known about possible cardiovascular effects from high exposure to particles in underground railway systems. This study investigates risk markers for CVD in employees exposed to particles in the Stockholm underground system. METHODS: 79 workers (54 men and 25 women) in the Stockholm underground were investigated between November 2004 and March 2005. All were non-smokers aged 25-50 years. Three exposure groups were delineated: 29 platform workers with high exposure to particles, 29 train drivers with medium exposure and 21 ticket sellers with low exposure (control group). A baseline blood sample was taken after 2 non-working days, and a second sample after 2 working days, for analysis of levels of plasminogen activator inhibitor-1 (PAI-1), high-sensitivity C-reactive protein (hs-CRP), interleukin-6, fibrinogen, von Willebrand factor and factor VII. The study investigated changes in plasma concentrations between sample 1 and sample 2, and differences in average concentrations between the groups. RESULTS: No changes between sample 1 and 2 were found that could be attributed to particle exposure. However, the highly exposed platform workers were found to have higher plasma concentrations of PAI-1 and hs-CRP than the ticket sellers and train drivers. This suggests that particle exposure could have a long-term inflammatory effect. These differences remained for PAI-1 in the comparison between platform workers and ticket sellers after adjusting for body mass index. CONCLUSIONS: Employees who were highly exposed to airborne particles in the Stockholm underground tended to have elevated levels of risk markers for CVD relative to employees with low exposure. However, the differences observed cannot definitely be linked to particle exposure as such.

Airborne occupational exposures and risk of oesophageal and cardia adenocarcinoma.

BACKGROUND: The reasons for the increasing incidence of and strong male predominance in patients with oesophageal and cardia adenocarcinoma remain unclear. The authors hypothesised that airborne occupational exposures in male dominated industries might contribute. METHODS: In a nationwide Swedish population based case control study, 189 and 262 cases of oesophageal and cardia adenocarcinoma respectively, 167 cases of oesophageal squamous cell carcinoma, and 820 frequency matched controls underwent personal interviews. Based on each study participant's lifetime occupational history the authors assessed cumulative airborne occupational exposure for 10 agents, analysed individually and combined, by a deterministic additive model including probability, frequency, and intensity. Furthermore, occupations and industries of longest duration were analysed. Relative risks were estimated by odds ratios (OR), with 95% confidence intervals (CI), using conditional logistic regression, adjusted for potential confounders. RESULTS: Tendencies of positive associations were found between high exposure to pesticides and risk of oesophageal (OR 2.3 (95% CI 0.9 to 5.7)) and cardia adenocarcinoma (OR 2.1 (95% CI 1.0 to 4.6)). Among workers highly exposed to particular agents, a tendency of an increased risk of oesophageal squamous cell carcinoma was found. There was a twofold increased risk of oesophageal squamous cell carcinoma among concrete and construction workers (OR 2.2 (95% CI 1.1 to 4.2)) and a nearly fourfold increased risk of cardia adenocarcinoma among workers within the motor vehicle industry (OR 3.9 (95% CI 1.5 to 10.4)). An increased risk of oesophageal squamous cell carcinoma (OR 3.9 (95% CI 1.2 to 12.5)), and a tendency of an increased risk of cardia adenocarcinoma (OR 2.8 (95% CI 0.9 to 8.5)), were identified among hotel and restaurant workers. CONCLUSIONS: Specific airborne occupational exposures do not seem to be of major importance in the aetiology of oesophageal or cardia adenocarcinoma and are unlikely to contribute to the increasing incidence or the male predominance.

Cutaneous melanoma: hints from occupational risks by anatomic site in Swedish men.

AIMS: To improve knowledge of the epidemiology of melanoma by comparing occupational risks of cutaneous melanoma (CM) by anatomic site in Swedish workers. METHODS: Male workers employed in 1970 and living in the country in 1960 were followed up from 1971 to 1989 using the Swedish Registers of Death and Cancer. A more specifically exposed subcohort included men reporting the same occupation in 1960 and 1970. For each location, occupational risk ratios (RRs) were extracted from Poisson regression models adjusted by age, period, town size, and geographical area. To diminish the influence of socioeconomic factors, intrasector analyses, comparing only jobs belonging to the same occupational sector, were performed. Risk patterns for different locations were compared. RESULTS: High RRs for different sites were found among workers exposed to UV sources (dentists, physiotherapists, and lithographers), and sun exposed workers (harbour masters, and lighthouse/related work). Risk excesses were seen in fur tailors, tanners/fur dressers, patternmakers/cutters, electrical fitters/wiremen, telephone/telegraph installers/repairmen, and some glass/pottery/tile workers. Results for lower and upper limbs were significantly correlated but somewhat independent of those found in thorax, the most frequent location. Correlation between head/neck and thorax was moderate. Specific risk excesses were found for rolling mill workers in head/neck, for chimney sweeps in upper limbs, and for aircraft pilots/navigators/flight engineers in lower limbs. CONCLUSIONS: High RRs in the trunk among occupations with UV exposure from artificial sources suggest an effect not restricted to exposed sites. An unusual distribution of cases and RRs in chimney sweeps, rolling-mill, or glass/pottery/tile workers suggests local effects of exposures. The not previously reported risk excess in this job and in fur related processes, and the RR in electrical fitters and telephone/telegraph installers deserve further investigation. Disparities between locations, as RRs in thorax and limbs, may reflect differences in aetiological mechanisms.

Paternal occupational exposures and childhood cancer.

The objective of the study described here was to test the hypothesis that paternal occupational exposure near conception increases the risk of cancer in the offspring. We conducted a cohort study based on a population of 235,635 children born shortly after two different censuses in Sweden. The children were followed from birth to 14 years, and cases of cancer were identified in the Swedish Cancer Registry. Occupational hygienists assessed the probability of exposure to different agents in each combination of the father's industry and occupation as reported in the censuses. We also analyzed individual job titles. We compared the cancer incidence among children of exposed fathers to that among children of unexposed fathers using Cox proportional hazards modeling. The main findings were an increased risk of nervous system tumors related to paternal occupational exposure to pesticides [relative risk (RR) = 2.36; 95% confidence interval (CI), 1.27-4.39] and work as a painter (RR = 3.65; 95% CI, 1.71-7.80), and an increased risk of leukemia related to wood work by fathers (RR = 2.18; 95% CI, 1.26-3.78). We found no associations between childhood leukemia and paternal exposure to pesticides or paint. Our results support previous findings of an increased risk of childhood brain tumors and leukemia associated with certain paternal occupational exposures. Some findings in previous studies were not confirmed in this study.

A population-based case-referent study of myocardial infarction and occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite. Stockholm Heart Epidemiology Program (SHEEP) Study Group.

This case-referent study investigated the risk of myocardial infarction from occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite. We identified first-time, nonfatal myocardial infarctions among men and women 45-70 years of age in Stockholm County from 1992 through 1994. We selected referent subjects from the population to match the demographic characteristics of the cases. A lifetime history of occupations was obtained by questionnaire. The response rate was 81% for the cases and 74% for the referents, with 1,335 cases and 1,658 referents included in the study. An occupational hygienist assessed occupational exposures, coding the intensity and probability of exposure for each subject. We adjusted relative risk estimates for tobacco smoking, alcohol drinking, hypertension, diabetes mellitus, overweight, and physical inactivity at leisure time. The relative risk of myocardial infarction was 2.11 (95% confidence interval = 1.23-3.60) among those who were highly exposed and 1.42 (95% confidence interval = 1.05-1.92) among those who were intermediately exposed to combustion products from organic material. We observed an exposure-response pattern, in terms of both maximum exposure intensity and cumulative dose. Exposure to dynamite and organic solvents was possibly associated with an increased risk. The other exposures were not consistently associated with myocardial infarction.

Occupational exposure to carcinogens in the European Union.

OBJECTIVES: To construct a computer assisted information system for the estimation of the numbers of workers exposed to established and suspected human carcinogens in the member states of the European Union (EU). METHODS: A database called CAREX (carcinogen exposure) was designed to provide selected exposure data and documented estimates of the number of workers exposed to carcinogens by country, carcinogen, and industry. CAREX includes data on agents evaluated by the International Agency for Research on Cancer (IARC) (all agents in groups 1 and 2A as of February 1995, and selected agents in group 2B) and on ionising radiation, displayed across the 55 industrial classes. The 1990-3 occupational exposure was estimated in two phases. Firstly, estimates were generated by the CAREX system on the basis of national labour force data and exposure prevalence estimates from two reference countries (Finland and the United States) which had the most comprehensive data available on exposures to these agents. For selected countries, these estimates were then refined by national experts in view of the perceived exposure patterns in their own countries compared with those of the reference countries. RESULTS: About 32 million workers (23% of those employed) in the EU were exposed to agents covered by CAREX. At least 22 million workers were exposed to IARC group 1 carcinogens. The exposed workers had altogether 42 million exposures (1.3 mean exposures for each exposed worker). The most common exposures were solar radiation (9.1 million workers exposed at least 75% of working time), environmental tobacco smoke (7.5 million workers exposed at least 75% of working time), crystalline silica (3.2 million exposed), diesel exhaust (3.0 million), radon (2.7 million), and wood dust (2.6 million). CONCLUSION: These preliminary estimates indicate that in the early 1990s, a substantial proportion of workers in the EU were exposed to carcinogens.

Cancer incidence among European man-made vitreous fiber production workers.

OBJECTIVES: This study analyzed cancer incidence among man-made vitreous fiber workers. METHODS: A cancer incidence follow-up was conducted among 3685 rock-slag wool (RSW) and 2611 glass wool (GW) production workers employed for > or =1 year in Denmark, Finland, Norway, or Sweden, and the standardized incidence ratios (SIR) were calculated on the basis of national incidence rates. RESULTS: Overall cancer incidence was close to expectation. Lung cancer incidence was increased among the RSW [SIR 1.08, 95% confidence interval (95% CI) 0.85-1.36] and GW (SIR 1.28, 95% CI 0.91-1.74) workers. For both subcohorts, a trend was suggested for time since first employment (P-value for linear trend 0.1 and 0.2, respectively). Neither subcohort showed an association with employment during the early technological phase, when fiber exposure was high. The incidence of oral, pharyngeal, and laryngeal cancer was increased among the RSW (SIR 1.46, 95% CI 0.99-2.07) and the GW (SIR 1.41, 95% CI 0.80-2.28) subcohorts. Despite a trend in risk for these neoplasms among the GW workers with time since first employment, the lack of a positive relation with other indirect indicators of fiber exposure points against a causal interpretation. No association between RSW or GW exposure and the risk of other neoplasms was suggested. CONCLUSIONS: These lung cancer results are similar to those of a mortality study that included a larger number of factories. For other cancers there was no suggestion of an association with RSW or GW exposure.

Non-neoplastic mortality of European workers who produce man made vitreous fibres.

OBJECTIVE: To study mortality from non-neoplastic diseases among European workers who produce man made vitreous fibres (MMVF). METHODS: 11,373 male workers were studied, who were employed for at least 1 year in the production of rock or slag wool (RSW), glass wool (GW), and continuous filament (CF) in 13 factories from seven European countries. Workers were followed up from the beginning of production, between 1933 and 1950 to 1990-2 and contributed 256,352 person-years of observation. Standardised mortality ratios (SMRs) were calculated with national mortalities for reference; an internal exposure-response analyses based on multivariate Poisson regression models was also conducted. RESULTS: Mortality from bronchitis, emphysema, and asthma was not increased (SMR 1.03, 95% confidence interval (95% CI) 0.82 to 1.28). In RSW workers, there was no overall increase in mortality from non-malignant renal diseases (SMR 0.97, 95% CI 0.36 to 2.11), although there was the suggestion of an increase in risk with duration of employment. Mortality from ischaemic heart disease was not increased overall (SMR 1.03, 95% CI 0.96 to 1.11), but RSW and CF workers with > or = 30 years since first employment had a higher risk. RSW and CF workers showed an increased mortality from external causes, mainly motor vehicle accidents and suicide, which was higher among workers with a short duration of employment. CONCLUSIONS: Mortality from most non-neoplastic diseases does not seem to be related to employment in the MMVF industry. The results on mortality from ischaemic heart disease and non-malignant renal diseases, however, warrant further investigations.

Lung cancer mortality among European rock/slag wool workers: exposure-response analysis.

OBJECTIVES: The purpose was to analyze the relationship between semi-quantitative indices of exposure to manmade vitreous fibers and lung cancer mortality among European rock/slag wool (RSW) workers. METHODS: The study population comprised 9,603 male workers employed in RSW production in seven factories in Denmark, Norway, Sweden, and Germany, followed up for mortality as of 1990-91. Estimates of past exposure to respirable fibers were used to calculate cumulative exposure with a 15-year lag and maximum annual exposure based on employment history up to 1977. Rate ratios were estimated via multivariate Poisson regression, adjusting for country, age, calendar year, time since first employment, and employment status. RESULTS: A total of 159 lung cancer deaths were included in the analysis of which 97 among workers with more than one year of employment. We found nonstatistically significant trends in lung cancer risk according to cumulative exposure. Relative risks (RR) in the four quartiles were 1.0 (reference), 1.3 (95 percent confidence interval [CI] = 0.8-2.4), 1.2 (CI = 0.7-2.1), and 1.5 (CI = 0.7-3.0, P test for trend = 0.4). When workers with less than one year of employment were excluded, there was no increased risk; the RRs in the four quartiles were 1.0, 0.9 (CI = 0.4-2.0), 0.8 (CI = 0.3-1.9), and 1.0 (CI = 0.4-2.7). No trend was present according to maximum annual exposure. The results were not consistent among countries. CONCLUSIONS: We found a positive association between exposure to respirable fibers and lung cancer mortality. However, the lack of statistical significance, the dependence of the results on inclusion of short-term workers, the lack of consistency among countries, and the possible correlation between exposure to respirable fibers and to other agents reduce the weight of such evidence.

Comparison of information on occupation and lifestyle habits obtained from European man-made vitreous fibre production workers and their relatives.

BACKGROUND: Studies of the aetiology of fatal diseases often rely on data obtained from relatives, which can cause loss of precision and introduce bias. We assessed the quality of such information on demographics, occupation, smoking and alcohol habits. METHODS: We compared contemporary interviews, based on a structured questionnaire, with male workers from the man-made vitreous fibre production industry in four European countries and their relatives. The participation rate was 63% (74 pairs of workers and relatives). RESULTS: Only minor differences in the ability to answer the questions appeared among workers and relatives, except for specific occupational questions. There was moderate to excellent agreement for demographics, residential and work history (kappa or intraclass correlation range: 0.44-0.98). For smoking habits, beer and wine consumption the agreement was good to excellent (range: 0.59-0.99). In particular, number of different residential areas, jobs, industries, and duration of wine drinking were significantly underreported by the relatives. No general determinant for reduced agreement appeared. CONCLUSIONS: In general, the quality of information obtained from relatives appeared good. However, information on specific occupational exposures may be improved by supplementing the information from relatives with details obtained from colleagues, occupational hygiene experts or occupation-exposure matrices.

Assessment of past exposure to man-made vitreous fibers in the Swedish prefabricated house industry.

Large quantities of man-made vitreous fibers (MMVF) are handled in the Swedish prefabricated wooden house industry. The present study is part of a program to investigate mortality, cancer incidence, and current as well as previous exposure to MMVF among workers in the Swedish prefabricated wooden house industry. Since measurements of historical fiber exposure levels are lacking, these were calculated by the application of a matrix of multipliers to recently measured MMVF levels. The multipliers represented changes over time in production rate, technical properties of the fibers, manual handling vs. automation, and ventilation control. The multipliers were based on a similar matrix, developed for the MMVF-manufacturing industry, which was modified to reflect the conditions in the wooden house industry. The model was developed for the highest-exposed job title in the study, insulators. One hundred and twenty samples of airborne fiber were taken in 11 plants to reflect current exposure levels. The highest mean fiber exposure level for insulators was assessed as 0.18 f/ml (geometric mean), which occurred during the mid-1970s, compared to 0.10 f/ml at the end of the 1980s and the early 1960s. Changes in production rate, improved ventilation control, and the surface area of the total amount of MMVF sheets handled per insulator were the most important variables of the model. No increased risk of lung cancer was found in the present industry.

Cancer mortality among man-made vitreous fiber production workers.

We have updated the follow-up of cancer mortality for a cohort study of man-made vitreous fiber production workers from Denmark, Finland, Norway, Sweden, United Kingdom, Germany, and Italy, from 1982 to 1990. In the mortality analysis, 22,002 production workers contributed 489,551 person-years, during which there were 4,521 deaths. Workers with less than 1 year of employment had an increased mortality [standardized mortality ratio (SMR) = 1.45; 95% confidence interval (CI) = 1.37-1.53]. Workers with 1 year or more of employment, contributing 65% of person-years, had an SMR of 1.05 (95% CI = 1.02-1.09). The SMR for lung cancer was 1.34 (95% CI = 1.08-1.63, 97 deaths) among rock/slag wool workers and 1.27 (95% CI = 1.07-1.50, 140 deaths) among glass wool workers. In the latter group, no increase was present when local mortality rates were used. Among rock/slag wool workers, the risk of lung cancer increased with time-since-first-employment and duration of employment. The trend in lung cancer mortality according to technologic phase at first employment was less marked than in the previous follow-up. We obtained similar results from a Poisson regression analysis limited to rock/slag wool workers. Five deaths from pleural mesothelioma were reported, which may not represent an excess. There was no apparent excess for other categories of neoplasm. Tobacco smoking and other factors linked to social class, as well as exposures in other industries, appear unlikely to explain the whole increase in lung cancer mortality among rock/slag wool workers. Limited data on other agents do not indicate an important role of asbestos, slag, or bitumen. These results are not sufficient to conclude that the increased lung cancer risk is the result of exposure to rock/slag wool; however, insofar as respirable fibers were an important component of the ambient pollution of the working environment, they may have contributed to the increased risk.

Fiber exposure assessment in the Swedish rock wool and slag wool production industry in 1938-1990.

OBJECTIVE: A multiplicative model was developed to assess past exposure to respirable fibers among rock wool and slag wool production workers in Sweden in 1938-1990. METHODS: Information on the job titles, work tasks and employment times of 1487 workers exposed to man-made vitreous fibers was obtained from company records and interviews with older employees. A mathematical model developed earlier for assessing historical fiber exposure, based on factory averages, was further developed. Matrices of multipliers for each plant that were specific for job title were modified to assess fiber exposure with respect to job title and calendar period. The model was based on measurements made in 1977. Two methods of exposure assessment were compared, cumulative exposure based on factory average (model I) and cumulative exposure based on job title (model II). RESULTS: The exposure changed considerably in the two factories during the period 1938-1990, and it varied also between job titles. The estimated average fiber (f) exposure level at the two plants in the middle of the 1940s was 1.32 and 0.78 f.ml-1. These values are 26 and 16 times higher, respectively, than the exposure in 1980. Process changes, as well as the addition of binders and oil, reduced the exposure drastically around 1950. The mean cumulative respirable fiber exposure for the 1487 subjects was 1.44 (range 0.05-18.40) f.ml-1.year. The cleaners had 14 times higher annual fiber exposure than the preproduction workers. CONCLUSIONS: Model II was judged to be more valid than model I in assessing exposure to man-made vitreous fibers.

Cancer incidence, mortality and exposure-response among Swedish man-made vitreous fiber production workers.

OBJECTIVE: The objective of this study was to provide an extended follow-up of workers in three Swedish plants producing man-made vitreous fibers (MMVF). METHOD: Mortality and cancer incidence was investigated among 3539 male and female workers, employed for at least one year before 1978. Mortality was followed from 1952 to 1990 and cancer incidence from 1958 to 1989. National and regional mortality and cancer incidence rates were used to calculate the expected numbers. RESULTS: Twenty-seven lung cancer deaths were observed compared with 23 expected (standardized mortality ratio 117, 95% confidence interval 81-176), based on regional mortality. With a latency time of 30 years, the lung cancer risk was significantly elevated, but not trend was found for the standardized mortality ratio with increasing duration of exposure to MMVF. The lung cancer and stomach cancer mortality was higher in the rock wool industry than in the fiber glass industry. Fiber exposure from 1938 to 1990 was estimated in the two rock wool plants by applying a model for historical fiber exposure estimation, specific for different job titles in the rock wool production industry. No relationship was found between individually cumulated rock wool fiber exposure and lung cancer or stomach cancer risk. CONCLUSIONS: The numbers of lung cancers and stomach cancer cases were low and did not therefore allow more general conclusions regarding the cancer hazard for exposed workers. A large European study in progress will probably allow more precise conclusions.

An index of past asbestos exposure as applied to car and bus mechanics.

Different ways to describe historic fibre exposure from asbestos-containing friction materials were studied and compared for a group of 103 car and bus mechanics with more than 20 years employment and 15 years of asbestos exposure. A model was constructed to calculate cumulative asbestos exposure from friction materials including duration, intensity and exposure last year. The model is a combination of an additive and a multiplicative model, where an asbestos index was constructed that takes both near field and far field exposure into consideration. The model was based upon data from the international literature and quantitative asbestos measurements performed 1976-1988 in Swedish car repair workshops. The fibres were counted by phase-contrast microscopy with fibre criteria of length > 5 microns and aspect ratio > or = 3:1. The mechanics' fibre exposure at 398 repair workshops during a period of 48 years were calculated using the model. The mean cumulative exposure was estimated to be 2.6 f ml-1 * year. The annual cumulative exposure was highest for truck mechanics in the early 1960s. The car mechanics had a time-weighted average fibre exposure range of 0.11-0.41 f ml-1 (mean 0.21 f ml-1) in 1965 compared to 0.003-0.08 f ml-1 (mean 0.021 f ml-1) in 1985. In order to validate the model, the mechanic's fibre exposure estimated using the model were compared with representative asbestos exposure measurements for car mechanics during the 1960s and the 1970s (correlation coefficient = 0.69). Five lung physiological variables (FVC, TLC, FEV1, TLco and CV%) were used to study exposure-response relationships. None of the exposure parameters suggested any significant relationship between exposure and decrease in lung function.

Characterization of current exposure to man-made vitreous fibres (MMVF) in the prefabricated house industry in Sweden.

The exposure to man-made vitreous fibres (MMVF) was investigated at 11 Swedish plants manufacturing prefabricated wooden houses. Current fibre levels were studied by monitoring personal exposure using the membrane filter technique. All samples were analysed by phase contrast optical microscopy (PCOM) according to Swedish standard rules; they were also analysed using a set of modified criteria for fibre counting, developed for this study, which in addition also required straight, parallel and/or convergent edges of the fibres. The objective of this alternating counting method, the modified fibre method, was to exclude fibres with appearance other than MMVF, that might be present in the wood industries. The method was validated by scanning electron microscopy (SEM). In all, 120 samples were taken and 273 analyses were performed. The mean exposure (GM), analysed by the standard method, was for insulators 0.10 f ml-1 (range 0.03-0.30 f ml-1) and for woodcutters 0.09 f ml-1) (range 0.05-0.19 f ml-1). Analysed by the modified fibre method the insulators were exposed to 0.029 f ml-1 (range 0.013-0.077 f ml-1 and the cutters to 0.021 f ml-1 (range 0.014-0.033 f ml-1). A significant difference was observed between the exposure for near-field workers/job titles and far-field workers/job titles. Analysis of fibre levels by the modified fibre method indicated that only a minor proportion, around 25%, of the total airborne fibres were MMVFs. The reliability of the alternative modified counting method was high, and a high correlation (r = 0.94) with the SEM results was also achieved.

Effects within the week on forced vital capacity are correlated with long term changes in pulmonary function: reanalysis of studies on car painters exposed to isocyanate.

OBJECTIVES: To examine if car painters who work with polyurethane paints that contain hexamethylenediisocyanate (HDI) and hexamethylenediisocyanate biuret trimer (HDI-BT) develop acute as well as chronic impairment of lung function. METHODS: In this study data were reanalysed from two earlier studies on a group of car painters to see if a decrease in lung function within the week is a marker of vulnerability in those workers. Data on changes in forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) within the week were available for 20 car painters who were also examined six years later. RESULTS: 10 men showed a decline in FVC within the week. There were no significant differences in age, duration of employment, exposures during the follow up period, or smoking between car painters who had decline in lung function within the week and car painters who had not. A significant correlation was found between the change in FVC within the week and the long term (six year) change in FVC, standardised for the effects of aging and smoking, and adjusted for the number of peak exposures. CONCLUSIONS: The results suggest that the decrease in FVC within the week might serve as a guide to identify car painters at risk of a further decrement in lung function above the effects of aging, smoking, and exposure.

Occupation, occupational exposure to chemicals and rheumatological disease. A register based cohort study.

The cumulative incidence of rheumatoid arthritis (RA) was compared between different occupations, and between different exposure groups based on a job-exposure matrix (JEM). The study population comprised those subjects who in 1980 lived in one of 13 Swedish counties, were born between 1905 and 1945, and who had stated the same occupation in the censuses of 1960 and 1970, a total of 375,035 men and 140,139 women. The study population was followed concerning hospital care for rheumatoid arthritis in 1981-1983 by lineage to the Swedish Hospital Discharge Register. In general there were rather small differences in the relative risk of RA in different exposure groups and different occupations. Most of the occupations associated with an increased risk of RA were occupations in which it was possible to work when the disease was present, i.e. cost accountants, estimating clerks and working proprietors in the retail trade. However, an increased relative risk of RA was also observed in some occupations where selection of RA patients out of heavy work should have biased genuinely increased relative risks towards unity. Such occupations were farmers, upholsterers, lacquerers, concrete workers, and hair-dressers. Substantial handling of organic solvents, according to the JEM, was associated with an increased relative risk.

Methodology and utility of a job-exposure matrix.

We have previously reported a study in which a job-exposure matrix was applied to census data, identifying, e.g., polychlorinated biphenyls (PCBs) and creosote as increasing the risk of urothelial cancer. In this article, we expand on some theoretical issues, and present detailed accounts of constructed linkages for PCBs, creosote, and phenols. For agents of interest, one should emphasize the positive predictive value rather than the sensitivity in the construction of the matrix. The reverse is true for confounding factors; to avoid residual confounding after restriction to subjects unexposed for the confounding factors, one should emphasize sensitivity, possibly compromising the positive predictive value. This discrepancy between agents of interest and confounding factors may limit the application of a general matrix for studying several different diseases. The construction of the matrix is much harder, if sensitivity rather than positive predictive value is emphasized for an agent. Confounding from industry-related agents arises due to a true mixed exposure in certain work tasks, but also due to a gross classification of occupations in the census. One should not confuse different levels of the positive predictive value with exposure dose. A "dose-response" with different levels of positive predictive value reflects an accuracy of the matrix, not a biological phenomenon. Studies with exposure information from a job-exposure matrix applied to registers with scant information on occupation and industry may be warranted for exposures and diseases for which previous studies with a detailed documentation of exposure have low precision.