Epidemiologic study of cancer mortality among Israeli asphalt workers

BACKGROUND: We describe the results of a cancer mortality study among asphalt workers in Israel. METHODS: Personal identifiers and employment histories of 2,176 workers were extracted from company records. RESULTS: Mortality from all malignant neoplasms was significantly reduced in the whole cohort (SMR 0.68, 95% confidence interval (CI) 0.56-0.83). SMR for lung cancer was elevated in workers exposed to bitumen (SMR 1.05, 95% CI 0.62-1.66). No significant elevation or reduction in mortality was observed in relation to a specific site. SMRs for lung cancer was higher among ever exposed to bitumen than among unexposed. There was no association between lung cancer risk and estimated exposure to bitumen fume, and no dose-response was apparent. CONCLUSIONS: While the results of this cohort study indicate a slightly increased SMR for lung cancer, it did not produce evidence of a causal link between lung cancer and exposure to bitumen fume.     

Mortality from obstructive lung diseases and exposure to polycyclic aromatic hydrocarbons among asphalt workers

Work in the asphalt industry has been associated with nonmalignant respiratory morbidity and mortality, but the evidence is not consistent. A historical cohort of asphalt workers included 58,862 men (911,209 person-years) first employed between 1913 and 1999 in companies applying and mixing asphalt in Denmark, Finland, France, Germany, Israel, the Netherlands, and Norway. The relations between mortality from nonmalignant respiratory diseases (including the obstructive lung diseases: chronic bronchitis, emphysema, and asthma) and specific chemical agents and mixtures were evaluated using a study-specific exposure matrix. Mortality from obstructive lung diseases was associated with the estimated cumulative and average exposures to polycyclic aromatic hydrocarbons and coal tar (p values of the test for linear trend = 0.06 and 0.01, respectively). The positive association between bitumen fume exposure and mortality from obstructive lung diseases was weak and not statistically significant; confounding by simultaneous exposure to coal tar could not be excluded. The authors lacked data on smoking and full occupational histories. In conclusion, exposures to polycyclic aromatic hydrocarbons, originating from coal tar and possibly from bitumen fume, may have contributed to mortality from obstructive lung diseases among asphalt workers, but confounding and bias cannot be ruled out as an explanation for the observed associations.     

Cancer mortality among European asphalt workers: an international epidemiological study. II. Exposure to bitumen fume and other agents

BACKGROUND: An increased risk of lung cancers among asphalt workers has been suggested in epidemiological studies based on large scale statistical analyses. METHODS: In a multi-country study of 29,820 male workers employed in road paving, asphalt mixing and roofing, 32,245 ground and building construction workers and 17,757 other workers from Denmark, Finland, France, Germany, Israel, the Netherlands, Norway, and Sweden, with mortality that was documented from 1953-2000. Exposures to bitumen fume, coal tar, 4-6 ring polycyclic aromatic hydrocarbons, organic vapor, diesel exhaust, asbestos, and silica dust were assessed via a job-exposure matrix. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) based on national mortality rates, as well as relative risks (RRs) based on Poisson regression models were calculated. RESULTS: The SMR of lung cancer among workers exposed to bitumen fume (1.08, 95% CI 0.99-1.18) was comparable to that of non-exposed workers (SMR 1.05, 95% CI 0.92-1.19). In a sub-cohort of bitumen-exposed workers without exposure to coal tar, the SMR of lung cancer was 1.23 (95% CI 1.02-1.48). The analysis based on the semi-quantitative, matrix-based exposures in the whole cohort did not suggest an increased lung cancer risk following exposure to bitumen fume. However, in an analysis restricted to road pavers, based on quantitative estimate of bitumen fume exposure, a dose-response was suggested for average level of exposure, applying a 15-year lag, which was marginally reduced after adjustment for co-exposure to coal tar. The results for cancer of the head and neck were similar to those of lung cancer, although they were based on a smaller number of deaths. There was no clear suggestion of an association with bitumen fume for any other neoplasm. CONCLUSIONS: The results of the analysis by bitumen fume exposure do not allow us to conclude on the presence or absence of a causal link between exposure to bitumen fume and risk of cancer of the lung and the head and neck.     

Cancer mortality among European asphalt workers: an international epidemiological study. I. Results of the analysis based on job titles

BACKGROUND: Inhalation of bitumen fumes is potentially carcinogenic to humans. METHODS: We conducted a study of 29,820 male workers exposed to bitumen in road paving, asphalt mixing and roofing, 32,245 ground and building construction workers unexposed to bitumen, and 17,757 workers not classifiable as bitumen workers, from Denmark, Finland, France, Germany, Israel, the Netherlands, Norway, and Sweden, with mortality follow-up during 1953-2000. We calculated standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) based on national mortality rates. Poisson regression analyses compared mortality of bitumen workers to that of building or ground construction workers. RESULTS: The overall mortality was below expectation in the total cohort (SMR 0.92, 95% CI 0.90-0.94) and in each group of workers. The SMR of lung cancer was higher among bitumen workers (1.17, 95% CI 1.04-1.30) than among workers in ground and building construction (SMR 1.01, 95% CI 0.89-1.15). In the internal comparison, the relative risk (RR) of lung cancer mortality among bitumen workers was 1.09 (95% CI 0.89-1.34). The results of cancer of the head and neck were similar to those of lung cancer, based on a smaller number of deaths. There was no suggestion of an association between employment in bitumen jobs and other cancers. CONCLUSIONS: European workers employed in road paving, asphalt mixing and other jobs entailing exposure to bitumen fume might have experienced a small increase in lung cancer mortality risk, compared to workers in ground and building construction. However, exposure assessment was limited and confounding from exposure to carcinogens in other industries, tobacco smoking, and other lifestyle factors cannot be ruled out.     

Mortality of copper cadmium alloy workers with special reference to lung cancer and non-malignant diseases of the respiratory system, 1946-92.

OBJECTIVES--To identify and quantify any relations between occupational exposure to cadmium oxide fume and mortalities from lung cancer and from chronic non-malignant diseases of the respiratory system. METHODS--The mortality experience of 347 copper cadmium alloy workers, 624 workers employed in the vicinity of copper cadmium alloy work (vicinity workers), and 521 iron and brass foundry workers (all men) was investigated for the period 1946-92. All subjects were first employed in these types of work in the period 1922-78 and for a minimum period of one year at one of two participating factories. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS--Compared with the general population of England and Wales, mortality from lung cancer among copper cadmium alloy workers was close to expectation (observed deaths 18, expected deaths 17.8, standardised mortality ratio (SMR) 101, 95% confidence interval (95% CI) 60 to 159). A significant excess was shown for lung cancer among vicinity workers but not among iron and brass foundry workers (vicinity workers: observed 55, expected 34.3, SMR 160, 95% CI 121 to 209, P < 0.01; iron and brass foundry workers: observed 19, expected 17.8, SMR 107, 95% CI 64 to 167). Increased SMRs for non-malignant diseases of the respiratory system were shown for each of the three groups (alloy workers: observed 54, expected 23.5, SMR 230, 95% CI 172 to 300, P < 0.001; vicinity workers: observed 71, expected 43.0, SMR 165, 95% CI 129 to 208, P < 0.001; iron and brass foundry workers: observed 34, expected 17.1, SMR 199, 95% CI 137 to 278, P < 0.01). Work histories of the copper cadmium alloy workers were combined with independent assessments of cadmium exposures over time to develop individual estimates of cumulative exposure to cadmium; this being a time dependent variable. Poisson regression was used to investigate risks of lung cancer and risks of chronic non-malignant diseases of the respiratory system in relation to three levels of cumulative cadmium exposure (< 1600, 1600-4799, > or = 4800 micrograms.m-3.y). After adjustment for age, year of starting alloy work, factory, and time from starting alloy work, there was a significant positive trend (P < 0.01) between cumulative exposure to cadmium and risks of mortality from chronic non-malignant diseases of the respiratory system. Relative to a risk of unity for the lowest exposure category, risks were 4.54 (95% CI 1.96 to 10.51) for the middle exposure category and 4.74 (95% CI 1.81 to 12.43) for the highest exposure category. There was a non-significant negative trend between cumulative cadmium exposure and risks of mortality from lung cancer. Relative to a risk of unity for the lowest exposure category, risks were 0.85 (95% CI 0.27 to 2.68) for the middle exposure category and 0.81 (95% CI 0.18 to 3.73) for the highest exposure category. Similar findings were obtained when adjustment was made for age only. CONCLUSIONS--The findings are consistent with the hypothesis that exposure to cadmium oxide fume increases risks of mortality from chronic non-malignant diseases of the respiratory system. The findings do not support the hypothesis that exposure to cadmium oxide fume increases risks of mortality for lung cancer.     

Mortality of mastic asphalt workers

This study was conducted to investigate the adverse health effects of exposure to bitumen fumes. A cohort of 679 mastic asphalt workers was followed from 1959 to 10 June 1986, during this period 169 deaths occurred. The overall standardized mortality ratio (SMR) was 163 (95% confidence interval (95% CI) 141-190), the SMR was 225 (95% CI 172-288) for cancer and 223 (95% CI 130-358) for external causes. Among persons aged 40 to 89 years, significant increases were seen for lung cancer (SMR 290, 95% CI 188-429), nonpulmonary cancer (SMR 200, 95% CI 141-276), and liver cirrhosis (SMR 467, 95% CI 188-962). Bronchitis, emphysema, and asthma also occurred in excess (SMR 207, 95% CI 95-393). In conclusion, the inhalation of bitumen fumes may have contributed to the elevated mortality from cancer and respiratory diseases among mastic asphalt workers.     

Exposures and mortality among chrysotile asbestos workers. Part II: mortality

A retrospective cohort mortality study was conducted among a cohort of 1,261 white males employed one or more months in chrysotile asbestos textile operations and followed between 1940 and 1975. Statistically significant excess mortality was observed for all causes combined (standardized mortality ratio [SMR] = 150), lung cancer (SMR = 135), diseases of the circulatory system (SMR = 125), nonmalignant respiratory diseases (SMR = 294), and accidents (SMR = 134). Using estimated fiber exposure levels in conjunction with detailed worker job histories, exposure-response relationships were investigated. Strong exposure-response relationships for lung cancer and asbestos related non-malignant respiratory diseases were observed. Compared with data for chrysotile miners and millers, chrysotile textile workers were found to experience significantly greater lung cancer mortality at lower lifetime cumulative exposure levels. Factors such as differences in airborne fiber characteristics may partially account for the large differences in exposure response between textile workers and miners and millers.     

陶瓷厂矿工人死因队列研究

为评价陶瓷厂矿工人中癌症和其他疾病的死亡率，对江西及湖南的八个陶瓷厂矿共１２９４４人队列进行研究，追访到１９９４年底，共计２７５７０１．８人年，死亡２２９０人，全死因标化死亡率与全国居民平均水平持平，死亡超高的疾病主要是肺结核，非恶性呼吸系疾病，心知管疾病和肝癌。影响工人寿命的主要疾病是恶性肿瘤，心血管疾病，非恶性呼吸系疾病和脑血管疾病。     

Statistical modelling of the determinants of historical exposure to bitumen and polycyclic aromatic hydrocarbons among paving workers

INTRODUCTION: An industrial hygiene database has been constructed for the exposure assessment in a study of cancer risk among asphalt workers. AIM: To create models of bitumen and polycyclic aromatic hydrocarbons (PAH) exposure intensity among paving workers. METHODS: Individual exposure measurements from pavers (N = 1581) were collected from 8 countries. Correlation patterns between exposure measures were examined and factors affecting exposure were identified using statistical modelling. RESULTS: Inhalable dust appeared to be a good proxy of bitumen fume exposure. Bitumen fume and vapour levels were not correlated. Benzo(a)pyrene level appeared to be a good indicator of PAH exposure. All exposures steadily declined over the last 20 years. Mastic laying, re-paving, surface dressing, oil gravel paving and asphalt temperature were significant determinants of bitumen exposure. Coal tar use dictated PAH exposure levels. DISCUSSION: Bitumen fume, vapour and PAH have different determinants of exposure. For paving workers, exposure intensity can be assessed on the basis of time period and production characteristics.     

Nonmalignant mortality among workers in six Norwegian aluminum plants

OBJECTIVES: This study investigated the associations between exposure to fluorides and polycyclic aromatic hydrocarbons (PAH) and mortality from nonmalignant diseases among workers in the Norwegian primary aluminum industry. METHODS: Mortality among 10,857 men, employed for more than 3 years in 1 of 6 aluminum plants, was investigated from 1962 to 1996, giving 239,246 person-years during follow-up. Ajob-exposure matrix covering all 6 plants was used to estimate the individual exposure to total fluorides and particulate PAH. The observed cause-specific deaths were compared with expected figures calculated from national rates. Dose-response relations were investigated by internal comparisons using Poisson regression and by stratified analyses for standardized mortality ratio. Potential confounding by smoking was investigated in subanalyses restricted to 3 of the plants for which information on smoking habits was accessible. RESULTS: Mortality from circulatory disease was slightly lower than expected [SMR 0.95, 95% confidence interval (95%CI) 0.9-1.0], while there was an increased mortality from asthma, emphysema, and chronic bronchitis combined, SMR 1.2 (95% CI 1.0-1.5). Mortality from these diseases was associated with cumulative exposure to fluorides. The rate ratio in the internal analysis rose steadily to 2.5 (95% CI 1.5-4.3) for the upper exposure category. No association was observed between cumulative fluoride exposure or PAH exposure and circulatory mortality. CONCLUSIONS: The study showed an association between exposure to potroom emissions measured by fluorides and mortality from asthma, emphysema, and chronic bronchitis combined.     

Mortality from nonmalignant diseases of the respiratory, genitourinary and nervous systems among workers exposed to styrene in the reinforced plastics and composites industry in the United States.

OBJECTIVES: Mortality from diseases of the nervous system and nonmalignant diseases of the respiratory and genitourinary systems was examined for workers exposed to styrene. METHODS: Altogether 15,826 styrene-exposed workers in 30 plants in the reinforced plastics and composites industry were included. Vital status was ascertained through 31 December 1989. Individual exposure estimates were developed based on job functions, existing industrial hygiene data, process changes, engineering controls, work practices, and the use of personal protective equipment. Analyses were based on cause-specific standardized mortality ratios (SMR) and the Cox proportional hazards model. Mortality data were analyzed by latency, duration of exposure, average exposure, cumulative exposure, and process category. RESULTS: For diseases of the nervous system, the SMR was 0.56 [95% confidence interval (95% CI) 0.31-0.95]. Mortality from nonmalignant genitourinary diseases was not increased (SMR 0.87, 95% CI 0.46-1.50). Latency, duration of exposure, average exposure, cumulative exposure, and process category showed no association between styrene exposure and these 2 types of disease. A small increase in mortality from nonmalignant respiratory diseases was found (SMR 1.21, 95% CI 0.98-1.47), mainly due to "other nonmalignant respiratory diseases" (SMR 1.40, 95% CI 1.04-1.84). The highest increase occurred for short exposure duration (SMR 1.79 for <1 year's exposure) or low exposure (SMR 2.15 for <10 ppm-years); there were no increased risks in the high exposure categories. The Cox proportional hazard model revealed no association between styrene exposure and the diseases. CONCLUSIONS: No relationship was found between mortality from any of the diseases examined and any of the styrene exposure indices. The findings were compared with those reported in a European study of styrene-exposed workers.     

An updated mortality study of workers at a petroleum refinery in Beaumont,Texas

The mortality experience of 7,119 workers who were employed at a Beaumont, Texas, refinery for at least 1 year between 1945 and 1987 was investigated. Mortality analyses based on standardized mortality ratios (SMRs) and 95% confidence intervals (95%CI) showed overall mortality was significantly lower than expected compared with the U.S. general population (SMR <=;=> 82, 95%CI = 79–86). Total cancer mortality was also lower than expected (SMR = 92, 95% CI = 84–100). Significant mortality deficits from several malignant and nonmalignant diseases were reported. A significant mortality increase in the broad category of lymphatic and hematopoietic cancers was found (SMR = 133, 95%CI = 103–170). This increase was attributed to a nonsignificant elevation in leukemia of all cell types combined (SMR = 139, 95%CI = 92–201) and a borderline significant increase in other lymphatic tissue cancer (SMR = 158, 95%CI = 101–235). The elevation in leukemia was confined to workers hired before 1950. Furthermore, the leukemia excess was shown to have peaked during the 1960s, with mortality no longer elevated post-1980. Analyses of cell type-specific leukemias showed a similar temporal pattern for acute myeloid leukemia (AML) which was not significantly elevated (SMR = 136, 95%CI = 59–268). Mortality from other leukemia cell types was similar to or lower than expected. Mortality from non-Hodgkin's lymphoma (NHL) (SMR = 140, 95%CI = 88–211) and multiple myeloma (MM) (SMR = 121, 95%CI = 55–230) were increased, but neither was statistically significant nor likely to be related to refinery employment. No death from asbestosis was reported, and mortality from mesothelioma and pulmonary fibrosis was lower than expected. Lung cancer mortality for the overall cohort was similar to expected. For the overall cohort, analyses by duration of employment and time since first employment showed no evidence of any trends for increasing cause-specific mortality. Separate analyses of male workers employed in operator jobs showed mortality patterns that were more favorable than those of the total cohort. Maintenance craftworkers showed statistically significant elevations in mortality for prostate cancer (SMR = 145, 95%CI = 107–194), leukemia (SMR = 179, 95%CI = 111–273), and other lymphatic tissue cancer (SMR = 233, 95%CI = 138–368). Detailed analyses indicated that, among maintenance craftworkers, mortality was elevated for AML, NHL, and MM, but none was significant. Furthermore, no upward trend by duration of maintenance jobs was observed. A small increase of lung cancer was observed among maintenance craftworkers (SMR = 120, 95%CI = 99–145), which was borderline significant. No relationship between lung cancer and duration of maintenance employment was found. In contrast, a deficit of pulmonary fibrosis was reported among maintenance craftworkers (SMR = 62, 95%CI = 17–159). These findings are discussed in conjunction with results from other refinery studies, and the limitations of the study are discussed. Am. J. Ind. Med. 33:61–81, 1998. © 1998 Wiley-Liss, Inc.     

The Drake Health Registry Study: cause-specific mortality experience of workers potentially exposed to beta-naphthylamine

OBJECTIVE: To examine the cause-specific mortality experience of an occupational cohort with probable past exposure to beta-naphythylamine (BNA). METHODS: Subjects were 374 male and 26 female workers employed at a Pennsylvania chemical plant that produced or used beta-naphthylamine (BNA) between 1940 and 1981. Vital status through 1998 was determined for 97.5% of the cohort and cause of death for 100% of 79 deaths. Limited industrial hygiene data and reports from former employees were used to categorize workers as high, medium, or low risk for BNA exposure. Statistical analyses included US and local county-based standardized mortality ratios (SMRs). RESULTS: We observed statistically significantly elevated county rate-based SMRs for all causes combined (SMR = 1.98, 95% confidence interval (CI) = 1.56-2.49), all malignant neoplasms combined (28 deaths, SMR = 3.08, 95% CI = 2.05-4.46), respiratory system cancer (12 deaths, SMR = 3.91, 95% CI = 2.02-6.83), and bladder cancer (four deaths, SMR = 16.83, 95% CI = 4.59-43.1). Three bladder cancer cases were classified as high risk (SMR = 26.79, 95% CI = 5.53-78.29). Mortality risks were also elevated for most other malignant and non-malignant cause of death categories examined. CONCLUSIONS: Bladder cancer risk remains highly elevated among Drake/Kilsdonk workers and appears to be causally related to past BNA exposure. While lifestyle and behavioral risk factors may explain some of the mortality excesses for non-urological cancers, the possibility remains that BNA exposure may have also played a role in these and other observed cancer excesses.     

Lung cancer risk among refractory brick workers exposed to crystalline silica: a retrospective cohort study.

We conducted a retrospective cohort study among 1,022 refractory brick workers exposed to crystalline silica. Mortality from lung cancer (SMR = 1.77) and respiratory diseases (SMR = 3.15) was elevated in workers first employed less than or equal to 1957 who are likely to have shared the highest exposure to crystalline silica. Workers with at least 19 years of cumulative employment in the plant experienced particularly increased risks for lung cancer (SMR = 2.01) and respiratory diseases (SMR = 3.89). Relative mortality from these specific causes increased with years since first employment (that is, first exposure) and decreased with age at first employment. Indirect adjustment for smoking habits and the lack of excess mortality from cardiovascular diseases and emphysema indicated little effect of smoking on the increased risks for lung cancer and respiratory diseases.     

Asthma mortality in male workers of the dye industry in Korea

Workers in the dye industry are exposed to various chemicals, of which reactive dye is a well-known occupational asthmagen. This study examined the relationship between asthma mortality and occupational exposure in the dye industry. The cohort comprised 66,089 male workers, including 904 workers in the dye industry, who underwent medical examinations from 1995 to 2003 at a medical service institute located in Incheon, Korea. Deaths were also observed during the 1995 to 2003 period. The mortality was analyzed using the standardized mortality ratio (SMR) compared to the Korean general population, and the mortalities from asthma in dye manufacturing workers and other workers were compared using the standardized rate ratio (SRR). The all-cause mortality in dye industry workers was significantly lower than in the general population (SMR=0.40, 95% CI 0.24-0.63), while the asthma mortality (SMR=9.03, 95% CI 1.86-26.39) was significantly higher. Deaths from non-malignant respiratory diseases were higher in dye industry workers, but were not statistically significant (SMR=2.0, 95% CI 0.41-5.86). In the internal comparison, the all-cause mortality was the same in both groups, while the mortalities from non-malignant respiratory diseases (SRR=6.04, 95% CI 4.00-9.44) and asthma (SRR=23.29, 95% CI 11.05-58.83) were higher in dye industry workers than in workers in other industries. Because asthma is a life-threatening disease, special consideration and preventive measures must be taken for workers in the dye industry.     

Mortality of a cohort of U.S. workers employed in the crushed stone industry, 1940-1980

The mortality of 3,246 males who had been employed 1 or more years during 1940-1980 at 20 crushed stone operations was evaluated for possible association between employment and death from lung cancer, pneumoconiosis, and other respiratory diseases. Four deaths were attributed to pneumoconiosis. Based on available work histories, at least two of these deaths were probably due to dust exposures in the crushed stone industry. Mortality attributed to pneumoconiosis and other nonmalignant respiratory diseases, including chronic obstructive lung disease, was significantly increased overall (SMR: 1.98; 95%CI: 1.21-3.05), and especially so for a subcohort of crushed stone workers that processed granite (SMR: 7.26; 95%CI: 1.97-18.59). With regard to lung cancer, overall SMRs were elevated (although not statistically significant). Analyzed by rock type, there was a significantly elevated lung cancer SMR among granite workers with at least 20 years latency (SMR: 3.35; 95%CI: 1.34-6.90). Although not definitive, results of this study are consistent with the hypothesis that exposure to respirable silica dust is a risk factor for lung cancer.     

Cancer mortality in a cohort of male German iron foundry workers

BACKGROUND: Observations of an increased incidence of cancers of the upper aero-digestive tract (pharynx, esophagus, larynx, lung) among workers of local German foundries gave rise to concern about a potentially elevated occupational risk of those cancer sites. The purpose of the study was to examine whether occupational exposure in iron foundries increases the risk of cancer. METHODS: A historical cohort study of 17,708 male German production workers in 37 iron foundries who were first employed in 1950-1985 with a minimum employment period of 1 year was initiated. Employment and occupational histories were collected. Mortality was compared with that of the German general population during 1950-1993 using a new method for computing the SMR when not all causes of death are available (called SMR*). RESULTS: Mortality from all causes was elevated to SMR = 115.4 (95% confidence interval (CI) = 111.9-119.1), as was for total cancer (SMR* = 123.8, CI = 102.1-152.6), especially cancers of the lung (SMR* = 163.9, CI = 123.9-223.0) and liver (SMR* = 322.5, CI = 149.5-844.8), and diseases of the respiratory system (SMR* = 147.6, CI = 100.4-221.5). Non-significant elevations of mortality were also found for cancers of the mouth and pharynx (SMR* = 153.5, CI = 82.3-359.8) and larynx (SMR* = 173.1, CI = 85.5-550.5). Mortality from various causes of death was higher among workers with shorter exposure periods than among long-term employees. The elevated mortality persisted for years and decades after termination of employment. CONCLUSIONS: The results provide further evidence for an increased risk of lung cancer and possibly other cancers of the upper aero-digestive tract among foundry workers. Special attention should be paid to the strongly increased mortality from liver cancer and the mortality pattern among employees having terminated work.     

Respiratory mortality among firefighters

Although firefighters have been shown in some studies to suffer chronic respiratory morbidity from their occupational exposures, an increased risk for dying from non-malignant respiratory diseases has not been documented in any previous retrospective cohort mortality study. In order to assess the possibility that an unusually strong "healthy worker effect" among firefighters might mask this increased risk, a mortality analysis of firefighters was carried out in three cities in relation to the United States population and also to a comparison cohort of police officers. The firefighters were employed between 1945 and 1980 and experienced 886 deaths by 1 January 1984; compared with the United States population they had a significantly reduced risk of dying from all causes (SMR = 82, 95% confidence interval, 77-87), and from non-malignant circulatory diseases (SMR = 81, 95% confidence interval 73-89), but no significant difference in risk of non-malignant respiratory diseases (SMR = 88, 95% confidence interval 66-117). Compared with police, the firefighters experienced a trend toward improved mortality outcomes for all causes investigated (SMR = 82), but they had an excess of deaths from non-malignant respiratory diseases (SMR = 141). The results indicate that firefighters are probably at increased risk for dying from non-malignant respiratory diseases; this increased risk may have been missed in previous studies because of the limitations of using a general reference population.     

Respiratory mortality among firefighters.

Although firefighters have been shown in some studies to suffer chronic respiratory morbidity from their occupational exposures, an increased risk for dying from non-malignant respiratory diseases has not been documented in any previous retrospective cohort mortality study. In order to assess the possibility that an unusually strong "healthy worker effect" among firefighters might mask this increased risk, a mortality analysis of firefighters was carried out in three cities in relation to the United States population and also to a comparison cohort of police officers. The firefighters were employed between 1945 and 1980 and experienced 886 deaths by 1 January 1984; compared with the United States population they had a significantly reduced risk of dying from all causes (SMR = 82, 95% confidence interval, 77-87), and from non-malignant circulatory diseases (SMR = 81, 95% confidence interval 73-89), but no significant difference in risk of non-malignant respiratory diseases (SMR = 88, 95% confidence interval 66-117). Compared with police, the firefighters experienced a trend toward improved mortality outcomes for all causes investigated (SMR = 82), but they had an excess of deaths from non-malignant respiratory diseases (SMR = 141). The results indicate that firefighters are probably at increased risk for dying from non-malignant respiratory diseases; this increased risk may have been missed in previous studies because of the limitations of using a general reference population.     

Cohort mortality study of Swedish pulp and paper mill workers-nonmalignant diseases

OBJECTIVES: The aim of this study was to determine mortality among pulp and paper mill workers according to the main mill pulping process, department, and gender, particular reference being given to diseases of the circulatory and respiratory systems. METHODS: The cohort of 18 163 men and 2 291 women employed between 1939 and 1999 and with >1 year of employment was followed for mortality from 1952 to 2001 (acute myocardial infarction from 1969). Standardized mortality ratios (SMR) with 95% confidence intervals (95% CI) were estimated by comparing the observed number of deaths with the expected number for the entire Swedish population. Exposure was assessed from personnel files in the mills. Data from an exposure measurement database are also presented. RESULTS: There were 5898 deaths in the cohort. Total mortality had an SMR of 1.02 (95% CI 0.98-1.06) for the men in the sulfate mills and an SMR of 0.93 (95% CI 0.90-0.97) for the men in the sulfite mills. Mortality from acute myocardial infarction was increased among the men in both the sulfate and sulfite mills [SMR 1.22 (95% CI 1.12-1.32) and SMR 1.11 (95% CI 1.02-1.21), respectively] and by department in sulfate pulping (SMR 1.29, 95% CI 1.07-1.54), paper production (SMR 1.26, 95% CI 1.06-1.49), and maintenance (SMR 1.16, 95% CI 1.02-1.30). Mortality from cerebrovascular disease, diabetes mellitus, and nonmalignant respiratory diseases was not increased. CONCLUSIONS: Death from acute myocardial infarction, but not cerebrovascular diseases, was increased in this cohort and was probably related to a combination of different occupational exposures (eg, dust, sulfur compounds, shift work, and noise).