Mortality in employees of a Scottish paper mill

To assess possible health risks associated with the manufacture of paper, we carried out a retrospective analysis of mortality among 4,242 men and women employed at a Scottish paper mill between 1955 and 1992. During follow-up to 1994, 959 subjects had died giving an SMR of 0.85 (95% CI 0.80–0.90) in comparison with the national population. Mortality from all cancer (SMR 0.77, 95% CI 0.68–0.88) and particularly from lung cancer (SMR 0.64, 95% CI 0.50–0.81) was lower than expected. An excess of lymphatic and hematopoietic cancer (11 deaths, SMR 2.17) was observed in the making department. These findings do not support an occupational hazard of lung cancer as suggested by several earlier studies. The excess of lymphatic and hematopoietic cancer in the making department was unexpected, and may be a chance occurrence. Am. J. Ind. Med. 32:535–539, 1997. © 1997 Wiley-Liss, Inc.     

Mortality and incidence of cancer in a cohort of Swedish chimney sweeps: an extended follow up study.

Despite 200 years of efforts to regulate safety in this occupation, chimney sweeps have increased mortality from cancer, ischaemic heart disease, and respiratory disease. Mortality and incidence of cancer were examined in a cohort of 5542 Swedish chimney sweeps employed through their national trade union at any time between 1918 and 1980. Previous studies of this cohort found increased risks of ischaemic heart disease, respiratory disease, accidental deaths, and various neoplasms. By increasing follow up, we sought to increase the power of the study and examine disease time trends. Mortality analysis was extended 7.5 years to cover the period 1951-90; cancer incidence analysis was extended six years to cover the period 1958-87. New findings include increased incidence and mortality of prostate cancer (SMR 169, 95% CI 106-256, 22 observed) and increased incidence of total haematolymphatic cancers (SIR 151, 95% CI 106-209, 36 observed). When only the most recent follow up period was analysed, previously observed risks persisted for total lung cancer (SIR 178, 95% CI 99-293), oat cell lung cancer (SIR 240, 95% CI 103-472), bladder cancer (SIR 247, 95% CI 131-422), and oesophageal cancer (Obs/Exp = 2/1.1). Mortality from ischaemic heart disease (SMR 98, 95% CI 76-123) and respiratory disease (SMR 111, 95% CI 56-199) declined during recent follow up, although significant excess mortality remained during analysis of the entire study period (ischaemic heart disease SMR 128, 95% CI 112-145; respiratory disease SMR 159, 95% CI 115-213). In analyses of the entire study period, risks of ischaemic heart disease and lung, bladder, and oesophageal cancer were adjusted for smoking; oesophageal cancer was also adjusted for use of alcohol. All risks remained significantly raised. Exposure-response analyses showed significant positive associations between duration of employment and risks for mortality from lung, oesophageal, and total cancer. Chimney sweeps remain at increased risk for cancers of the lung, oesophagus, and bladder. Our study supports a casual role for exposure to chimney soot, which contains carcinogens including polycyclic aromatic hydrocarbons. Extended follow up of this cohort now shows increased risks of prostate and haematolymphatic cancers.     

Mortality study in an asbestos cement factory in Naples, Italy

The objective of this paper is to investigate mortality among 1247 male asbestos-cement workers employed in an asbestos-cement plant located in Naples. The cohort included 1247 men hired between 1950 and 1986. The follow-up began on January 1st 1965. The vital status and causes of death were ascertained up to December 31 2005. Cause-specific mortality rates of the Campania Region population were used as reference. Relative risks were estimated using Standardized Mortality Ratios (SMRs), and the confidence intervals were calculated at a 95% level (95% CI). A significant increase in mortality was observed for respiratory disease (81 deaths; SMR = 187; 95% CI = 149- 233), particularly for pneumoconiosis (42 deaths; SMR = 13 313; 95% CI = 9595-17 996) of which 41 deaths for asbestosis (SMR = 43 385; 95% CI = 31 134-58 857), for pleural cancer (24 deaths; SMR = 2617; 95% CI = 1677-3893), for lung cancer (84 deaths; SMR=153; 95% CI = 122-189) and for peritoneal cancer (9 deaths; SMR = 1985; 95% CI = 908-3769). Non-significant increases were also observed for rectum cancer (6 deaths; SMR = 157; 95% CI = 58-342). In conclusion, consistently with other mortality studies on asbestos-cement workers performed in different countries, an increased mortality from asbestosis, lung cancer, pleural and peritoneal mesothelioma was detected in the present cohort.     

Mortality among workers exposed to polychlorinated biphenyls (PCBs) in an electrical capacitor manufacturing plant in Indiana: an update

An Indiana capacitor-manufacturing cohort (n=3,569) was exposed to polychlorinated biphenyls (PCBs) from 1957 to 1977. The original study of mortality through 1984 found excess melanoma and brain cancer; other studies of PCB-exposed individuals have found excess non-Hodgkin lymphoma and rectal, liver, biliary tract, and gallbladder cancer. Mortality was updated through 1998. Analyses have included standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) using rates for Indiana and the United States, standardized rate ratios (SRRs), and Poisson regression rate ratios (RRs). Estimated cumulative exposure calculations used a new job-exposure matrix. Mortality overall was reduced (547 deaths; SMR, 0.81; 95% CI, 0.7-0.9). Non-Hodgkin lymphoma mortality was elevated (9 deaths; SMR, 1.23; 95% CI, 0.6-2.3). Melanoma remained in excess (9 deaths; SMR, 2.43; 95% CI, 1.1-4.6), especially in the lowest tertile of estimated cumulative exposure (5 deaths; SMR, 3.72; 95% CI, 1.2-8.7). Seven of the 12 brain cancer deaths (SMR, 1.91; 95% CI, 1.0-3.3) occurred after the original study. Brain cancer mortality increased with exposure (in the highest tertile, 5 deaths; SMR, 2.71; 95% CI, 0.9-6.3); the SRR dose-response trend was significant (p=0.016). Among those working >or= 90 days, both melanoma (8 deaths; SMR, 2.66; 95% CI, 1.1-5.2) and brain cancer (11 deaths; SMR, 2.12; 95% CI, 1.1-3.8) were elevated, especially for women: melanoma, 3 deaths (SMR, 5.99; 95% CI, 1.2-17.5); brain cancer, 3 deaths (SMR, 2.87; 95% CI, 0.6-8.4). These findings of excess melanoma and brain cancer mortality confirm results of the original study. Melanoma mortality was not associated with estimated cumulative exposure. Brain cancer mortality did not demonstrate a clear dose-response relationship with estimated cumulative exposure.     

Cancer mortality among magazine printing workers.

OBJECTIVE: After an inquiry from the employees of an offset printing plant, a historical cohort study was conducted to investigate cancer mortality among these workers. METHODS: The cohort comprised 262 men, who contributed 2771 person-years of observation. 16 deaths were identified during the follow up period (1980-91). Expected numbers of deaths were derived from age specific regional rates. Standardised mortality ratios (SMR) and 95% confidence intervals (95% CIs) were calculated. RESULTS: An increased cancer mortality was found after 10 years of employment (SMR 213, 95% CI 98 to 405, based on nine deaths), mainly due to a high mortality from lung cancer (SMR 381, 95% CI 104 to 975, four deaths), and from oesophageal cancer (SMR 1049, 95% CI 216 to 3065, three deaths). For workers with at least 20 years since the start of employment, the SMR was 262 (95% CI 105 to 540) for all cancer sites, 447 (95% CI 92 to 1306) for lung cancer, and 1094 (95% CI 132 to 3952) for oesophageal cancer. The increased cancer mortality was concentrated among pressmen. CONCLUSION: Although based on small numbers, the findings suggest an increased risk of cancer among these workers, which should be further investigated.     

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).     

Mortality among taxi drivers in Rome: A cohort study

The mortality pattern of taxi drivers in Rome as possibly exposed mainly to gasoline engine exhausts was evaluated by means of a historical cohort study. A total of 2,311 male subjects registered as taxi drivers between 1950 and 1975 was followed from 1965 through 1988. The overall mortality was lower than expected on the basis of regional (Latium) reference rates (692 deaths, standardized mortality ratio [SMR] = 0.89, 95% confidence interval [CI] 0.82–0.96), whereas the number of recorded deaths for malignant neoplasms was about the expected (205 deaths, SMR = 0.99, 95% CI 0.86–1.13). Mortality from circulatory and respiratory diseases was lower than expected. Diabetes was significantly increased (42 deaths, SMR = 1.73, 95% CI = 1.25–2.34). An increased SMR appeared for respiratory cancer (SMR = 1.23, 95% CI = 0.98–1.50), mainly due to lung cancer (observed [O] = 76, SMR = 1.23, 95% CI = 0.97–1.54); two pleural cancers were also recorded. The excess of lung cancer deaths was present only among those enrolled in the most recent period (1965–1975) (45 deaths, SMR = 1.40, 95% CI = 1.02–1.87), especially among those of younger age (<65 years) (SMR = 1.86); there was no relation between lung cancer mortality and latency since first enrollment in the cooperatives or duration of membership. There are difficulties in interpreting the excess of lung cancer on the basis of occupational exposures; however, the increased risk observed among workers employed in more recent calendar periods may be due to heavier exposure in the last decades; further follow-up of the cohort may elucidate whether there is an increasing lung cancer risk among taxi drivers. © 1994 Wiley-Liss, Inc.     

Health findings from a mortality and morbidity surveillance of refinery employees

PURPOSE: To present results from a prospective mortality (1973-1998) and morbidity (1990-1998) surveillance of a refinery population in California. METHODS: Mortality and illness-absence data were extracted from the Shell Oil Company's Health Surveillance System (HSS). Mortality data were compared to the United States, the state of California, and Contra Costa County, where the refinery is located. Morbidity data were compared to other company manufacturing employees. The standardized mortality/morbidity ratio (SMR/SMbR) was used as a measure of risk. Morbidity frequency and duration of absence were calculated by age, sex, and four health risk factors (smoking, high blood pressure, hypercholesterolemia, and obesity). RESULTS: With the United States as a comparison, the all causes combined SMR was 0.84 [95% confidence interval (CI) = 0.78-0.90], and the SMR for all cancer was 0.75 (95% CI = 0.64-0.88). Statistically significant deficits in mortality were found for lung cancer (SMR = 0.60) and leukemia (SMR = 0.26). Morbidity frequency and duration of absence among smokers were substantially higher than those of nonsmokers. Similar results were also noted for obese employees when compared to those of normal weight. CONCLUSIONS: Regardless of the comparison population, significantly fewer deaths were seen for all causes combined, all cancer, lung cancer, and leukemia. The study also showed no increased mortality from cancer of the stomach, kidney, skin, prostate, and brain. The increased morbidity frequency and duration of absence were associated with the presence of known health risk factors. These study findings are useful in setting priorities for medical programs and directing efforts such as health promotion and disease prevention strategies.     

Mortality of workers exposed to toluene diisocyanate in the polyurethane foam industry.

OBJECTIVE: To evaluate cancer mortality among United States workers exposed to toluene diisocyanate (TDI) in the manufacture of polyurethane foam. METHODS: This cohort mortality study included 4611 men and women employed in four polyurethane foam plants for at least three months between the late 1950s and 1987. The mortality experience of the cohort was then compared with that of the general United States population. RESULTS: Current and past industrial hygiene data indicated that air concentrations in 1984-5 were below the current United States standard of 0.04 mg/m3 but exceeded the standard before 1980. Mortality ratio (SMR) 2.78, 95% confidence interval (95% CI) 0.57-8.13) and non-Hodgkin's lymphoma (SMR 1.54, 95% CI 0.42-3.95) were increased, but not significantly. There was one male breast cancer. However, breast cancer was not increased in women (SMR 0.74). No other cancer category had an increased number of deaths compared with the general population. Only non-Hodgkin's lymphoma and Hodgkin's disease showed a possible relation with time since first employment and no cancer death category showed a strong relation with duration of employment. Mortality from non-malignant respiratory disease was not increased (SMR 0.86). CONCLUSIONS: This young cohort has few deaths and short follow up. The findings are therefore not conclusive. Further years of follow up will enable better evaluation of mortality.     

Mortality of a cohort of men in a silicosis register: further evidence of an association with lung cancer

Lung cancer mortality from 1980 to 1986 was studied in a cohort of 1,419 men in a silicosis register who had no previous exposure to asbestos and polyaromatic hydrocarbons. The 28 deaths from lung cancer were statistically in excess of expected (SMR 2.03; 95% CI 1.35-2.93). Excess risks of lung cancer were found in both underground workers (SMR 3.41; 95% CI 1.10-7.97; based on 5 deaths) and surface workers (SMR 1.87, 95% CI 1.18-2.81; based on 23 deaths). All lung cancer deaths were smokers. There was an increase in SMRs with longer latency periods and years of exposure, with the greatest risk found in those who had worked for 30 or more years after more than 30 years since first exposed (SMR 3.07, based on 16 deaths). The risk for lung cancer was higher in those with tuberculosis (SMR 2.52; 95% CI 1.52-3.94) and showed an increasing trend with severity of silicosis, from category 1 to 3 and from category A to C, with highest risk in those with tuberculosis and category 3 (SMR 4.44 based on 3 deaths) or tuberculosis and category C (SMR 7.63 based on 7 deaths). Most of the excess lung cancer risk in silicotics is due to smoking, but a synergistic effect between smoking and silica/silicosis on the risk of lung cancer is also likely. In particular, a possible role of silicosis and tuberculosis as the fibrotic seedbed for malignant growth in the lung is strongly supported.     

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 Sardinian lead and zinc miners: 1960-88.

The mortality of 4740 male workers of two lead and zinc mines was followed up from 1960 to 1988. Exposure to respirable dust was comparable in the two mines, but the median concentration of silica in respirable dust was 10-fold higher in mine B (12.8%) than in mine A (1.2%), but the mean annual exposure to radon daughters in underground workplaces differed in the opposite direction (mine A: 0.13 working levels (WL), mine B: 0.011 WL). Total observed deaths (1205) were similar to expected figures (1156.3) over a total of 119 390.5 person-years at risk. Underground workers of mine B had significant increases in risk of pulmonary tuberculosis (SMR 706, 95% confidence interval (95% CI) 473-1014) and non-malignant respiratory diseases (SMR 518; 95% CI 440-1606), whereas the only significant excess at mine A was for non-malignant respiratory diseases (SMR 246; 95% CI 191-312). Total cancer and lung cancer mortality did not exceed the expectation in the two mines combined. A 15% excess mortality for lung cancer, increased up to an SMR 204 (95% CI 89-470) for subjects employed > or = 26 years, was, however, found among underground workers in mine A who on the average experienced an exposure to radon daughters 10-fold higher than those of mine B. By contrast, despite their higher exposure to silica, mine B underground workers experienced a lower than expected lung cancer mortality. A ninefold increase in risk of peritoneal and retroperitoneal cancer combined was also found among underground workers of mine A (SMR 917; 95% CI 250-2347; based on four deaths). A causal association with workplace exposures is unlikely, however, as the SMR showed an inverse trend by duration of employment. These findings are consistent with low level exposure to radon daughters as a risk factor for lung cancer among metal miners. Exposure to silica at the levels estimated for the mine B underground environment did not increase the risk of lung cancer.     

A study of mortality among 14,730 male workers in 12 Norwegian ferroalloy plants: cohort characteristics and the main causes of death.

OBJECTIVES: Concern about the health hazards of exposure to workers in the ferroalloy industry has initiated this historical cohort study. The aim was to examine the mortality pattern among male employees in 12 Norwegian ferroalloy plants. METHODS: All men employed for at least six months who started their first employment during 1933-91 were eligible for the cohort. Deaths observed during 1962-90 were compared with expected figures calculated from national mortalities. Internal comparisons of rates were performed by Poisson regression analysis. The final cohort comprised 14,730 male employees who were observed for 288,886 person-years. RESULTS: Mortality from all causes of death was slightly increased (3390 deaths, standardised mortality ratio (SMR) 1.08, 95% confidence interval (95% CI) 1.04-1.11). Regression analysis of total mortality showed a significant negative trend for the rate ratios with increasing duration of employment. An increased mortality was found among employees in urban plants compared with employees in rural plants (rate ratio (RR) 1.21, 95% CI 1.13-1.29). Excess deaths from cancer (SMR 1.11) and sudden death (SMR 1.47) were found among employees with at least three years of employment. Mortality from accidents, poisonings, and violence was increased among all employees (SMR 1.28). Excess deaths from this cause were however only found for the time after the end of employment in this industry and not during employment (SMR 0.90). CONCLUSIONS: The increased mortality from cancer and sudden death could be related to work exposures, at least in subgroups, and these results warrant further studies. The excess deaths from accidents, poisonings, and violence were probably not related to work exposures. The mortality results for short term workers and other information indicate that systematic errors contribute to the increased overall mortality.     

Cohort mortality and cancer incidence survey of recent entrants (1982-91) to the United Kingdom rubber industry: preliminary findings

OBJECTIVES—To monitor the occurrence of stomach and lung cancer in a newly defined cohort of United Kingdom rubber workers and to report findings for other cancers in an early period of follow up.
METHODS—A prospective cohort of 9031 male and female workers from 42 United Kingdom rubber factories has been enumerated. All employees had a minimum of 12 months employment and were first employed at one of the participating factories in the period 1982-91. Mortality data were available for the period 1983-98 and cancer registration data for the period 1983-94. The mortality and cancer incidence experienced by the cohort were compared with expected values based on national rates defined by period, age, and sex.
RESULTS—Mortality from lung cancer was close to expectation (men: observed (obs) 11, expected (exp) 12.70, standardised mortality ratio (SMR) 87, 95% confidence interval (95% CI) 43 to 155; women: obs 0, exp 1.34, SMR 0, 95% CI 0 to 275). Mortality from stomach cancer was unexceptional (men: obs 1, exp 2.69, SMR 37, 95% CI 1 to 207; women: obs 0, exp 0.24, SMR 0, 95% CI 0 to 1537). Many statistical comparisons were made both for mortality data and for cancer registration data; only one difference between observed and expected numbers was significant (mortality from cancer of the testis: obs 3 exp 0.51, SMR 589, 95% CI 122 to 1722). Corresponding findings for incident cancers of the testis were unexceptional (obs 5, exp 5.13, standardised registration ratio (SRR) 97, 95% CI 32 to 227).
CONCLUSION—The findings should be treated with caution as they relate to an early period of follow up. Nevertheless, they hold out the prospect that the increased SMRs for stomach and lung cancers reported for historical cohorts of United Kingdom rubber workers may not be apparent in more recent cohorts.


Keywords: rubber workers; lung cancer; stomach cancer; cohort study     

Cancer mortality study of employees at lead battery plants and lead smelters, 1947-1995

BACKGROUND: This study has examined cancer mortality of a cohort of male U.S. workers exposed to lead. METHODS: The cohort consisted of 4,518 workers at lead battery plants and 2,300 at lead smelters. Vital status was ascertained between 1947 and 1995. Site-specific cancer standardized mortality ratios (SMRs) and 95% confidence intervals (95% CIs), based on the mortality rates of the U.S. male population and adjusted for age and calendar time, were calculated for the total cohort as well as subcohorts stratified by various exposure parameters. In addition, a nested case-control study of stomach cancer (30 cases and 120 age-matched controls) was also conducted. RESULTS: Mortality from all cancers was as expected (897 observed deaths, SMR = 103.8, 95% CI: 97.1-110.8). Mortality was significantly raised for stomach cancer (SMR = 147.4, 95% CI: 112. 5-189.8), lung cancer (SMR = 116.4, 95% CI: 103.9-129.9), and cancer of the thyroid and other endocrine glands (SMR = 308.0, 95% CI: 133. 0-606.8). There was a nonsignificant mortality deficit from kidney cancer (SMR = 63.6, 95% CI: 33.9-108.7). For bladder cancer, mortality was significantly lower than expected (SMR = 55.5, 95% CI: 31.7-90.1). Nonsignificant mortality deficits were also reported for cancer of the central nervous system (SMR = 74.8, 95% CI: 41.9-123. 4) and lymphatic and hematopoietic cancer (SMR = 92.2, 95% CI: 72. 4-115.7). Additional analyses by type of facility (lead battery plants vs. lead smelters), length of employment, latency, and period of hire were also performed. In the nested case-control study of stomach cancer, odds ratios were calculated for various exposure indices, and none was found to be elevated. Furthermore, no exposure-response relationship between lead exposure and stomach cancer was found in the nested case-control study. CONCLUSIONS: A significant mortality increase from stomach cancer was found. However, based on the analyses in the cohort study and the nested case-control study, the increase did not appear to be related to lead exposure. A small, but statistically significant mortality increase from lung cancer was also observed. The small increase, in the absence of an exposure-response relationship, could be the result of confounding due to smoking, and was not likely causally related to lead exposure. Although the significant increase in cancer of the thyroid and other endocrine glands appeared to be consistent with an occupational interpretation, the small number of deaths (8), the lack of information on potential confounding factors, and the lack of reporting of a similar increase in other studies underscore the need to view this finding with caution. No increased mortality was found for kidney cancer, bladder cancer, cancer of the central nervous system, or lymphatic and hematopoietic cancer.     

Upper aerodigestive cancer in battery manufacturers and steel workers exposed to mineral acid mists.

OBJECTIVE--To assess the risk of cancer from inhalation of mineral acid mists. METHODS--A cohort study and nested case-control study of upper aerodigestive tumours were carried out in men employed since 1950 at two battery plants and two steel works in Britain. The cohort was identified from personnel records and included 2678 men with definite exposure to acid mists (mainly sulphuric acid), 367 with possible exposure, and 1356 who were unexposed. Mortality was compared with that in the national population by the person-years method. Cases of upper aerodigestive cancer were identified from death certificates and cancer registrations, and their exposure to acids was compared with that of age matched controls (five per case) from the same plant by conditional logistic regression. RESULTS--In follow up to 31 December 1993, 93% of men were traced, including 1277 who had died. Among the men definitely exposed to acid mists, overall mortality was less than in the national population (standardised mortality ratio (SMR) 0.92, 95% confidence interval (95% CI) 0.85-0.98) as was mortality from all cancers (SMR 0.92, 95% CI 0.79-1.05) and specifically from cancer of the larynx (SMR 0.48, 95% CI 0.01-2.70) and lung (SMR 0.98, 95% CI 0.78-1.22). A total of 15 incident or fatal cases of upper aerodigestive cancer were identified during follow up. When these men were compared with controls, risk was moderately increased in those who had worked for at least five years in jobs entailing exposures to sulphuric or hydrochloric acid in excess of 1 mg/m3 (OR 2.0, 95% CI 0.4-10). CONCLUSIONS--These findings are consistent with those from other studies which have indicated a hazard of upper aerodigestive cancer from acid mists. However, they indicate that any risk from exposures to sulphuric and hydrochloric acid below 1 mg/m3 is small.     

Mortality in a cohort of sugar refinery workers in Arezzo Province, Italy

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate mortality of a cohort of 1,767 male workers employed in a sugar refinery plant located in the Province of Arezzo, Italy, where asbestos had been used from the 1960's for the insulation of thermohydraulic systems and for furnaces. In 1987-88 workers removed the asbestos-cement insulation from the plant. METHODS: The cohort was composed by male workers who were employed in the plant between 1 March 1962 and 1 February 1996, and had worked for at least 2 months. Follow-up started on 1 March 1962, and ended on 31 May, 2003. The population mortality for Tuscany Region was used as the reference. The relative risk was estimated by Standardized Mortality Ratio (SMR) and the confidence intervals were calculated at a 95% level (95% CI). RESULTS: The majority of workers were employed during the summer only. Significant decreases in mortality were observed for overall mortality (SMR = 78; 95% CI = 69-88), all cancers (SMR = 80; 95% CI = 65-97), cardiovascular diseases (SMR = 64; 95% CI = 50-81), lung cancer (SMR = 66; 95% CI = 43-98), and gastrointestinal diseases (SMR = 53; 95% CI = 26-98). Non-significant increases were observed for kidney cancer (SMR = 229; 95% CI = 92-472), and diseases of the nervous system (SMR = 155; 95% CI = 71-294). Kidney cancer mortality for workers employed for > = 5 years was significantly higher (SMR = 508; 95% CI = 105-1485). CONCLUSIONS: Mortality for asbestos-related diseases did not show any increase. The higher kidney cancer mortality for workers employed for > = 5 years could be due to exposures to various carcinogens, that occurred not only in the sugar refinery plant, given that the workers were seasonal and did other jobs during the rest of the year. Asbestos-related deaths could occur in the future among some workers who in 1987-88 were employed on the removal of asbestos-cement insulation from the plant.     

Mortality in Florida professional firefighters, 1972 to 1999

BACKGROUND: Exposure to occupational hazards among firefighters may lead to increased mortality from cancer, lung, or heart disease. METHODS: Age- and gender-adjusted mortality rates of 34,796 male and 2,017 female Florida professional firefighters between 1972 and 1999 were compared with the Florida general population. RESULTS: One thousand four hundred eleven male and 38 female firefighter deaths with known causes were identified. In male firefighters, mortality due to all causes and most non-malignant diseases was significantly less than expected. There was no excess overall mortality from cancer, but excesses existed for male breast cancer [standardized mortality ratio (SMR = 7.41; 95% confidence interval (CI): 1.99-18.96) and thyroid cancer (SMR = 4.82; 95% CI: 1.30-12.34)]. Mortality from bladder cancer was increased and approached statistical significance (SMR = 1.79; 95% CI: 0.98-3.00). Firefighters certified between 1972 and 1976 had excess mortality from bladder cancer (SMR = 1.95; 95% CI: 1.04-3.33). Female firefighters had similar morality patterns to Florida women except for atherosclerotic heart disease (SMR = 3.85; 95% CI: 1.66-7.58). CONCLUSIONS: Excess mortality risk from bladder cancer may be related to occupational exposure during firefighting. The thyroid cancer and breast cancer risk in males, as well as the excess risk of cardiovascular disease mortality noted in females warrant further investigation.     

Cohort study of mortality among leather tanners in the Lower Valdarno area

BACKGROUND: Epidemiological studies of tanners have shown increased risk for a number of cancer sites, namely: lung, bladder, kidney and urinary organs as well as stomach, intestine, pancreas, nose and nasal cavities, together with leukemias and soft tissue sarcomas. OBJECTIVE: To study cause specific mortality of leather tanners in Tuscany (Valdarno Inferiore area). METHODS: The cohort included 4874 workers (4150 males and 724 females) employed in 92 tanneries operating in 1996 (Valdarno Inferiore Tanneries Census) which were also operating on 31-12-1970. Ascertainment of vital status was completed for all individuals on 31-12-1998 (end of follow-up), and the cause of death was known for all deceased subjects. Demographic and work history data were obtained from factory payrolls. Regional mortality rates were used for comparison to calculate SMR (Standardised Mortality Ratio) and 90% Confidence Intervals (CI). In addition to the overall cohort analysis, for men only separate analyses were completed for finishers, chrome tanners and vegetable tanners. RESULTS: The study showed an increased mortality from lung cancer among finishers, Standardised Mortality Ratio (SMR) 145, 19 observed (obs) (90% Confidence Intervals, 90% CI 95-212), from bladder cancer in the overall cohort (SMR 134, 9 obs, 90% CI 70-233) and among finishers (SMR 125, 2 obs, 90% CI 22-393) and from pancreatic cancer among finishers (SMR 120, 2 obs, 90% CI 21-379). Mortality from lymphoemopoietic cancer is above expected, and the increase is mainly due to myeloid leukaemia, both in males (SMR 208, 5 obs, 90% CI 82-437) and females (SMR 599, 2 obs, 90% CI 106-1887). No deaths from soft tissue sarcoma were observed. A new finding of the study was the increased mortality from cancer of the endocrine glands (SMR 566, 4 obs, 90% CI 194-1297), psychiatric disorders (SMR 195, 6 obs, 90% CI 85-385) and blood diseases (SMR 329, 4 obs, IC 90% 112-752). CONCLUSIONS: The observations of increased lung cancer mortality among finishers, of bladder cancer in the overall cohort and among finishers, as well as an increase in pancreatic cancer among the latter, confirm previous epidemiological findings among tanners. The increase in myeloid leukemia mortality for both males and females, and the absence of deaths from cancer of the connective tissue, which includes soft tissue sarcomas, are worthy of note. The results should be valued with caution, given the small number of cases and the novelty of some observations.     

Mortality among firefighters from three northwestern United States cities.

To explore whether exposure among firefighters to fire smoke could lead to an increased risk of cancer, lung disease, and heart disease, the mortality of 4546 firefighters who were employed by the cities of Seattle and Tacoma, WA and Portland, OR for at least one year between 1944 and 1979 were compared with United States national mortalities and with mortality of police officers from the same cities. Between 1945 and 1989, 1169 deaths occurred in the study population and 1162 death certificates (99%) were collected. Mortality due to all causes, ischaemic heart disease, and most other non-malignant diseases was less than expected based upon United States rates for white men. There was no excess risk of overall mortality from cancer but excesses of brain tumours (standardised mortality ratio (SMR) = 2.09, 95% confidence interval (95% CI) 1.3-3.2) and lymphatic and haematopoietic cancers (SMR = 1.31, 95% CI = 0.9-1.8) were found. Younger firefighters (< 40 years of age) appeared to have an excess risk of cancer (SMR = 1.45, 95% CI 0.8-2.39), primarily due to brain cancer (SMR = 3.75, 95% CI 1.2-8.7). The risk of lymphatic and haematopoietic cancers was greatest for men with at least 30 years of exposed employment (SMR = 2.05, 95% CI 1.1-3.6), especially for leukaemia (SMR = 2.60, 95% CI 1.0-5.4).