Mortality of United Kingdom oil refinery and petroleum distribution workers, 1951-1998

The mortality experienced by cohorts of 28 630 oil refinery workers and 16 480 petroleum distribution workers has been investigated. Study subjects were all those male employees first employed in the period 1946-1974 at one of eight UK oil refineries or at one of 476 UK petroleum distribution centres; all subjects had a minimum of 12 months employment with some employment after 1 January 1951. The observed numbers of cause-specific deaths were compared with expectations based on national mortality rates. The resultant standardized mortality ratios (SMRs) were significantly below 100 for all causes, in both oil refinery workers (observed, 9341; expected, 10 649.7; SMR = 88) and petroleum distribution workers (observed, 6083; expected, 6460.3; SMR = 94). Significantly elevated SMRs were shown in oil refinery workers for cancer of the gall bladder (observed, 24; expected, 14.0; SMR = 172), cancer of the pleura (observed, 38; expected, 15.0; SMR = 254) and melanoma (observed, 36; expected, 22.2; SMR = 162). Significantly elevated SMRs were not found in petroleum distribution workers for any site of cancer. SMRs for selected causes of death were calculated by period from commencing employment, by year of hire and by job type. The only findings that suggested the presence of an occupational cancer hazard were an excess of mesothelioma in oil refinery workers and an excess of leukaemia in petroleum distribution workers, both excesses occurring in long-term follow-up for workers first employed >30 years ago.     

Mortality of workers at a nickel carbonyl refinery, 1958-2000

Background: Excess risks of respiratory cancer have been shown in some groups of nickel exposed workers. It is clear, however, that not all forms of nickel exposure are implicated in these excess risks.

Aim: To determine whether occupational exposures received in a modern nickel carbonyl refinery lead to increased risks of cancer, in particular nasal cancer and lung cancer.

Methods: The mortality experienced by a cohort of 812 workers employed at a nickel refinery was investigated. Study subjects were all male workforce employees first employed in the period 1953–92 who had at least five years' employment with the company. Observed numbers of cause specific deaths were compared with expectations based on national mortality rates; SMRs were also calculated by period from commencing employment, year of commencing employment, and type of work.

Results: Overall, standardised mortality ratios (SMRs) were close to 100 for all causes (Obs 191, SMR 96, 95% CI 83 to 111), all neoplasms (Obs 63, SMR 104, 95% CI 80 to 133), non-malignant diseases of the respiratory system (Obs 18, SMR 97, 95% CI 57 to 153), and diseases of the circulatory system (Obs 85, SMR 94, 95% CI 75 to 116). There were no significantly increased SMRs for any site of cancer. There was a non-significant excess for lung cancer (Obs 28, Exp 20.17, SMR 139, 95% CI 92 to 201), and in subgroup analyses a significantly increased SMR of 231 (Obs 9) was found for those 142 workers with at least five years' employment in the feed handling and nickel extraction departments. In the total cohort there was a single death from nasal cancer (Exp 0.10).

Conclusions: The non-significant excess of lung cancer deaths may well be a chance finding, but in light of previous studies some role for nickel exposures cannot be excluded.

     

Mortality of UK oil refinery and petroleum distribution workers, 1951-2003

BACKGROUND: The health of UK petroleum industry workers has been monitored for many years. AIM: To identify any long-term adverse health outcomes from occupational exposures in this industry. METHODS: The mortality (1951-2003) and cancer morbidity (1971-2003) experienced by cohorts of 28,555 oil refinery workers and 16,477 petroleum distribution workers has been investigated. Study subjects were all those males first employed in the period 1946-74 at one of eight UK oil refineries or 476 UK petroleum distribution centres; all subjects had a minimum of 12 months employment with some employment after 1 January 1951. Observed numbers of cause-specific deaths and site-specific cancer registrations were compared with expectations based on national mortality and cancer incidence rates. RESULTS: Standardized mortality ratios (SMRs) were significantly <100 for all causes both in oil refinery workers (Obs 11,156, SMR 89) and in petroleum distribution workers (Obs 7320, SMR 96). Significantly elevated SMRs were shown in oil refinery workers for cancer of the pleura (mesothelioma) (Obs 64, SMR 261) and melanoma (Obs 48, SMR 168). Significantly elevated SMRs were not found in petroleum distribution workers for any site of cancer. Significantly elevated standardized registration ratios (SRRs) were only shown in oil refinery workers and for cancer of the pleura (mesothelioma) (Obs 115, SMR 274), melanoma (Obs 85, SMR 129) and other skin cancer (Obs 983, SRR 117). CONCLUSIONS: The only findings that showed clear evidence of an occupational cancer hazard were those for mesothelioma in oil refinery workers.     

A cohort mortality and cancer incidence survey of recent entrants (1982-91) to the UK rubber industry: findings for 1983-2004

AIM: To monitor the occurrence of cancer in a recently defined cohort of UK rubber workers. METHODS: A cohort of 8651 male and female workers from 41 UK 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 and cancer incidence data for the period 1983-2004 were compared with expected values based on appropriate national rates. RESULTS: Mortality from lung cancer was close to expectation for males [observed 22, standardized mortality ratio (SMR) 93] and females (observed 2, SMR 70). Mortality from stomach cancer was also unexceptional in males (observed 4, SMR 86) and females (observed 0, SMR 0). Although based on small numbers, significantly elevated mortality was shown for multiple myeloma in males (observed 5, SMR 385) and females (observed 2, SMR 952). All seven of these latter deaths occurred in workers from the general rubber goods (GRG) sector. CONCLUSIONS: The findings should be treated with caution as they relate to a relatively early period of follow-up. Nevertheless, they hold out the prospect that the elevated SMRs for stomach and lung cancers reported for historical cohorts of UK rubber workers will not be present in more recent cohorts. The elevated occurrence of multiple myeloma may represent no more than a chance finding. Alternatively, these findings may reflect the presence of an unrecognized occupational cancer hazard in parts of the GRG sector of the UK rubber industry.     

A mortality cohort study of seamen in Italy.

A total of 2,208 male subjects, enrolled as merchant marine seamen at the Civitavecchia (Italy) harbor from 1936 to 1975 were followed up through 1989 in order to evaluate their mortality experience. Available information about the number of sailings made it possible to divide subjects into two subgroups: 948 workers with at least one sailing (cohort A) and 1,260 with no reported sailing (cohort B). Fewer than expected overall deaths were observed in both cohorts (cohort A: SMR = 0.83; cohort B: SMR = 0.81), mainly due to a lower mortality from circulatory, respiratory, and digestive diseases. Lung cancer deaths were significantly increased in cohort A (O = 30, SMR = 1.71, 95% CI = 1.15-2.44), whereas no excess was observed in cohort B (O = 6, SMR = 0.57, 95% CI = 0.21-1.26). Among subjects employed aboard ship, a trend in SMRs for lung cancer increasing with duration of employment was observed. Furthermore, three neoplasms of other parts of the respiratory system (including one mesothelioma) were detected in cohort A (SMR = 5.87), and one in cohort B. The study substantiates an increased risk of respiratory cancer among subjects with an occupational history of sailing; past exposure to asbestos and to other environmental carcinogens aboard could be implicated.     

Mortality among a cohort of United Kingdom steel foundry workers with special reference to cancers of the stomach and lung, 1946-90.

OBJECTIVE--The aim was to describe cause specific mortality among steel foundry workers and to determine if any part of the experience may be due to occupation. DESIGN--Historical prospective cohort study. SETTING--Nine steel foundries in England and one in Scotland. SUBJECTS--10,438 male production employees first employed in the period 1946-65 and with a minimum period of employment of one year. MAIN OUTCOME MEASURES--Observed and expected numbers of deaths for the period 1946-90. RESULTS--Compared with the general population of England and Wales, standardised mortality ratios (SMRs) for all causes and all neoplasms were 115 (observed deaths (Obs) 3976) and 119 (Obs 1129) respectively. Statistically significant excesses were found for cancer of the stomach (Obs 124, expected deaths (Exp) 92.5, SMR 134, 95% confidence interval (95% CI) 111-160) and cancer of the lung (Obs 551, Exp 378.3, SMR 146, 95% CI 134-158). A raised SMR (153) was also found for non-malignant diseases of the respiratory system. Classifications of jobs attracting either higher dust or higher fume exposures did not usefully predict these increased SMRs. Poisson regression was used to investigate risks of mortality from all cancers, cancer of the stomach, cancer of the lung, and non-malignant diseases of the respiratory system associated with duration of employment in the foundry area, the fettling shop, the foundry area/fettling shop, and the industry in general. Monotonic dose-response relations were not found, although there were positive trends for lung cancer and employment in the foundry area/fettling shop (1.0, 1.21, 1.44, 1.26) and for diseases of the respiratory system and employment in the fettling shop (1.0, 1.37, 1.18, 1.35). CONCLUSIONS--Confident interpretation of the causes of the raised SMRs was not possible. There was limited evidence of an occupational role in the excesses of lung cancer and diseases of the respiratory system. Smoking history was shown, in an indirect way, to be an unlikely explanation.     

Mortality among aircraft manufacturing workers

OBJECTIVES: To evaluate the risk of cancer and other diseases among workers engaged in aircraft manufacturing and potentially exposed to compounds containing chromate, trichloroethylene (TCE), perchloroethylene (PCE), and mixed solvents. METHODS: A retrospective cohort mortality study was conducted of workers employed for at least 1 year at a large aircraft manufacturing facility in California on or after 1 January 1960. The mortality experience of these workers was determined by examination of national, state, and company records to the end of 1996. Standardised mortality ratios (SMRs) were evaluated comparing the observed numbers of deaths among workers with those expected in the general population adjusting for age, sex, race, and calendar year. The SMRs for 40 cause of death categories were computed for the total cohort and for subgroups defined by sex, race, position in the factory, work duration, year of first employment, latency, and broad occupational groups. Factory job titles were classified as to likely use of chemicals, and internal Poisson regression analyses were used to compute mortality risk ratios for categories of years of exposure to chromate, TCE, PCE, and mixed solvents, with unexposed factory workers serving as referents. RESULTS: The study cohort comprised 77,965 workers who accrued nearly 1.9 million person-years of follow up (mean 24.2 years). Mortality follow up, estimated as 99% complete, showed that 20,236 workers had died by 31 December 1996, with cause of death obtained for 98%. Workers experienced low overall mortality (all causes of death SMR 0.83) and low cancer mortality (SMR 0.90). No significant increases in risk were found for any of the 40 specific cause of death categories, whereas for several causes the numbers of deaths were significantly below expectation. Analyses by occupational group and specific job titles showed no remarkable mortality patterns. Factory workers estimated to have been routinely exposed to chromate were not at increased risk of total cancer (SMR 0.93) or of lung cancer (SMR 1.02). Workers routinely exposed to TCE, PCE, or a mixture of solvents also were not at increased risk of total cancer (SMRs 0.86, 1.07, and 0.89, respectively), and the numbers of deaths for specific cancer sites were close to expected values. Slight to moderately increased rates of non-Hodgkin''s lymphoma were found among workers exposed to TCE or PCE, but none was significant. A significant increase in testicular cancer was found among those with exposure to mixed solvents, but the excess was based on only six deaths and could not be linked to any particular solvent or job activity. Internal cohort analyses showed no significant trends of increased risk for any cancer with increasing years of exposure to chromate or solvents. CONCLUSIONS: The results from this large scale cohort study of workers followed up for over 3 decades provide no clear evidence that occupational exposures at the aircraft manufacturing factory resulted in increases in the risk of death from cancer or other diseases. Our findings support previous studies of aircraft workers in which cancer risks were generally at or below expected levels.       

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.     

Mortality among workers in an Italian cigarette factory

A cohort study was conducted to evaluate the mortality pattern among female and male workers in a cigarette factory. The study followed 972 female workers and 761 male workers with at least 6 months of cumulative employment from 1 January 1962 through 1 July 1996. Among women, mortality from all causes of death [standardized mortality ratio (SMR) = 0.9; 95% confidence interval (CI) = 0.8-1.1] and mortality from all malignant neoplasms (SMR = 1.1; CI = 0.9-1.3) were consistent with reference rates. Male workers had a significantly reduced overall mortality (SMR = 0.8; CI = 0.7-0.9), while mortality from all malignant neoplasms was as expected (SMR = 0.9; CI = 0.7-1.0). Among female workers the frequencies of deaths from diseases of nervous system (SMR = 2.0; CI = 1.1-3.4) and from non-Hodgkin's lymphoma (NHL) (SMR = 2.7; CI = 1.0-5.6) were elevated at a statistically significant level. No association between duration of employment and diseases of nervous system was observed. A higher risk for NHL, based on three deaths, was reported among female workers with 15 or more years of employment (SMR = 8.1; CI = 2.2-21.0). Although based on small numbers, the excess of NHL here reported suggests that potential exposure to foliar residues of pesticides should be thoroughly considered in tobacco manufacturing.     

Cancer mortality among women in the Russian printing industry.

BACKGROUND: This study evaluates cancer mortality among women employed in two large printing plants in Moscow. METHODS: A total of 3,473 women who were actively employed as of December 31, 1978, with a minimum of 2 years employment were followed from 1 January 1979 to 31 December 1993. There were 47,791 person-years observed, with only 51 women lost to follow-up (1.5%). Standardized mortality ratios (SMRs) were calculated using the population of Moscow to generate expected numbers. Analyses by job (compositors, press operators, and bookbinders), age hired, latency, and duration of employment were conducted. RESULTS: Among women employed in the two printing plants, there was a significant excess of esophageal cancer, based on seven deaths (expected = 2.7, SMR = 2.7, 95% CI = 1.1-5.4). Four of the seven esophageal cancer deaths occurred among bookbinders (expected = 1.0, SMR = 4.1, 95% CI = 1.1-10.4), all among workers hired before 1957 (expected = 0.6, SMR = 7.1, 95% CI = 1.9-18.3), the last year benzene was used in bookbinding. Ovarian cancer was also significantly elevated among bookbinders (12 observed, 4.2 expected, SMR = 2.9, 95% CI = 1.5-5.0), which, along with one death from mesothelioma of the abdomen, might be related to the use of asbestos-contaminated talc fillers in paper. Press operators had significantly elevated mortality from stomach cancer (observed = 9, expected = 4.1, SMR = 2.2, 95% CI = 1.0-4.2) and, based on two deaths each, melanoma and bladder cancer. CONCLUSIONS: Women in this printing industry cohort experienced excess mortality of cancer of the esophagus and stomach, with suggested increases of melanoma and bladder cancer. Further follow-up of this cohort, which would allow more in-depth analysis of rare cancer sites, latency, and duration of employment, is warranted. Gender comparisons within the cohort should also be conducted to clarify the role of occupational and lifestyle factors in the etiology of cancer among workers in the printing industry.     

Cancer incidence and cancer mortality in a cohort of UK semiconductor workers, 1970-2002

OBJECTIVE: To examine cancer risks in a cohort of workers employed in the manufacture of semiconductors. METHODS: The mortality (1970-2002) and cancer morbidity (1971-2001) experienced by a cohort of 1807 male and female workforce employees from a semiconductor factory in the West Midlands (UK) have been investigated. Standardized mortality ratios (SMRs) and standardized registration ratios (SRRs) were used to assess mortality and morbidity, respectively. RESULTS: Overall mortality was close to expectation in males [SMR 99, 95% (confidence interval) CI 79-122] and significantly below expectation in females (SMR 74, 95% CI 65-85). Incidence of all sites of cancer was somewhat elevated in males (SRR 130, 95% CI 95-173) but close to expectation in females (SRR 94, 95% CI 82-109). There were significant deficits of deaths from cancer of the oesophagus in males and females combined and from cancer of the breast in females. Significantly elevated SRRs were found in males for cancer of the rectum [Observed (Obs) 6, SRR 284, 95% CI 104-619], in females for cancer of the pancreas (Obs 10, SRR 226, 95% CI 108-415) and malignant melanoma (Obs 11, SRR 221, 95% CI 110-396) and in males and females combined for cancer of the rectum (Obs 19, SRR 199, 95% CI 120-310) and malignant melanoma (Obs 12, SRR 217, 95% CI 112-379). Detailed work history data were unavailable for analysis. The finding of excess morbidity was not mirrored in the corresponding mortality findings. CONCLUSIONS: The study found elevated morbidity for a number of cancer sites that may be unconnected with occupation. Elimination of all possible occupational causes will, however, require more detailed analyses of cancer risks in relation to exposure histories.     

Cohorte des travailleurs du nucléaire à Électricité de France : mortalité des agents statutaires sur la période 1968–2003

BackgroundWe conducted a mortality study on a cohort of French nuclear workers employed at Électricité de France (EDF). A first cancer mortality analysis had covered the period 1968–1994. This paper presents results from a mortality analysis including nine additional years of follow-up to cover workers employed from 1968 to 2003.MethodsThe cohort includes 22 393 workers, 97% of whom are males. Employment data were updated using the EDF personnel file. Vital status was ascertained using the French National Registry of Population, and further completed using EDF personnel and pension files. Causes of death were obtained from the National registry of causes of death. Standardised Mortality Ratios (SMR) were computed using national rates as references. Variations of all causes and all cancers SMRs were studied according to demographic and occupational characteristics.ResultsAt the study end point (31/12/2003), 74% of workers are still in active employment. Only 0.3% of workers are lost to follow-up. The median duration of follow-up is 20 years. Causes are ascertained for 96% of deaths. The total number of deaths is 874, 307 of which are cancer deaths. SMRs for all causes and cancers show a significant deficit compared to the French national mortality. No significant excess was observed for any of the cancer sites studied. Non-significant excesses are observed for pancreatic, pleural, kidney and brain cancer. Significant variations of all causes SMRs according to age at study entry and attained age are observed. Significant variations of all causes and all cancers SMRs according to diploma at employment are observed, with a reduced SMR for a higher level of diploma.ConclusionThere is a significant deficit of mortality compared to the general population, reflecting a strong Healthy Worker Effect. Although nine years of follow-up were added, this cohort is made up of young workers, most of whom are still in active service. Regular updating of the follow up of this cohort is planned, aiming for an occupational health surveillance of workers occupationally exposed to ionizing radiation in France.     

Mortality among workers at the Savannah River Site

BACKGROUND: Workers employed at the Savannah River Site (SRS) were potentially exposed to a range of chemical and physical hazards, many of which are poorly characterized. We therefore compared the observed deaths among workers to expectations based upon death rates for referent populations. METHODS: The cohort included 18,883 SRS workers hired between 1950 and 1986. Vital status and cause of death information were ascertained through 2002. Sex-specific standardized mortality ratios (SMR) were computed using U.S. and South Carolina mortality rates. SMRs were tabulated separately for monthly-, weekly-, and hourly-paid men. RESULTS: Males had fewer deaths from all causes [SMR=0.80, 90% confidence interval (CI): 0.78, 0.82], all cancers (SMR=0.85, 90% CI: 0.81, 0.89), and lung cancer (SMR=0.88, 90% CI: 0.82, 0.95) than expected based upon US mortality rates. The SMR for cancer of the pleura was 4.25 (90% CI: 1.99, 7.97) for men. The SMR for leukemia was greater than unity for monthly-paid (SMR=1.33, 90% CI: 0.88, 1.93) and hourly-paid (SMR=1.36, 90% CI: 1.02, 1.78) men. Female workers had fewer deaths from all causes (SMR=0.75, 90% CI: 0.69, 0.82) than expected, but more deaths than expected from cancer of the kidney (SMR=2.58, 90% CI: 1.21, 4.84) and skin (SMR=3.90, 90% CI: 2.11, 6.61). CONCLUSIONS: While the observed numbers of deaths in most categories of cause of death were less than expected, there are greater than expected numbers of deaths due to cancer of the pleura and leukemia, particularly among hourly-paid male workers. It is plausible that occupational hazards, including asbestos and ionizing radiation, contribute to these excesses.     

Mortality from cancer and other causes among airline cabin attendants in Germany, 1960-1997

Airline cabin attendants are exposed to several potential occupational hazards, including cosmic radiation. Little is known about the mortality pattern and cancer risk of these persons. The authors conducted a historical cohort study among cabin attendants who had been employed by two German airlines in 1953 or later. Mortality follow-up was completed through December 31, 1997. The authors computed standardized mortality ratios (SMRs) for specific causes of death using German population rates. The effect of duration of employment was evaluated with Poisson regression. The cohort included 16,014 women and 4,537 men (approximately 250,000 person-years of follow-up). Among women, the total number of deaths (n = 141) was lower than expected (SMR = 0.79, 95% confidence interval (CI): 0.67, 0.94). The SMR for all cancers (n = 44) was 0.79 (95% CI: 0.54, 1.17), and the SMR for breast cancer (n = 19) was 1.28 (95% CI: 0.72, 2.20). The SMR did not increase with duration of employment. Among men, 170 deaths were observed (SMR = 1.10, 95% CI: 0.94, 1.28). The SMR for all cancers (n = 21) was 0.71 (95% CI: 0.41, 1.18). The authors found a high number of deaths from acquired immunodeficiency syndrome (SMR = 40; 95% CI: 28.9, 55.8) and from aircraft accidents among the men. In this cohort, ionizing radiation probably contributed less to the small excess in breast cancer mortality than reproductive risk factors. Occupational causes seem not to contribute strongly to the mortality of airline cabin attendants.     

Mortality of UK electricity generation and transmission workers, 1973-2002

OBJECTIVE: To examine mortality from cancer and non-malignant causes among a large cohort of UK electricity generation and transmission workers. METHODS: The mortality experienced by a cohort of 83,923 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2002. All employees had worked for at least 6 months with some employment between 1973 and 1982. Standardized mortality ratios (SMRs) were used to assess mortality in the total cohort and in three sub-cohorts: power station workers, substation and transmission workers and workers at non-operational locations. These classifications were based on the place of work of the first known job. RESULTS: Overall mortality was significantly below that expected, based on national rates [males: observed (Obs) 18,773, expected (Exp) 22,497.9, SMR 83; females: Obs 1122, Exp 1424.9, SMR 79]. Statistically significant deficits of deaths were also found for most of the major disease groupings. However, significant excesses of deaths were found in male power station workers for cancer of the pleura (Obs 129, Exp 30.3, SMR 426) and in male workers from non-operational locations for cancer of the brain (Obs 55, Exp 36.0, SMR 153). There was also a non-significant excess of deaths from cancer of the breast in male power station workers (Obs 10, Exp 5.3, SMR 190). CONCLUSIONS: Mortality was exceptionally low for most causes of death but late health effects from earlier asbestos exposure were still in evidence.     

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.     

Historic cohort study in Montreal's fur industry

A historic cohort mortality study was carried out among two groups of male workers in the Montreal fur industry: 263 dressers and dyers and 599 fur garment manufacturers. The first group is exposed to a very wide variety of chemicals used in tanning, cleaning, and dyeing fur, including substances considered to be carcinogenic and/or mutagenic. The second group is exposed to residue from the dressing and dyeing stage and to respirable fur dust. The cohorts consisted of all active members of two unions as of January 1, 1966. The mean age of the workers was 43.2 and the mean number of years since first employment 14.1. The follow-up period was from January 1, 1966, to December 31, 1981; 95% of the workers were successfully traced. Observed deaths were compared with those expected based on mortality rates of the population of metropolitan Montreal. Standardized mortality ratios (SMRs) for the manufacturers were significantly low, probably because of the ethnic composition of the cohort and a healthy worker effect. SMRs for the dressers and dyers were also low, but not as low as for the manufacturers. When attention was restricted to the French Canadians in the cohort, the observed deaths were close to the expected; there was a noteworthy excess of colorectal cancer (four observed, 0.8 expected) for dressers and dyers. Apart from this weak suggestive evidence, the results did not indicate any excess mortality risks in the fur industry. However, because of the relatively small number of expected and observed deaths in the cohort and especially among the heavily exposed dressers and dyers, the confidence intervals around SMR estimates were wide and excess risks cannot be ruled out.     

Cancer mortality among municipal pest-control workers

Objectives: This epidemiological study was carried out in order to investigate the hypothesis of a relationship between cancer occurrence and occupational exposure in a population of municipal pest-control workers exposed to a wide range of pesticides and other chemicals. Methods: The study was designed as a mortality historical cohort study. The cohort comprised all subjects ever employed in a municipal pest-control service between 1979 and 1994. The follow-up period lasted from 1979 to 2000. The mortality rates of pest-control workers were compared with those of a regional population. A job exposure matrix was developed, which took into account four types of chemicals: formaldehyde, ethylene oxide, insecticides and rodenticides. Results: None of the 181 subjects of the cohort, leading to 3,107 person-years, was lost to follow-up. Thirty-nine of them died, and all the causes of deaths were ascertained. The standardized mortality ratios (SMRs) for all causes of deaths and for all cancer causes were significantly greater than unity: 1.61 (1.14–2.20) and 2.24 (1.39–3.43), respectively. Non-significant excesses were observed for most cancer sites, except for lung cancer, which had a low SMR. We obtained significant excesses for cancer in workers with more than 20 years of employment [SMR=2.42 (1.43–3.82)]. Cancer mortality tended to increase insignificantly with formaldehyde and rodenticides exposures, whereas no clear patterns were observed for ethylene oxide and insecticides. However, significant excesses were observed for the highest exposure levels of formaldehyde, insecticides and rodenticides. Conclusions: This study showed a statistically significant excess of cancer mortality in a population of municipal pest-control workers exposed to a wide variety of chemicals. These cancer sites might be related to occupational activities, since they tended to be more frequently observed when duration of employment increased.     

Cancer mortality in German carbon black workers 1976-98

Background

Few studies have investigated cancer risks in carbon black workers and the findings were inconclusive.

Methods

The current study explores the mortality of a cohort of 1535 male German blue‐collar workers employed at a carbon black manufacturing plant for at least one year between 1960 and 1998. Vital status and causes of death were assessed for the period 1976–98. Occupational histories and information on smoking were abstracted from company records. Standardised mortality ratios (SMR) and Poisson regression models were calculated.

Results

The SMRs for all cause mortality (observed deaths (obs) 332, SMR 120, 95% CI 108 to 134), and mortality from lung cancer (obs 50, SMR 218, 95% CI 161 to 287) were increased using national rates as reference. Comparisons to regional rates from the federal state gave SMRs of 120 (95% CI 107 to 133) and 183 (95% CI 136 to 241), respectively. However, there was no apparent dose response relationship between lung cancer mortality and several indicators of occupational exposure, including years of employment and carbon black exposure.

Conclusions

The mortality from lung cancer among German carbon black workers was increased. The high lung cancer SMR can not fully be explained by selection, smoking, or other occupational risk factors, but the results also provide little evidence for an effect of carbon black exposure.     

A cohort mortality study of U.K. carbon black workers, 1951-1996

BACKGROUND: Carbon black, a powdered form of elemental carbon is used in the manufacture of rubber products, paints, plastics, and inks. In 1974, the Health and Safety Executive initiated a cohort mortality study on possible carcinogenic effects on carbon black workers. METHODS: The mortality of a cohort of 1,147 male manual workers from five U.K. factories manufacturing carbon black was investigated for the period 1951-1996. All subjects were employed in the carbon black industry for 12 months or more, and all were first employed before 1975. Limited work histories were used to calculate estimates of individual cumulative exposure to carbon black, using a job-exposure matrix derived by the study team. RESULTS: Based on serial rates for the general population of England and Wales, significantly elevated mortality was observed in the main study cohort for all causes (Obs 372, Exp 328.7, SMR 113, P < 0.05) and for lung cancer (Obs 61, Exp 35.3, SMR 173, P < 0.001). There were highly elevated lung cancer SMRs at two of the factories, and unexceptional SMRs at the remaining three factories. There was no indication of lung cancer SMRs increasing with period from first employment. Poisson regression analyses failed to find significant trends of lung cancer risks increasing either with cumulative exposure to carbon black (4 levels) or with duration of employment at the participating factories (4 levels). CONCLUSIONS: Confident interpretation of the elevated SMRs found for lung cancer in two of the factory subcohorts is not possible but the study has been unable to link cumulative exposure to carbon black with elevated risks of lung cancer.