Epidemiologic study of workers exposed to vinyl chloride in Porto Marghera: mortality update

The investigation describes mortality of vinyl chloride exposed workers in the Montedison-Enichem plant located in Porto Marghera, near Venice, Italy. A total of 1658 workers employed from start of production (1950), present in 1956 or successively hired until 1985, were followed up between 01.01.1973 and 31.07.1999, for a total of 41.037 person years at risk: 248 deaths were observed. Mortality from all causes compared with regional population was lower than expected, (SMR 0.75; 90% CI 0.68-0.83) and from all malignant neoplasms similar to expected (SMR 0.94; 90% CI 0.81-1.09). SMR for primary liver cancer was significantly increased (SMR 2.78 90% CI 1.86-4.14). In the first year since leaving employment observed mortality was significantly above the null value for all causes (SMR 2.76; 90% CI 1.94-3.91), all malignant neoplasms (SMR 1.89; 90% CI 0.97-3.92) and cardiovascular diseases (SMR 2.37; 90% CI 1.13-4.95). Mortality rates for liver angiosarcoma (6 cases) increased with latency (trend test x 2 (1df) = 25.20 p < 0.001) and cumulative exposure (trend test x 2 (1df) = 61.00 p < 0.001), there were no cases with duration of employment less than 12 years, latency less than 10 years and for cumulative exposure less than 2.379 ppm-years. Mortality rates for hepatocellular carcinoma (12 cases) and liver cirrhosis (20 cases) showed a similar pattern for cumulative exposure. Observed mortality from lung cancer was higher than expected among those workers whose only job title was bagger. In the analysis accounting for latency, age and calendar period the RR for only bagger was 2.31 (90% CI 1.15-4.61). Mortality pattern for all causes, all malignancies and cardiovascular disease increased by time since employment, as expected in presence of a particularly strong Healthy Worker Effect (HWE). These results and the increased SMR values during the first year since leaving employment indicate that workers were selected into employment on the basis of good health conditions and early selective removal of weaker ones followed. The study results confirm the causal relationship between VCM exposure and liver angiosarcoma, and add supplementary evidence in favour of a causal explanation of the excess risk for hepatocellular carcinoma and liver cirrhosis as well as lung cancer among only baggers.     

Mortality experience of employees exposed to 2-mercaptobenzothiazole at a chemical plant in Nitro, West Virginia.

Mortality trends for 1059 production workers at a rubber chemicals plant in Nitro, West Virginia were examined to find whether they had increased mortality from cancer associated with exposure to 2-mercaptobenzothiazole (MBT). This chemical and its derivatives are vulcanising agents that have been manufactured at the plant since 1935. Analyses were conducted on MBT exposed employees by cumulative exposure and time since first exposure, and were also stratified by past assignment to p-aminobiphenyl (PAB) related departments; PAB is a potent bladder carcinogen that was used at the plant between 1935 and 1955. There was an excess of bladder cancer in MBT workers who had PAB related assignments (standardised mortality ratio (SMR) = 3200, 95% confidence interval (95% CI) 1286-6593). In employees without a job assignment with exposure to PAB, there were no associations between exposure to MBT and increased rates of most malignant neoplasms. The SMR for bladder cancer was increased based on three deaths (SMR = 455, 95% CI 94-1328), although these results were too few to evaluate trends by cumulative exposure category. The possibility of confounding by PAB for exposures for jobs that covered all areas of the plant for these three cases must be considered in the light of the potency of PAB as a bladder carcinogen. There were no deaths from bladder cancer among MBT workers hired after the end of manufacture and use of PAB, but the expected number of deaths was only 0.03.     

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.     

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 study on cancer mortality among workers in the pulp and paper industry in Catalonia,Spain

We examined mortality in a retrospective follow-up study of 3,241 workers employed between 1970–1992, in four pulp and paper mills in Catalonia, Spain. Vital status was determined for 95% of the cohort. Exposure was reconstructed using job histories and a company exposure questionnaire. Standardized mortality ratios (SMR) were derived using mortality rates of Spain as the reference. For all workers, mortality from all causes (SMR = 76; 95%; confidence intervals [CI] = 65–88; 189 deaths) and all malignant neoplasms (SMR = 93; CI = 72–119; 65 deaths) were less than the expected. Excess risk was observed for mortality from all neoplasms in females (SMR = 168; CI 84–303; 11 deaths), for large intestine cancer in both sexes (SMR = 250; CI = 115–525; 8 deaths), particularly after 10 years of employment and latency (SMR = 355; CI = 154–701; 8 deaths), and for breast cancer in females (SMR = 286; CI = 77–732; 4 deaths). These findings suggest that workers employed in the pulp and paper industry may have an excess risk of specific cancers. © 1996 Wiley-Liss, Inc.     

Cause-specific mortality in the unionized U.S. trucking industry

BACKGROUND: Occupational and population-based studies have related exposure to fine particulate air pollution, and specifically particulate matter from vehicle exhausts, to cardiovascular diseases and lung cancer. OBJECTIVES: We have established a large retrospective cohort to assess mortality in the unionized U.S. trucking industry. To provide insight into mortality patterns associated with job-specific exposures, we examined rates of cause-specific mortality compared with the general U.S. population. METHODS: We used records from four national trucking companies to identify 54,319 male employees employed in 1985. Cause-specific mortality was assessed through 2000 using the National Death Index. Expected numbers of all and cause-specific deaths were calculated stratifying by race, 10-year age group, and calendar period using U.S. national reference rates. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were calculated for the entire cohort and by job title. RESULTS: As expected in a working population, we found a deficit in overall and all-cancer mortality, likely due to the healthy worker effect. In contrast, compared with the general U.S. population, we observed elevated rates for lung cancer, ischemic heart disease, and transport-related accidents. Lung cancer rates were elevated among all drivers (SMR = 1.10; 95% CI, 1.02-1.19) and dockworkers (SMR = 1.10; 95% CI, 0.94-1.30); ischemic heart disease was also elevated among these groups of workers [drivers, SMR = 1.49 (95% CI, 1.40-1.59); dockworkers, SMR = 1.32 (95% CI, 1.15-1.52)], as well as among shop workers (SMR = 1.34; 95% CI, 1.05-1.72). CONCLUSIONS: In this detailed assessment of specific job categories in the U.S. trucking industry, we found an excess of mortality due to lung cancer and ischemic heart disease, particularly among drivers.     

Mortality in New Zealand workers exposed to phenoxy herbicides and dioxins

Aims: To evaluate mortality in New Zealand phenoxy herbicide producers and sprayers exposed to dioxins. Methods: Phenoxy herbicide producers (n = 1025) and sprayers (n = 703) were followed up from 1 January 1969 and 1 January 1973 respectively to 31 December 2000. A total of 813 producers and 699 sprayers were classified as exposed to dioxin and phenoxy herbicides. Standardised mortality ratios (SMR) were calculated using national mortality rates. Results: At the end of follow up, 164 producers and 91 sprayers had died. Cancer mortality was reduced for sprayers (SMR = 0.82, 95% CI 0.57 to 1.14) and increased in exposed production workers (SMR = 1.24, 95% CI 0.90 to 1.67), especially for synthesis workers (SMR = 1.69), formulation and lab workers (SMR = 1.64), and maintenance/waste treatment/cleaning workers (SMR = 1.46). Lymphohaematopoietic cancer mortality was increased in exposed production workers (SMR = 1.65, 95% CI 0.53 to 3.85), especially for multiple myeloma (SMR = 5.51, 95% CI 1.14 to 16.1). Among sprayers, colon cancer (SMR = 1.94, 95% CI 0.84 to 3.83) showed increased mortality. Conclusions: Results showed 24% non-significant excess cancer mortality in phenoxy herbicide producers, with a significant excess for multiple myeloma. Associations were stronger for those exposed to multiple agents including dioxin during production. Overall cancer mortality was not increased for producers and sprayers mainly handling final technical products, although they were likely to have been exposed to TCDD levels far higher than those currently in the general New Zealand population.     

Mortality among pulp and paper workers in Berlin, New Hampshire

Cause specific mortality was analysed among 883 white male workers from a paper company in Berlin, New Hampshire. Subjects were assigned to different exposure groups on the basis of their having worked in the pulp mill, the paper mill, or elsewhere in the paper company. A standardised mortality ratio (SMR) analysis was used to compare death rates for each of the exposure groups with United States national rates. For all the subjects, deaths due to all causes, all malignant neoplasms, and lung cancer were close to the number expected and excesses were noted for cancers of the digestive system and leukaemia. Among pulp mill workers, the number of cancers of the digestive system was raised and the SMR for pancreatic cancer was especially high (SMR = 305, 95% CI = 98-712). Among paper mill workers, more deaths were due to leukaemia and cancers of the digestive system than expected. These results are consistent with the findings from other studies that employment in pulp and paper mills is associated with excess mortality due to digestive and lymphopoietic cancers.     

Mortality among pulp and paper workers in Berlin, New Hampshire.

Cause specific mortality was analysed among 883 white male workers from a paper company in Berlin, New Hampshire. Subjects were assigned to different exposure groups on the basis of their having worked in the pulp mill, the paper mill, or elsewhere in the paper company. A standardised mortality ratio (SMR) analysis was used to compare death rates for each of the exposure groups with United States national rates. For all the subjects, deaths due to all causes, all malignant neoplasms, and lung cancer were close to the number expected and excesses were noted for cancers of the digestive system and leukaemia. Among pulp mill workers, the number of cancers of the digestive system was raised and the SMR for pancreatic cancer was especially high (SMR = 305, 95% CI = 98-712). Among paper mill workers, more deaths were due to leukaemia and cancers of the digestive system than expected. These results are consistent with the findings from other studies that employment in pulp and paper mills is associated with excess mortality due to digestive and lymphopoietic cancers.     

Cause specific mortality and cancer incidence among employees exposed to 2,3,7,8-TCDD after a 1953 reactor accident.

OBJECTIVE: To evaluate the long term health consequences of past occupational exposure to 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). METHODS: Cancer incidence and cause specific mortality were examined up to and including 1992 in a group of 243 men with external comparisons and internal dose-response analyses. Model based estimates of TCDD dose (expressed in micrograms/kg body weight) were developed for all cohort members with an approach that incorporated detailed accounts of each employee's work activities, analyses of TCDD in blood lipid of 138 employees, and internally derived estimates of elimination rates of TCDD. RESULTS: The estimated dose of TCDD for 135 men was > or = 0.1 microgram/kg body weight and for 69 men > or = 1 microgram/kg body weight. Increased cancer risk ratios were found with higher doses of TCDD and longer interval since first exposure for all sites combined and digestive and respiratory cancers in particular. Within the high dose group (> or = 1 microgram/kg body weight), total cancer mortality was increased > or = 20 years after first exposure (13 cases, standardised mortality ratio (SMR) 1.97, 95% confidence interval (95% CI) 1.05-3.36) as was respiratory cancer (six cases, SMR 3.06; 95% CI 1.12-6.66). Among current cigarette smokers, 12 cancer deaths occurred in the high dose group (SMR 3.42, 95% CI 1.77-5.97) compared with seven deaths at lower doses of TCDD (SMR 1.29, 95% CI 0.52-2.66). Regression analyses based on the Cox's proportional hazards model provided further evidence of a relation between cumulative dose of TCDD and occurrence of both overall and digestive cancer. No evidence of an effect of TCDD on overall mortality or deaths due to circulatory disease was found and no cases of non-Hodgkin's lymphoma or soft tissue sarcoma have been found to date. CONCLUSIONS: Our findings are consistent with a carcinogenic effect induced by TCDD at doses > or = 1 microgram/kg body weight. With such a small cohort, the risk estimates are not very stable and could be affected by selection and confounding.     

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.     

Cause of death among workers of a refinery in Rome]

We evaluated mortality among subjects employed in an oil refinery plant in Rome, Italy. We studied two subgroups of refinery employees: blue collar and white collar workers. A total of 682 men (505 blue collars, 148 white collars, 29 unknown) employed between 1965 and 1992, were followed up for mortality since employment in the plant to July 1999. Standardized Mortality Ratios (SMR), and their 90% Confidence Intervals (90% CI), comparing mortality rates of the cohort members with those of the general population of the Lazio region. For blue collar workers, we performed analyses by latency since first employment and by duration of employment for selected cancer sites. We observed 94 total deaths (100.8 expected) (SMR = 0.93; 90% CI = 0.78-1.11) among blue collar workers and 16 total deaths (31.7 expected) (SMR = 0.50; 90% CI = 0.32-0.77) among white collar workers, and a large deficit of deaths from non-neoplastic cardiovascular diseases (respectively SMR = 0.60; 90% CI = 0.41-0.86 and SMR = 0.18; 90% CI = 0.03-0.56). All cancer mortality was slightly increased only in blue collars (SMR = 1.27 CI = 0.97-1.65). There was an excess risk from cancer of the lung (20 obs SMR = 1.80, 90% CI = 1.19-2.62), bladder (5 obs SMR = 3.19, 90% CI = 1.26-6.72), and benign/unspecified cancer of the brain (4 obs SMR = 4.11, 90% CI = 1.12-10.6). The lower mortality from cardiovascular disease indicates the presence of a strong healthy worker effect. The findings of elevated mortality from cancer of the lung and bladder in blue collar workers are in agreement with those of other studies. Confounding factors from cigarette smoking might have played only a marginal role in influencing the results. Exposure to polynuclear aromatic hydrocarbons (PAHs) is a plausible explanation for the excesses found.     

Mortality of workers exposed to methylene chloride employed at a plant producing cellulose triacetate film base.

OBJECTIVE: To study mortality among 1785 employees of a factory that produced cellulose triacetate film base at Brantham in the United Kingdom. Also, to investigate patterns of mortality after exposure to methylene chloride; in particular, mortality from liver and biliary tract cancer, lung cancer, pancreatic cancer, and cardiovascular disease. SUBJECTS AND METHODS: All male employees with a record of employment at the film factory in 1946-88. A total of 1473 subjects worked in jobs that entailed exposure to methylene chloride. The mean duration of exposure was nine years at 19 ppm (eight hour time weighted average). RESULTS: In the cohort, 334 deaths were identified up to 31 December 1994. Mortalities for the cohort were compared with national and local rates and expressed as standardised mortality ratios (SMR). In the subcohort of workers exposed to methylene chloride, substantially reduced mortalities compared with national and local rates were found for all causes, all cancers, and the principal cancer sites of interest. The significantly reduced lung cancer mortalities in exposed workers (SMR 48) seemed to reflect the restrictions on smoking at the workplace. In contrast, mortality from ischaemic heart disease in exposed workers, although lower than national rates (SMR 92), was slightly increased compared with local rates. However, mortality from ischaemic heart disease was lower in active employees (SMR 83) where a direct effect of exposure to methylene chloride should be concentrated. No in service mortality due to ischaemic heart disease was found in workers with the highest cumulative exposure (> or = 800 ppm-years). CONCLUSIONS: The study provided no indication that employment at the plant, or exposure to methylene chloride, had adversely affected the mortalities of workers.     

Cancer mortality in an Italian rubber factory.

The purpose of the study was to describe the mortality experience of an Italian cohort of rubber workers and an attempt was made to identify any occupational cancer hazards that might currently be affecting men employed in this type of work. A total of 4917 male workers who first started working in a large rubber factory between 1962 and 1972 have been followed up until 31 January 1983. The number of deaths from all causes and from malignant neoplasms was determined and compared with the expected number of deaths calculated from mortality rates for the province in which the population of the plant lived. Mortality from all causes was 85% of that expected. A slight overall excess of deaths from cancer (SMR = 119) was found; this was entirely due to the excess mortality in the 35-44 age group. In order further to evaluate the possible existence of a cancer risk SMRs were analysed by duration of exposure, time since first exposure, and for specific sites of cancer. A trend in SMR with duration of exposure was found for employees with 10 years of follow up or more. A high risk for some tumour sites emerged.     

Cancer mortality in an Italian rubber factory

The purpose of the study was to describe the mortality experience of an Italian cohort of rubber workers and an attempt was made to identify any occupational cancer hazards that might currently be affecting men employed in this type of work. A total of 4917 male workers who first started working in a large rubber factory between 1962 and 1972 have been followed up until 31 January 1983. The number of deaths from all causes and from malignant neoplasms was determined and compared with the expected number of deaths calculated from mortality rates for the province in which the population of the plant lived. Mortality from all causes was 85% of that expected. A slight overall excess of deaths from cancer (SMR = 119) was found; this was entirely due to the excess mortality in the 35-44 age group. In order further to evaluate the possible existence of a cancer risk SMRs were analysed by duration of exposure, time since first exposure, and for specific sites of cancer. A trend in SMR with duration of exposure was found for employees with 10 years of follow up or more. A high risk for some tumour sites emerged.     

Retrospective cohort mortality study of workers at an aircraft maintenance facility. I. Epidemiological results

A retrospective cohort study of 14,457 workers at an aircraft maintenance facility was undertaken to evaluate mortality associated with exposures in their workplace. The purpose was to determine whether working with solvents, particularly trichloroethylene, posed any excess risk of mortality. The study group consisted of all civilian employees who worked for at least one year at Hill Air Force Base, Utah, between 1 January 1952 and 31 December 1956. Work histories were obtained from records at the National Personnel Records Centre, St. Louis, Missouri, and the cohort was followed up for ascertainment of vital state until 31 December 1982. Observed deaths among white people were compared with the expected number of deaths, based on the Utah white population, and adjusted for age, sex, and calendar period. Significant deficits occurred for mortality from all causes (SMR 92, 95% confidence interval (95% CI) 90-95), all malignant neoplasms (SMR 90, 95% CI 83-97), ischaemic heart disease (SMR 93, 95% CI 88-98), non-malignant respiratory disease (SMR 87, 95% CI 76-98), and accidents (SMR 61, 95% CI 52-70). Mortality was raised for multiple myeloma (MM) in white women (SMR 236, 95% CI 87-514), non-Hodgkin's lymphoma (NHL) in white women (SMR 212, 95% CI 102-390), and cancer of the biliary passages and liver in white men dying after 1980 (SMR 358, 95% CI 116-836). Detailed analysis of the 6929 employees occupationally exposed to trichloroethylene, the most widely used solvent at the base during the 1950s and 1960s, did not show any significant or persuasive association between several measures of exposure to trichloroethylene and any excess of cancer. Women employed in departments in which fabric cleaning and parachute repair operations were performed had more deaths than expected from MM and NHL. The inconsistent mortality patterns by sex, multiple and overlapping exposures, and small numbers made it difficult to ascribe these excesses to any particular substance. Hypothesis generating results are presented by a variety of exposures for causes of death not showing excesses in the overall cohort.     

Respiratory cancer mortality among workers employed in thermoelectric power plants

A historical cohort study of 406 workers was undertaken to evaluate the possible health hazards of employment in traditional electric power plants with particular regard to cancer mortality. The total mortality was below that expected [observed 40, standardized mortality ratio (SMR) 87] on the basis of national rates. Cancer mortality was slightly increased (SMR 112), mainly because of an excess of respiratory cancer (observed 9, SMR 171, 90% CI 89-299). Lung cancer deaths were higher than expected among those less than 60 years of age and among those with a duration of exposure and a latency period since first employment of over 10 years (observed 7, SMR 184). Furthermore, the increase was more pronounced among maintenance workers and workers in general services. Previous data indicated that there had been past exposure to some known respiratory carcinogens (ie, asbestos, polycyclic aromatic hydrocarbons). This study suggests that a possible lung cancer risk from traditional electricity generating plants should be considered and further studied.     

Mortality among three refinery/petrochemical plant cohorts. I. 1970 to 1982 active/terminated workers

This study updates mortality rates for 19,075 active and terminated workers at three refinery/petrochemical plants. Mortality rates of the workers were compared with both national and state rates. The results indicated deficits of deaths for all causes, all malignant neoplasms, and respiratory and prostate cancer. The noteworthy finding was a statistically significant increase in leukemia among Louisiana male subjects (standardized mortality ratio [SMR], 181; 95% confidence interval [CI], 122 to 259), which showed suggestive trends of increasing SMRs with increasing tenure. This excess was largely due to increased chronic lymphocytic leukemia (SMR, 351; 95% CI, 168 to 645). The rate of kidney cancer remained elevated among Louisiana male subjects, but this finding was no longer significant, and there were no patterns in SMRs by tenure and latency. Mesothelioma was increased at the Louisiana (SMR, 198; 95% CI, 72 to 430) and Texas (SMR, 246; 95% CI, 99 to 507) locations. The leukemia findings have prompted a study of leukemia incidence at the Louisiana location.     

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.     

Retrospective cohort mortality study of workers at an aircraft maintenance facility. I. Epidemiological results.

A retrospective cohort study of 14,457 workers at an aircraft maintenance facility was undertaken to evaluate mortality associated with exposures in their workplace. The purpose was to determine whether working with solvents, particularly trichloroethylene, posed any excess risk of mortality. The study group consisted of all civilian employees who worked for at least one year at Hill Air Force Base, Utah, between 1 January 1952 and 31 December 1956. Work histories were obtained from records at the National Personnel Records Centre, St. Louis, Missouri, and the cohort was followed up for ascertainment of vital state until 31 December 1982. Observed deaths among white people were compared with the expected number of deaths, based on the Utah white population, and adjusted for age, sex, and calendar period. Significant deficits occurred for mortality from all causes (SMR 92, 95% confidence interval (95% CI) 90-95), all malignant neoplasms (SMR 90, 95% CI 83-97), ischaemic heart disease (SMR 93, 95% CI 88-98), non-malignant respiratory disease (SMR 87, 95% CI 76-98), and accidents (SMR 61, 95% CI 52-70). Mortality was raised for multiple myeloma (MM) in white women (SMR 236, 95% CI 87-514), non-Hodgkin's lymphoma (NHL) in white women (SMR 212, 95% CI 102-390), and cancer of the biliary passages and liver in white men dying after 1980 (SMR 358, 95% CI 116-836). Detailed analysis of the 6929 employees occupationally exposed to trichloroethylene, the most widely used solvent at the base during the 1950s and 1960s, did not show any significant or persuasive association between several measures of exposure to trichloroethylene and any excess of cancer. Women employed in departments in which fabric cleaning and parachute repair operations were performed had more deaths than expected from MM and NHL. The inconsistent mortality patterns by sex, multiple and overlapping exposures, and small numbers made it difficult to ascribe these excesses to any particular substance. Hypothesis generating results are presented by a variety of exposures for causes of death not showing excesses in the overall cohort.