Mortality in miners and millers of crocidolite in Western Australia.

It is known that 6505 men and 411 women were employed in the mining and milling of crocidolite at Wittenoom in the Pilbara region of Western Australia between 1943 and 1966. Employment was usually brief (median duration four months) and exposure intense (median estimated cumulative exposure 6 fibres/cc years). The vital status of 73% of the men and 58% of the women employed in the industry was known at 31 December 1980, providing 95 264 person-years of follow up with 820 deaths in men and 4914 person-years with 23 deaths in women. The standardised mortality ratio (SMR) for all causes in men was 1.53 (95% confidence interval 1.43 to 1.64). Statistically significant excess death rates were observed in men for neoplasms, particularly malignant mesothelioma (32 deaths), neoplasms of the trachea, bronchus, and lung (SMR 2.64), and neoplasms of the stomach (SMR 1.90); respiratory diseases, particularly pneumoconiosis (SMR 25.5); infections, particularly tuberculosis (SMR 4.09); mental disorders particularly alcoholism (SMR 4.87); digestive diseases, particularly peptic ulceration (SMR 2.46) and cirrhosis of the liver (SMR 3.94); and injuries and poisonings, particularly non-transport accidents (SMR 2.36). The excess mortality from pneumoconiosis, malignant mesothelioma, and respiratory cancers, but not stomach neoplasms, was dependent on time since first exposure and cumulative exposure. There was no increase in mortality from laryngeal cancer (SMR 1.09) or neoplasms other than those listed. The SMR for all causes in women was 1.47 (95% confidence interval 0.98-2.21) and for neoplasms 1.99; there was one death from malignant pleural mesothelioma.     

Mortality study of workers compensated for asbestosis in Poland, 1970-1997

The aim of the study was to assess the risk of asbestos-related malignancies among persons with diagnosed asbestosis. The study covered a cohort composed of 907 men and 490 women afflicted by asbestosis, diagnosed is 1970-1997. The follow-up of the cohort continued until 31 December 1999. In all, 421 deaths were registered and causes of death were retrieved for 93.3% of the deceased. A significantly increased mortality was observed both in the male 1300 deaths; SMR = 127; 95%CI: 113-142) and female (121 deaths, SMR = 150; 95%CI: 124-179) cohorts. The elevated number of deaths in the male and female cohorts were noted mainly due to respiratory diseases (men: 42 deaths; SMR = 344; 95%CI: 248-465; women: 20 deaths, SMR = 789; 95%CI: 482-1219) malignant neoplasms (men: 91 deaths, SMR = 146; 95%CI: 118-179; women: 34 deaths, SMR = 159; 95%CI: 110-222), including lung cancer (men: 39 deaths, SMR = 168; 95% CI: 119-230; women: 13 deaths, SMR = 621; 95%CI: 331-1062) and pleural mesothelioma (men: 3 deaths, SMR = 2680; 95%CI: 553-7832; women: 3 deaths, SMR = 7207; 95%CI: 1031-14612). Taking into account a cumulative dose of fibers, it was found that a significantly increased mortality from lung cancer and pleural mesothelioma applied to persons exposed to a dose above 25 f-y/ml. The results indicate that persons with asbestosis are at higher risk of developing malignant neoplasms, especially lung cancer and mesothelioma.     

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 and morbidity among Lithuanian asbestos-cement producing workers

OBJECTIVES: This study investigated the incidence of cancer and cause-specific mortality among workers in the two Lithuanian asbestos-cement factories. METHODS: The study included 1887 asbestos-cement workers, 1285 men and 602 women, and 37000 person-years. The two factories were active from 1956 (A) and 1963 (B), and the workers were observed from 1978 to 2000. The analysis was based on a comparison between the observed and expected numbers of cancer and causes of death. The observed numbers of cancer were obtained through linkage with the national cancer registry. The date and causes of death were obtained from two different sources. The expected numbers were calculated on the basis of gender- and age-specific incidence and mortality rates in 5-year periods from the whole country. Standardized incidence ratios (SIR) and standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were calculated. Duration of employment and time since first exposure were used as indicators of exposure. RESULTS: During the follow-up, 1978-2000. 473 deaths were observed versus 489 expected. There was no excess risk of deaths from nonmalignant respiratory diseases, except for an elevated risk of mortality in relation to the digestive organs other than cancer, 18 observed versus 12.2 expected (95% CI 0.9-2.3). There was no excess risk for any types of cancer, except for colorectal cancer in men, 17 observed cases (SIR 1.6, 95% CI 1.6-2.6) and one case of mesothelioma in a woman. CONCLUSIONS: This study on asbestos-exposed workers did not show any excess risk of respiratory cancer or deaths of pneumoconiosis.     

Mortality and exposure response among 14,458 electrical capacitor manufacturing workers exposed to polychlorinated biphenyls (PCBs)

BACKGROUND: We expanded an existing cohort of workers (n = 2,588) considered highly exposed to polychlorinated biphenyls (PCBs) at two capacitor manufacturing plants to include all workers with at least 90 days of potential PCB exposure during 1939-1977 (n = 14,458). Causes of death of a priori interest included liver and rectal cancers, previously reported for the original cohort, and non-Hodgkin lymphoma (NHL), melanoma, and breast, brain, intestine, stomach, and prostate cancers, based on other studies. METHODS: We ascertained vital status of the workers through 1998, and cumulative PCB exposure was estimated using a new job exposure matrix. Analyses employed standardized mortality ratios (SMRs; U.S., state, and county referents) and Poisson regression modeling. RESULTS: Mortality from NHL, melanoma, and rectal, breast, and brain cancers were neither in excess nor associated with cumulative exposure. Mortality was not elevated for liver cancer [21 deaths; SMR 0.89; 95% confidence interval (CI), 0.55-1.36], but increased with cumulative exposure (trend p-value = 0.071). Among men, stomach cancer mortality was elevated (24 deaths; SMR 1.53; 95% CI, 0.98-2.28) and increased with cumulative exposure (trend p-value = 0.039). Among women, intestinal cancer mortality was elevated (67 deaths; SMR 1.31; 95% CI, 1.02-1.66), especially in higher cumulative exposure categories, but without a clear trend. Prostate cancer mortality, which was not elevated (34 deaths; SMR 1.04; 95% CI, 0.72-1.45), increased with cumulative exposure (trend p-value = 0.0001). CONCLUSIONS: This study corroborates previous studies showing increased liver cancer mortality, but we cannot clearly associate rectal, stomach, and intestinal cancers with PCB exposure. This is the first PCB cohort showing a strong exposure-response relationship for prostate cancer mortality.     

Cancer mortality in rubber tire workers in Poland

The study aimed at assessing cancer risk in a cohort of workers employed in the rubber tire production. The cohort consisted of 17,747 workers (11,660 men and 6087 women) employed in a rubber tire plant for at least three months during the years 1950-1995. The cohort follow-up was completed on December 31, 1995. Deaths by causes were analyzed using standardized mortality ratio (SMR) calculated by the person-years method. The mortality pattern of the general population of Poland was used as the reference. The study indicated significantly lower total mortality in the cohort (men: SMR = 72; women: SMR = 62) as compared to the general population, which is an example of a well known "healthy worker effect". The number of deaths from malignant neoplasms was also lower than expected (men: SMR = 67; women: SMR = 64). Only in a very small sub-cohort of men involved in dosing and mixing of raw material for the production of rubber, an excess of total mortality (SMR = 104) and from all cancers (SMR = 115) was found. Mortality from all neoplasms was enhanced (SMR = 108) in the sub-cohort of women employed in the technical service work area. When analyzing individual cancer sites in men of the whole cohort or sub-cohorts, the observed number of deaths from cancers of the lip, tongue, pharynx, stomach, gallbladder, pancreas, peritoneum, articular cartilage, connective tissue, skin, testis, prostate, bladder, kidney, brain, as well as from Hodgkin's disease, multiple myeloma and leukemia was larger than the expected number. Among women the excess mortality was due to cancers of the large myeloma and leukemia. The SMR calculated for these sites were statistically insignificant. The cohort under study was "young" and thus relatively small numbers of deaths were recorded. The excess mortality, based quite frequently on single cases of selected cancer sites, cannot be regarded as a basis for final conclusions. Nevertheless, the fact that these observations are in agreement with the findings of other authors who carried out studies in the rubber industry of other countries justifies the need to follow-up this cohort in the future.     

Mortality in a cohort of asbestos cement workers in Carrara, Italy

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate the mortality of 262 workers (200 men and 62 women) employed in an asbestos cement plant located in Carrara, Italy, exposed to a mixture of chrysotile and crocidolite asbestos in a ratio of 2:5. METHODS: Follow-up started on 1 January, 1963. The vital status and causes of death were ascertained on 31 December, 2003. The Tuscany population mortality was used as reference. The relative risk was estimated by Standardized Mortality Ratio (SMR) and the confidence intervals were calculated at 95% level [95%CI]. RESULTS: Among men, a significant increase in mortality was observed for respiratory disease (14 deaths; SMR = 244.1; IC95% = 133.4-409.5), particularly for pneumoconiosis (10 deaths; SMR= 1,800; IC95% = 856.9-3,300.0; of which 5 deaths due to asbestosis; SMR = 120,000; IC95% = 37,000-270,000), and for pleural cancer (4 deaths; SMR = 2,500; IC95% = 676.8-6,400.0). Non-significant increases were also observed for lung cancer (10 deaths; SMR = 114.2; IC95% = 54.8-209.9), and gastric cancer (7 deaths; SMR= 167.1; IC95% = 67.2-344.3). Among women, significant increases were observed for pneumoconiosis (1 death; SMR = 17,000; 95%CI = 425-93,000), and for liver cancer (3 deaths; SMR = 765.0; IC95% = 157.8-2,200.0). CONCLUSIONS: For males our results were consistent with other mortality studies on asbestos-cement workers. No other cohort studies on asbestos cement workers have dealt with mortality of female workers.     

Health of vermiculite miners exposed to trace amounts of fibrous tremolite.

A small cohort of 194 men with low exposure to fibrous tremolite (mean 0.75 f/ml y) in the mining and milling of vermiculite in South Carolina experienced 51 deaths 15 years or more from first employment. The SMR (all causes) was 1.17 reflecting excess deaths from circulatory disease. There were four deaths from lung cancer and 3.31 expected (SMR 1.21, 95% CI 0.33-3.09). Three of the four deaths were in the lowest exposure category (less than 1 f/ml y); no death was attributed to mesothelioma or pneumoconiosis. These findings contrast with those in Montana where the vermiculite ore was heavily contaminated with fibrous tremolite. A radiographic survey of 86 current and recent South Carolina employees found four with small parenchymal opacities (greater than or equal to 1/0) and seven with pleural thickening. These proportions were not higher than in a non-exposed group and much lower than had been observed in Montana. Examination of sputum from 76 current employees showed that only two specimens contained typical ferruginous bodies, confirming low cumulative fibre exposure. Any possible adverse effects of work with vermiculite, minimally contaminated with fibrous or non-fibrous tremolite, were thus beyond the limits of detection in this workforce.     

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.     

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.     

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.     

Mortality experience of glass fibre workers.

A historical prospective mortality study was conducted at an insulating wool plant in Ontario, Canada, on 2576 men who had worked for at least 90 days and were employed between 1955 and 1977. Eighty eight deaths were found in the 97.2% of men traced. Mortality was compared by the person-years method with that of the Ontario population. Measurements taken since 1977 show very low fibre concentrations. The overall standardised mortality ratio (SMR) was 78%, significantly below 100. Among plant only employees, seven deaths were attributed to lung cancer compared with 4.22 expected, a non-significant excess (SMR = 166; 95% confidence limits 67 to 342). No confirmed cases of mesothelioma were observed and no other disease was significantly increased in plant workers.     

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.     

Cohort study of mortality of vermiculite miners exposed to tremolite

A cohort of 406 men employed before 1963 for at least one year in a vermiculite mine in Montana was followed up until July 1983. The vermiculite ore as fed to the mill contained 4-6% of amphibole fibre in the tremolite series. Vital status was established in all but one of the 406 and death certificates were obtained and coded for 163 of the 165 men who died. Compared with white men in the United States, the cohort experienced excess mortality from all causes (SMR 1.17), respiratory cancer (SMR 2.45), non-malignant respiratory disease (SMR 2.55), and accidents (SMR 2.14). Four deaths were from malignant mesothelioma (proportional mortality 2.4%). Compared with Montana death rates, the SMR for respiratory cancer was somewhat higher (3.03). Man-year analyses of respiratory cancer and estimated cumulative exposure gave a relation that did not depart significantly from linearity. The results of this and case-referent analyses indicate an increased risk of mortality from respiratory cancer in this cohort of about 1% for each fibre year of exposure. In relation to estimated exposure the mortality experienced by the cohort from both lung cancer and mesothelial tumours was higher than in chrysotile mining.     

Cohort study of mortality of vermiculite miners exposed to tremolite.

A cohort of 406 men employed before 1963 for at least one year in a vermiculite mine in Montana was followed up until July 1983. The vermiculite ore as fed to the mill contained 4-6% of amphibole fibre in the tremolite series. Vital status was established in all but one of the 406 and death certificates were obtained and coded for 163 of the 165 men who died. Compared with white men in the United States, the cohort experienced excess mortality from all causes (SMR 1.17), respiratory cancer (SMR 2.45), non-malignant respiratory disease (SMR 2.55), and accidents (SMR 2.14). Four deaths were from malignant mesothelioma (proportional mortality 2.4%). Compared with Montana death rates, the SMR for respiratory cancer was somewhat higher (3.03). Man-year analyses of respiratory cancer and estimated cumulative exposure gave a relation that did not depart significantly from linearity. The results of this and case-referent analyses indicate an increased risk of mortality from respiratory cancer in this cohort of about 1% for each fibre year of exposure. In relation to estimated exposure the mortality experienced by the cohort from both lung cancer and mesothelial tumours was higher than in chrysotile mining.     

An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.     

An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy.

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.     

Dust exposure and mortality in chrysotile mining, 1910-75.

We report a further follow-up of a birth cohort of 11 379 workers exposed to chrysotile. The cohort consisted of 10 939 men and 440 women, born 1891-1920, who had worked for at least a month in the mines and mills of Asbestos and Thetford Mines in Quebec. For all subjects, length of service and estimates of accumulated dust exposure were obtained, with a smoking history for the vast majority. Three methods of analysis, two based on the "man-years" methods, the other a "case-and-multiple-controls" approach, gave results consistent with one another and with previous analyses. By the end of 1975, 4463 men and 84 women had died. Among men, the overall excess mortality, 1926-75 was 2% at Asbestos and 10% at Thetford Mines, much the dustier region. The women, mostly employed at Asbestos, had a standardised mortality ratio (SMR) all causes, 1936-75) of 0.90. Analysis of deaths 20 years or more after first employment showed that in men with short service (less than five years) there was no discernible correlation with dust exposure. Among men employed at least 20 years, there were clear excesses in those exposed to the heaviest dust concentrations. Reanalysis in terms of exposure to age 45 showed definite and consistent trends for SMRs for total mortality, for lung cancer, and for pneumoconiosis to be higher the heavier the exposure. The response to increasing dose was effectively linear for lung cancer and for pneumoconiosis. Lung cancer deaths occurred in non-smokers, and showed a greater increase of incidence with increasing exposure than did lung cancer in smokers, but there was insufficient evidence to distinguish between multiplicative and additive risk models. There were no excess deaths from laryngeal cancer, but a clear association with smoking. Ten men and one woman died from pleural mesothelioma. If the only subjects studied had been the 1904 men with at least 20 years' employment in the lower dust concentrations, averaging 6.6 million particles per cubic foot (or about 20 fibres/cc), excess mortality would not have been considered statistically significant, except for pneumoconiosis. The inability of such a large epidemiological survey to detect increased risk at what, today, are considered unacceptable dust concentrations, and the consequent importance of exposure-response models are therefore emphasised.     

Mortality in the Sami population of North Norway, 1970-98

AIMS: The pattern of mortality among many groups of indigenous people has been shown to be disadvantageous in comparison with the general population. Knowledge regarding causes of death among the Sami population in the northern part of Norway is limited. The Sami constitute an ethnic minority whose lifestyle diverges from that of the rest of the population. METHODS: A cohort of 19,801 persons of Sami origin was followed up to evaluate specific causes of mortality during the period 1970-98. Standardized mortality rates (SMR) were calculated using the rural population of the three Norwegian counties included in the study as a reference population. RESULTS: Among Sami, 5,955 total deaths were observed, as opposed to 5,537 expected (SMR = 1.08). For both Sami women and men a significantly higher SMR for cerebrovascular diseases was found, which was more pronounced for women. For Sami men, an excess SMR for violent death was observed (SMR 1.32, 95% confidence interval (CI) 1.20-1.46); this was highest among Sami men living in a reindeer-breeding family. For both genders, mortality from all malignant neoplasms combined was lower than in the reference population. SMRs were 0.86 (95% CI 0.79-0.94) and 0.89 (95% CI 0.80-0.99) for men and women, respectively. Low SMRs were also observed for chronic liver diseases, 0.18 (95% CI 0.02-0.63) and 0.12 (95% CI 0.00-0.68) for Sami men and women, respectively. To be a member of a reindeer breeding household appeared to offer protection from mortality caused by circulatory system diseases in men, especially mortality from ischaemic heart disease. CONCLUSIONS: The total mortality in the North Norway Sami population, an ethnic minority in Norway, was slightly higher when compared with a regional reference population. The differences observed when evaluating mortality by diagnosis might be due to lifestyle, diet, psychosocial, and/or genetic factors.     

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.