Significant Deficit Of Mortality Research Articles

Understanding excess mortality during COVID in Belgium: the influence of health and social factors

Abstract Background This study aims to investigate how pre-existing health status and social background contribute to excess mortality during the COVID-19 crisis in Belgium. Methods The study population consists of 1.4 million adult members of Solidaris, the second largest health insurance fund in Belgium. Pre-existing health status was identified using health care reimbursement data, including medication use. Social characteristics included financial support, migrant background, and household composition. Excess mortality during the COVID-19 crisis was measured as the relative difference between all-cause mortality in 2020 or 2021 versus the pooled yearly estimates in 2015-2019. Yearly age- and sex-adjusted mortality rate ratios (MRR) were estimated using Poisson regression to study potential differences by health status and social factors. Results Compared with healthy persons, all investigated health problems were associated with increased mortality, with most notably an MRR of 8.4 (CI 8.0-8.9) for persons with cancer in 2021. Compared with 2015-2019, MRRs for persons with mental disorders (anxiety, depression) and diabetes were significantly higher than expected in 2020. Interestingly, mortality for persons with mental disorders was significantly lower than expected in 2021. Significant mortality deficits were also observed for persons with cancer and chronic respiratory conditions (COPD, asthma) in 2020 and 2021. After controlling for social characteristics, only the mortality deficits for persons with cancer and chronic respiratory conditions remained significant (p < 0.005), with respectively, 17% and 11% lower mortality in 2020, and 12% and 6% lower mortality in 2021. Conclusions Large mortality differences were observed by pre-existing health problem and social background during the COVID-19 crisis. A significant mortality deficit was observed for persons with cancer and chronic respiratory conditions in 2020 and in 2021. Key messages • Information on pre-existing health problems and social background are key to understanding excess mortality patterns. • The already large health and social inequalities in mortality did not widen further during the COVID-19 crisis in Belgium.

First mortality analysis in the French cohort of uranium millers (F-Millers), period 1968-2013.

Epidemiological studies in cohorts of uranium millers can be informative to improve knowledge of the health effects of uranium, but are very rare. The aim of this study was to analyze, for the first time, mortality in a French cohort of uranium millers. The F-Millers cohort includes permanent contract workers employed at least 6months at French uranium milling plants. Vital status and causes of death were obtained from national registries between 1968 and 2013, in order to perform comparisons with French national and local mortality rates by computing standardized mortality ratios (SMRs) with 95% confidence intervals (95% CI). The cohort includes 1291 workers. The average duration of follow-up is 32.1years. At the end of follow-up, 448 workers were deceased and 13 lost to follow-up. We observed a significant deficit of mortality for all causes combined when the national reference was considered (SMR 0.81; 95% CI [0.74;0.89]), but no significant difference when the local reference was considered (SMR 0.97; 95% CI [0.88;1.07]). Significant excesses were observed only in a subgroup of 552 workers hired at the manufacturing unit, mainly when the local reference was considered. No significant excess of mortality was observed at the scale of the full cohort. The cause-specific excesses of mortality observed in the subgroup of workers hired at the manufacturing unit were based on small number of cases, but would warrant further investigations. Undertaking analytical studies and combined analyses of cohorts of uranium millers would help to study the influence of potential risk factors and obtain more precise results.

Effets de la contamination chronique à l’uranium sur la mortalité : bilan d’une étude-pilote chez les travailleurs de l’industrie nucléaire en France

BackgroundThis article presents the mortality data compiled among a cohort of workers at risk of internal uranium exposure and discusses the extent to which this exposure might differentiate them from other nuclear workers. MethodsThe cohort consisted of 2897 Areva-NC-Pierrelatte plant workers, followed from 1st January 1968 through 31st December 2006 (79,892 person-years). Mortality was compared with that of the French population, by calculating Standardized Mortality Ratios (SMR) and 95 % confidence intervals (CI95 %). External radiation exposure was reconstructed using external dosimetry archives. Internal uranium exposure was assessed using a plant-specific job-exposure-matrix, considering six types of uranium compounds according to their nature (natural and reprocessed uranium [RPU] and solubility [fast-F, moderate-M, and slow-S]). Exposure-effect analyses were performed for causes of death known to be related to external radiation exposure (all cancers and circulatory system diseases) and cancer of uranium target-organs (lung and hematopoietic and lymphatic tissues, HLT). ResultsA significant deficit of mortality from all causes (SMR=0.58; CI95 % [0.53–0.63]), all cancers (SMR=0.72; CI95 % [0.63–0.82]) and smoking related cancers was observed. Non-significant 30 %-higher increase of mortality was observed for cancer of pleura (SMR=2.32; CI95 % [0.75–5.41]), rectum and HLT, notably non-Hodgkin's lymphoma (SMR=1.38; CI95 % [0.63–2.61]) and chronic lymphoid leukemia (SMR=2.36; CI95 % [0.64–6.03]). No exposure-effect relationship was found with external radiation cumulative dose. A significant exposure-effect relationship was observed for slowly soluble uranium, particularly RPU, which was associated with an increase in mortality risk reaching 8 to 16 % per unit of cumulative exposure score and 10 to 15 % per year of exposure duration. ConclusionThe Areva-NC-Pierrelatte workers cohort presents a non-significant over-mortality from HLT cancers, notably of lymphoid origin, unrelated to external radiation exposure. The pilot study suggests an association between mortality from the HLT and lung cancers and exposure to slowly soluble RPU compounds. The results of this study should be investigated further in more powerful studies, with a dose-response analysis based on individual assessment of uranium absorbed dose to uranium-target organs.

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

Background We 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. Methods The 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. Results At 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. Conclusion There 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 in nuclear workers of the French electricity company: Period 1968–2003

Background We conducted a mortality study on a cohort of French nuclear workers employed at Électricité de France (EDF). A first cancer mortality analysis was based on the 1968–1994 period. This paper presents the results from a mortality analysis including nine additional years of follow-up without consideration of exposure, covering the 1968–2003 period. Methods The 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 National Registry of Population and further completed using EDF personnel and pension files. Causes of death were obtained through the National Causes of Death file. Standardized mortality ratios (SMRs) were computed using national rates as references. Variations of all-cause and all-cancer SMRs were studied according to demographic and occupational characteristics. Results At the study end point (31/12/2003), 74% of workers were still in active service. Only 0.3% of workers were lost to follow-up. The median duration of follow-up was 20 years. Causes were ascertained for 96% of deaths. The total number of deaths was 874, 307 of which were cancer deaths. SMRs for all causes and cancers show a significant deficit compared to the French national mortality rates. No significant excess was observed for any of the cancer sites studied. Nonsignificant excesses were observed for pancreatic, pleural, kidney, and brain cancer. Significant variations of all-cause SMRs according to age at study entry and attained age were observed. Significant variations of all-cause and all-cancer SMRs according to education level at employment were observed, with a reduced SMR for a higher level of education. Conclusion There 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 in an extended follow-up of British coal workers

The Pneumoconiosis Field Research (PFR) programme was established in the 1950s, to evaluate effects of coal mining exposures on the health and mortality of British coal workers. Surveys of working miners were carried out at 5-yearly intervals, initially in 24 collieries but later concentrating on 10, collecting detailed work histories and health information for each recruit. Here we report on cause-specific mortality in a cohort of almost 18,000 men from 10 British collieries, followed up for periods up to 47 years, yielding over 516,000 life-years of follow-up. External analyses compared cause-specific death rates in the cohort to those of the population of the regions in which the collieries were situated, using Standardised Mortality Ratios (SMRs). The causes investigated included lung cancer, stomach cancer, non-malignant respiratory disorders and cardiovascular disorders. SMRs showed evidence of an initial healthy worker effect diminishing over time. Several causes, including non-malignant respiratory disease and lung cancer, showed a significant deficit of mortality at the start of the study period with an excess in the latter part of the follow-up period. In these results, effects of working conditions are likely to be confounded with smoking habits. Overall, we believe our results may be generalised to the British coal industry since nationalisation.

Second Cancer Incidence and Cause-Specific Mortality Among 3104 Patients With Hairy Cell Leukemia: A Population-Based Study

The introduction of new treatments for hairy cell leukemia has resulted in improved patient survival but also engendered increasing concern about the possibility of excess second cancers. The available evidence is conflicting, with most risk estimates based on sparse numbers. To our knowledge, no study has evaluated cause-specific mortality in patients with hairy cell leukemia. We quantified second cancer incidence and cause-specific mortality among 3104 two-month survivors of hairy cell leukemia who were reported to 16 population-based registries in the Surveillance, Epidemiology and End Results (SEER) Program between 1973 and 2002. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were used to quantify the risk of second cancers and causes of death, respectively. The cumulative probability of a second cancer among survivors of hairy cell leukemia was calculated using a competing risk model. All statistical tests were two-sided. Mean follow-up of hairy cell leukemia survivors was 6.5 years (range, 2 months-29.3 years). Second cancer risk was statistically significantly elevated (SIR = 1.24, 95% confidence interval [CI] = 1.11 to 1.37) compared with the general population. Survivors had statistically significantly higher risks of Hodgkin lymphoma (SIR = 6.61, 95% CI = 2.13 to 15.42), non-Hodgkin lymphoma (SIR = 5.03, 95% CI = 3.77 to 6.58), and thyroid cancer (SIR = 3.56, 95% CI = 1.30 to 7.74) and a lower risk of lung cancer (SIR = 0.63, 95% CI = 0.42 to 0.90). The cumulative probability of all second cancers was estimated to be 31.9% (95% CI = 26.2 to 37.6) 25 years after hairy cell leukemia diagnosis. Among 10,000 hairy cell leukemia patients, a total excess of about 34 cancers, including 21 non-Hodgkin lymphomas, 2 Hodgkin lymphomas, and 7 solid tumors (including 2 thyroid cancers), might be observed per year. Deaths due to solid tumors were not elevated compared with the general population (SMR = 0.9), and there were statistically significant deficits in mortality due to both cardiovascular (SMR = 0.67, 95% CI = 0.56 to 0.80) and cerebrovascular (SMR = 0.61, 95% CI = 0.38 to 0.93) disease. Patients with hairy cell leukemia are at increased risk of Hodgkin lymphoma, non-Hodgkin lymphoma, and thyroid cancer. The decrease in lung cancer incidence and smoking-associated vascular mortality may reflect an inverse association of tobacco use with hairy cell leukemia. Future studies should address the roles of immunologic impairment inherent to hairy cell leukemia, treatment modalities, and other factors as codeterminants of morbidity and mortality in hairy cell leukemia survivors.

Updated mortality study of workers at a petroleum refinery in Torrance, California, 1959 to 1997.

The updated cohort consisted of 3328 workers who were employed at the Mobil (now ExxonMobil) Torrance, California, refinery for at least 1 year between 1959 and 1997. The vital status of the cohort was determined through a variety of sources, including company employment or retirement records, the Social Security Administration's Death Master File, and the National Death Index. The updated study covered an observation period of 38 years from 1960 to 1997, with a total of 60,612 person-years of observation. A total of 705 (21.2%) cohort members were identified as having died. Mortality data were analyzed in terms of cause-specific standardized mortality ratios (SMRs) and 95% confidence intervals (95% CIs), with expected deaths based on US national cause-, gender-, race-, year-, and age-specific mortality rates. The overall mortality of the cohort was significantly lower than expected when compared with the US general population (SMR, 81.9; 95% CI, 76.0 to 88.2). Overall cancer mortality was also lower than expected (SMR, 79.8; 95% CI, 67.9 to 93.1). For specific cancer sites, significant mortality deficits were observed for cancer of the digestive system (SMR, 70.9; 95% CI, 49.4 to 98.6) and cancer of the respiratory system (SMR, 74.1; 95% CI, 55.5 to 97.0). No significant increase was reported for any site-specific cancer. For nonmalignant diseases, no significant increase was observed for any cause. In particular, significant mortality deficits were reported for ischemic heart disease (SMR, 87.7; 95% CI, 77.2 to 99.3), chronic endocardial disease and other myocardial insufficiencies (SMR, 8.3; 95% CI, 0.2 to 46.0), all other heart disease (SMR, 64.2; 95% CI, 43.0 to 92.2), and influenza and pneumonia (SMR, 59.2; 95% CI, 33.1 to 97.6). Detailed analysis by length of employment did not reveal any significant mortality excess or upward trend. Analyses of male employees by job classification (process and maintenance) were conducted. Among maintenance workers, mortality from cirrhosis of the liver (SMR, 190.1; 95% CI, 101.2 to 325.1) and suicide (SMR, 208.6; 95% CI, 111.1 to 356.7) were significantly elevated. However, these mortality excesses did not seem to be related to employment at the refinery. No other causes of death showed significant increase among maintenance workers. A similar separate analysis was conducted for process workers, and no significant excess was detected for any cause. The findings from the present study are discussed in conjunction with results from previous investigations of employees at the Torrance refinery and with results from other refinery studies. Potential limitations of the study are also discussed.

Health Findings from a Mortality and Morbidity Surveillance of Refinery Employees

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

An updated mortality study of workers at a petroleum refinery in Beaumont, Texas, 1945 to 1996.

The present investigation represents an update of a previous cohort mortality study of 7543 workers who were employed at a petroleum refinery in Beaumont, Texas, for at least 1 year between 1945 and 1996. The updated study covered an observation period of 51 years, from 1946 to 1996, with a total of 208,627 person-years of observation. A total of 3020 (40.0%) cohort members were known to have died. The mortality data were analyzed in terms of cause-specific standardized mortality ratios (SMRs) and 95% confidence intervals (95% CIs). The overall mortality of the cohort was significantly lower than expected when compared with that of the general US population (SMR, 95.7; 95% CI, 92.3 to 99.2). Overall cancer mortality was also lower than expected (SMR, 85.8; 95% CI, 79.4 to 92.5). For specific cancer sites, significant mortality deficits were observed for the following: buccal cavity and pharynx, esophagus, large intestine, rectum, larynx, lung, and bladder and other urinary organs. No significant increase was reported for any site-specific cancer. A non-significant increase in acute myeloid leukemia was observed among male employees (SMR, 147.2; 95% CI, 76.1 to 257.2). Detailed analyses indicated that the excess was restricted to workers hired before 1950. No increase was detected for other leukemia cell-types, non-Hodgkin's lymphoma, or multiple myeloma. For non-malignant diseases, the majority of SMRs were below 100, and no significant increase was observed for any cause. In particular, significant mortality deficits were reported for ischemic heart disease (SMR, 91.0; 95% CI, 85.4 to 96.9), non-malignant respiratory disease (SMR, 61.5; 95% CI, 52.2 to 72.0), pulmonary fibrosis (SMR, 51.0; 95% CI, 22.0 to 100.4), cirrhosis of the liver (SMR, 47.2; 95% CI, 30.6 to 69.7), and accidents (SMR, 81.7; 95% CI, 66.3 to 99.6). Separate analyses of male workers by job classification (process and maintenance) were conducted. Mortality from acute myeloid leukemia was elevated among employees in maintenance jobs (8 observed deaths vs 4.31 expected; SMR, 185.5; 95% CI, 80.1 to 365.6). However, no upward trend by length of service was found. A detailed analysis indicated that the acute myeloid leukemia mortality excess was limited to maintenance workers who were hired before 1950. No other significant excess was detected for any cause among maintenance or process workers. These findings from the present study were discussed in conjunction with results from previous investigations of employees at the Beaumont refinery and with results from other refinery studies. Potential limitations of the study were also discussed.

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

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

Mortality among maintenance employees potentially exposed to asbestos in a refinery and petrochemical plant.

This paper reports the mortality experience from 1948 to 1989 of 2,504 maintenance employees who had a minimum of one year of employment in jobs with potential exposure to asbestos at a Texas refinery and petrochemical plant. For the purposes of this study, "potential exposure" is equated with those jobs or crafts having the greatest direct potential proximity to, or which worked directly with, asbestos-containing materials, especially asbestos-containing thermal insulation. Approximately one-half of the study population had 10 years or longer potential exposure, and 80% had their first potential exposure before 1970. The total population exhibited significantly lower mortality for all causes, the standardized mortality ratio (SMR = 77); and for all cancer (SMR = 85), as compared to residents in the surrounding communities. Statistically significant deficits in mortality were also observed in a number of noncancerous diseases such as heart disease (SMR = 78; 95% CI = 69-88), nonmalignant respiratory disease (SMR = 70; 95% CI = 50-95), and cirrhosis of the liver (SMR = 44; 95% CI = 22-79). Mortality among employees who had 20 years or longer since their first potential exposure was also examined; the pattern of mortality was similar to that exhibited by the total cohort, with a slight increase in the SMR for most of the causes. The only statistically significant excess of mortality found was a fourfold increase in mesothelioma (5 observed and 1.2 expected deaths) the SMR was 428 (95% CI = 139-996) for the total cohort and was 469 (95% CI = 152-1093) for those who had 20 years or more since first potential exposure. In contrast to asbestos industry worker studies, mortality for lung cancer was substantially lower than the general population (SMR = 81; 95% CI = 63-103). The observed number of deaths for cancer of the larynx was virtually the same as expected (3 observed vs. 2.8 expected). This study also showed decreased mortality for cancers of gastrointestinal organs such as the esophagus (SMR = 78), stomach (SMR = 63), large intestine (SMR = 91), rectum (SMR = 55), or pancreas (SMR = 90)--cancers that have been reported to be elevated in studies of various industry workers directly exposed to asbestos.

Mortality among Persons Mining and Milling Attapulgite Clay

Abstract To evaluate the possible carcinogenicity and fibrogenicity of occupational exposure to a non-asbestos mineral fibre, a cohort of 2302 males employed for at least one month between 1940 and 1975 at an attapulgite (clay fibre) mining and milling facility was followed through 1975. Among those successfully traced (94%), 317 had died compared to 388.1 expected deaths based on age-, calendar year-, and race-specific rates for United States males. A significant deficit of mortality (SMR = 43, 90% CI 23–76) due to nonmalignant respiratory disease (NMRD) was observed. A marked deficit of NMRD was seen regardless of induction-latency period, or duration employed. A statistically significant excess of mortality due to lung cancer was observed among whites (SMR = 193, 90% CI 121–293); a deficit occurred among nonwhites (SMR = 53, 90% CI 21–112). Lung cancer risk in either race was not altered substantially with induction-latency period or duration employed. The findings for NMRD are consistent with the hypothesis that short fibres ( μ m in length) are not fibrogenic.

A retrospective cohort mortality study of males mining and milling attapulgite clay.

To evaluate the possible health effects of occupational exposure to a nonasbestos mineral fiber, a cohort of 2,302 males employed for at least 1 month between 1940 and 1975 at an attapulgite (clay fiber) mining and milling facility was followed through 1975. A significant deficit of mortality (SMR = 43, 90% CI 23-76) from nonmalignant respiratory disease (NMRD) was observed for the cohort based on age-, calendar year-, and race-specific rates for U.S. males. A marked deficit of NMRD was seen regardless of presumed dust exposure level, induction-latency period, or duration employed. A statistically significant excess of mortality from lung cancer was observed among whites (SMR = 193, 90% CI 121-293), but a deficit occurred among nonwhites (SMR = 53, 90% CI 21-112). Lung cancer risk in either race was not altered substantially with presumed dust exposure level, induction-latency period, or duration employed with one exception-those employed for at least 5 years in high-exposure-level jobs.

Mortality of a municipal worker cohort: I. Males.

A retrospective cohort mortality study was conducted on 11,499 full-time municipal employees of the City of Buffalo, New York, who were employed at least one day between January 1, 1950 and October 1, 1979 and worked a minimum of five years. This paper outlines the method of the study and presents the all cause and cause-specific mortality for the male cohort of 10,128. Statistically significant deficits in mortality are seen for infectious diseases, diseases of the circulatory system, diseases of the respiratory system, and all external causes. Statistically significant increased mortality is seen for both malignant and benign neoplasms. All cause mortality was significantly lower than expected for professional, manager, and clerical workers. White-collar workers exhibit a decreased risk of mortality from all diseases of the circulatory system, all diseases of the respiratory system, and all external causes of death. No statistically significant increased or decreased risk of mortality from specific cancer sites is seen for white-collar workers. Blue-collar workers show statistically significant deficits in mortality from infectious diseases, all diseases of the circulatory system, all respiratory diseases, and all external causes. Blue-collar workers exhibit statistically significant increases for benign and malignant neoplasms and in particular, malignant neoplasms of the esophagus, large intestine, and rectum. The meaning of these findings will be clarified through analyses of specific worker groups.

Cancer and Aplastic Anemia in British Columbia Farmers<xref ref-type="fn" rid="FN2">2</xref>

For evaluation of occupational mortality in agriculture, age-standardized proportional mortality ratios (PMR) were calculated for 28,032 male farmers with the use of British Columbia (B.C.) death registrations collected from 1950 to 1978. Farmers had significantly elevated risks of death from cancer of the lip (PMR = 191, P = .05), stomach (PMR = 119, P less than .0001), and prostate gland (PMR = 113, P less than .001). In addition, leukemia was higher than expected (PMR = 122, P less than .01), as was aplastic anemia (PMR = 174, P less than .01). The elevated risks were fairly consistent over the 29-year period for stomach, prostate gland, and lip cancer, as well as for leukemia. The PMR for aplastic anemia was highest for the years 1950-59 and declined over the next 19 years. Farmers also showed significant mortality deficits for several important cancer sites, including esophagus (PMR = 59, P less than .0001), colon (PMR = 84, P less than .001), larynx (PMR = 62, P less than .01), and lung (PMR = 66, P less than .0001) for the period 1950-78. More detailed studies in B.C. will be necessary to confirm and extend these cancer-agriculture associations.

Mortality of workers potentially exposed to organic and inorganic brominated chemicals, DBCP, TRIS, PBB, and DDT.

A historical prospective mortality study was conducted on 3579 white male workers employed between 1935 and 1976 with potential exposures to brominated compounds including 1,2-dibromo-3-chloropropane (DBCP), Tris (2,3-dibromopropyl) phosphate, polybrominated biphenyls (PBB), various organic and inorganic bromides, and DDT. The vital status as of 31 December 1976 was determined for 3384 (95%) of these workers: 2806 (79%) were still living and 578 (16%) had died. Death certificates were obtained for 541 deaths (94% of all deaths). The mortality experience of the entire cohort and several subcohorts was compared with that of United States white men adjusted for age and calendar time. The comparison statistic was the commonly used standardised mortality ratio (SMR). Historical industrial hygiene data were not available, and the workers were classified by their work areas or departments in order to estimate their potential exposures. Overall mortality for the entire cohort and several subgroups was significantly lower than expected. For the entire cohort, significant mortality deficits were observed in diseases of the circulatory system, non-malignant respiratory disease, and diseases of the digestive system. On the other hand, mortality from diabetes mellitus was significantly raised for the cohort. No significant overall or cause-specific mortality excess was detected among employees potentially exposed to either TRIS or DDT. A significant mortality excess due to diseases of the circulatory system was observed among workers potentially exposed to DBCP. Mortality from testicular cancer was significantly higher than expected among those potentially exposed to other organic bromides. The common potential exposure of those who had died of testicular cancer was methyl bromide. Owing to the lack of accurate historical exposure information and the fact that many workers were potentially exposed to a multitude of chemicals, it is difficult to draw definitive statements on the causations of the observed mortality excesses.

Long-term mortality study of oil refinery workers. I. Mortality of hourly and salaried workers.

This longitudinal study examined the mortality and cancer experience of workers at the Gulf Oil refinery located in Port Arthur, Texas. The cohort was studied over a period of 41 years, from 1937 to 1978, and consisted of 16,880 employees, with an accumulation of 406,198 person-years; 4361 deaths were observed. Emphasis of this study was placed on the experience of the hourly and salaried male workers employed one day or more and those with a minimum of one year employment. The standardized mortality ratio analysis revealed generally favorable mortality experience of the refinery workers, including that of overall cancer. Statistically significant deficits in mortality were found for several cancer sites including bladder, liver, and esophageal cancer. Many of the increased cancer risks suggested in the literature were not confirmed in this study. Although bone cancer was found to be increased significantly, review of those death certificates raises questions as to the accuracy of the recording and coding of this cancer. Sample size of this study is capable of providing sufficient statistical power for the detection of a twofold increase in mortality risk for many cancers, if such risk exists.