Mortality among employees at a plastics and resins research and development facility.

OBJECTIVES--The study was undertaken to update a previous study of employees from a resins and plastics research and development facility and to further examine the mortality of these employees with particular emphasis on deaths due to pancreatic cancer. METHODS--This retrospective cohort study examined mortality from 1962 to 1992 for 257 men who were employed for at least one year during a 14 year period from 1962 to 1975 at a plastics and resins research and development facility. During the operative period, the primary activities involved applications and process development for polypropylene, polystyrene, epoxy resins, and to a lesser extent high density polyethylene. RESULTS--The cohort was young and was followed up for an average of 26 years. Although mortality for all causes among employees who worked at least one year at this facility was low (standardised mortality ratio (SMR) 0.74), the death rate from cancer was moderately higher than that of the general population (14 observed and 9.4 expected deaths). There were four observed and 0.5 expected deaths from pancreatic cancer among men who worked at this facility for at least one year, which resulted in a statistically increased SMR of 8.88 (95% confidence interval 2.42-22.74). All cases of pancreatic cancer had "laboratory" jobs, and their ages at death were relatively young compared with deaths in the general population from pancreatic cancer. Lung cancer mortality was high but not significant with seven observed and 3.5 expected deaths. There were no deaths due to non-malignant respiratory disease (1.9 expected). CONCLUSIONS--The increased cancer mortality was entirely due to excess deaths from pancreatic and lung cancers. No causative agent or process for these cases of pancreatic cancer has been identified. This study shows no increased colorectal cancer mortality as was found among another group of workers involved in the manufacture of polypropylene.     

Professor Matthew Stewart: Asbestosis research 1929–1934

Matthew Stewart, Professor of Pathology at Leeds University, developed an interest in asbestosis during the late 1920s. In 1929, the Medical Research Council (MRC), encouraged by an advisory committee, funded research into asbestosis at Leeds University. Stewart supported by physicians designed a program of clinical, radiological and physiological studies to follow up Merewether's affected asbestos workers. Unfortunately, this met with opposition from industry, and the Home Office Factory Department was reluctant to assist, so it was abandoned. Industry did, however, cooperate with Stewart's studies on the effects of exposing guinea pigs in the factory environment, but this led to little in the way of publication. The failure of the Leeds School to realize its potential in investigating the effects of asbestos in humans, results in part from the discouragement it received and in part from the limited time and energies available to persons with a wide range of active interests. Some 45 years were to elapse before the MRC were enabled to carry out an analysis of the clinical, radiological and physiological data of a population of asbestos workers. Am. J. Ind. Med. 32:562–569, 1997. © 1997 Wiley-Liss, Inc.     

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. © 1996 Wiley-Liss, Inc.     

Mortality in a cohort of pentachlorophenol manufacturing workers, 1940–1989

Mortality in a cohort of 770 workers with potential pentachlorophenol (PCP) exposure was evaluated from 1940 through 1989. The study cohort is a subset of a larger cohort of workers with potential exposure to higher chlorinated dioxins. Total mortality and cancer mortality, in the PCP cohort were slightly lower than expected in comparison to the U.S. white male population. There were 229 total deaths with 242.5 expected (SMR = 94, 95% confidence interval 83–108), and 50 cancer deaths with 52.6 expected (SMR = 95, 95% confidence interval 71–125). In comparison with unexposed employees, the risk ratio for total mortality was 1.03 (95% confidence internal 0.90–1.17), and the risk ratio for all cancer mortality was 0.95 (95% confidence interval 0.71–1.26). In most cause of death categories of a priori interest no deaths were observed in the cohort. A small excess of other and unspecified lymphopoietic cancer deaths was observed but did not appear to be related to exposure. Excesses of deaths due to cancer of the kidney, gastric and duodenal ulcer, cirrhosis of the liver, and all accidents were observed in comparison with the U.S. white male population and with unexposed employees. These were associated with increasing estimated cumulative PCP exposure after lagging exposures by 5 and 15 years. Despite the limited size and the generally favorable total mortality experience of the cohort, it was concluded that cohort members may have incurred increased risk of death due to some specific causes. The risks could not, however, be attributed conclusively to PCP exposure and may have been associated with other occupational and nonoccupational factors. Additional mortality surveillance of this cohort will be performed. © 1996 Wiley-Liss, Inc.     

Influence of age at death on accuracy of death certificate disease diagnosis: findings in 475 consecutive deaths of mesothelioma among asbestos insulation workers and asbestos factory workers.

Age at death had no appreciable influence on accuracy of death certificate diagnoses of 475 consecutive deaths of mesothelioma among asbestos insulation and asbestos factory workers, until age 75 or older.     

Lung function among asbestos cement factory workers: cross-sectional and longitudinal study

Ventilatory capacity tests and standardized respiratory questionnaires were used in 1973 and in 1980 to measure the effect of mixed dust exposure in the asbestos cement industry on respiratory symptoms and lung function in 65 exposed workers and 30 controls (exposed to polyvinyl chloride but not to asbestos). Workers exposed to asbestos had 1) a higher prevalence of breathlessness and chest pain, and a higher incidence of breathlessness; 2) lower 1980 values of forced vital capacity (FVC) (0.27-0.83 liters) and forced expiratory volume in 1 sec (FEV1) (0.23-0.62 liters); and 3) a faster decline (nearly 40 ml/year) in FVC and FEV1 between 1973 and 1980. The FVC annual decrease was 52.5 ml in the subjects with more than 15 years since first asbestos exposure, whereas it was 24.3 ml in those with less than 15 years, suggesting a faster decline after 15 years of exposure. The effect of asbestos exposure and smoking habits was less than additive as regards pulmonary function.     

Mortality among a cohort of electric utility workers, 1960–1991

Overall mortality trends among an electrical utility workforce are examined. The study cohort (n = 40,335) included all workers with at least 1 year of work experience from 1960–1991; 3,753 deaths were observed in this cohort. Standardized mortality ratios (SMRs) and internal cohort analyses were used to assess mortality trends for the entire cohort and for specific occupational groups. Most SMRs were ≤ 1.0 and were generally lower for noncancer (cardiovascular, COPD, and injuries) than for cancer mortality. Compared to office staff, rate ratios (RR) were higher for respiratory cancers for field staff [(RR = 2.3 95% Cl, 1.0–5.0) linecrew (RR = 2.2 95% Cl, 1.5–3.1), and power plant occupations (RR = 2.4, 95% Cl, 1.6–3.6)]. Nonmanagement occupations had rate ratios for motor vehicle injuries and all types of injuries, within a range of 2.5–4.7, with all lower Cls > 1.0. The healthy worker effect is an important factor in explaining the difference between SMR and internal cohort analyses results. The SMR results indicate that this workforce has lower rates for overall mortality, cardiovascular disease, cancer and nonintentional injury. A consistent finding in the internal cohort analyses that merits further research was higher mortality rates for respiratory cancer and injuries among nonoffice staff. Am. J. Ind. Med. 31:534–544, 1997. © 1997 Wiley-Liss, Inc.     

Mortality of a police cohort: 1950–1990

This study presents findings from an updated retrospective cohort mortality study of male police officers from January 1, 1950 to December 31, 1990 (n = 2,593; 58,474 person-years; 98% follow-up). Significantly higher than expected mortality rates were found for all cause mortality (Standardized mortality ratio [SMR] = 110; 95% confidence interval [95% CI] = 1.04–1.17), all malignant neoplasms (SMR = 125; 95%CI = 1.10–1.41), cancer of the esophagus (SMR = 213; 95%CI = 1.01–3.91), cancer of the colon (SMR = 187; 95%CI = 1.29–2.59), cancer of the kidney (SMR = 208, 95%CI = 1.00–3.82), Hodgkin's disease (SMR = 313; 95%CI = 1.01–7.29), cirrhosis of the liver (SMR = 150; 95%CI = 1.00–2.16), and suicide (SMR = 153; 95%CI = 1.00–2.24). All accidents were significantly lower (SMR = 53; 95%CI = 0.34–0.79). Mortality by years of police service showed higher than expected rates for (1) all malignant neoplasms in the 1- to 9-years-of-service group; (2) all causes, bladder cancer, leukemia, and arteriosclerotic heart disease in the 10 to 19-year group; and (3) colon cancer and cirrhosis of the liver in the over 30 years of service group. Hypotheses for findings are discussed. Am. J. Ind. Med. 33:366–373, 1998. © 1998 Wiley-Liss, Inc.     

Mortality of workers at a nuclear materials production plant at Oak Ridge,Tennessee, 1947–1990

The Y-12 plant at Oak Ridge, Tennessee, produced nuclear materials for the U.S. government's nuclear weapons program beginning in 1943. Workers at Y-12 were exposed to low dose, internal, alpha radiation and external, penetrating radiation, as well as to beryllium, mercury, solvents, and other industrial agents. This paper presents updated results from a long-term mortality study of workers at Y-12 between 1947 and 1974, with follow-up of white men through 1990 and data reported for the first time for women and men of other races. Vital status was determined through searches of the National Death Index and other records, and the workers' mortality was compared to the national population's using standardized mortality ratios (SMRs). Total mortality was low for all Y-12 workers and total cancer mortality was as expected. Among the 6,591 white men, there were 20% more lung cancer deaths than expected (95% confidence interval /CI/ 1.04–1.38). Death rates from brain cancer and several lymphopoietic system cancers were also elevated among white men, with SMRs of 1.28 and 1.46. Mortality from cancer of the pancreas, prostate, and kidney was similarly elevated. There was evidence of excess breast cancer among the 1,073 female workers (SMR 1.21, 95% CI 0.60–2.17). Lung cancer mortality among these workers warrants continued surveillance because of the link between internal alpha radiation exposure and this disease, but other agents, notably beryllium, also merit consideration as potential causes of lung cancer. Other cancers and agents should also be investigated as part of a comprehensive study of the health consequences of the production of nuclear weapons. © 1996 Wiley-Liss, Inc.     

Occupational exposure to asbestos: Population at risk and projected mortality-1980–2030

Estimates have been made of the numbers of cancers that are projected to result from past exposures to asbestos in a number of occupations and industries. From 1940 through 1979, 27,500,000 individuals had potential asbestos exposure at work. Of these, 18,800,000 had exposure in excess of that equivalent to two months employment in primary manufacturing or as an insulator (> 2-3 f-yr/ml). 21,000,000 of the 27,500,000 and 14,100,000 of the 18,800,000 are estimated to have been alive on January 1, 1980. It is further estimated that approximately 8,200 asbestos-related cancer deaths are now occurring annually. This will rise to about 9,700 annually by the year 2000. Thereafter, the mortality rate from past exposure will decrease, but still remain substantial for another three decades.     

Mortality from asthma, chronic obstructive pulmonary disease, respiratory system cancer, and stomach cancer among paper mill workers: a case-referent study

In an earlier case-referent study from a soft-paper mill with levels of paper dust exceeding 5 mg/m3, an increased mortality was found (OR = 3.8, p less than 0.05) from asthma and chronic obstructive pulmonary disease (COPD) among the employed. Furthermore, other studies on paper mill workers have also indicated an increased mortality from lung cancer. The main objectives of the present case-referent study were to investigate the mortality from asthma. COPD, and lung cancer in two other Swedish paper mills. In these mills, the levels of paper dust have been below 3 mg/m3. The subjects for the study were all men who died between 1961 and 1985 from asthma and COPD (n = 31), respiratory cancer (n = 27), and stomach cancer (n = 33) selected in three parishes surrounding two paper mills. As referents we randomly selected about six times as many men who had died from nonmalignant nonrespiratory diseases in these parishes (n = 550). On the basis of information found in the personnel records in the mills, the men were classified into different occupational categories or as unexposed. No increased risk of asthma or COPD was found among the workers exposed to paper dust. However, it was found that there was significantly increased mortality (OR = 5.7, p less than 0.05) for asthma and COPD among workers in a previous log sorting department. The study also showed a significantly increased risk of lung cancer (OR = 2.1, p less than 0.05) among maintenance workers. There was no increased risk of stomach cancer in the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cancer incidence among laboratory workers in biomedical research and routine laboratories in Israel: Part II-nested case-control study

BACKGROUND: A case-control study nested within a cohort study of biomedical laboratory workers was conducted to examine whether the excess cancer morbidity that we found can be explained by exposure to a particular group of substances, taking into consideration potential confounders. METHODS: The study population included 163 cases and two matched control groups: laboratory workers (311) and general population (448) workers. RESULTS: Multiple conditional regression analysis showed that working in research laboratories involved an increased risk of cancer generally among women [risk ratio 2.2 (1.2-4.3)], and of breast cancer particularly [risk ratio 2.3 (1.1-4.7). Seventy-six percent (76%) of breast, 87% of thyroid, 60% of ovary and prostate, 94% of melanoma, and 50% of leukemia cases were ever exposed to at least one known human carcinogen. CONCLUSION: Our results exclude the possibility that the excess cancer morbidity was related to personal risk factors but they may be explained by exposure factors. Am. J. Ind. Med. 44:611-626, 2003.     

Cancer incidence among laboratory workers in biomedical research and routine laboratories in Israel: Part I-the cohort study

BACKGROUND: Laboratory work is associated with exposure to a mixture of carcinogens. METHODS: The cohort is comprised of 4,300 laboratory workers. Cancer incidence was followed from 1960 to 1997. RESULTS: A total of 230 cases were included in the cohort. The overall cancer standardized incidence ratio (SIR) was 1.04 (0.91-1.18). When a 20-year latency was introduced, SIR was increased significantly: 1.35 (1.13-1.61). Among routine workers and researchers, SIR was elevated significantly for the total population and for women, when a 20-year latency was introduced. SIR was also elevated significantly in research, routine, bacteriology and virology, and isotope laboratories. With respect to specific sites, significantly increased SIR was observed in breast, ovary, and thyroid cancer among women; and prostate cancer, leukemia, and melanoma among men. CONCLUSIONS: We suggest that work in research and biomedical laboratories might involve an increased risk of certain types of cancer. Am. J. Ind. Med. 44:600-610, 2003.     

Cancer incidence and mortality in workers employed at a transformer manufacturing plant: update to a cohort study

BACKGROUND: This study is an extension of a previously published analysis of cancer mortality in a transformer manufacturing plant where there had been extensive use of mineral oil transformer fluid. The objectives of the present study were to update the mortality analysis and include deaths for the past 6 years as well as to do an analysis of cancer incidence of the cohort. METHODS: A cohort of 2,222 males working at a transformer manufacturing plant between 1946 and 1975 was constructed. Using a classical historical cohort study design, cancer incidence and mortality were determined through record linkage with Canadian provincial and national registries. The rates of cancer incidence and mortality experienced by this cohort were compared to that of the Canadian male population. RESULTS: A statistically significant increased risk of developing and dying of pancreatic cancer was found but not an increase in overall cancer mortality. This was consistent with the previous report from this group. Interestingly, the cohort demonstrated a statistically significant risk of overall cancer incidence and specific increased incidence of gallbladder cancer. CONCLUSIONS: This study contributes further evidence to the growing body of literature indicating the carcinogenic properties of mineral oils used in occupational settings, in particular those used prior to 1970s.