Mortality of petroleum refinery workers (original) (raw)
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An epidemiological study of petroleum refinery employees
British journal of industrial medicine, 1986
A cohort study of 14179 current and former Chevron USA employees at the Richmond and El Segundo, California, refineries was conducted. The cohort consisted of everyone working at either refinery for a minimum of one year. The observed mortality of the cohort, by cause, was compared with the expected based on the United States mortality rates, standardised for age, race, sex, and calendar time. Analyses by refinery, job category, hire date, duration of employment, and latency were performed. For the entire cohort, mortality from all causes was 72.4% of that expected, a deficit that was statistically significant. In addition, a significantly lower mortality was found for all forms of cancer combined, digestive cancer, lung cancer, heart disease, non-malignant respiratory disease, diseases of the digestive system, and accidents. Only lymphopoietic cancer showed a pattern of increased risk suggestive of a possible relation to an occupational exposure. The excess appears confined to canc...
Further follow up of mortality in a United Kingdom oil refinery cohort
Occupational and Environmental Medicine, 1993
Results-of an extension of follow up (1976 to 1989) of a cohort of workers employed for at least one year between 1 January 1950 and 31 December 1975 at oil distribution centres in Britain are presented. Over 99%/o of the workers were successfully traced to determine their vital status at 31 December 1989. The mortality observed was compared with that expected from the death rates of all the male population of England and Wales. The mortality from all causes of death for the total study population was less than that of the comparison population, and reduced mortality was also found for many of the major non-malignant causes of death. No healthy worker effect was found for ischaemic heart disease, and raised mortality from this disease was found in particular for one company and in several job groups. Raised mortality was also found for aortic aneurysm. Mortality from all neoplasms was lower than expected overall, largely due to a deficit of deaths from malignant neoplasm of the lung. Raised mortality patterns from all neoplasms, malignant neoplasm of the lung, and several non-malignant disease groups were found for general manual workers although the mortality from many of these diseases for all men in this social class in the national population is also high. There was increased mortality from malignant neoplasms of the larynx and prostate but these tended to be in isolated subgroups. Mortality from malignant neoplasm of the kidney was raised overall and in drivers in particular. Mortality from leukaemia was high at one company and in drivers overall.
American Journal of Industrial Medicine, 1987
A proportionate mortality ratio (PMR) analysis of all deaths recorded from 1975 to 1985 among New Hampshire white male residents (age 20 years or older) was performed using death certificate information. Among automobile mechanics, the analysis revealed increases in mortality from leukemia (PMR = 178, N = 6); cancers of the oral cavity (PMR = 163, N = 4), lung (PMR = 112, N = 36), bladder (PMR = 169, N = 5 ) , rectum (PMR = 182, N = 4), and lymphatic tissues (PMR = 200, N = 6); and cirrhosis of the liver (PMR = 140, N = 13) and suicide (PMR = 177, N = 22; p < 0.05). Workers in the gasoline service station industry experienced a leukemia mortality excess (PMR = 328, N = 3; p < 0.05) as well as increases in deaths from suicide (PMR = 162, N = 4), emphysema (PMR = 245, N = 4), and mental and psychoneurotic conditions (PMR = 394, N = 3). These workers are potentially exposed to a variety of substances including gasoline vapor, benzene, solvents, lubricating oils and greases, and asbestos (from brake and clutch repair) as well as welding fumes and car and truck exhaust. Despite limitations regarding the small number of deaths and methodologic constraints, the results of this analysis suggest that one or more of the exposures experienced by these workers poses a significant carcinogenic risk. More definitive epidemiologic studies are required to determine if the leukemia excess is associated with exposure to benzene, gasoline, or other workplace substances.
Mortality study of cancer risk among oil refinery workers
International Archives of Occupational and Environmental Health, 1989
The mortality experience of 1595 male workers employed in one of the largest Italian refineries in the period from 1949-1982 was examined From the comparison with national and local death rates, increases in mortality owing to lung and kidney cancers, brain tumors, and leukemias emerged No definite trends according to duration of exposure and years since first exposure were apparent The increases regarding cancer of the lung, kidney and brain appeared to be associated with the early period of operations Analysis by exposure category suggested an association of the increased mortality from leukemias with working in production (observed = 2 ; expected = 0 61) Kidney cancer mortality was elevated among maintenance workers (obs = 2 ; exp = 0 18) Small numbers prevented firmer conclusions Workers in the moving department had a significantly increased mortality from all cancers (obs = 22 ; exp = 11 7), and lung cancer (obs = 11 ; exp = 3 6) Confounding by smoking could be excluded as sufficient explanation of the three-fold increase in lung cancer deaths. It was in moving that highest airborne levels of polynuclear aromatic hydrocarbons had been discovered in an independent environmental investigation.
Epidemiology, 2001
We evaluated the mortality and cancer experience of employees of the chemical industry in the United States and western Europe, as reported in the peer-reviewed literature between 1966 and 1997 (Ͼ1 million workers and Ͼ15 million personyears). Cohort studies (N ϭ 461) were grouped (N ϭ 181) so that specific populations could be traced from the earliest to the most recently published report, and we extracted observed and expected numbers of cases for each of 35 mortality and 23 cancer incidence endpoints. We then generated standardized mortality ratios or standardized incidence ratios and 95% confidence intervals, and undertook meta-analyses of subcohorts (for example, gender, latency, or duration of employment), as well as the entire cohort. With few exceptions, the observed cause-specific mortality and site-specific cancer incidences were reassuring: overall, 10% fewer deaths were observed than expected. Fewer than expected deaths from all causes, cardiovascular disease, noncancer respiratory disease, cirrhosis of the liver, and external causes were observed, some or all of which may be attributed to a "healthy worker effect." Meta-analyses revealed weak to moderate excesses of lung and bladder cancers likely caused by occupational exposure to known human carcinogens. We also observed a 10-15% increase in lymphatic and hematopoietic cancers. Additional research is required to gain a more complete understanding of the potential role that methodology and environmental or occupational influences may play in these associations.
The use of regression analyses in a cohort mortality study of welders
Journal of Chronic Diseases, 1986
Using an internal nonexposed comparison group, and two types of regression analysis, we have reanalyzed the data from a cohort mortality study of 3247 welders and 5432 nonwelders who worked in Western Washington during the period 195&1976. Previous analyses relied primarily on the standardized mortality ratio (SMR) for lung cancer as a summary statistic to estimate relative risk; welders were compared to the U.S. population, stratified by age, sex, race, and calendar time. In the present study, nonwelders from the same union were used as the reference group; an internal referent group is often preferable to the U.S. population because it is likely to have shared similar lifestyles (e.g. smoking habits) as the exposed. Cox regression was used to estimate relative risk. In addition, the data was analyzed via logistic regression in order to compare Cox to logistic regression. A regression analysis of these data enabled us to analyze exposure as a continuous variable and simultaneously adjust for potentially confounding variables without stratification. Interactions terms could also be easily tested. The previous analysis found as SMR for lung cancer of 1.32 (p = 0.06). Cox regression with an internal comparison group yielded similar results. Issues discussed include the differences between logistic and Cox regression, the appropriate variable for time in Cox regression, and the definition of risk set in Cox regression. Finally, a newly available program is discussed which selects random samples of the risk sets used in Cox regression, in order to do a case-control analysis.
American Journal of Industrial Medicine, 1988
Occupational cohort studies are usually carried out without the benefit of information on smoking habits of cohort members. One common approach to avoid confounding bias related to smoking habits is to carry out an internal analysis, comparing workers with different degrees of occupational exposure. The premise behind this approach is that within a cohort there is unlikely to be correlation between degree of exposure and smoking habits. If this were untrue, smoking could confound the disease-exposure relationships. Our purpose was to verify the premise. The study sample consisted of 857 French-Canadian men born between 1910 and 1930, with 11 or fewer years of education, and interviewed around 1980 in the context of an occupational cancer case-control study. For each man we had information on smoking habits, job history, and a history of the chemicals he was exposed to in each of his jobs. We computed two indices of the dirtiness of workers' job histories: one based on the job titles held by the man and a second based on the degree of exposures to workplace substances. There was no correlation between these indices of job dirtiness and smoking history. We also examined the smoking-exposure relationship among the subsets of men who had been occupationally exposed to ten especially noticeable substances. Within the subsets, there was no indication of a consistent difference among the smoking subgroups in level or duration of exposure to these index substances. These findings do not support the view that nonsmokers sought out cleaner job environments than smokers; they imply that internal analyses of "dose-response" in cohort studies are unlikely to be seriously confounded by smoking habits.