Studies of the mortality among nuclear industry workforces have been carried out, and nationally combined analyses performed, in the U.S., the UK and Canada. This paper presents the results of internationally combined analyses of mortality data on 95,673 workers (85.4% men) monitored for external exposure to ionizing radiation and employed for 6 months or longer in the nuclear industry of one of the three countries. These analyses were undertaken to obtain a more precise direct assessment of the carcinogenic effects of protracted low-level exposure to external, predominantly gamma, radiation. The combination of the data from the various studies increases the power to study associations between radiation and specific cancers. The combined analyses covered a total of 2,124,526 person-years (PY) at risk and 15,825 deaths, 3,976 of which were due to cancer. There was no evidence of an association between radiation dose and mortality from all causes or from all cancers. Mortality from leukemia, excluding chronic lymphocytic leukemia (CLL)--the cause of death most strongly and consistently related to radiation dose in studies of atomic bomb survivors and other populations exposed at high dose rates--was significantly associated with cumulative external radiation dose (one-sided P value = 0.046; 119 deaths). Among the 31 other specific types of cancer studied, a significant association was observed only for multiple myeloma (one-sided P value = 0.037; 44 deaths), and this was attributable primarily to the associations reported previously between this disease and radiation dose in the Hanford (U.S.) and Sellafield (UK) cohorts. The excess relative risk (ERR) estimates for all cancers excluding leukemia, and leukemia excluding CLL, the two main groupings of causes of death for which risk estimates have been derived from studies of atomic bomb survivors, were -0.07 per Sv [90% confidence interval (CI): -0.4, 0.3] and 2.18 per Sv (90% CI: 0.1, 5.7), respectively. These values correspond to a relative risk of 0.99 for all cancers excluding leukemia and 1.22 for leukemia excluding CLL for a cumulative protracted dose of 100 mSv compared to 0 mSv. These estimates, which did not differ significantly across cohorts or between men and women, are the most comprehensive and precise direct estimates of cancer risk associated with low-dose protracted exposures obtained to date. Although they are lower than the linear estimates obtained from studies of atomic bomb survivors, they are compatible with a range of possibilities, from a reduction of risk at low doses, to risks twice those on which current radiation protection recommendations are based.(ABSTRACT TRUNCATED AT 400 WORDS)
The study provides a systematic review of the empirical evidence for associations between job burnout and secondary traumatic stress (STS) among professionals working with trauma survivors, indirectly exposed to traumatic material. Differences in the conceptualization and measurement of job burnout and STS were assumed to moderate these associations. A systematic review of literature yielded 41 original studies, analyzing data from a total of 8,256 workers. Meta-analysis indicated that associations between job burnout and STS were strong (weighted r = .69). Studies applying measures developed within the compassion fatigue framework (one of the conceptualizations of job burnout and STS) showed significantly stronger relationships between job burnout and STS, indicating a substantial overlap between measures (weighted r = .74; 55% of shared variance). Research applying other frameworks and measures of job burnout (i.e., stressing the role of emotional exhaustion) and STS (i.e., focusing on symptoms resembling posttraumatic stress disorder or a cognitive shift specific for vicarious trauma) showed weaker, although still substantial associations (weighted r = .58; 34% of shared variance). Significantly stronger associations between job burnout and STS were found for: (a) studies conducted in the United States compared to other countries; (b) studies using English-language versions of the questionnaires compared to other-language versions, and (c) research in predominantly female samples. The results suggest that, due to high correlations between job burnout and STS, there is a substantial likelihood that a professional exposed to secondary trauma would report similar levels of job burnout and STS, particularly if job burnout and STS were measured within the framework of compassion fatigue.
Objective-To analyse the risk of second primary cancers during long term foliow up of patients with Hodgkin's disease.
We describe the analysis of cohort study data with a standard FORTRAN program which should run on most computers. It provides a summary measure of the mortality (or incidence) rate ratio between the study cohort and some standard population, based either on person-years at risk or on proportional mortality, and adjusted for age, sex and calendar period; a test of the statistical significance of the ratio; and a set of observed death rates in the study cohort. Results may also be produced in a form suitable for use with GLIM. The analysis may be subdivided into a range of time intervals since each subject was first exposed to risk. The program provides for movement of subjects between different 'level-of-exposure' subgroups within the cohort, and for various methods of censoring. It allows considerable flexibility in data management, and is available with complete documentation and a worked example. The program should enable epidemiologists with little computing experience to carry out formal analysis of cohort studies.
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