patterns and health outcomes in deployed service personnel. It ends with studies of environmental exposures. In each instance, the study populations and methods—including study design, measures of exposure, and assessment of outcomes—used by the investigators are described. Tables that summarize the studies are included at the end of the chapter.
The traditional 5% level of statistical significance is used in reporting findings. Results that did not reach the 5% level of statistical significance are described as nonsignificant.
Studies of workers in the uranium-processing and uranium-machining industry are essential for understanding the long-term health effects of uranium exposure. Cohort studies assessing mortality patterns in processing workers have been conducted for some time. The studies of interest include uranium millers and other processors working in plants that process and refine uranium ore into metals for commercial and nuclear use. During refinement and enrichment, workers are exposed to a number of hazardous substances, including chemical toxicants and potential carcinogens. Processing workers are exposed primarily to uranium oxides and derivative uranium compounds produced during the refinement process and other substances that contribute to adverse health outcomes. The studies described present a picture of diverse work histories and varied levels of exposure to enriched uranium, soluble and insoluble uranium compounds, other radioactive elements (such as radium and thorium), and other potentially hazardous industrial chemicals (such as sulfuric acid and fluorocarbons).
In occupational settings, exposure is often prolonged, occurring over a period of several months to years in contrast with the shorter periods of exposure experienced by Gulf War veterans in friendly-fire incidents. Exposure also was greatest in the early years of the procurement and processing initiative in the United States, when safety measures were not as stringent. In occupational studies, exposure is generally assessed through work histories using cumulative measurement of exposure. Inhalation of dust that contains uranium compounds was the primary route of entry of uranium in processing plants, a route analogous to that of many Gulf War veterans exposed to depleted uranium during friendly-fire incidents.
This section first details the cohorts reviewed in Volume 1, including updates on the cohorts published after the release of the report in 2000. That information is summarized in Table 7-1. In general, cohorts that did not have updates since that report are not included here, but they are included if there are data on health outcomes in them that were not considered in Volume 1. The section then describes new processing cohorts, including studies of uranium processors in the United Kingdom.