Symptoms: Symptoms consistent with a nonmalignant respiratory disorder may be identified by using standardized self-administered or interview-administered questionnaires.
Pulmonary-function testing: Pulmonary-function testing, particularly spirometry, is commonly used to evaluate respiratory function clinically and in epidemiologic studies. Major measures include forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1:FVC ratio. The latter is indicative of COPD and asthma. A statistical association between a pulmonary-function test result and a measured exposure suggests that the exposure agent has the potential to produce disease in people who are sufficiently exposed.
Radiographic (imaging) studies: “Chest X-ray” testing is particularly useful for diagnosing interstitial lung diseases, such as pneumoconiosis. Such methods are widely used in studies of occupational cohorts exposed to agents other than uranium but have had only limited application to uranium-exposed workers.
There are numerous diseases of the nervous system, and, as described in Chapters 7 and 8, the epidemiologic studies of uranium-exposed populations do not specify individual neurologic diseases in their analyses. Prevalence, incidence, and risk factors vary among nervous system diseases. Several studies have suggested an increased risk of amyotrophic lateral sclerosis in Gulf War veterans (IOM, 2006a), but no risk factor has been identified. Neurocognitive and neurobehavioral outcomes have been assessed in a group of Gulf War veterans who were exposed to depleted uranium.
Birth defects occur in about one in 33 live births in the United States (CDC, 2007a). The numerous types of birth defects—several thousand have been identified—include structural defects, chromosomal abnormalities, and birth-defect syndromes (California Birth Defects Monitoring Program, 2006; March of Dimes, 2006). The most common birth defects in the United States are cleft palate, cleft lip, and Down syndrome (March of Dimes, 2006). Birth defects are caused by genetic and environmental factors (for example, chemicals and infectious agents) or a combination of such factors. The causes of most cases of birth defects are unknown (CDC, 2007a).
In addition to birth defects, adverse outcomes of pregnancy include early pregnancy loss (before 8 weeks), spontaneous abortion (8-20 weeks), ectopic pregnancy, and late fetal death and stillbirth. Such outcomes, especially early