A small cohort of Gulf War veterans exposed to DU as a result of friendly-fire accidents has been followed biennially for 16 years to identify uranium-related changes in health, including serum concentrations of free thyroxine and thyroid-stimulating hormone (TSH) as measures of thyroid function (McDiarmid et al., 2000, 2001, 2004, 2006, 2007a,b, 2009). Overall, consistent differences in mean concentrations of free thyroxine and TSH have not been observed when comparing those with high to those with low urinary uranium concentrations. One exception occurred when mean free thyroxine concentrations were found to be lower in the high uranium-exposed group at the 2001 evaluation, but no differences were observed in subsequent evaluations occurring in 2003, 2005, or 2007 (McDiarmid et al., 2007a, 2009; Squibb and McDiarmid, 2006). Although up to 77 DU-exposed Gulf War veterans have been evaluated in this cohort over time, at any single time point only a small subset of individuals were assessed. For example, 35 members underwent clinical evaluation during the most recent 2007 follow-up (McDiarmid et al., 2009). Thus, comparisons are based on small numbers. Additionally, the authors did not adjust for potential confounders between the two groups.
Three secondary studies assessed thyroid function in Gulf War veterans on the basis of self-reports. In 1997, a mail survey of the entire Canadian military contingent of 2924 male veterans who served in the Gulf War and 3241 Canadian veterans who were in the military but had not been posted to the gulf region were asked about the presence of goiter (a form of thyroid disease) or thyroid trouble. Positive responses were reported by 0.9% of the Gulf War veterans and 0.7% of the nondeployed veterans 20-44 years old and by 2.0% of deployed and 1.3% of nondeployed veterans 45-64 years old; the median age of the deployed was 36 years, and that of the nondeployed was 37 years (Goss Gilroy, 1998).
In a study conducted among Kansas veterans, deployed veterans were more likely than their nondeployed counterparts to report thyroid conditions (OR 2.32, 95% CI 0.81-6.67), but numbers were small and therefore estimates of association imprecise (Steele, 2000). Gray et al. (2002), examining Seabee commands, observed an increase in thyroid conditions among the Gulf War deployed Seabees when compared to Seabees deployed elsewhere (OR 1.87, 95% CI 1.16-3.03) but not when compared to the nondeployed members of this cohort (OR 1.49, 95% CI 0.89-2.50).
Obesity is a state of excess adipose tissue mass. The most widely used method to measure obesity is through the body mass index (BMI), defined as the weight in kilograms divided by the square of the height (in meters). Overweight is usually defined as a BMI > 25 kg/m2, while the cutoff point for obesity is a BMI > 30 kg/m2. In the year 2000, the prevalence of obesity in the United States was approximately 30%, while more than 60% of adults older than 20 were overweight. Genetic factors, sedentary lifestyles, and diet are the major determinants of obesity. Obesity was not studied separately in Volume 4.
A study of 686 Danish Gulf War veterans and 231 nondeployed veterans included measurements of weight and height (Ishoy et al., 1999b). The exams were conducted in 1997.