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A nested case-control study was used to investigate the relation between a range of electromagnetic field exposures and brain tumor risk in the US Air Force. Cumulative extremely low frequency and radiofrequency/microwave electromagnetic field potential exposures were estimated from a job-exposure matrix developed for this study. Ionizing radiation exposures were obtained from personal dosimetry records. Men who were exposed to nonionizing electromagnetic fields had a small excess risk for developing brain tumors, with the extremely low frequency and radiofrequency/microwave age-race-senior military rank-adjusted odds ratios being 1.28 (95% confidence interval (Cl) 0.95-1.74) and 1.39 (95% Cl 1.01-1.90), respectively. By contrast, men who were exposed to ionizing radiation had an age-race-senior military rank-adjusted odds ratio of 0.58 (95% Cl 0.22-1.52). These results support a small association between extremely low frequency and radiofrequency/microwave electromagnetic field exposure and no association between ionizing radiation exposure and brain tumors in the US Air Force population. Military rank was consistently associated with brain tumor risk. Officers were more likely than enlisted men to develop brain tumors (age-race-adjusted odds ratio (OR) = 2.11, 95% Cl 1.48-3.01), and senior officers were at increased risk compared with all other US Air Force members (age-race-adjusted OR = 3.30, 95% Cl 1.99-5.45).

Unlabelled: We compared the cancer incidence of male United States Air Force (USAF) aircrew (342 cancers, 532,980.97 man-years) with non-flying Air Force officers (827 cancers, 1,084,370.08 man-years) between 1975-89., Methods: Incident cancer cases for both aviators and non-flying officers were obtained from USAF hospitalization records. Age-adjusted standardized incidence ratios (SIR's) were calculated for aircrew using data from the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program. Aviator age-adjusted cancer rate ratios were also obtained using non-flying officers as an internal comparison group., Results: We observed statistically significant excesses of aircrew cancers for all sites, testis, and urinary bladder. All other aviator cancer classifications were not significantly different from the comparison cohort; most notably, cancers of the colon and rectum, skin (both malignant melanoma and non-epithelial), brain and nervous system, Hodgkin's Disease and leukemias., Conclusion: Previous studies of commercial pilots that demonstrated excesses of these cancers may have been biased by the use of external comparison groups. We used an internal comparison population to reduce selection bias, information bias and confounding. From these data we detected notable excess aircrew cancer risk for cancers of the testis, urinary bladder, and all sites combined.

The association between prior hearing losses and susceptibility to future permanent threshold shifts was examined by a matched pairs case-control study. Data were obtained from the United States Air Force Hearing Conservation Data Registry, which contains over three million audiometric records. Cases with permanent hearing losses were matched with normal controls for relative noise exposure intensity, years of exposure, and age. Based on analysis with normal or abnormal baseline hearing as the risk factor, cases with abnormal initial hearing were no more likely than controls to develop future permanent threshold shifts (odds ratio = 1.06, 95% confidence interval 0.61-1.85).