Incidence of leukemia in occupations with potential electromagnetic field exposure in United States Navy personnel.

Leukemia is the fourth most commonly occurring cancer in the United States population between the ages of 17 and 34 years, an age group heavily represented in the US Navy. Historical computerized military career records maintained at the Naval Health Research Center, San Diego, California, were used to determine person-years at risk (total, 4,072,502 person-years) by demographic characteristics and occupation for active-duty naval personnel during 1974-1984. Computerized inpatient medical records were searched for first hospitalizations for leukemia. Cases of leukemia (n = 102) were verified by using pathology reports or Navy Medical Board or Physical Evaluation Board findings. For comparisons, age-adjusted incidence rates and standardized incidence ratios were calculated by using rates for the US population provided by the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. The overall age-adjusted incidence rate of leukemia in active-duty naval personnel was found to be very close to that of the Surveillance, Epidemiology, and End Results program population (6.0 vs. 6.5 per 100,000 person-years). Only one occupation, electrician's mate, emerged with a borderline statistically significant excess risk of leukemia (standardized incidence ratio compared with the Surveillance, Epidemiology, and End Results program population = 2.4, 95% confidence interval 1.0-5.0). This finding is intriguing in the light of several studies showing an excess risk of leukemia associated with exposure to electromagnetic fields.