Acute leukemia in electrical workers: a New Zealand case-control study

Objectives: To assess the risks for adult-onset acute leukemia associated with electrical employment in New Zealand. Methods: The occupational and environmental exposures histories of 110 incident leukemia cases and 199 general population controls were compared. The cases were recruited through referrals to treatment centers in New Zealand between 1989 and 1991. For subjects classified as having worked in one or more of the "electrical occupations," the degree of exposures to extremely low frequency electromagnetic fields (ELF-EMFs) was assessed in detail using a job-exposure matrix. Results: An odds ratio of 1.9 (95% Cl 1.0-3.8) was found for subjects who had ever worked in an electrical occupation. Significantly increased risks for leukemia are seen amongst welders/flame cutters (OR = 2.8 (95% Cl 1.2-6.8)) and telephone line workers (OR = 5.81 (95% Cl 1.2-27.8)). The excess leukemia risk appeared to be confined to acute non-lymphocytic leukemia (OR = 2.31 (95% Cl 1.2-4.6)), in comparison to acute lymphoblastic leukemia (OR = 0.9 (95% Cl 0.3-2.9)) but for the latter category the numbers were very small. A dose-response effect was also found, with acute leukemia risk rising with increasing occupational magnetic field exposure, based on both current and historical occupational field exposure estimates. Conclusions: The findings of the current study indicate a significantly elevated risk of acute leukemia for electrical workers overall, and for the specific occupational categories of welders/flame cutters and telephone line workers. A dose-response effect was also found, indicating that acute leukemia risk was related to historical and current magnetic field exposures in an occupational context.