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

Objectives: To assess the risks for adult-onset acute leukemia associated w ith electrical employment in New Zealand. Methods: The occupational and environmental exposures histories of 110 inci dent 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 m ore of the "electrical occupations," the degree of exposures to extremely l ow 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 h ad ever worked in an electrical occupation. Significantly increased risks f or 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 le ukemia 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 s mall. A dose-response effect was also found, with acute leukemia risk risin g with increasing occupational magnetic field exposure, based on both curre nt and historical occupational field exposure estimates. Conclusions: The findings of the current study indicate a significantly ele vated risk of acute leukemia for electrical workers overall, and for the sp ecific occupational categories of welders/flame cutters and telephone line workers. A dose-response effect was also found, indicating that acute leuke mia risk was related to historical and current magnetic field exposures in an occupational context.