Background: Exposure to 60-Hz magnetic fields may increase breast cancer risk by suppressing the nocturnal production of melatonin. The use of medications associated with reduced melatonin levels could modify this relationship.
Methods: We recontacted participants in a population-based case-control study of residential magnetic field exposure and breast cancer risk and interviewed them regarding medication use during the 10 years before diagnosis. Cases were diagnosed between November 1992 and March 1995, and magnetic field levels were measured in the home at diagnosis. We obtained medication use information by telephone interview from 558 cases and 588 controls.
Results: Breast cancer risk was not associated with exposure to residential magnetic fields, regardless of medication use.
Conclusions: These results support previous findings that magnetic field exposure does not increase breast cancer risk.