Food and Drug Administration low-level extremely-low-frequency magnetic field exposure facility

We describe the design, construction details, and performance characteristi cs of an exposure system designed to provide very well controlled extremely -low-frequency magnetic field exposures of in vitro samples. This system us es Helmholtz coils placed inside temperature-controlled mu-metal chambers t o provide simultaneous ac and de field exposures at any relative angle with minimal residual background field. The system has both exposed and sham-ex posed chambers and is operated under computer control in such a way as to e nsure blind exposure of samples. (C) 1999 Wiley-Liss, Inc.