Reply to ‘‘Comment on ‘Constraints on biological effects of weak extremely-low-frequency electromagnetic fields’ ’’

Kirschvink [preceding Comment, Phys. Rev. A 46, 2178 (1992)] objects to my conclusions [Phys. Rev. A 43, 1039 (1991)] that weak extremely-low-frequency (ELF) electromagnetic fields cannot affect biology on the cell level. He argues that I did not properly consider the interaction of such fields with magnetite (${\mathrm{Fe}}_3$ ${\mathrm{O}}_4$) grains in cells and that such interactions can induce biological effects. However, his model, designed as a proof of principle that the interaction of weak 60-Hz ELF fields with magnetite domains in a cell can affect cell biology, requires, by his account, a magnetic field of 0.14 mT (1400 mG) to operate, while my paper purported to demonstrate only that fields smaller than 0.05 mT (500 mG) must be ineffective. I then discuss ELF interactions with magnetite generally and show that the failure of Kirschvink’s model to respond to weak fields must be general and that no plausible interaction with biological magnetite of 60-Hz magnetic fields with a strength less than 0.05 mT can affect biology on the cell level.