Where are the thresholds for biological effects of non-endogenous low frequency, low intensity electric and magnetic: Fields?: Introduction to a "Mini Symposium": Definition of the problem

A number of laboratory experiments have shown in vitro and in vivo biological effects of very low intensity exogenous electric and magnetic fields. Intensities are so low that one would expect the applied signals to be submerged by organism generated electrical noise. In many cases calculated values of the induced electric fields are even below thermal noise. Some epidemiological studies suggest possible health effects at even lower field intensities. The magnitudes of the fields under discussion are specified and some of the problems encountered in developing models and explaining effects are introduced.