A surprising answer in the search for a comprehensive health protection exposure metric for radiofrequency (RF) fields

Matter can interact with light in 3 different ways (known by 1910): by absorption of energy [\it thermal \rm hazard] or by absorption of linear momentum (radiation pressure) or of angular momentum (torque) or of both [\it nonthermal \rm hazards].$^{1,2}$ The same is true for RF fields; indeed, microwave wattmeters may operate on a momentum absorption principle.$^{3,4}$ But most RF health protection standards today are based solely on \it thermal \rm effects, ignoring nonthermal effects. Formal expressions for scientifically valid exposure metrics will be presented. It will be shown that nonthermal effects depend on field frequency, polarization and spatial configuration as well as on field strength, so a \it general \rm metric valid for \it all \rm fields may not exist. But with some approximations, the \it magnetic induction current \rm may constitute an adequate \it practical \rm exposure metric for RF fields. $^1$M. Lundquist, BAPS \bf 50\rm (1):620(2005). $^2 $M. Lundquist, BAPS \bf 50\rm (1):1178(2005). $^3$A. L. Cullen, Proc. IEE \bf 99\rm Pt4(2):100-110(Apr 1952). $^4$A. L. Cullen \& I. M. Stephenson, Proc. IEE \bf 99\rm Pt4(4):294-301(Dec 1952).