Biological Effects Due to Weak Electric and Magnetic Fields: The Temperature Variation Threshold

Abstract

A large number of epidemiological and experimental studies suggest that prolonged (>100 s) weak 50-60-Hz electric and magnetic field (EMF) exposures may cause biological effects(NIEHS Working Group, NIH, 1998; Bersani, 1999). We show, however, that for typical temperature sensitivities of biochemical processes, realistic temperature variations during long exposures raise the threshold exposure by two to three orders of magnitude over a fundamental value, independent of the biophysical coupling mechanism. Temperature variations have been omitted in previous theoretical analyses of possible weak field effects, particularly stochastic resonance (Bezrukov and Vodyanoy 1997a. Nature. 385:319-321; Astumian et al., 1997 Nature. 338:632-633; Bezrukov and Vodyanoy, 1997b. Nature. 338:663; Dykman and McClintock, 1998. Nature. 391:344; McClintock, 1998;. Gammaitoni et al., 1998. Rev. Mod. Phys. 70:223-287). Although sensory systems usually respond to much shorter (approximately 1 s) exposures and can approach fundamental limits (Bialek, 1987 Annu. Rev. Biophys. Biophys. Chem. 16:455-468; Adair et al, 1998. Chaos. 8:576-587), our results significantly decrease the plausibility of effects for nonsensory biological systems due to prolonged, weak-field exposures.

Childhood leukemia: electric and magnetic fields as possible risk factors.

“…But the accumulated change in flux or receptorbound number also varies because of other natural processes, which constitute a generalized chemical noise (N), including the sources listed in Table 6. The totality of the sources of competing chemical change on Table 6, (N ∆N + N ∆T + N ∆C + N ∆M + N ∆E ), can be expected to be much larger for humans in vivo than for cellular preparations studied in vitro (Weaver et al 1999). Therefore, for the intact organism, the overall chemistrybased signal-to-noise ratio can be written symbolically as…”

“…If the competing changes can be regarded as random (and independent), then each of the competing changes can be added as the sum of their magnitudes squared (Weaver et al 1999). In summary, the in vivo human biochemical environment exhibits considerable noise.…”

“…This inherent, background noise must be quantitatively reconciled with the relatively small levels of 60-Hz EMF "signal" if one is to predict alteration of ongoing biochemical processes by EMFs. The effect threshold for voltage-gated channels in single, long cells is predicted to be about 50 V/m, which in a human-sized organism corresponds to the electric field induced by a magnetic field of about 1 T (10,000 G) (Weaver et al 1999). If temperature noise is ignored, the threshold electric field is about 0.1 V/m, which corresponds to a magnetic field of 6,000 µT (60 G) (Weaver et al 1999).…”

“…The effect threshold for voltage-gated channels in single, long cells is predicted to be about 50 V/m, which in a human-sized organism corresponds to the electric field induced by a magnetic field of about 1 T (10,000 G) (Weaver et al 1999). If temperature noise is ignored, the threshold electric field is about 0.1 V/m, which corresponds to a magnetic field of 6,000 µT (60 G) (Weaver et al 1999). As system size increases, fundamental noise tends to increase at a slower rate than does the induced EMF signal.…”

The Effect of Spatially Inhomogeneous Electromagnetic Field and Local Inductive Hyperthermia on Nonlinear Dynamics of the Growth for Transplanted Animal Tumors

“…Therefore, the cell cycle shifts from the non-proliferative to proliferative phase that leads to increased antitumor activity of the drug (Ivkov et al, 2005;Jin et al, 1998;Orel et al,2005). It is well known that EF can influence the chemical reactions to raise their activation energies above threshold levels of thermal noise (Weaver et al,1999). Nonthermal effects can reduce existing disadvantages on all of the classical thermal treatment (Blank & Soo, 2001;Longo & Ricci, 2007).…”