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Titolo:
Energy deposition processes in biological tissue: Nonthermal biohazards seem unlikely in the ultra-high frequency range
Autore:
Pickard, WF; Moros, EG;
Indirizzi:
Washington Univ, Dept Elect Engn, St Louis, MO 63130 USA Washington Univ St Louis MO USA 63130 Elect Engn, St Louis, MO 63130 USA Washington Univ, Mallinckrodt Inst Radiol, Radiat Oncol Sect, St Louis, MOUSA Washington Univ St Louis MO USA diol, Radiat Oncol Sect, St Louis, MOUSA
Titolo Testata:
BIOELECTROMAGNETICS
fascicolo: 2, volume: 22, anno: 2001,
pagine: 97 - 105
SICI:
0197-8462(200102)22:2<97:EDPIBT>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
SHIELDED EXPOSURE SYSTEM; ELECTROMAGNETIC-FIELDS; DIELECTRIC-PROPERTIES; CROSS-SECTIONS; IRRADIATION; ABSORPTION; MAGNETITE; DESIGN; LEVEL;
Keywords:
specific absorption rate; constitutive parameters; SAR; magnetosomes; dielectric relaxation; multiphoton absorption;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Pickard, WF Washington Univ, Dept Elect Engn, 1 Brookings Dr, St Louis, MO63130 USA Washington Univ 1 Brookings Dr St Louis MO USA 63130 63130 USA
Citazione:
W.F. Pickard e E.G. Moros, "Energy deposition processes in biological tissue: Nonthermal biohazards seem unlikely in the ultra-high frequency range", BIOELECTROM, 22(2), 2001, pp. 97-105

Abstract

The prospects of ultra high frequency (UHF, 300-3000 MHz) irradiation producing a nonthermal bioeffect are considered theoretically and found to be small. First, a general formula is derived within the framework of macroscopic electrodynamics for the specific absorption rate of microwaves in a biological tissue; this involves the complex Poynting vector, the mass density of the medium, the angular frequency of the electromagnetic field, and the three complex electromagnetic constitutive parameters of the medium. In thefrequency ranges used for cellular telephony and personal communication systems, this model predicts that the chief physical loss mechanism will be ionic conduction, with increasingly important contributions from dielectric relaxation as the frequency rises. However, even in a magnetite unit cell within a magnetosome the deposition rate should not exceed 1/10 k(B)T per second. This supports previous arguments for the improbability of biological effects at UHF frequencies unless a mechanism can be found for accumulatingenergy over time and space and focussing it. Second, three possible nonthermal accumulation mechanisms are then considered and shown to he unlikely: (i) multiphoton absorption processes; (ii) direct electric field effects onions; (iii) cooperative effects and/or coherent excitations. Finally, it is concluded that the rate of energy deposition from a typical field and within a typical tissue is so small as to make unlikely any significant nonthermal biological effect. Bioelectromagnetics 22:97-105, 2001. (C) 2001 Wiley-Liss, Inc.

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Documento generato il 31/03/20 alle ore 10:14:36