G. D'Inzeo

Systematic review of wireless phone use and brain cancer and other head tumors

We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta-analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long-term use (≥ 10 years). Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer-term use (≥ 10 years).

Method of Analysis and Filtering Properties of Microwave Planar Networks

A method of analysis of planar microwave structures, based on a field expansion in term of resonant modes, is presented. A first advantage of the method consists in the possibility of taking into account fringe effects by introducing, for each resonant mode, an equivalent model of the structure. Moreover, the electromagnetic interpretation of the filtering properties of two-port networks, particularly of the transmission zeros, whose nature has been the subject of several discussions, is easily obtained. The existence of two types of transmission zeros, modal and interaction zeros is pointed out. The first ones are due to the structures resonances, while the second ones are due to the interaction between resonant modes. Several experiments performed on circular and rectanguIar microstrips in the frequency range 2-18 GHz have shown a good agreement with the theory.

Integrated models for the analysis of biological effects of EM fields used for mobile communications

The understanding of the modalities of interaction of electromagnetic (EM) fields with biological material is a key point in the identification of possible induced effects. Since the beginnings of bioelectromagnetic research studies, most of the attention has been focused on the effects on nervous systems and neuronal cells. The importance of this target has recently increased due to the wide diffusion of mobile terminals, used close to the head. In this paper, an integrated interaction model is proposed. The model, validated in each part of its components with experimental data, allows to obtain a quantitative link from the external applied field to the effects on neurons (isolated or linked to similar others). The models is firstly based on the evaluation of the EM field at cellular membrane level, then on the evaluation of the effects induced on each component of the model growing from the low biophysical level (membrane channels) to the biological one (neuron time behavior). The use of well-assessed models for the simulations of each part allows both the evaluation of the effect at different levels of complexity and the employment of this effect acting as an input on the upper level. This approach allows, for the first time, a complete quantitative evaluation of the effects on neurons due to the fields from the existing mobile systems, and can be a useful instrument for the evaluation of the possible health impact of new technologies.

Feasibility for Microwaves Energy to Affect Biological Systems Via Nonthermal Mechanisms: A Systematic Approach

The understanding of possible nonthermal bio-effects has been an open question during the last five decades. In this paper, the authors present a critical literature review of the models of the interaction mechanisms, together with an overview of all the publications finding positive results for in vitro and in vivo studies. The systematic approach consisted of pooling together the positive studies on the basis of the endpoints and the biological systems, to identify specific plausible targets of the action of the electromagnetic fields and the related pathways. Such a classification opens the way to the discussion of some hypotheses of interaction mechanisms considered as first transduction step. The authors conclude that only through a multiscale methodology it is possible to perform a comprehensive study of the nonthermal effects, based on affordable and realistic in silico models.

Effect of high exogenous electric pulses on protein conformation: myoglobin as a case study.

Protein folding and unfolding under the effect of exogenous perturbations remains a topic of great interest, further enhanced by recent technological developments in the field of signal generation that allow the use of intense ultrashort electric pulses to directly interact at microscopic level with biological matter. In this paper, we show results from molecular dynamics (MD) simulations of a single myoglobin molecule in water exposed to pulsed and static electric fields, ranging from 10(8) to 10(9) V/m, compared to data with unexposed conditions. We have found that the highest intensity (10(9) V/m) produced a fast transition (occurring within a few hundreds of picoseconds) between folded and unfolded states, as inferred by secondary structures and geometrical analysis. Fields of 10(8) V/m, on the contrary, produced no significant denaturation, although a relevant effect on the protein dipolar behavior was detected.

Quantitative assessment of dielectric parameters for membrane lipid bi-layers from RF permittivity measurements

In this article, we propose and validate theoretical and experimental methods to quantitatively assess the Debye dielectric model of membrane lipid bi-layers. This consists of two steps: permittivity measurements of biological solutions (liposomes), and estimation of the model parameters by inverse application of the Effective Medium Theory. The measurements are conducted in the frequency domain between 100 MHz and 2 GHz using a modified coaxial connector, at the temperatures of 27 and 30 degrees C. Estimations have been performed using a three-layered model based on the Maxwell-Wagner formulation. Debye parameters (mean value +/- standard error) found from fitting experimental data are: epsilon(s) = 11.69 +/- 0.09, epsilon(infinity) = 4.00 +/- 0.07, f(relax) = 179.85 +/- 6.20 MHz and epsilon(s) = (1.1 +/- 0.1) x 10(-7) S/m. This model can be used in microdosimetric studies aiming to precisely determine the E-field distribution in a biological target down to the single cell level. In this context the use of an accurate membrane dielectric model, valid through a wide frequency range, is particularly appropriate.

Microdosimetry for Nanosecond Pulsed Electric Field Applications: A Parametric Study for a Single Cell

A microdosimetric study of nanosecond pulsed electric fields, including dielectric dispersivity of cell compartments, is proposed in our paper. A quasi-static solution based on the Laplace equation was adapted to wideband signals and used to address the problem of electric field estimation at cellular level. The electric solution was coupled with an asymptotic electroporation model able to predict membrane pore density. An initial result of our paper is the relevance of the dielectric dispersivity, providing evidence that both the transmembrane potential and the pore density are strongly influenced by the choice of modeling used. We note the crucial role played by the dielectric properties of the membrane that can greatly impact on the poration of the cell. This can partly explain the selective action reported on cancerous cells in mixed populations, if one considers that tumor cells may present different dielectric responses. Moreover, these kinds of studies can be useful to determine the appropriate setting of nsPEF generators as well as for the design and optimization of new-generation devices.

Mixed Quantum-Classical Methods for Molecular Simulations of Biochemical Reactions With Microwave Fields: The Case Study of Myoglobin

Contradictory data in the huge literature on microwaves bio-effects may result from a poor understanding of the mechanisms of interaction between microwaves and biological systems. Molecular simulations of biochemical processes seem to be a promising tool to comprehend microwave induced bio-effects. Molecular simulations of classical and quantum events involved in relevant biochemical processes enable to follow the dynamic evolution of a biochemical reaction in the presence of microwave fields. In this paper, the action of a microwave signal (1 GHz) on the covalent binding process of a ligand (carbon monoxide) to a protein (myoglobin) has been studied. Our results indicate that microwave fields, with intensities much below the atomic/molecular electric interactions, cannot affect such biochemical process.

A 3-D Microdosimetric Study on Blood Cells: A Permittivity Model of Cell Membrane and Stochastic Electromagnetic Analysis

This paper describes a microdosimetric study on erythrocytes in two parts: an assessment of the membrane dielectric model from permittivity measurements of erythrocyte solutions and its uncertainty, and a quasi-static electromagnetic (EM) analysis solving the Laplace equation, both analytically and numerically. To evaluate the role of the estimated uncertainty, a stochastic EM solution has been conducted; our results highlight the fundamental role of the dielectric modeling on the reliability of electric field values in the cell membrane. Numerical data, from 3-D cell models, confirm the dependence of the electric field distribution on the extra-cellular field polarization.

A coplanar-waveguide system for cells exposure during electrophysiological recordings

In order to investigate the biological effects of microwave electromagnetic fields as those emitted from mobile telecommunications equipment, a suitable exposure system has been designed. The system is specific for real time acquisition of cellular membrane ionic currents, i.e. patch-clamp recordings. Both the numerical and the experimental characterization of the system is considered, in terms of EM field distribution and SAR inside the Petri dish containing the biological target. Results show a good efficiency of the system in terms of SAR induced in the sample by incident input power.