Claudio R. Fernández, Giovani Bulla and Alvaro A. A. de Salles Electrical Engineering Department

II Congreso Interamericano de Salud Ambiental

Taller Radiaciones No IonizantesDr. Carlos Barceló -presidente

“Los Riesgos de la Telefonía Móvil y el Principio de

Precaución”

Claudio R. Fernández, Giovani Bulla and Alvaro A. A. de Salles

Electrical Engineering Department

Federal University of Rio Grande do Sul - UFRGS

P. Alegre, RS, Brazil. To be presented by Dr. Carlos Eduardo C. Abrahão,

CoViSA, Campinas, SP, Brazil.

• I. INTRODUCTION

• II. MODELLING

• III. RESULTS

• IV. DISCUSSIONS AND CONCLUSIONS

“Los Riesgos de la Telefonía Móvil y el Principio de Precaución”

I. INTRODUCTION-Motivation and

Relevance

• The use of cell phones by young and children has been strongly stimulated.• The concern regarding safety increase.• The exposure limits were adopted based on studies made for adults.

““Los Riesgos de la Telefonía Móvil y el Principio de Precaución”

I. INTRODUCTION- Motivation and Relevance

•Today there are more than 1,6 billions of cell phones in the world.

•A substantial percentage of this now includes children and teenagers.


I. UK and WHO The UK Department of Health said:

"Our advice is that all children under the age of 16 should use a precautionary approach”.Daily Thelegraph, Jan. 12 2005. Dr. Gro Harlem Brundtland, Director-general of the WHO said in July 1, 2002 :

“I would be cautious about letting children use mobile phones for hours everyday, because we don’t know enough about the damage”. Microwave News, VXXII, n. 4, July/August 2002, p. 8.


I. INTRODUCTION -

This work • “Finite Difference Time Domain”-FDTD simulations of the “Specific Absorption Rate”-SAR in the head of a child and adults when using cell phones are presented.

• A new model based on a 10 year old child computed tomographic images is used.

• The electromagnetic parameters were fitted to this age.


• I. INTRODUCTION

• II. MODELLING

• III. RESULTS



•The geometric and the electromagnetic (e.g., relative permittivity and conductivity) parameter differences between the adult and the child were considered in the simulations.

II. MODELLING


II. MODELLING: The Antropomorphic

Numerical Models

Saggital cut of the 10 years old child rotated model.

Saggital cut of the adult rotated model.


The Fitted Electromagnetic Parameters where obtained from “Changes in the dielectric properties of rat tissues as a function of age at microwave frequencies”, A. Peyman, A. A. Rezazadeh and C. Gabriel, Phys. in Med. and Biol., 46, 2001, 1617-1629.

II. MODELLING:


PHYSICAL PROPERTIES FOR THE ADULT MAN AND FITTED FOR THE 10 YEARS OLD CHILD AT 1800 MHZ

Age adult 10 years old Properties ρ(g/cm3) εr σ(Ω-1/m) εr σ(Ω-1/m) Air 0.00 1.00 0.00 1.00 0.00 Average Skull 1.85 15.56 0.43 18.48 0.54 Skin (Wet) 1.01 43.85 1.23 54.63 1.53 Average Muscle 1.04 54.44 1.39 61.68 1.57 Average Brain 1.03 43.54 1.15 52.52 1.44 Vitreous Humour 1.01 68.57 2.03 81.81 2.47 Fat (Mean) 0.92 11.02 0.19 13.15 0.23 Eye Tissue (Sclera) 1.17 53.57 1.60 63.91 1.95 Brain Spinal Fluid 1.01 67.20 2.92 80.17 3.55 Nerve (Spinal chord) 1.04 30.87 0.84 36.83 1.02 Lens Nucleus 1.10 34.65 0.79 41.34 0.96

II. MODELLING: The Fitted Electromagnetic Parameters


II. ANTROPOMORPHIC NUMERICAL MODELS

• The cranial perimeters in both models were approximated from ellipsis. The calculated values are in close agreement with those shown by F. Schoenborn, M. Burkhardt, and N. Kuster in “Differences in energy absorption between heads of adults and children in the near field of sources”, Health Physics, vol 74, No. 2, pp. 160-168, Febr. 1998.

SPATIAL DISCRETIZATION Model Adult 10 years old Cases A B and C Scale factor 1 1 Cranial perimeter (mm) 563.5 523.9 Δx (mm) 0.764 0.946 Δy (mm) 1.920 1.892 Δz (mm) 1.920 2.044 Antenna distance (mm) 14.51 14.19

• I. INTRODUCTION

• II. MODELLING

• III. RESULTS



III. RESULTS

The results were compared with those obtained for the 1g average SAR in the adult, assumed to be in the 1,6 W/kg SAR recommended IEEE/ANSI exposure limit.


III. RESULTS


SAR in the Head Adult 10 years old child

Comparison with O. P. Gandhi, G. Lazzi, and C. M. Furse, “Electromagnetic Absorption in the human head and neck

for mobile telephones at 835 MHz and 1900 MHz”, IEEE Trans. on MTT, v. 44, No. 10, pp. 1884-1897, Oct 1996.


III. RESULTS


• SAR for the adult.

• The SAR results for the children are compared to these results.


• SAR for the children using adult electro-magnetic parameters.

• 1g-SAR: increase of ~60% with respect to the adult.

III. RESULTS


• SAR for the children using fitted electro-magnetic parameters.

• 1g-SAR: increase of ~80% with respect to the adult.

III. RESULTS

Model Adult 10 years old childElectromagnetic Adult Adult Children parameters

Normalised values (W/kg) Peak SAR (one voxel) 1.704 3.356 3.636 1g-SAR 1.600 2.618 2.868 10g-SAR 1.319 1.984 2.119

Percentage difference (increase/decrease) Peak SAR (one voxel) +6.5% +109.7%

+127.3% 1g-SAR 0% +63.6% +79.2% 10g-SAR -18% +24.0% +32.5%

III. RESULTS


• I. INTRODUCTION

• II. MODELLING

• III. RESULTS



IV. DISCUSSIONS AND CONCLUSIONS

• The SAR in the 10 years old child was calculated and compared to the results obtained for adult.

• SAR results around 80% higher than those for the adults were observed for the children.

• This is expected to be due to differences in dimensions and electromagnetic parameters, and is in accordance with the results obtained in O. P. Gandhi, G. Lazzi, and C. M. Furse, “Electromagnetic Absorption in the human head and neck for mobile telephones at 835 MHz and 1900 MHz”, IEEE Trans. on MTT, v. 44, No. 10, pp. 1884-1897, Oct 1996. .



• Due to the increase in the use of mobile phones by children, and since compliance tests use head phantoms based exclusively on adult data, the results shown in this paper may suggest that further theoretical and experimental research must be done in order to evaluate these issues, aiming to reduce risks for the children.



This is in accordance to the WHO – World Health Organization effort, included in the WHO Children’s EMF Research Agenda, recommending research studies relevant to the risk of adverse health effects in children from exposure to electromagnetic fields-EMF, available at www.who.int/peh- emf/research/children/en/print.html.


Electrical Engineerind Department, Federal University of Rio Grande do Sul- UFRGS

Porto Alegre, RS, Brazil.


Claudio R. Fernández: [email protected] Bulla: [email protected]

Alvaro A. A . de Salles: [email protected]

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Claudio R. Fernández, Giovani Bulla and Alvaro A. A. de Salles Electrical Engineering Department