Capri, THz, 2002

Bernard VeyretPIOM Laboratory

College of Chemistry and Physics, Bordeaux

b.veyret@enscpb.fr

Biological Effects in the Microwave, Thz, and Infrared Regions

Biological Effects in the Microwave, Thz, and Infrared Regions

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Frequency SpectrumFrequency SpectrumFrequency SpectrumFrequency Spectrum

1 GHz50/60 Hz

static RF

THz gap

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HistoryHistory

• Microwaves (radars, hyperthermia)

• Mobile telephony (analog, TDAM, CDMA)

• Wireless communications

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Biophysicalintercation

Biochemical changes

Biological effect

Health effect

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Scientific approachesScientific approaches

Biological modelsDosimetry

Biological modelsDosimetry

animalsanimals

cellscells

FoundationsFoundations

epidemiologyepidemiology

humanshumans

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Sources of informationSources of information• Databases

– WHO EMF project (www.who.int/peh-emf/), IEEE, Information Venture, etc.

• Reports, Reviews– ICNIRP, WHO, …– ‘ McKinlay ’, ‘ Stewart ’, ‘ Zmirou ’ ‘ Health Canada ’,

etc.

• Scientific societies– BEMS, EBEA, URSI, etc.

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Sources of informationSources of information

• Peer-reviewed articles

Out of 31,049 refs, only one on THz!

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WHO database mobile telephony signals

WHO database mobile telephony signals

• Cancer relevant or related• completed ongoing total

epidemiology 8 18 26bioassays 6 8 14sensitized in vivo 11 7 18acute in vivo 22 5 27in vitro 50 26 76Total 97 64 161

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WHO databasemobile telephony signals

WHO databasemobile telephony signals

• Non cancer• completed ongoing total

epidemiology 4 0 4human 45 21 66acute in vivo 32 10 42in vitro 15 10 25Total 96 41 137

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WHO databaseWHO database

• mm waves: 12 references (< 94 GHz)

• THz and IR: 0 reference

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Centimetre waves ( > 3 cm)Centimetre waves ( > 3 cm)

• Mechanism: heating• Metric: SAR (W/kg)• ICNIRP basic restriction: 2 W/kg (10 g) • Dosimetry (dielectric properties, numerical

simulations, etc.): satisfactory• Epidemiology:

– Cancer: unconclusive, large study in progress– Symptoms: unconclusive

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cm wavescm waves

• Humans– Minor alterations of sleep, EEG, etc.– No evidence of hypersensitivity

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Whole-body exposure systemWhole-body exposure system

ITIS

mice

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Head-only exposureHead-only exposure

Loop antenna

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Head-mainly exposureHead-mainly exposure

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cm wavescm waves

• Animals – Cancer: negative– Blood-brain-barrier: some evidence > 1 W/kg

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In vitro: exposure systemsIn vitro: exposure systems

Petri dishes

1800 MHz

Kuster et al.

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cm wavescm waves

• Cells– Proliferation: negative– Genotoxicity: negative– Heat shock proteins: positive?

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Millimetre waves (3 cm > > 3 mm)Millimetre waves (3 cm > > 3 mm)

• Basic restriction: irradiance E ICNIRP: 10 W/m2

• Absorption by the skin

• Initial article from Germany: Grundler, W. and Keilmann, F. (1978) Nonthermal effects of millimeter microwaves on yeast growth. Z Naturforsch [C], 33, 15-22.

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mm waves in the FSUmm waves in the FSU

• Basic research and medical applications

• Betski ’s school: 10 mW/cm2 non resonant

• Sitko ’s school: µW/cm2 resonant

• Skin disorders, gastric ulcers, heart disease, and cancer

• Today, most of the Russian scientists work in Europe and USA

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mm wavesmm waves

• Main review: Pakhomov, Bioelectromagnetics, 19, 393-413 (1998)

• Main research groups: Temple University, Philadelphia, and Brooks AF base, TX, USA,

• Research activity likely to increase in the coming years (R-Lan, radar, etc.)

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Main target: skinMain target: skin

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mm waves: cancermm waves: cancer

• Carcinogenesis 2001 Oct;22(10):1701-8

• Lack of effect of 94 GHz radio frequency radiation exposure in an animal model of skin carcinogenesis

• Mason et al. Brooks, TX, USA

• 3.33 W/m2, 10 sec, twice a wk for 12 wks

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Spectrum of waterSpectrum of water

IR THz

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THz (3 mm > > 15 µm)THz (3 mm > > 15 µm)

• ICNIRP: 1000 W/m2 (1,041 µm to 1 mm,10 s to 8 h) based on thermal effects on the cornea

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Far infrared (15 µm > > 3 µm)Far infrared (15 µm > > 3 µm)

• Few studies besides the thermal effect on the cornea

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MechanismsMechanisms• Very low energy of the microwave photon

1 GHz = 4 x 10-6 eV 1 THz = 4 x 10-3 eVkT = 3 x 10-2 eV

covalent bond = 3 eVionisation = 12.5 eV

• Only well-established mechanisms is heating

• Other mechanisms are being explored and tested in

the laboratory

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ConclusionConclusion

• Most of the research is done in the cm range because of mobile communications

• Above 10 GHz, – The skin is the main target– A lot more research is needed for health risk

assessment– Exposure systems and biological models are

becoming available