1 / 16

Mechanisms

Mechanisms. Good-quality investigations. Good Laboratory Practice Blind protocol (double blind for volunteers) Sham exposure (fittizio) Positive control Uniform exposure Dosimetry per organ Temperature control Several exposure levels High-enough statistical power

laddie
Télécharger la présentation

Mechanisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mechanisms Rome Jan 06

  2. Good-quality investigations • Good Laboratory Practice • Blind protocol (double blind for volunteers) • Sham exposure (fittizio) • Positive control • Uniform exposure • Dosimetry per organ • Temperature control • Several exposure levels • High-enough statistical power • Independent replication/confirmation Rome Jan 06

  3. Electromagnetic spectrum mm static ELF RF intermediate MRI Induction 50/60 Hz 900, 1800 MHz Transport of electricity Mobile telephony Rome Jan 06

  4. Current density • In the body, the ELF currents (endogenous or induced) circulate between cell because the membrane has a low conductivity (10-8 S/m) (and high capacity 1 µF/cm2) Rome Jan 06

  5. ELF exposure V2 E B50 Hz V1 V1 V2 Rome Jan 06

  6. Effects of induced currents j >1000 mA/m2: fibrillation, major risk 100–1000 mA/m2: stimulation of excitable tissues, health risks, 10–100 mA/m2: visual and nervous effects, bone healing, 1–10 mA/m2 : minor biological effects ? Rome Jan 06

  7. Serotonin receptor(Massot et al. Brain Research 2001) E S Rome Jan 06

  8. Exposure system in vitro Rome Jan 06

  9. ELF exposure system in vitro Madec et al. Bioelectrochemistry, 2003 Rome Jan 06

  10. Experimental studies: cancer Cancerogenesis = multi-phase process 1 Initiation 2 Promotion 3 Progression Modification of anarchic Hyperplasy DNA division metastases Are ELF magnetic fields tumour promotors? Rome Jan 06

  11. nongenotoxic mechanisms genotoxic mechanisms Ca 2+ ODC, melatonine  Proliferation  Apoptosis  DNA repair Genes Damage to DNA Nucleus Cellular Transformation Cytoplasm Rome Jan 06

  12. Experiments on cancer - No initiating effect 4 bioassays : 8 months to 2 years (> 18 hours/day) B = 2, 5, 20, 50, 200, 1000, 2000, 5000 T - No established promoting effect Chemically-induced or tumour-prone animals • Liver cancer (3 studies,negative) • Leukemia/lymphoma(6 studies, negative) • Skin cancer (6 studies, 4 negative) • Mammary cancer (11 studies, 6 positive) No effect Controversy? Rome Jan 06

  13. Experimental studies: genotoxicity Major research effort (> 50 studies) Mutation, micronuclei, chomosome aberrations, DNA fragmentation, DNA repair, etc.) • ELF 50/60 Hz are not genotoxic Synergy with ionizing radiation to elicit mutation with B = 0.1 to 0.5 mT? Rome Jan 06

  14. Experimental studies: Examples  Melatonine Hormone of rythmes biological rhythms, antiradical action - suppression of nocturnal rise of melatonin • in rodents but not in humans… - Suppression of the antiproliferative effect of melatonineon breast cancer cells at B =1.2 µT? Rome Jan 06

  15. Calcium oscillations Rome Jan 06

  16. Conclusions on ELF • Problems • * Epidemiology: classification • * Experimental: reproductibility • Small amplitude of effects • * Epidemiology: low RR for a rare disease • * Experimental: c-jun x 2 vs. TPA: c-jun x 50 • No coherence bet. epidemiology & experimental • * Epidemiology: childhood leukemia • * Experimental: no animal model Rome Jan 06

More Related