Loading in 2 Seconds...
Loading in 2 Seconds...
Electromagnetic Fields (EMF) and Health Risk: A Scientific Perspective Martin Blank, PhD Columbia University
James Thurber The Thurber Carnival - 1945 ‘Electricity was leaking all over the house’
Involuntary Exposure to EMF Cell Phone Antennas in lower Manhattan, as shown on the cover of New York magazine October 4, 2004
RF RF /------------------ thermal effects --------------------/ /------------------non-ionizing radiation -------------------/ /-- ionizing radiation --/
EMF Safety Assumes • only ionizing radiation causes chemical change • EMF cell damage is only caused by heating • safe EMF limits can be set in terms of heating rate (SAR) • EMF exposure limits can be set separately for each EM spectrum subdivision • EMF Research Shows • non-ionizing EMF also causes chemical change • EMF cell damage occurs without heating • non-thermalEMFeffects occur below the safety limits • • biological reactions are stimulated across spectrum and effects may be additive
Studying Health Impact • Epidemiology • Correlation, qualitative relation • Dose-Response, quantitative relation • Laboratory research • Mechanism, scientific plausibility
Epidemiology of childhood leukemia • EMF-RAPID Report to Congress (1999) on ELF ‘EMF… not entirely safe… minimize exposure to magnetic fields…’ • Epidemiology threshold for childhood leukemia is 3-4mG (Greenland et al, 2000; Ahlbom et al, 2000) • IARC - International Agency for Research on Cancer (2002) Exposure to electric and magnetic fields (EMF) is possible cause of cancer • ELF background ~1mG; appliances >> 4mG
Biological Thresholds in the ELF Range Biological System Threshold Reference Enzyme reaction rates Na,K-ATPase 2-3mG Blank & Soo, 1996 cytochrome oxidase 5-6mG Blank & Soo, 1998 ornithine decarboxylase ~20mG Mullins et al, 1999 Electron transfer rate Belousov-Zhabotinsky <5mG Blank & Soo, 2001 Stress protein synthesis HL60, Sciara, yeast, <8mG Goodman et al, 1994 breast (HTB124, MCF7) <8mG Lin et al, 1998 chick embryo (anoxia) ~20mG DiCarlo et al, 2000 Disease related block melatonin inhibition of breast carcinoma 2<12mG Liburdy et al, 1993 Safety limit (ELF) ~1000mG ICNIRP, 1997 Leukemia epidemiology 3-4mG
Cells answer safety question! Cells synthesize stress proteins in reaction to potentially harmful stimuli in the environment (e.g., changes in temperature, toxic ions, pH, alcohol, etc.). DNA → mRNA → protein EM fields stimulate the stress response.
Stress Response: Evidence of Molecular Damage • stress response: ‘... defense reaction of cells to damage that environmental forces inflict on macromolecules.’ Kültz, Physiol Rev (2005) • genes stimulated along with stress genes sense and repair damage to DNA, proteins • stimulated by ELF and RF
EMF affects breast cancer cell growth Melatonin, Tamoxifeninhibit MCF7 breast cancer cell growth. Liburdy et al. J Pineal Res, 1993 2mG does not affect inhibition; 12mG overcomes the inhibition and cells continue to grow. EMF threshold is between 2mG and 12mG. Experiment has been repeated in six labs.
EMF Specific Domain in HSP70 HSP HSP HSP MYC A MYC C MYC B -230 -192 -166 -160 -107 -100 -68 +1 (bp) -320 A TF T A T A HSP70 Sp1 AP-2 HSE Sp1 AP-2 HSE SRE Sp1 AP-2 EMF Domain (non-thermal) Heat Shock Domain (thermal) . Lin et al (1999) J Cellular Biochem 75:170-176.
60 N N e e g g a a t t i i v v e e C C o o n n t t r r o o l l B B a a c c k k g g r r o o u u n n d d 50 E E M M 40 30 20 10 0 EMF-Specific DNA can be moved Chloramphenicol transferase (CAT) Activity Luciferase Activity counts counts 60 50 40 30 20 10 0 Experimental Conditions Experimental Conditions Lin et al (2001) J Cellular Biochem 81:143-148.
EMF breaks DNA ‘Comet Assay’ 60Hz, 2hrs a. control b. 1G c. 2.5G d. 5G Lai, Singh (1997) REFLEX (2004): DNA damage at 0.35G
RF also reacts with DNA RF stimulates stress response • C. elegans (dePomerai et al, 2000) • Human epithelial cells (Kwee et al, 2001) • Human endothelial cells (Leszczynski et al, 2002) • Chick embryos (Shallom et al, 2002) • Drosophila (Weisbrot et al, 2003) RF damages DNA (strand breaks) • Human T-lymphoblastoid cells (Phillips et al, 1998) • Human lymphocytes (Mashevich et al, 2003) • Human fibroblasts, HL60 (REFLEX, 2004)
Specific Absorption Rate (SAR)does not measure biological dose The stress response is stimulated - in ELF, SAR ~10-12 W/kg (no heating) - in RF, SAR ~10-1 W/kg Biological dose is not related to heating rate SAR is no basis for a safety standard! Blank, Goodman. BEMS 25:642-646, 2004
Health Risk of RF Fields • Cellular studies - RF stimulates protein synthesis, DNA damage • Animal studies - lymphoma in mice, Repacholi et al (1997) - blood-brain barrier leaks, Persson et al (1997) - micronuclei in blood, Carlo (2001) • Epidemiology - cell phones and cancer, acoustic neuroma 10yr, RR>3 (Kundi et al, 2004; Lonn et al, 2004) - radio and TV antennas Cherry (San Francisco); Szmigielski (Poland); Hocking (Sydney); short wave case in Rome
Sutro Tower Study (Cherry, 2002) Tower: 577m Antennas: 400-570m FM: 54.7kW TV: 616kW UHF: 18.3MW • Risk Ratio for all childhood cancers (1937-1988) • is elevated (at 3km, 1µW/cm2, RR>5) • falls off with distance from antennas
Effects of EMF on Cells • ELF/RF interact with DNA in many cells - activate DNA, protein synthesis → cancer - cause DNA damage → cancer • Many frequencies active; may be synergistic • ELF thresholds (field strength, duration) are below safety limits • Thermal basis (SAR) for RF safety is flawed!
EMF Safety Needs a Scientific Basis • IEEE guideline: “The RF safety standard should be based on science.” • EMF research requires a biological standard to replace thermal (SAR) standard • EMF research requires protection against cumulative biological effects stimulated by EMF across the EM spectrum
Above all: Minimize EMF Exposure! Precautionary Principle • Prudent Avoidance - for public • ALARA – as low as reasonably attainable – for regulatory agencies