Electromagnetic Fields (EMF) and Health Risk: A Scientific Perspective
Electromagnetic Fields (EMF) and Health Risk: A Scientific Perspective Martin Blank, PhD Columbia...
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Transcript of Electromagnetic Fields (EMF) and Health Risk: A Scientific Perspective Martin Blank, PhD Columbia...
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
RFRF
/------------------non-ionizing radiation -------------------/ /-- ionizing radiation --//------------------ thermal effects --------------------/
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-thermal EMF effects 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 ReferenceEnzyme reaction rates
Na,K-ATPase 2-3mG Blank & Soo, 1996cytochrome oxidase 5-6mG Blank & Soo, 1998ornithine decarboxylase ~20mG Mullins et al, 1999
Electron transfer rateBelousov-Zhabotinsky <5mG Blank & Soo, 2001
Stress protein synthesisHL60, Sciara, yeast, <8mG Goodman et al, 1994breast (HTB124, MCF7) <8mG Lin et al, 1998 chick embryo (anoxia) ~20mG DiCarlo et al, 2000
Disease relatedblock melatonin inhibition of breast carcinoma 2<12mG Liburdy et al, 1993
Safety limit (ELF) ~1000mG ICNIRP, 1997Leukemia 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 growthEMF affects breast cancer cell growth
Melatonin, TamoxifenMelatonin, Tamoxifen inhibit inhibit MCF7 breast cancer cell growth. MCF7 breast cancer cell growth. Liburdy et al. J Pineal Res, 1993Liburdy et al. J Pineal Res, 1993
2mG does not affect inhibition; 2mG does not affect inhibition; 12mG overcomes the inhibition 12mG overcomes the inhibition and cells continue to grow.and cells continue to grow.
EMF threshold is between 2mG EMF threshold is between 2mG and 12mG.and 12mG.
Experiment has been repeated Experiment has been repeated in six labs.in six labs.
Human DNA is ~2meters long and has ~3 billion base pairs
-230-230 -160-160 +1 (bp)+1 (bp)-320-320 -192-192 -107-107 -68-68-100-100-166-166
HSPHSPMYCMYC AA
HSP70HSP70
Sp1Sp1 AP-2AP-2 HSEHSE Sp1Sp1 AP-2AP-2 HSEHSE SRESRE
AATFTF
TTAATTAA
Sp1Sp1 AP-2AP-2
HSPHSPMYCMYC CC
HSPHSPMYCMYC BB
Heat Shock DomainHeat Shock Domain (thermal)(thermal)
EMF EMF DomainDomain(non-(non-thermal)thermal)
. .
EMF Specific Domain in HSP70
Lin et al (1999) J Cellular Biochem 75:170-176.
EMF-Specific DNA can be moved
countscounts
Chloramphenicol transferase Chloramphenicol transferase (CAT) Activity(CAT) Activity
00
1010
2020
3030
4040
5050
6060
BBaacckkggrroouunnddEEMM
NNeeggaattiivvee CCoonnttrrooll
Luciferase ActivityLuciferase Activitycountscounts
00
1010
2020
3030
4040
5050
6060
BBaacckkggrroouunnddEEMM
NNeeggaattiivvee CCoonnttrrooll
Experimental ConditionsExperimental Conditions Experimental ConditionsExperimental 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 DNARF 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