Health Concerns with Electromagnetic and Electrostatic Field Exposure EE292 Health

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Health Concerns with Electromagnetic and
Electrostatic Field ExposureEE292Health
Safety Seminar January 2009 Denard Lynch
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Electromagnetic Fields and Public Health (defns)

• Electromagnetic waves are characterized by their
  wavelength, frequency, energy
• Affect on biological systems is determined by
• Intensity of field
• Amount of energy per photon (prop. to freq.)
• EM waves at low freq. electromagnetic fields
• EM waves at high freq. electromagnetic radiation
• Ionizing radiation has enough photon energy to
  break atomic bonds
• Non-ionizing radiation refers to all other EM
  radiation where photon energy cant break atomic
  bonds.
• NOTE even high intensity NIR cant cause
  ionization!

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Biological Effects

• Biological Effect is when exposure to EM fields
  causes a detectable change in the biological
  system
• Adverse Health Effect is when biological effect
  cant normally be compensated for by the
  biological system (e.g. human body)
• Some biological effects are innocuous, even
  beneficial some are immediately or potentially
  harmful

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Biological Effects(contd)

• Fields at freq gt 1MHz primarily cause heating
• At lows levels, heat is handled by normal
  thermoregulatory processes
• At high levels, thermal damage may accrue (eg.
  Microwave oven)
• Other effects have been reported but not
  scientifically established

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Biological Effects(contd)

• Fields at freq lt 1MHz primarily induce electric
  charges and currents
• Low levels have no established effect
• High levels may interfere with electro-neural
  systems
• Other effects (e.g. cancer, memory loss) have
  also been reported but not established.

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Electric Fields

• Exist when V exists Dont penetrate body
• Cause charge buildup Induce currents
• Static has little effect if no discharge (e.g.
  lightning) or unless very intense
• ELF leads to mostly electrostatic heating

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MagneticFields

• Exist when I flows Easily penetrate body
• magnetizes body induces currents
• Static minimal effect unless very intense
• ELF mostly heating effect due to joule heating
  from induced currents

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Electromagnetic Fields and Public Health

• International Electric and Magnetic Fields (EMF)
  Project
• Launched by World Health Organization (WHO)
• Objective arrive at scientifically sound
  recommends for health risk assessment of
  exposure to static and time-varying electric and
  magnetic fields
• Includes static (0Hz), extremely low freq. (ELF,
  lt300Hz), Intermediate Freq. (IF, 300Hz 10MHz),
  and radio freq. (RF, 10MHz 300GHz).

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What they do

• Review scientific literature
• Identify gaps in knowledge
• Focus research
• Formally assess health risks of EMF exposure
• Encourages international standards
• Provides info on perception, communication,
  management of risk
• Advises national programs and non-gov institutions

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How they do it

• Project overseen by International Advisory
  Committee (IAC)
• Many participating international orgs
• Scientific work done by International Commission
  on Non-Ionizing Radiation Protection (ICNIRP) and
  independent WHO collaborating institutions.

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Recent Results.

• IARC evaluation completed 2001, published 2002
• ELF magnetic fields ELF magnetic fields
  classified as 2B Possible Carcinogen
• based on limited evidence from epidemiological
  studies of childhood leukaemia
• other data inadequate
• 2B other explanations possible

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25, 26
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Typical Values of EMF
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Customer Looking at New Lot
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Customer Looking at New Lot
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Existing House
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Customer Looking at New Lot

• 25 mG

Recall 1T 10,000G 25mG 2.5?T
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Customer Looking at New Lot

• 12 mG

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Customer Looking at New Lot

• 8 mG

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Customer Looking at New Lot

• 3 mG

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Customer Looking at New Lot

• 1.2 mG

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Existing House

• 2 - 5 mG

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Typical House

• 0.2 - 2 mG

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Appliance EMF

• 25 mG

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Appliance EMF

• 1 - 3 mG

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Appliance EMF

• 3000 mG

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Appliance EMF
100 mG

• 30

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Appliance EMF

• 30

10 mG
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Equipment EMF

• 50-300mG

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Equipment EMF

• 2-30mG

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Typical Ranges of Magnetic Fields

• 0.3 - 13 mG

30 m
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Typical Ranges of Magnetic Fields

• 0.3 - 13 mG

30 m
0.1 - 3 mG
15 m
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Typical Ranges of Magnetic Fields

• 0.1 - 11 mG

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Typical Ranges of Magnetic Fields
0.1 - 11 mG

• 5 - 1000 mG
• (2' away)

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Typical Ranges of Magnetic Fields
0.1 - 11 mG

• 5 - 1000 mG
• (2' away)

0.2 - 30 mG
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People love their Cell Phones
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(No Transcript)
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• SAR Distributions for 3 sizes of Scaled Human
  Bodies at 900MHz

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Summary

• No argument that unwanted exposure to extreme
  levels can have negative health effects
• For normal levels, heating is the basis for
  current guidelines
• Other effects may accrue with long-term exposure
  to low levels, but have not yet been
  scientifically established

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REFERENCES 1. water.usgs.gov/admin/memo/QW/qw92.0
1.html (American Society for Testing Materials,
1990 Annual Book of ASTM Standards, Section 11,
Water and Environmental Technology,
Designation D 1193 77, p. 45 47) 2.
www.ceramaseal.com/reference/dielectric.cfm 3.
www.isi-seal.com/Technical_Info/Tech_Dielectric_St
rength.htm 4. Physics for Scientists
Engineers, 3rd Ed., Raymond A. Serway, Saunders
College Publishing 1990 5. accept.la.asu.edu/cours
es/phy110/ds/appendixC.html 6. www.occuphealth.fi/
e/info/anl/395/kitumb.htm 7. www-training.llnl.gov
/wbt/hc/Electrical/Accident.html 8.
www.prl.ernet.in/bobra/EARTH/html1/chapt3.htm 9
www.osha-slc.gov/SLTC/constructionelectrical/elect
rical_incidents/eleccurrent.html 10.
www-training.llnl.gov/wbt/hc/Electrical/GFCIworks.
html 11. www.osha-slc.gov/SLTC/constructionelectri
cal/electrical_incidents/powertools.html 12.
www.jlab.orh/ehs/manual/EHSbook-392.html 13.
www.physics.udel.edu/wwwusers/watson/scen103/collo
q2000/safety.html 14. ICNIRP Guidelines
GUIDELINES FOR LIMITING EXPOSURE TO TIME-VARYING
ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS (up
to 300 GHz) 15. www.who.int/peh-emf/publications/W
hat_is_EMF/section2.htm 16. www.who.int/peh-emf/pu
blications/facts_press/efact/efs181.html (Electrom
agnetic Fields and Public Health The
International EMF Project, Fact Sheet N181) 17.
www.who.int/peh-emf/publications/facts_press/efact
/efs182.html (Electromagnetic Fields and Public
Health The International EMF Project, Fact Sheet
N182) 18. University of Guelph Safety Policy
Manual, Policy 851.07.13 19. www.statpower.com/tec
h4-1.htm 20. www.argo.ca/p11_circuit_breakers_.htm
l 21. www.stayhealthy.com/profiles/bc1_how.cfm 22.
Electrical Detection of Acupuncture Points, N.
Barlea, H. Sibianu, R. V. Ciupa (http//bavaria.ut
cluj.ro/mbirlea/m/04m.htm)
47
23. www.nasatech.com/Briefs/Apr00/MSC22491.html 24
. members.tripod.com/StormTrooper_2/index2.htm
25. Electromagnetic Fields and Public Health,
Extremely low frequency fields and cancer,
International EMF Project, Fact Sheet No 263 26.
WHOs International EMF Project and results so
far, presentation by Dr MH Repacholi,
Co-ordinator, Radiation and Environmental Health,
World Health Organization, Geneva,
Switzerland 27. Electromagnetic Fields and
Public Health, Mobile Telephones and their Base
Stations, International EMF Project, Fact Sheet
No 193 28. RF Sources Why are Cell Phones
Special?, James C. Lin, U of Illinois,
presentation to ICNORP Rio Brazil, Oct. 2008
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Electrical Hazards and SafetyEE292Health
Safety Seminar January 2009 Denard Lynch
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Electrical Safety

• Electric Potential
• Potential for good Potential for harm
• The Body Electric
• So you want to be a conductor!
• Sparks, Arcs, Ionization and Dielectric breakdown
• Play Safe!

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Electrical Potential

• Potential for good
• Contributions to civilization (productivity,
  learning)
• Clean, quiet, controllable transmission and
  distribution of energy
• Potential for harm
• Invisible, lurking
• Indiscriminant discharge (cant tell intended
  from accidental uses)

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The Body Electric

• As a circuit combination of R, C, some L
• C in order of 100 200pF
• Approximate R of body parts
• Ear ear 100 Ohms (int)
• Hand foot 400 600 Ohms (int)
• Wet skin 1000 Ohms
• Dry skin 100K 1000K Ohms
• Muscle more conductive than fat!
• For protection purposes,
• Body 500 Ohms between major extremities
• 1500 Ohms between perspiring hands of a worker

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Why does a body conduct?

• Mostly because of high water content
• Distilled water is actually an insulator
• approx 18M Ohms/cm
• Minerals, ions in water actually conduct
• Conductivity is used to determine impurities in
  water
• Body fluids are water-based but full of other
  elements that make it a good conductor

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Shock progression

• Slight sensation (1mA)
• Feel a shock but not painful (5mA)
• Painful, may invoke reflexes (10mA)
• Muscle contraction, breathing difficulty
  possible asphyxiation (50mA)
• Cardiac interference possible fibrillation
  (100mA)
• Almost certain fibrillation, possible nerve
  damage (1A)
• Cardiac arrest, severe burns (interl/externl)
  (5A)
• (Note 6A is operating parameters for
  Defibrillator)

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Effect of Current on Body
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Outcome depends on

• Age, sex of victim, skin condition, health,
  composition of blood, alcohol in blood
• Contact voltage, pressure, insulation (e.g.
  shoes)
• Path through the body
• Frequency
• Duration of exposure
• Delay til resuscitation/ emergency care

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Duration ofexposure..
10s
For all I - t values to the left Not
harmful For all I t values to the right Of the
curve - dangerous situations! Re Denards
10-2 rule of Thumb
1s
0.1s
mA -gt
REFERENCE 8
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msec
mA -gt
Area 1 no reaction Area 2 normally not
dangerous Area 3 usually no risk of
fibrillation Area 4 possible fibrillation, with
P50 Area 5 danger of fibrillation, with Pgt50
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Frequency Dependence
5, 9, 12, 14
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How to become a conductor

• Direct contact
• Up to 120V, conduction through skin
• gt 200V, burn through
• Lightning Rod
• Present in a high voltage gradient electric field
• Dielectric breakdown of insulating material(s)
• Geometry plays a role
• Domino effect, progressive

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Dielectric Strength
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Pressure Dependence of Air
760 Torr(760mmHg) 1 Atmosphere 0 psig
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Joule Heating
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Consider electric field that exists between two
conducting bodies
Potential exists between any two points in the
field
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If the facing surfaces are not parallel.
The eqi-potential contour lines distort
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If the conductor(s) has sharp edges..
the voltage gradient in the vicinity of the
point becomes non-linear, and very high near the
edges often exceeding the dielectric breakdown
limits of the inter-posed material.
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Step Potential
Electric Field Lines
-

Potential difference, V
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Step Potential
Equi-potential Contour Lines
-

Potential difference, V
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Circa 1996 (16.6kV wye)
REFERENCES 24
69
REFERENCES 24
70
Note no humans or animals died during the making
of this film!!
REFERENCES 24
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Physiological Effects
5, 6, 9, 12, 13, 18
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Safety Measures

• Protective devices
• Circuit breakers, fuses
• Usually just to protect equipment
• Ground Fault Circuit Interupters
• Wont help if one imitates a light bulb

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Safety Measures

• Protective devices
• Circuit breakers, fuses
• Usually just to protect equipment
• Ground Fault Circuit Interrupters
• Wont help if one imitates a light bulb
• Double insulated tools
• Help if maintained and dry
• Protective clothing, gear
• Good if maintained and used, but have limits
• Shielding for magnetic / electric fields
• Safety procedures, policies
• Also good for prevention if understood and
  followed

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What if something happens?

• Immediately
• Disconnect supply from victim (1st choice) or
  victim from supply
• Use long, insulated item if necessary (e.g. dry
  wood)
• Remove / separate victim from other dangers
• Solicit help!
• Start resuscitation / first aid if qualified

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What if.contd

• Follow-up
• After a shock incident, victim may be dazed,
  irritable (suffered internal damage) SEEK
  FURTHER MEDICAL ASSISTANCE
• Report accident to appropriate people
• Contribute to review and improvement of
  preventative measure if appropriate.
• Seek therapy or counseling if appropriate

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Some working guidelines

• Know and follow all safety procedures
• Never work alone
• strange dog rule of thumb / one hand
• Make sure cords. Tools and other equipment are in
  good shape
• Shut off power first! (lock / tag out)
• Test, short circuit / earth
• Keep hands dry, protect wounds

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REFERENCES 1. water.usgs.gov/admin/memo/QW/qw92.0
1.html (American Society for Testing Materials,
1990 Annual Book of ASTM Standards, Section 11,
Water and Environmental Technology,
Designation D 1193 77, p. 45 47) 2.
www.ceramaseal.com/reference/dielectric.cfm 3.
www.isi-seal.com/Technical_Info/Tech_Dielectric_St
rength.htm 4. Physics for Scientists
Engineers, 3rd Ed., Raymond A. Serway, Saunders
College Publishing 1990 5. accept.la.asu.edu/cours
es/phy110/ds/appendixC.html 6. www.occuphealth.fi/
e/info/anl/395/kitumb.htm 7. www-training.llnl.gov
/wbt/hc/Electrical/Accident.html 8.
www.prl.ernet.in/bobra/EARTH/html1/chapt3.htm 9
www.osha-slc.gov/SLTC/constructionelectrical/elect
rical_incidents/eleccurrent.html 10.
www-training.llnl.gov/wbt/hc/Electrical/GFCIworks.
html 11. www.osha-slc.gov/SLTC/constructionelectri
cal/electrical_incidents/powertools.html 12.
www.jlab.orh/ehs/manual/EHSbook-392.html 13.
www.physics.udel.edu/wwwusers/watson/scen103/collo
q2000/safety.html 14. ICNIRP Guidelines
GUIDELINES FOR LIMITING EXPOSURE TO TIME-VARYING
ELECTRIC, MAGNETIC AND ELECTROMAGNETIC FIELDS (up
to 300 GHz) 15. www.who.int/peh-emf/publications/W
hat_is_EMF/section2.htm 16. www.who.int/peh-emf/pu
blications/facts_press/efact/efs181.html (Electrom
agnetic Fields and Public Health The
International EMF Project, Fact Sheet N181) 17.
www.who.int/peh-emf/publications/facts_press/efact
/efs182.html (Electromagnetic Fields and Public
Health The International EMF Project, Fact Sheet
N182) 18. University of Guelph Safety Policy
Manual, Policy 851.07.13 19. www.statpower.com/tec
h4-1.htm 20. www.argo.ca/p11_circuit_breakers_.htm
l 21. www.stayhealthy.com/profiles/bc1_how.cfm 22.
Electrical Detection of Acupuncture Points, N.
Barlea, H. Sibianu, R. V. Ciupa (http//bavaria.ut
cluj.ro/mbirlea/m/04m.htm) 23.
www.nasatech.com/Briefs/Apr00/MSC22491.html 24.
members.tripod.com/StormTrooper_2/index2.htm