Thermal and Non-thermal Effects
of Non-ionizng EMF
Henry Lai
Department of Bioengineering
University of Washington
Seattle, WA
USA
Thermal effects are relatively easy to
understand.
-microwave cooking
-heating causes cellular and physiological
changes
Non-thermal effects- biological responses
not related to heating or increase in
temperature.
-difficult to prove
Do non-thermal effects exist?
Arguments for non-thermal effects:
(1)Effects at low intensity
(2)Heating effects different from EMF effects
(3)Modulations produce different effects at
same exposure conditions
(4)ELF EMF has biological effects
Low Intensity Effects
de Pomerai (2000; 0.001W/kg); Fesenko (1999; 0.001
mW/cm2); Ivaschuk (1999; 0.026W/kg); Kwee (2001;
0.0021W/kg); Magras and Xenos (1999; 0.0001180.001053mW/cm2); Mann (1998; 0.02mW/cm2) ;
Marinelli (2004; 0.036W/kg); Navakatikian and
Tomashevskaya (1994; 0.0027-0.027W/kg);
Nittby(2007; 0.0006-0.06W/kg); Persson (1997; 0.00040.008W/kg); Phillips (1998; 0.0024-0.024W/kg);
Polonga-Moraru (2002; 15mW/cm2); Pyrpasopoulou
(2004; 0.0005W/kg); Salford (2003; 0.02W/kg);
Sarimov (2004; 0.0054W/kg); Schwartz (1990;
0.00015W/kg); Somosy (1991; 0.024W/kg); Stagg
(1997; 0.0059W/kg); Wolke (1996; 0.001W/kg);Yurekli
(2006; 0.0113W/kg)
‘Microwave pulse’ hearing effect
Auditory system responses to microwave
pulses at a threshold of 0.6 mJ/g/pulse.
-thermoelastic effect
-micro-thermal effects
The Case of David de Pomerai
De Pomerai et al. (Nature 405:417-418,
2000)- reported an increase in a molecular
stress response (heat shock gene expression)
in worms after exposure to a RFR at a SAR
of 0.001 W/kg.
Dawe, Smith, Thomas, Greedy, Vasic, Gregory, Loader,
de Pomerai (2006) A small temperature rise may
contribute towards the apparent induction by
microwaves of heat shock gene expression in the
nematode Caenorhabditis elegans. Bioelectromagnetics
27(2):88-97.
“We conclude that our original interpretation of a nonthermal effect of microwaves cannot be sustained; at
least part of the explanation appears to be thermal.”
Heating effects different from EMF effects
Wachtel (1975) Seaman & Wachtel (78)- activity
of neurons insolated abdominal ganglion of
Aphysia- heating had opposite effect.
de Pomerai (2000, 2003)- needed thermal heating
of 3oC to produce the same effect of a 0.5oC
increase by EMF; EMF enhanced growth and
development of C. elegens, whereas heating
produced the opposite effects.
But, microwave/RF heating is not the same as ‘heating’.
RFR energy absorption pattern in the body is not
uniform. (Chou, C.K., Guy, A.W., McDougall, J., Lai, H.
Specific absorption rate in rats exposed to 2450-MHz
microwaves under seven exposure conditions.
Bioelectromagnetics 6:73-88, 1985. )
It is not possible to simulate RF heating.
Even if heat is removed when exposed to RFR, i.e., no
significant increase in temperature is detected,
thermoregulatory responses are activated which can in
turn lead to alterations in other physiological responses.
Modulations produce different effects at same
exposure conditions- e.g., frequency, exposure
system
Frey (1975)-BBB- pulsed field more effective than CW
Oscar and Hawkins (1977)-BBB- pulsed field more effective than
CW
Sanders (1985)-brain metabolism- 500 pps more effective than
250 pps modulation
Arber and Lin (1985)-neuron activity- AM increase; CW
decrease
Lai (1988)-hippocampal acetylcholine-pulsed- CW no effect
D’Ambrosio (2002)-genetic effect- modulated field- CW no effect
Huber (2002)-EEG- modulated field-CW no effect
Hoyto (2008)-lipid peroxidation, caspase 3 activity- modulated
field- CW no effect
Luukkonen (2009)-free radicals-CW- modulated field no effect
Biological effects of ELF EMF are well
established.
ELF EMF cannot produce significant
thermal effect.
Arguments for non-thermal effects:
(1)Effects at low intensity
(2)Heating effects different from EMF effects
(3)Modulations produce different effects at
same exposure conditions
(4)ELF EMF effects
Is thermal/non-thermal consideration
a necessary condition for EMF
exposure standard setting?
Is thermal/non-thermal consideration a
necessary condition for EMF exposure
standard setting?
My answer is ‘no’.
Standards should base on at what level of
exposure biological/health effects are
observed.
The de Lorge Experiments
de Lorge and Ezell (1980) trained rats on an ‘auditory
observing- response task’. Rats were then irradiated
with 1280-MHz or 5620-MHz RFR during
performance. Disruption of behavior was observed at
SAR of 3.75 W/kg for 1280-MHz and 4.9 W/kg for
5620-MHz. Disruption occurred within 30-60
minutes of exposure.
“It is concluded that the rat’s observing behavior is
disrupted at a lower power density at 1.28 than at
5.62 GHz because of deeper penetration of energy at
the lower frequency, and because of frequencydependent differences in anatomic distribution of the
absorbed microwave energy.”
de Lorge (1984) trained monkeys on the ‘auditory
observing- response task’. Monkeys were exposed to
RFR of 225, 1300, and 5800 MHz. Disruption of
performance was observed at 8.1 mW/cm2 (SAR 3.2
W/kg) for 225-MHz, 57 mW/cm2 (SAR 7.4 W/kg) for
1300 MHz, and 140 mW/cm2 (SAR 4.3 W/kg) for 5800
MHz, when body temperature increased by 1oC.
Conclusion: Disruption of behaviour occurred when
an animal was exposed at a SAR ~ 4 W/kg (whole body
average). Disruption occurred after 30-60 minutes of
exposure and when body temperature increased by
1oC.
Thomas et al. (1975) tested 5-10 min after 30 min
exposure to pulsed 2450-, 2860-, 9600-MHz RFR.
DRL response disrupted at 2450-MHz > 2 W/kg,
2860 MHz >2.7 W/kg, 9600-MHz >1.5 W/kg.
Schrot et al. (1980) bar press for food after 30 min
exposure to pulsed 2800-MHz RFR disrupted at
SARs of 0.7 and 1.7 W/kg.
Does RFR produce behavioral effects below 4 W/kg
after short-term exposure? ‘YES’
In many instances, effects on behavior were
observed at a SAR less than 4 W/kg. (DeWitt et al.
[1987] 0.14 W/kg; Gage [1979] 3 W/kg; King et al.
[1971] 2.4 W/kg; Lai et al. [1989] 0.6 W/kg;
Mitchell et al. [1977] 2.3 W/kg; Navakatikian and
Tomashevskaya [1994] 0.027 W/kg; Schrot et al.
[1980] 0.7 W/kg; Thomas et al. [1975] 1.5 to 2.7
W/kg; Wang and Lai [2000] 1.2 W/kg).
Low Intensity Effects
de Pomerai (2000; 0.001W/kg); Fesenko (1999; 0.001
mW/cm2); Ivaschuk (1999; 0.026W/kg); Kwee (2001;
0.0021W/kg); Magras and Xenos (1999; 0.0001180.001053mW/cm2); Mann (1998; 0.02mW/cm2) ;
Marinelli (2004; 0.036W/kg); Navakatikian and
Tomashevskaya (1994; 0.0027-0.027W/kg);
Nittby(2007; 0.0006-0.06W/kg); Persson (1997; 0.00040.008W/kg); Phillips (1998; 0.0024-0.024W/kg);
Polonga-Moraru (2002; 15mW/cm2); Pyrpasopoulou
(2004; 0.0005W/kg); Salford (2003; 0.02W/kg);
Sarimov (2004; 0.0054W/kg); Schwartz (1990;
0.00015W/kg); Somosy (1991; 0.024W/kg); Stagg
(1997; 0.0059W/kg); Wolke (1996; 0.001W/kg);Yurekli
(2006; 0.0113W/kg)
Other considerations
Effects of long-term exposure
D’Andrea et al. (1986a) 2450 MHz, 7 hrs/day, 7
days/wk, 14 weeks, 0.7 W/kg- disrupted operant
behavior.
D’Andrea et al. (1986b) 2450 MHz, 7 hrs/day, 7
days/wk, 90 days, 0.14 W/kg- small disruption in
operant behavior.
“The threshold for behavioral and physiological
effects of chronic RFR exposure in the rat occurs
between 0.5 mW/cm2 (0.14 W/kg) and 2.5 mW/cm2
(0.7 W/kg).”
Interactions with Other Environmental Factors
Example: Kues and Monahan [1992] and Kues et al.
[1990; 1992] reported synergistic effects of drugs on
corneal endothelium damages and retinal
degeneration in the monkey induced by repeated
exposure to RFR. They found that application of the
drugs timolol and pilocarpine to the eye before RFR
exposure could lower the threshold of the RFR effect
by 10 folds (from 10 to 1 mW/cm2).
There are many reports of EMF interaction
with drugs/chemicals, stressors, ionizing
radiation, etc.