An Expert Panel Report prepared at the request of the Royal Society of Canada for Health Canada

http://www.rsc.ca

"In summary, there is strong evidence that microwave irradiation produces behavioural and associated biochemical changes at or below the occupational exposure limits. Further, the opioid system appears to be affected by these exposures in some way and similar effects appear to occur with non-thermal exposures. These results suggest the possibility that the effects reported are non-thermal and hence dependent on another field characteristic."

S. typhimuriu (TA1535, TA100, TA98)
8,500-9,600 MHz pulsed, 1, 5, 45 W/m2 ; up to 2 h.
Increased mutation frequency
Dutta and Nelson, (1978); Dutta et al., (1979a)

S. cerevisiae
2,450 MHz (CW); 20W/m2 ; 40 W/kg; up to 2h.
Increased mutation frequency
Dutta and Nelson, (1978); Dutta et al., (1979a)

Rat kangaroo bone marrow cells
2,450 MHz. 0.2, 1.0, or 5.0W/cm 2 for up to 30 min
Increased chrosomal aberrations
Yao and Jiles, (1970)

Human lymphocytes
954 MHz
Increased chrosomal aberrations
Maes et al., (1995)

Human lymphocytes
167 MHz
Increased chrosomal aberrations
Khalil et al., (1993)

Human subjects
30-300 GHZ. 10-50 W/cm 2 : occupational
Increased chromosomal aberrations
Garaj-Vrhovac et al., (1990b)

Mice
9,400 MHz (PW). 0.1-10mW/cm 2 : 1 h/d. 5 d/wk.
Increased chromosomal aberrations
Manikowska et al., (1979)

Sperm cells of male CBA/CEY mice
2,450 MHz. CW: 0.05-20W/kg: 30 min/d. 6 d/wk. 2 weeks
Increased chromosomal aberrations.
Increased chromosome translocations and other cytogenetic
Manikowska-Czerska et al., (1985)

Biological justification for neurological clinical effects of radio frequency radiation.

Does neural tissue or brain tissue have unique susceptibility to MW? Is looking for clinical neurologic effects associated with exposure to MW justified in terms of a biological basis?

These important questions may be answered in either structural terms (starting with gross anatomy, proceeding to cellular anatomy and ending at the molecular level of refinement) or in purely functional terms (including both electrophysiological and neuropharmacological considerations).

From a gross anatomical structural perspective, it is arguable that the brain may have unique anatomic vulnerability to MW exposure. Of all anatomical structures, the head has the closest proximity to mobile phones, radios and similar hand-held devices.

This leads to a relatively high specific absorption rate (SAR) the brain compared to the rest of the body. For example, Cleveland and Athey (1989) measured SARs in models of the human head exposed to hand held portable radios transmitting at frequencies in the 800 MHz band using an isotropic implantable electric-field probe to measure internal fields.

This study showed that antenna type and orientation were important factors in determining energy absorption. Furthermore, atypical operation of the transceiver (e.g. holding it in front of the eye rather than down the side of the face) may lead to even higher specific absorption rates. Within the head, the temporal lobe is the part of the brain in closest proximity to the hand held phone.

Temporal lobe damage is well documented to produce a variety of clinical neurologic complaints including memory problems and seizures.

From a histological (cellular) structural perspective, data pertaining to the neuronal and glial effects of MW are highly variable.

The human brain consists of approximately 100 billion brain cells (neurons); in addition, there are non-neuronal support cells called glial cells. Following exposure to RF fields (2450 MHz, 15 W/kg, 30 minutes), swollen neurons were documented in the hypothalamus and subthalamus of the Chinese Hampster (Albert and De Santis, 1975).

Neuronal swelling has also been reported by other workers (Hansson Mild, 1982; Hertz, 1975).

Finally, decreased Purkinje cells in the cerebellum have been reported by Albert and co-worker (1981) (rat, 2450 MHz, 3.4 W/kg, 21hr/d for 5 days).

In addition to the neuronal effects, the effects of MW (RF) on glial brain cells has also been studied. For example, Cleary et al. (1990c) demonstrated statistically significant time-dependent alterations in glioma cell (LN71) proliferation when the cells were exposed to 2450 MHz continuous wave radiofrequency radiation in vitro for 2 hours under isothermal conditions.

However, the most significant glial cellular effects may be on the blood-brain barrier (BBB). The blood-brain barrier which is structurally composed of astrocytes and endothelial tight junctions is the barrier that precludes the entry of a wide variety of chemicals, toxins and drugs into the central nervous system (CNS). Some studies have suggested MW (RF) induced increases in BBB permeability to compounds such as fluosescein (1200 MHz, continuous and pulsed, 2.4 mW/cm., rat), aluminum (900 MHz, continuous and pulsed, 7.5 W/kg, rat), mannitol (1200 MHz, continuous and pulsed, 75 mW/cm, rat), Evans blue (2450 MHz, pulsed, 240 W/kg, rat), inulin (1300 MHz, continuous and pulsed, 2 mW/cm, rat) and horseradish peroxidase (2450 MHz, continuous, 24 W/kg, mouse) (Frey et al., 1975; Fritze et