The power density values are displayed in Figure 2 in respect to line of sight / without line of sight and the distance to the antenna site. It is obvious, that especially in proximity to the antenna site (< 250 m), the GSM radiation levels are scattering due to various influencing parameters and cannot be calculated easily by using antenna power and distance models only. Table 1 shows a significant systematic difference between the percentile data from line of sight and without line of sight measurements. Figure 2 displays the separated sets of data with trend lines decreasing exponentially to larger distances with lower exposures for without line of sight measurements in the range of 90% reduction (-10 dB). In general, the radiation exposure is predominantly determined by e.g. the following parameters:
The distance profiles were taken for selected locations and different antenna heights and positions. For high antenna positions (e.g. 50 – 90 m, pole mount position) the maximum power at ground level is reached in about 300 meter and is rather moderate. For low antenna positions (15 – 20 m, typical roof top position) the maximum power at ground level is relatively high and is reached in about 50 meter. Figure 4 shows the average (mean) density values found in distance ranges. We observed no straightforward exponential decrease by distance only. The slight increase in the distance range of 150 – 200 meter (1,480 µW/m2) can be explained by the influence of high antenna positions with maximum values shifted to larger distances.
Directly below roof top positions (e.g. schools, preschools, homes) significant exposures in the range of a few 1,000 µW/m2 were observed due to secondary side lobes and reflections. During our data collection, the highest exposure values in the range of 10,000 – 100,000 µW/m2 were observed very close to low antenna / roof top positions at inside and outside locations in line of sight and distance < 100 meter.
The data for FM radio, TV, DECT cordless phone and other significant HF sources show that the GSM cellular phone tower radiation is the dominating HF source in residential areas. DECT signals were detected in 60 inside locations. The maximum DECT power density levels were 0.01 µW/m2 (20th percentile), 1 µW/m2
(50th percentile) and 1,680 µW/m2 (95th percentile). High exposure levels > 1,000 µW/m2 were only detected when the DECT cordless base station was located in the same room or very close to the testing site.
The results of this study show that the GSM cellular phone tower radiation is the dominating HF source in residential areas in Germany. The median power density is found in the range of 200 µW/m2 (50. percentile) with the maximum value exceeding 100,000 µW/m2. No location reached or exceeded the official standard values for the USA or Germany.
For comparison, thermal (official threshold), other non-thermal (recommendations), and cellular tower exposure reference values are listed in the table 2 below.
Comparison of Standard Threshold Values and Recommendations
(electromagnetic fields, non ionizing radiation)
|
Total Power Density
|
Standards, GSM1800/GSM1900/UMTS/DECT (e.g.)
|
|
FCC/ANSI – USA
|
10,000,000 µW/m2
|
Germany, England, Finland and Japan
|
10,000,000 µW/m2
|
Belgium
|
1,200,000 µW/m2
|
Switzerland and Italy
|
90,000 µW/m2
|
Recommendations / References (e.g.)
|
|
Ecolog Study, Germany (Ecolog 2000)
|
10,000 µW/m2
|
Cellular tower radiation – significant exposure level, 95th percentile (this study)
|
6,300 µW/m2
|
Salzburg, Austria (Resolution 2000)
|
1,000 µW/m2
|
Cellular tower radiation – median level, 50th percentile (this study)
|
200 µW/m2
|
High exposure, Oeko-Test (OekoTest 2001)
|
100 µW/m2
|
EU Parliament (STOA 2001)
|
100 µW/m2
|
Cellular tower radiation – background level, 20th percentile (this study)
|
10 µW/m2
|
Low exposure, Oeko-Test (Oeko Test 2001)
|
10 µW/m2
|
Nighttime exposure, Baubiology Standard (SBM 2000)
|
0.1 µW/m2
|
Successful communication with GSM mobile phone, system coverage requirements
|
0.001 µW/m2
|
Natural cosmic microwave radiation (Maes 2000)
|
0.000001 µW/m2
|
Therefore, in respect to recent studies and review of articles regarding non-thermal biological effect of e.g. digital pulsed GSM radiation, the stoa study concluded with a considerable concern revealing a need clear need for radio frequency safety. For example, 25 % of the locations the long term exposure levels are very high above 1,000 µW/m2, which has been suggested to be the average threshold value for non-thermal biological effects. These levels are reached especially in proximity of the antenna sites, directly below antenna sites and in line of sight in a distance of < 250 m. Two of the most important limiting factors are the distance and the direct line-of-sight to the antenna site. But, in proximity to the antenna site, the GSM radiation levels are scattered due to various influencing parameters and cannot be calculated easily by using antenna power and distance models only. In general, exposures for without line of sight locations are about 90% (-10 dB) lower than those for line of sight.
In comparison to recommendations for exposure assessment (OEKOTEST 2001), the statistical data evaluation is the following (see figure 2):
20 % of data in the range of low exposure below 10 µW/m2 (20th percentile, background level)
25 % of data in the range of medium exposure between 10 – 100 µW/m2
55 % of data in the range of high exposure above 100 µW/m2
Very few measurement data are in the range of extreme exposure 10,000 µW/m2to 100,000 µW/m2.
Conclusions
As long as the only basis for official standards for high frequency radiation are thermal effects and heating of the body tissue (ICNIRP, ANSI, IEEE, NCRP, FCC, SSK, WHO) there is no need for the industry to invest into less emitting and saver products. More and more scientists state that the view of energy absorption only is insufficient to describe the possible rf radiation effects on human health. Potential biological effects need to be considered due to
Non-thermal or low intensity levels of HF radiation,
Chronic versus acute exposure and,
Pulsed HF radiation, which is reported to be more bioactive than constant wave RF radiation.
The human body reacts more complexly than acknowledged in the thermal model and is sensitive to extreme periodic stimuli. The biological system takes the “energy” as well as the “information” which is brought by the continuous pulsed modulation pattern. Much experimental evidence of non-thermal influences of microwave radiation on living systems have been published in the scientific literature during the last 30 years – relating both to in vitro and in vivo studies – and were reviewed just recently by the STOA commission for the European Parliament (STOA 2001). From the use of microwave wireless technologies e.g. the following non-thermal biological effects have been reported:
Changes in the electrical activity in the human brain (von Klitzing 1995)
Increase in DNA single and double strand breaks from RF exposure to 2.45 GHz (Lai & Singh 1996)
Increased lymphoma rates (2 fold) in transgenic mice exposed twice a day exposed to 30 minutes of cell phone (GSM) signals over 18 month (Repacholi 1997)
Increased permeability of the blood-brain barrier in rats (Persson 1997)
Production of heat shock proteins and cancer risk (French 2001)
Higher risk of uveal melanoma (Stang 2001)
Other reported effects include e.g. (STOA 2001):
Observation of an increase in resting blood pressure during exposure,
Increased permeability of the erythrocyte membrane,
Effects on brain electrochemistry (calcium efflux),
Increase of chromosome aberrations and micronuclei in human blood lymphocytes,
Synergistic effects with cancer promoting drugs and certain psychoactive drugs,
Depression of chicken immune systems,
Increase in chick embryo mortality,
Effects on brain dopamine/opiate electrochemistry,
Increases in DNA single and double strand breaks in rat brain,
Stressful effects in healthy and tumor bearing mice,
Neurogenetic effects and micronuclei formation in peritoneal macrophage.
In this review study, a threshold of 1,000 µW/m2 was pointed out for non-thermal biological effects. For locations with any long-term exposure, a further safety factor of 10 was recommended for pulsed cellular phone radiation sources as cellular phone base stations. In this case, the power densities should not exceed 100 µW/m2. Although, the power density of the radiation used in these experiments is typically found in the head area when using a cellular phone, the information content of the radiation emitted by the latter is the same; accordingly, these results are not irrelevant to the consideration of potential adverse health effects associated with chronic exposure to cellular or cordless base-station radiation.
From the scientific point of view, adverse human heath effects of non-thermal radiation levels cannot be exactly quantified, verified, or excluded at this time. Only limited toxicological information is available in respect to the widespread use and the economical impact of the cellular phone systems in industrial nations. On one side, there is always a demand for scientific proof for human adverse health effects and dose response when establishing official economically reasonable guideline exposure threshold values. On the other side, insufficient limit of detection, insufficient dosimetry and exposure control, and industry friendly research bias the risk assessment for long-term adverse health effects, especially in the field of the cellular phone industry. That makes it clear – that by definition – official guideline standard values can only limit the consequences of adverse health effects in the frame of the economical impact.
Recommendations
We recommend to follow the principle of prevention. This includes implementation of residential exposure minimization and prevention procedures in the frame of the technical feasibility as long as the non-thermal effects are not considered in any official standard and guideline. These will include especially sensitive locations as preschools, schools, hospitals, and residential areas. So far, no other technical aspects than interferences, system coverage and system performance are taken into account.
By official definition, the cellular phone system covers an area when the signal strength of about 0.001 µW/m2 is reached. We expect that with little effort, cities, communities, and the providers will be able to significantly reduce the long term rf radiation exposures to cellular phone towers in residential areas.
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HF-Radiation Levels of GSM Cellular Phone Towers in Residential Areas
Thomas Haumann1, Uwe Münzenberg2, Wolfgang Maes3
AND Peter Sierck4
1Umweltanalytik und Baubiologie, Meisenburgstrasse 25, D-45133 Essen, Germany
2AnBUS e.V., Mathildenstrasse 48, D-90762 Fürth, Germany
3Baubiologie Maes, Schorlemerstr. 87, D-41464 Neuss, Germany
4Environmental Testing & Technology, Inc., 1106 Second Street, Encinitas CA 92024, USA
References
BUWAL 2002 Schweizer Messvorschrift für GSM-Sender 2002, BUWAL – Bundesamt für Umwelt, Wald und Landschaft. (www.buwal.ch)
Ecolog 2000 Hennies K., Neitzke H.-P. & Voigt H., Mobilfunk und Gesundheit – Bewertung des wissenschaftlichen Erkenntnisstandes unter dem Gesichtspunkt des vorsorgenden Gesundheitsschutzes. Im Auftrag der T-Mobil. Hannover, April 2000 (ECOLOG-Institut für sozial-ökologische Forschung und Bildung, Nieschlagstr. 26, D-30449 Hannover, Germany)
French 2001 French P. W., Penny R., Laurence J. A. & McKenzie D. R. , Mobile phones, heat shock proteins and cancer. Differentiation 2001, 67 (4-5), pp. 93-97.
Lai & Singh 1996 Lai H. and Singh N.P. Single and double-strand DNA breaks after acute exposure to radiofrequency radiation. Int. J. Radiation Biol. 1996; 69: 13-521. See also: Singh N.P. and Lai H. Use of the microgel electrophoresis assay to study DNA strand breaks after microwave exposure. Proc. Asia Pacific Microwave Conf. (Editor: R.S. Gupta) 1996, Vol. 1 (B1-4), pp.51-55.
MAES 2000 Maes W., Stress durch Strom und Strahlung, 4th ed. 2000, Verlag Institut für Baubiologie und Oekologie IBN, Neubeuern, Germany.
OekoTest 2001 Test “Mobilfunk-Sendeanlagen”, Öko-Test 4/2001 Germany, April 2001, pp. 32 – 40. (www.oekotest.de)
PERSSON 1997 Persson B.R.R. et al., Blood-brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication, Wireless Networks 1997; 3: pp. 455-461.
Repacholi 1997 Repacholi M.H. et al. Lymphomas in E µ-Pim 1 transgenic mice exposed to pulsed 900 MHz electromagnetic fields. Radiation Res. 1997; Vol 147, pp. 631-640.
Resolution 2000 Salzburg Resolution on Mobile Telecommunication Base Stations – International Conference on Cell Tower Siting, Linking Science & Public Health, Salzburg, Austria, June 7-8, 2000. (www.land-sbg.gv.at/celltower)
SBM 2000 Baubiologie Maes and IBN, Standard der Baubiologischen Messtechnik SBM 2000, Richtwerte für Schlafbereiche, in “Stress durch Strom und Strahlung”, Maes W., 4th ed. 2000, pp. 542 – 545, Verlag Institut für Baubiologie und Oekologie IBN, Neubeuern, Germany. (www.maes.de)
Stang 2001 Stang A., Anastassiou G., Ahrens W., Bromen K., Bornfeld N., and Jöckel K.H., “The possible role of radio-frequency radiation in the development of uveal melanoma” in: Epidemiology 2001, Vol, 12, pp. 7-12.
STOA 2001 THE PHYSIOLOGICAL AND ENVIRONMENTAL EFFECTS OF NON-IONISING ELECTROMAGNETIC RADIATION, STOA – Scientific and Technological Options Assessment, Options Brief and Executive Summary, PE Nr. 297.574 March 2001, (www.europarl.eu.int/stoa/publi/pdf/00-07-03_en.pdf)
VDB 2002 VDB-Richtlinie, Teil II A 3, draft 2002, Verband Deutscher Baubiologen e.V. (www.baubiologie.net)
von Klitzing 1995 von Klitzing L. “Low-Frequency pulsed electromagnetic fields influence EEG of man.” Physica Medica, Vol. 11, No. 2, 77-80, April-June 1995, see also von Klitzing, L. in “Elektrosmog – Wohngifte – Pilze, Baubiologie – praktische Hilfe für jedermann”, Maes W., 1st Ed.1999, Haug-Verlag, Heidelberg, Germany.
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