RF frequency from Powerlines and Cancer 1997 paper

Personal Correspondence from Magda Havas.

Brad

Although this paper by Vignati and Giuliani was published in 1997, it is well worth reading as some of you may have missed it when it came out (see abstract below).

This paper documents radio frequencies flowing along power lines, something we are concerned about for a variety of reasons including the move to broadband over power lines (BPL). The RF can radiate from the wires inside buildings and thus expose occupants to RFR and not just ELF. The frequencies measured in this paper are in the kHz range.

While these frequencies may be placed on the wire deliberately, they may also occur because of improper filtering at the source of origin.

A few years ago, Dave Stetzer and I were invite to Bermuda to teach some people on the island how to measure dirty electricity, RFR, ground current, and ELF EMFs. While we were there, Dave was sitting on a chair near a bronze lamp in my room at the guest house, where we were staying, and he began to feel ill. Dave has become sensitive to EM radiation.

We began to measure the source of exposure and found that it was coming from an antenna several km away. However, he felt worse near the lamp. We measured the radiation in the room and found that it was coming in on the electrical wires in the wall and flowing along the wire to the nearby lamp. When we unplugged the lamp Dave felt slightly better. Dave took out his scopemeter and measured 104 MHz, which is an FM radio station. Presumably the radio station didn’t have appropriate filters to isolate the RF from the electrical wires.

Some of the RF we are exposed to inside buildings is coming through the air but some of it is radiating from electrical wires as Vignati and Giuliani document below. This complicates our exposure and hence our understanding of which frequencies are biologically active in epidemiological studies of both occupational and residential exposure. The move to BPL will increase our exposure to these frequencies and a lot more people are likely to become ill as a results.

-magda

p.s. I am attaching a copy of the paper but recognize that the CHE EMF list will remove it because they do not accept attachments. However, those of you who I have copied will be able to read it.

Vignati, M. and L. Giuliani, 1997. Radiofrequency exposure near high-voltage lines. Environ Health Perspect
105(Suppl 6):1569-1573 (1997).

Abstract
Many epidemiologic studies suggest a relationship between
incidence of diseases like cancer and leukemia and exposure to
50/60 Hz magnetic fields. Some studies suggest a relationship
between leukemia incidence in populations residing near
high-voltage lines and the distance to these lines. Other
epidemiologic studies suggest a relationship between leukemia
incidence and exposure to 50/60 Hz magnetic fields (measured
or estimated) and distance from the main system (220 or 120
V).

The present work does not question these results but is
intended to draw attention to a possible concurrent cause that
might also increase the incidence of this disease; the presence
on an electric grid of radiofrequency currents used for
communications and remote control.
These currents have been
detected on high- and medium-voltage lines. In some cases they
are even used on the main system for remote reading of electric
meters. This implies that radiofrequency (RF) magnetic fields
are present near the electric network in addition to the 50/60 Hz
fields.

The intensity of these RF fields is low but the intensity
of currents induced in the human body by exposure to magnetic
fields increases with frequency.

Because scientific research has
not yet clarified whether the risk is related to the value of
magnetic induction or to the currents this kind of exposure
produces in the human body, it is reasonable to suggest that the
presence of the RF magnetic fields must be considered in the
context of epidemiologic studies.

-magda

________________________________________________

Dr. Magda Havas,B.Sc. Ph.D.

Environmental & Resource Studies,

Trent University, Peterborough, Ontario, Canada, K9J 7B8

phone:? 705 748-1011 x 7882? ? fax:?705 748-1569

mhavas@trentu.ca

________________________________________________

——————————————————————————————————————————————————

Important research (Ozen 2007, see abstract below) compares induced currents generated within the body of adults and children at power line frequency (50 Hz) and by transients up to 100 kHz (dirty electricity).   It provides support for the biological importance of transients and complements the work that Sam Milham and Lloyd Morgan have done on the cancer cluster in the La Quinta Middle School (California) and the work that we’ve done regarding dirty electricity and its effects on diabetics, MS, and both students and teachers in schools.

The calculated induced current is greatest when the external magnetic field is perpendicular to the front of the body.  It is lower in children than adults (see below); and it increases with frequency (for the same magnetic flux density) (see below taken from Table 4).

In Table 4, the calculated induced current density in body models for a 1 micro Tesla external magnetic field (perpendicular to front of body) at various frequencies is as follows.  Induced current density (Jmax) is in microAmps/square meter.

average man:
1.  50 Hz – ~6 Jmax
2.  100 Hz – ~ 18
3.  10 kHz – ~ 2,400
4.  100 kHz – ~35,900

five-year old child:
1.  50 Hz – ~3.6 Jmax
2.  100 Hz – ~ 11
3.  10 kHz – ~ 1,400
4.  100 kHz – ~21,600

Induced current is critical from a biological perspective.   Stetzer, Hillman and Graham have been documenting the adverse effects of ground current and Kavet has published on the importance of contact current.  Now we have additional information on induced current without direct contact.  This is exactly what people are exposed to who have dirty electricity in their home/school/workplace.

This study shows that in addition to microwave frequencies and ELF we need to look at these intermediate frequencies because we generate them with our technology; because they permeate our environment and our body; and because they have been shown to be biologically active.

-magda

p.s.  For those of you who would like to contact the author, his email address is:  sukruozen@akdeniz.edu.tr

Ozen, S.  2007.  LOW-FREQUENCY TRANSIENT ELECTRIC AND MAGNETIC FIELDS COUPLING TO CHILD BODY, Radiation Protection Dosimetry (2007), pp. 1–6.

S. Ozen*
Department of Electrical and Electronics Engineering, Engineering Faculty, Akdeniz University, 07058 Antalya, Turkey

Much of the research related to residential electric and magnetic field exposure focuses on cancer risk for children. But until now only little knowledge about coupling of external transient electric and magnetic fields with the child’s body at low frequency transients existed. In this study, current densities, in the frequency range from 50 Hz up to 100 kHz, induced by external electric and magnetic fields to child and adult human body, were investigated, as in residential areas, electric and magnetic fields become denser in this frequency band. For the calculations of induced fields and current density, the ellipsoidal body models are used. Current density induced by the external magnetic field (1 mT) and external electric field (1 V/m) is estimated. The results of this study show that the transient electric and magnetic fields would induce higher current density in the child body than power frequency fields with similar field strength.

 

Radiofrequency Exposure Near  High-voltage Lines

 

Maurizio Vignati and Livio Giuliani

 

Istituto Superiore Prevenzione e Sicurezza del Lavoro, Rome, Italy

 

Environmental Health Perspectives 105, Supplement 6,

December 1997

 

 

Introduction

Data Transmission by Conveyed Waves Induced Currents in Human Tissues  Techniques of Measurement Values of RF Induction Measured under High-voltage Lines  Implications for Radiation Protection Implications in Epidemiologic Studies Conclusions

 

 

Abstract

Many epidemiologic studies suggest a relationship between incidence of diseases like cancer and leukemia and exposure to50/60 Hz magnetic fields. Some studies suggest a relationship between leukemia incidence in populations residing near high-voltage lines and the distance to these lines. Other epidemiologic studies suggest a relationship between leukemia incidence and exposure to 50/60 Hz magnetic fields (measured or estimated) and distance from the main system (220 or 120V). The present work does not question these results but is intended to draw attention to a possible concurrent cause that might also increase the incidence of this disease; the presence on an electric grid of radiofrequency currents used for communications and remote control. These currents have been detected on high- and medium-voltage lines. In some cases they’re even used on the main system for remote reading of electric meters. This implies that radiofrequency (RF) magnetic fieldfare present near the electric network in addition to the 50/60 Hz fields. The intensity of these RF fields is low but the intensity of currents induced in the human body by exposure to magnetic

fields increases with frequency. Because scientific research hasn’t yet clarified whether the risk is related to the value of magnetic induction or to the currents this kind of exposure produces in the human body, it is reasonable to suggest that the presence of the RF magnetic fields must be considered in the context of epidemiologic studies. –Environ Health Perspect  105(Suppl 6):1569-1573 (1997)

 

This paper is based on a presentation at the International  Conference on Radiation and Health held 3-7 November 1996

in Beer Sheva, Israel. Abstracts of these papers were previously  published in Public Health Reviews 24(3-4):205-431 (1996).  Manuscript received at EHP 28 February 1997; accepted 19  May 1997.

 

Address correspondence to Dr. M. Vignati, Istituto Superiore  Prevenzione e Sicurezza del Lavoro, Via Urbana 167, Rome

 00184, Italy. Telephone: 39 6 471 4243. Fax: 39 6 474 4017.  E-mail: vignatimz@etruria.net

 

Abbreviations used: RF, radiofrequency; EMF, electromotive  force; IRPA, International Radiation Protection Association;  µT, microtesla; nT, nanotesla; pT, picotesla.

 

 

Introduction

 

The Istituto Superiore Prevenzione e Sicurezza del Lavoro(Rome, Italy), where we work, is under the Ministry of Health and is concerned with research on safety in workplaces. In addition Institute investigators are called on as expert witnesses for state organizations and in civil and criminal courts. The experience we have acquired experimentally indicates that radiofrequency (RF) magnetic fields are emitted from power lines. The frequencies we have observed vary from 112 to 370kHz. The emissions are stable in frequency and are amplitude modulated by unintelligible signals. These RF fields have been detected near high-voltage lines (150-380 kV) using along-wave radio receiver. It was also possible to measure their intensity. At first there was some doubt about the origin of these magnetic fields: It was first hypothesized that corona and disturbances caused by load interruptions might be responsible for the excitation of the resonant frequencies of the lines. It was even hypothesized that RF currents generated by fluorescent lamps might somehow travel backward toward the high-voltage lines. All these hypotheses have been discarded. Corona and load interruptions produce a wide spectrum of frequencies,whereas the emissions we identified are of constant frequency and are amplitude modulated. The idea that RF currents attributable to fluorescent lamps might travel backward was proven to be technically impossible.

 

Data Transmission by Conveyed Waves

 

Based on information we obtained from other institutions but that is still incomplete, we concluded that the RF magnetic fields we identified were due to the lines being used for data communication systems. These systems are based on so-called conveyed waves that are produced when an RF generator feeds transmission line out of tune.

 

An inductor is wired between the 50/60 Hz power generator and the line to obtain the desired impedance and RF current flow over the line. A condenser is used to couple the Regenerator to the line.

 

Recently our Institute received a letter from Ente NazionaleEnergia Electtrica, the Italian electricity company, which referred to a specific case in which the company admits using transmissions on power lines (1). The letter also specifies power and frequencies. According to these data, transmission power asset to 10 W for each channel. This information is insufficient,  however, to give a quantitative idea of the phenomenon because the line impedance at the working frequency should also be given. lndeed, the most useful information to be determined would be the value of RF magnetic induction near high-voltage conductors. Therefore, it is necessary to determine the Recurrent that flows in these conductors rather than the RF power. According to information still to be confirmed, the RF current value should be around 10 mA. Frequencies used in this specific case range from 104 to 288 kHz. According to further information from Soreq NRC, Radiation Safety Division (2), 160 and 400 kV Israeli lines are used to transfer information.

The frequency range is 30 to 450 kHz, maximal transmission power 20 W, each signal no more than 10 W, line impedance400 ‡, and RF current 150 mA. These data might lead one to conclude that this phenomenon is negligible in terms of possible health effects, but we will show that this is not true.

 

Induction of Currents in Conductors and Living Tissues Exposed to RF Magnetic Fields

 

Let us consider an ideal loop inside a conductor, in which the  area S is crossed by a magnetic flux Ø. If Ø varies with time, an  electromotive force e (EMF) will be generated inside the loop, according to Equation 1.

e=dØ/dt [1]

 

If magnetic induction B is a sinusoidal function of time, with  frequency f and the conductor is wound N times around S,  Equation 1 becomes

e=2 fNBS [2]

 

If the conductor that we consider is human muscle tissue, we  can set N=1 in Equation 2; in this case the internal currents will depend on the electrical characteristics of the tissue.

 

At the frequencies we are concerned with, electric conductivity and dielectric constant are the important parameters. Data on these parameters and their dependence on frequency can be found in the literature. We considered the data from Tenforde  and Kaune (3) and Schwan (4). Figure 1 shows the pattern of dielectric constant and electric conductivity of human muscle tissue as a function of frequency.

 

Figure 1. Frequency  dependence of the dielectric  constant and conductivity of  human muscle tissue.

Dispersion : origin,  polarization of counterion  layer at cell surface or polarization of intracellular  structures connected to the  plasma membrane (tubular structures). Dispersion ß: origin, polarization of the cell membrane or polarization of cellular organelles (mitochondria, nucleus). Dispersion : origin, polarization of tissue water. Adapted from Schwan (4).

 

At very low frequencies, a few Hertz, for example, the dielectric constant of the plasmatic membrane is very high (3).

This implies that at these frequencies the currents flowing through the body follow an extra cellular pathway, i.e., the interior of the plasmatic membrane is shielded from applied fields by the plasma membrane. At frequencies around 50 Hz the dielectric constant decreases, although it still remains rather high. With the onset of phase ß (from 100 kHz to 10 mHz) these shielding properties become weaker and the membrane starts to be crossed more intensively by the currents. Cytoplasmatic resistance then becomes an important parameter in determining the passage of ionic currents through organized tissue structures.

 

Induced Currents in Human Tissues

 

The data available on dielectric constant and conductivity cane used together with Equation 2 and the laws of electrotechnics to determine the pattern of current density versus the frequency in the ideal loop, which is composed exclusively of human muscle tissue, when exposed to a uniform magnetic field.

 

Figure 2 shows the outcome of this process–the pattern of the capacitive current density, which is the component of the current advanced in phase by one-quarter period with regard tome that yields the current. This kind of current is related to phenomena of orientation of molecular electric dipoles contained in the circuit. The result is that this current density increases with frequency if induction is constant. In other words, as long as the frequency increases, smaller values of magnetic induction can produce the same value of current density.

 

Figure 2. Capacitive current density in a toroid of human muscle tissue (unitary radius) exposed to a unitary magnetic

induction.

 

Techniques of Measurement

 

Commercial instruments usually used for measuring 50/60 Hz fields have bandwidths of a few kHz and are not suitable for measuring RF fields. There is also a problem of sensitivity because the intensity of the RF fields produced by conveyed waves is very low. An inductive probe connected to a spectrum analyzer allows the detection of the RF magnetic fields (Figures3, 4) but the readings should be corrected according to the ratio between the spectrum analyzer input impedance and coil impedance at each frequency. We measured the fields by means of resonant circuits (L-C circuits), which can be tuned to the frequencies used by the conveyed waves. The instrument is made up of three elements: a metallic box with a calibrated variable condenser and scale by which the circuit can be tuned;

a copper coil wound on an insulating spool, which also functions as a probe; and an RF detector. A series of these interchangeable coils allows coverage of the entire frequency range. The signals are measured by an oscilloscope (Figure 5). The resonant circuit is connected to the oscilloscope directly without intermediate coaxial cable. This reduces the minimum capacitance value of the resonant circuit and ensures maximum range of tunable frequencies. The structural arrangement of the coils shields the coils from electric fields and a thin conducting layer of graphite-based lacquer surrounds the coil. This shield must be grounded.

 

Figure 3. Spectrum analysis of RF signals present just under one high-voltage line.

Figure 4. Spectrum analysis of RF signals present 100 m away from one high-voltage line.

Figure 5. Oscilloscope supporting variable condenser and coil.

 

A 16-cm diameter coil appears to be of sufficient size. Thenumber of turns in the coil varies according to frequency range.For instance, a coil with 280 turns wound in one layer allowsdetection of fields between 47 and 159 kHz. At resonance the EMF developed in the coil is multiplied Q times at the output, where Q is the quality factor of the parallel resonant circuit. The value of Q for a coil like the one previously described isabout 13, but it is possible to take measures to increase thevalue of Q considerably. Therefore, the instrument is fairlysensitive although it is simple. In our case, 10 p is the smallest  value of magnetic induction that can be measured using an oscilloscope with normal characteristics.

 

This system also allows us to measure the 50/60 Hz magnetic field. At these frequencies the resonant L-C circuit incompletely out of tune and therefore near a power line the voltage at the ends of the circuit is the sum of two signals. The first, at 50/60 Hz, is considered without any factor; the second signal, at RF, is superimposed on the first and varies in amplitude according to the tuning but assumes the maximum value at resonance (i.e., Q times the RF EMF).

 

Values of RF Induction Measured under  High-voltage Lines

 

We took several RF magnetic field measurements near high-voltage lines. In most cases the working voltage of the lines was not known. Once it was determined that characteristics of these RF fields were not related to line

Voltage, knowing the voltage rating of the lines became less important. On the other hand, in a recent experiment we found that even a buried medium-voltage (20 kV) line emits Romantic fields with characteristics similar to those found near high-voltage lines, so it is likely that conveyed waves are also used on medium-voltage lines whether buried or on poles.

 

Table 1 shows the characteristics of RF magnetic fields found at various sites. Distances to the transmission lines vary because it was almost impossible to take measurements at equal distances from the lines. Values ranged from 32 to 438 pT. Another measurement was made at Juliaborg, near Stockholm (Sweden), at the 25th International Congress on Occupational Health 15-20 September 1996.

 

In all cases the intensity of RF magnetic induction B decreases with distance to the high-voltage lines. At 207 kHz intensity decreases as shown: 17.6 m (265 pT); 20.2 m (203 pT); 26.6 m(135 pT); 34.8 m (81 pT); 43.7 m (54 pT); and 53 m (47 pT).

 

Implications for Radiation Protection

 

Let us consider the limit value (100 µT) that the International Radiation Protection Association (IRPA) recommends not be exceeded in exposure of populations to 50/60 Hz fields. According to Figure 2, at constant magnetic induction there are four orders of magnitude between the capacitive current density induced at 50/60 Hz and that induced at 100 kHz. This means that at 100 kHz a field strength of 10 not produces the same order of magnitude of capacitive current density produced by100 µT at 50/60 Hz. Note that 10 nT is 30 times less than 0.3  µT, the value at which some epidemiologic studies suggest statistically significant increases in the incidence of leukemia occur (5-8).

 

Although it is true that the values of RF magnetic induction we found are about two orders of magnitude smaller than 19 nT, its also true that electric current at 100 kHz can penetrate much more deeply through the plasmatic membrane than current at50/60 Hz.

 

Implications in Epidemiologic Studies

 

Many epidemiologic studies (5-28) suggest a relationship between incidence of diseases like cancer and leukemia and

exposure to 50/60 Hz magnetic fields. No epidemiologic study has yet considered this kind of exposure to RF magnetic fields, which may occur together with the 50/60-Hz exposure. Conveyed waves seem to be widely used on high-voltage lines. In Sweden their presence has been verified experimentally; another countries like Portugal and Israel, it was noted the characteristic inductors were placed at the ends of high-voltage conductors, a sure sign that the RF communication system issued in these countries as well. In the United States this system may also be in use but because of the many independent electric companies, it is not easy to determine the extent of its use. In addition, it is also likely that this transmission system issued on medium-voltage lines, which in some countries like

 Italy are buried under built-up areas, whereas in others are supported on pylons. In Italy, for example, we discovered medium-voltage line buried under the built-up area of a village.The line was emitting amplitude-modulated magnetic fields at125 kHz.

 

Finally, some regions of Italy use a remote-reading system for electric meters; this system also uses conveyed waves.

Characteristics of this system are not known and it also is not known whether the system is used in other countries.

 

There is an almost complete lack of information and awareness, both in Italy and in other countries, about the degree of diffusion of conveyed waves along electric networks. From physical standpoint the RF magnetic field of conveyed waves behaves almost the same as the 50/60 Hz magnetic field: it can cross buildings without strong attenuation. In fact, in both cases the eventual attenuation or disappearance of the electric component does not alter the magnetic component. The latter can only be altered when it crosses a good conductor of electricity and building materials are not good conductors. This fact was confirmed experimentally in the case of the medium-voltage buried line we examined.

 

In summary, we conclude the following.

The Scandinavian epidemiologic studies (5,12)examined a population residing near power lines. Therefore, it is likely that in the homes of the exposed subjects an important ratio might be found between there components of the magnetic field attributable to conveyed waves and the 50-Hz components. With regard to the studies performed in the United States, which were based on proximity to much lower voltage distribution lines, it would be necessary to verify the usage of conveyed waves on medium-voltage lines.

 

Currently there is considerable disagreement among scientist son the mechanism of interaction that determines negative effects on health at low-magnetic field intensities. Possible hypotheses are either direct action of the magnetic field or complex mechanism mediated by the currents induced in the biologic systems exposed. To emphasize the importance of investigating this last possibility further, the following two assumptions are made: a) for exposures to 50/60 Hz magnetic fields, leukemia incidence starts to increase at magnetic induction intensities around 0.2 µT, and b) this effect is the induced current density produced because of this magnetic induction.

 

Under these assumptions, we also must admit that the same incidence of illness is produced at lower values of magnetic induction if the frequency is higher. It was shown before that passing from 50/60 Hz to 100 kHz, a value of magnetic induction 20,000-fold lower, is capable of producing the same density of the capacitive component of current. This means that in passing from 50/60 Hz to 100 kHz the threshold for the same illness could be lowered from 0.2 µT to values probably ranging from 10 to 100 pT.

 

Values of RF magnetic induction around these orders of magnitude are frequently found near power lines. In fact, in our experiments we found magnetic induction levels of about 50 pT50 m from one of these lines.

 

Conclusions

 

In epidemiologic studies investigating possible links between 50/60-Hz magnetic field exposure and cancer or links between the disease and distance to an electric network, it appears important that possible exposure to RF magnetic fields joined to conveyed waves be considered. This may be important even incases of exposure not due to power lines, as in the U.S. studies, which are based on proximity to much lower voltage distribution lines. For example, the use of conveyed waves is theoretically possible on medium-voltage lines, either for remote control of substations or for the remote reading of electric meters.

 

Because the use of conveyed waves on electricity networks is secondary use, it is logical that epidemiologic studies be limited to the main effect, i.e., the search for possible effects of 50/60Hz fields. If it is found that RF magnetic fields are also capable of increasing leukemia incidence, RF magnetic fields must be considered a confounding factor with regard to the main effect.

 

References

1. Poulet G. Unpublished data.

2. Hareuveny R. Unpublished data.

3. Tenforde TS, Kaune WT. Interaction of extremely low frequency electric and magnetic fields with humans. Health Phys 53(6):585-606 (1987).

4. Schwan HP. Biophysical Principles of the Interaction of ELF Fields with Living Matter. New York:Plenum Press, 1985.

5. Feychting M, Ahlbom A. Magnetic fields and cancer in children residing near Swedish high-voltage power lines. Am J Epidemiol 138:467-481 (1993).

6. Verkasalo PK, Pukkala E, Hongisto MY, Valjus JE, Jarvinen PJ, Heikkila KV, Koskenvuo M. Risk of cancer in Finnish children living close to power lines. Br Med J 307:895-899 (1993).

7. Schreiber GH, Swaen GMH, Meijers JMM, Slangen JJM, Sturmans F. Cancer mortality and residence near electricity transmission equipment: a retrospective cohort study. Int J Epidemiol 22:9-15 (1993).

8. Ahlbom A, Feychting M, Kosekenvuo M, Olsen JH, Pukkala E, Schulgen G, Verkassalo P. Electromagnetic fields and childhood cancer. Lancet 342:1295-1296 (1993).

9. Wertheimer N, Leeper E. Electrical wiring configurations and childhood cancer. Am J Epidemiol 109:273-284 (1979).

10. Wertheimer N, Leeper E. Adult cancer related to electrical wires near the home. Int J Epidemiol 11:345-355 (1982).

11. McDowell ME. Mortality of persons resident in the vicinity of electricity transmission facilities. Br J Cancer 53:271-279 (1986).

12. Tomenius L. 50 Hz electromagnetic environment and incidence of childhood tumours in Stockholm County. Bioelectromagnetics 7:191-207 (1986).

13. Savitz DA, Wachtel H, Barnes FA, John EM, Tvrdik JG. Case-control study of childhood cancer and exposure to 60 Hz magnetic fields. Am J Epidemiol 128:21-38 (1988).

14. Coleman MP, Bell CMJ, Taylor KL, Primic-Zakelj M. Leukaemia and residence near electricity transmission equipment: case control study. Br J Cancer 60:793-798 (1989).

15. London SJ, Thomas DC, Bowman JD, Sobel E, Cheng TC, Peters JM. Exposure to residential electrical and magnetic fields and risk of childhood leukaemia. Am J Epidemiol 134:923-937 (1991).

16. Olsen JH. Residence near high voltage facilities and risk of cancer in children. Br Med J 207:891-895 (1993).

17. Poole C, Kavet R, Funch DP, Donelan K, Charry JM, Dreyer NA. Depressive symptoms and head aches in relation to proximity of residence to an alternate current transmission line right-of-way. Am J Epidemiol 137:318-330 (1993).

18. Floderus B, Persson T, Stenlund C, Wennberg A, Ost A, Knave B. Occupational exposure to electromagnetic fields in relation to leukaemia and brain tumors: a case-control study in Sweden. Cancer Causes Control  4:465-476 (1993).

19. Floderus B, Törnquist S, Stenlund C. Incidence of selected cancers in Swedish railway workers; 1961-79. Cancer Causes Control 5:189-194 (1994).

20. ThériaultG, GoldgergM, Miller AB, Armstrong B, GuénelP, Deadman J, Imbernon E, To T, Chevalier A, Cyr D et al. Cancer risks associated with occupational exposure to magnetic fields among electric utility workers in Ontario and Quebec, Canada, and France: 1970-1989. Am J Epidemiol 139:550-572 (1994).

21. Savitz DA, Loomis DB. Magnetic field exposure in relation to leukaemia and brain cancer mortality among electric utility workers. Am J Epidemiol 141:123-134 (1995).

22. Lindebohm ML. Magnetic fields of VDT and spontaneous abortion. Am J Epidemiol 136:1041-1051 (1992).

23. Tynes T, Andersen A. Electromagnetic fields and male breast cancer. Lancet 335:1596 (1990).

24. Demers DA, Thomas DB, Rosenblatt KA, Jimenez LM, McTiernan A,

Stalsberg H, Stemhagen A, Thompson WD, McCrea Curnen MG,Satariano W

et al. Occupational exposure to electromagnetic fields and breast cancer in

man. Am J Epidemiol 134:340-347 (1991).

25. Matanoski GM, Breysse PN, Elliot EA. Electromagnetic field exposure

and male breast cancer. Lancet 337:737 (1991).

26. Loomis DP. Cancer of breast among men in electrical occupations. Lancet

339:1482-1483 (1992).

27. Guénel P, Raskmark P, Andersen JB, Lynge E. Incidence of cancer in

persons with occupational exposure to electromagnetic fields in Denmark. Br J

Ind Med 50:758-764 (1993).

28. Dosemeci M, Blair A. Occupational cancer mortality among women

employed in the telephone industry. J Occup Med 36:1204-1209 (1994).

 


 

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