Dr. Magda Havas, PhD Environmental Studies Research Papers

Kingston Ontario Magnetic Fields

Posted on October 8, 2009

Havas, M. and J. MacKay. 2004. Street level Magnetic Fields within the City of Kingston, Ontario, Canada. Biological Effects of EMFs, 3rd International Workshop, Kos, Greece, 4-8 October, 2004. pp 318-325.


Magnetic flux density associated with power lines was measured in three communities within the City of Kingston (population 123,000), Ontario, Canada during a two-week period in August 2003. Spot measurements were taken during the day (0900–1700 h) and in the evening (1700–2100 h) Monday to Friday at intersections, along the sidewalk, and at the front door of buildings on both sides of the street. The mean magnetic flux density for downtown commercial, downtown residential, and suburban residential was 28, 3.2, and 4.0 mG respectively. Of the almost 4000 measurements taken in this study, 76% were above 2 mG, the lower limit associated with childhood leukemia in epidemiological studies. More specifically, the downtown commercial, downtown residential, and suburban communities had 97%, 68% and 42% of readings above 2 mG respectively. As many as 64% of the measurements in the commercial district were above 12 mG, which has been associated with enhanced growth of human breast cancer cells in vitro and 54% were above 16 mG, which has been associated with increased risk of miscarriages. Day and evening measurements within each community were similar with some exceptions. Magnetic flux densities at intersections were similar or slightly higher than values measured along residential streets and were significantly higher than street values in the Kingston’s commercial district. Exposure to street level magnetic fields may be considerable in some communities posing a potential risk to delivery personnel, street vendors, utility employees, maintenance workers, police, and others who spent time in this environment. These outdoor environments are important sources of electromagnetic field exposure for certain types of occupations but they may also contribute signficiantly to non-occupational exposure and should be included when calculating exposure estimates.

Table 2. Magnetic Flux Density (mG) for the City of Kingston, ON, Canada.

Magnetic Fields on city streets in Kingston, Ontario, Canada

Magnetic Fields on city streets in Kingston, Ontario, Canada

Biological Effects of ELF Fields, Chapter London

Posted on October 8, 2009

Havas, M. 2004. Chapter 10. Biological Effects of Low Frequency Electromagnetic Fields. pp 207-232. In: D. Clements-Croome (Ed.). Electromagnetic Environments and Health in Buildings. Spon Press, London, 535 pp.


The biological effects of low frequency electric and magnetic fields2 (EMF) have become a topic of considerable scientific scrutiny during the past two decades. The flurry of research in this area has contributed greatly to our understanding of the complex electromagnetic environment to which we are exposed but it has not abated the controversy associated with the harmful effects of electromagnetic fields. If anything it has polarized scientists into two camps, those who think exposure to low frequency electromagnetic fields causes health effects and those who do not. Those who believe there is a causal association are trying to find the mechanism responsible and those who question the concept of causality think this research is a waste of time and money.

Controversy is the norm when complex environmental issues with substantial economic and health consequences are scientifically scrutinized. Asbestos, lead, acid rain, tobacco smoke, DDT, PCBs (and more recently estrogen mimics) were all contentious issues and were debated for decades in scientific publications and in the popular press before their health effects and the mechanisms responsible were understood. In some cases the debate was scientifically legitimate, while in others interested parties deliberately confuse the issue to delay legislation (Havas et al 1984). The public, uncomfortable with scientific controversy and unable to determine the legitimacy of a scientific debate, wants a clear answer to the question, "Are low frequency electric and magnetic fields harmful?"

As a direct response to public concern three major reports, with multiple contributors with diverse expertise, have been published recently on the health effects of low frequency electric and magnetic fields: one by the U.S. National Research Council (1997), another by the National Institute of Environmental Health Sciences (Portier and Wolfe, 1998), and the most recent, still in draft form, by the California EMF Program (2001). These influential reports attempt to make sense of the many, and sometimes contradictory, documents from different fields of study, related to the health effects of power-line frequency fields.

The purpose of the present paper is three-fold:

(1) To characterize human exposure to low frequency electromagnetic fields;
(2) To identify key biological markers and possible mechanisms linked to EMF exposure;
(3) To comment on the concept of scientific consistency and bias.

The question "Are low frequency electric and magnetic fields harmful?" is valid and timely. The answer is likely to have far reaching consequences, considering our growing dependence on electric power, computer technology, and wireless communication, and it is likely to be of interest to a large population using, manufacturing, selling, and regulating this technology.

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EMF in 60 Ontario Communities

Posted on October 7, 2009

Havas, M. 2002. Intensity of electric and magnetic fields from power lines within the business district of 60 Ontario communities. The Science of the Total Environment 298:183-206.


Electric and magnetic fields were measured during the summer of 1998 in south-central Ontario within the business district of 60 communities, ranging in size from 1000 to 2.3 million people. The mean magnetic flux density for the 60 communities was 5.8 mG. Communities with larger populations generally had higher magnetic flux densities than those with smaller populations. Communities with populations above 100 000, between 50 000 and 100 000, between 10 000 and 50 000, and less than 10 000 had mean magnetic flux densities of 14, 7, 4 and 2.4 mG, respectively. The city of Kingston, population 123 000, had the highest mean magnetic flux density (47 mG) while Burks Falls, population 1000, had the lowest (0.8 mG). More than 90% of the sites measured in Kingston, Toronto, Oshawa, London, Pickering Village and Bellville were above 2 mG, the lower limit associated with childhood cancers. In only one community (Burks Falls) were all of the measurements in the business district below 2 mG. Diurnal variations were detected in the magnetic field (but not in the electric field) with highest fields measured during business hours. For electric fields, the mean for the 60 communities was 3.2 V/m. Electric fields were generally low. Eight communities had maximum field strengths above 30 V/m and all of these were associated with overhead wires. In larger communities with underground distribution lines the electric fields were low or undetectable (-0.1 V/m) but the magnetic fields were often high. High electric fields were generally associated with low magnetic fields but the relationship was not sufficiently robust to enable prediction of one from the other. Data for the business district measured during business hours appear to be relatively consistent for both electric field and magnetic flux density over a two-year period. T wo classification schemes that can be used independently or in combination are proposed to facilitate community comparisons. One is based on the average intensity of the fields (FI) and the other on the percentage of measurements that exceed a critical limit (CL) that has biological significance. The critical value of 5 V/m is proposed for electric fields and 2 mG for magnetic fields. Both classification schemes use the traffic light analogy for exposure (green-low, amber-medium, red-high exposure) with an additional category (black) for very high exposure. This classification system facilitates information transfer and can easily be understood and used by the public, public utilities, policy makers, and those wanting to practice prudent avoidance.  2002 Elsevier Science B.V. All rights reserved.

Havas 2002.  EMFs in 60 Ontario Communities

Havas 2002. EMFs in 60 Ontario Communities