Electromagnetic Fields - Why you should be concerned

by Brian Kohler

Introduction

Electricity always produces electric fields and magnetic fields. Although the electric and magnetic fields have different properties and can be measured separately, they are often grouped together and referred to as electromagnetic fields or EMFs.

Do electromagnetic fields cause cancer or other health effects? All of us are continually surrounded by EMFs, at work and at home. EMFs are produced by just about everything that uses or carries electricity - electric power transmission lines, video display terminals, motors, heaters, telecommunications equipment, and even cellular telephones, microwave ovens and police radar guns.

If there is the slightest possibility that electromagnetic fields could be affecting human health, then it should be taken extremely seriously because of the huge number of people who are exposed. In developed countries, it is fair to say that everyone is exposed. As with most hazards, there are groups of workers who are more heavily exposed than the rest of the population. They will be the canaries for the rest of society.

The Issue

The results of several studies, taken together, tend to show an association between exposure to EMFs and certain types of cancer. (It should be pointed out that an association between two events is not always proof of cause and effect).

What we know about EMFs and cancer is this. Several epidemiological studies have looked at two types of exposure to EMFs. Studies of residential exposure have tended to look for any evidence of cancer, but especially leukemia, lymphoma or central nervous system (CNS) tumors in children and adults. Studies of occupational exposure have tended to look for any evidence of cancer, but especially leukemia, lymphoma, CNS tumors, male and female breast cancer, pituitary gland cancer, and lung cancer in workers (adults).

In addition, there has been anecdotal, evidence. This means that there are cancer "clusters" that have been blamed on EMFs even though scientific proof of a connection does not exist, usually because the number of people involved was too small for statistical confidence. This does not mean the concerns are wrong, it only means that they cannot be proven to be right.

Besides cancer, other health effects that have been attributed to EMFs exposure include depressed immune response, neurological symptoms, and adverse pregnancy outcomes (miscarriages and birth defects). The linkage for most of these is statistically weak. However, new theories have been proposed that would explain why there could be a health effect.

Opinions differ as to what properties of which component (electric or magnetic) of EMF, if any, are creating the hazard. Recently, most research has focused on extremely low frequency and pulsed EMF, and static magnetic fields.

 

History

There is an interesting history to the study of health effects due to EMFs. Initially, the scientific community dismissed, without undertaking any studies, the possibility of health effects from EMFs. However, public health advocates and labour insisted, and when studies were finally undertaken there appeared to be a correlation between EMF exposure and certain health effects. Two studies in particular, done in the United States: one in 1979 that reported a higher incidence of cancer in children living near high current power lines; and one in 1987 that also linked childhood cancer and proximity to power lines; fueled concern which generated further investigations.

The Analysis

When investigating a cancer cluster, and trying to show a cause and effect relationship with something in the workplace, researchers normally want to observe the following:

Researchers also try to rule out confounding factors (like tobacco smoke, carbon monoxide or ozone in the workplace atmosphere, for example) and information bias. Random chance can produce unexplainable clusters of cancer as well.

One of the problems in proving a cause and effect relationship between EMFs and various health conditions has been the inability of most researchers to find a direct relationship between dose (length of exposure and intensity) and the effects on health. (A few have found such a relationship, but many have not).

Some scientists have argued that the inability to show a dose-response relationship in most studies proves that the observed health effects are random "clusters" of disease that are unrelated to EMFs. This theory has become weaker as more studies have included larger numbers of people.

Other researchers have tried to show that EMFs do affect certain biological processes and have proposed theories to explain the observations.

In the multi-stage theory of carcinogenesis. a cell must first be initiated (usually understood to mean that damage to the DNA must take place) and then promoted to an active, growing cancer by interference with normal inter- and intra-cellular functions. Most researchers do not seem to think that EMFs are cancer initiators. Rather, most feel that EMFs may act as promoters of cancer in some fashion.

If EMFs are cancer promoters or co-promoters, an observation of elevated rates of lung cancer is biologically plausible. This is because the lung tissue of many, or most, of us contains cells that have already been initiated through exposure to environmental pollutants. The lungs often bear the greatest burden of injury from external carcinogens because of the job they must do.

There are many possible and subtle ways that this may happen. For example, perhaps there is only a narrow range of frequencies and intensities that can have the most serious biological effects.

There is an unproved theory that EMFs may act as cancer promoters by suppressing the production in the body of a hormone called melatonin. Melatonin is a powerful hormone produced during dark hours that affects the production and regulation of other hormones in the body, including estrogen. Melatonin also acts as an antioxidant, protecting the body to some extent against cancer-causing free radicals that are constantly being produced through chemical reactions in the body. One of the ways free radicals are "disarmed" is through a process called intrasystem conversion. Intrasystem conversion of free radicals has been shown to be inhibited by magnetic fields of as little as 5 microteslas. If EMFs can affect hormone balance, then it would be biologically plausible for hormone mediated cancers, such as breast cancer, to also be affected.

Another interesting theory is that some people may be hypersensitive to EMFs, in much the same way that some people become hypersensitive to environmental chemicals. If this were the case, hypersensitivity to EMFs could be a disease with many different and interacting causes such as exposure to certain chemicals, stress allergies, as well as individual differences.

A fourth hypothesis, being promoted by British researchers, is that EMFs may attract and concentrate ions and radioactive substances such as radon and its decay products. These may exist in the form of gases or dusts. However, this may be just as likely to protect workers from carcinogens by drawing such materials out of the general workplace atmosphere and concentrating them near powered equipment, where fewer workers are likely to breathe them.

In Summary.

Studies overall support and association with childhood and adult leukemia. Childhood leukemia was more strongly linked to EMF exposure than adult leukemia. Studies with negative results exist, but most of these have identifiable methodological errors.

Studies overall support an association with childhood and adult central nervous system (CNS) tumors but the association is less conclusive. Brain tumors are more strongly associated with exposure among younger people. Even so, some of the studies showing this linkage had methodological flaws.

In addition, male breast cancer and cancer of the pituitary gland are very rare cancers but one Swedish study shows a possible link with EMF exposure.

Recently, a Boston University study suggested a link with female breast cancer, and a strong statistical link with lung cancer was made in a study released in September of this year by Dr.Gilles Theriault, a researcher at McGill University in Montreal. These are particularly alarming. Unlike CNS tumors and leukemia which are relatively rare, lung and breast cancer are the two leading causes of cancer death in Canada.

A definitive dose-response relationship for EMF exposure and health effects has been difficult to establish. Most studies have not shown such a relationship. However, the recent, massive, Ontario Hydro/Hydro-Québec/Électricité du France study of electrical utility workers did show a relationship between exposure (dose) and effect. As explained earlier, the existence of a dose-response relationship is a big step towards proof of cause and effect.

One problem for researchers is that different studies have tended to obtain different results (positive or negative). This tends to raise questions about the possibility that accidental correlations are being encountered. Why have there been so many studies, but as yet no definitive answers? The investigations into EMF have been plagued with many methodological problems, i.e.:

The Solution.

Taking all of the above into account, then, the question remains whether we should be concerned about electromagnetic fields.

For workers in occupations not considered to have high exposures, the level of concern at this time is probably small, but certainly not zero.

For workers in very exposed occupations, (e.g. telecommunications and electrical workers, operators of electrically powered heavy industrial equipment, maintenance electricians, video display terminal operators, etc.) the concern is much higher.

This advice is based on the evidence that so far seems to indicate that EMFS are probably "weak" carcinogens. Most likely they are promoters, rather than initiators, of cancer. This means that tissue that has already been "initiated such as the lungs of a smoker, would be more likely to develop cancer if exposed to EMF.

We should act on the precautionary principle. Our history tells us that usually, the seriousness of a hazard is underestimated at first. In the meantime, we can take low-cost, low effort steps to limit exposure to EMFs.

In workplaces, there must be education and information about the problem. Exposure levels can be measured, and strong sources can at least be labeled or signed, if they cannot be removed or shielded. Local unions can keep a tally of worker health complaints. Workers thought to be at risk should be metered with dosimeters (now available) so that we can build a data base for the future. Workers should put distance between themselves and EMF sources wherever possible.

Apart from workplace concerns, we can route new transmissions lines so they avoid people and make the hydro "right of ways" wider. We should not build our homes and our schools under or near strong EMF sources. We should design new appliances to minimize EMFs. And we should continue to do more studies.

We welcome your suggestions, comments or general inquiries.
Drop a line to the author brian@cep.ca

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