[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
EMF Editorial from NEJM July 3, 1997
Dear Radsafers,
I here copy paste the Editorial on EMF that was published on
July 3, 1997 in New England Journal of Medicine in case you
didn't see it. Hope the people NEJM don't mind - after all
it concerns how we spend money (has anyone an idea of the
total annual costs in the U.S. for example? Not only costs
for research, but also from law suits, administration, technical
costs and so on). It is from http://www.nejm.com/
If you have little time to read - start with the last paragraph.
I apologize for any paragraph break that may not follow the
original - some of this was lost in the copy-pasting.
bjorn_cedervall@hotmail.com
Depts. Medical Radiation Biology and Medical Radiation Physics,
Karolinska Institutet, Box 260,
S-171 76 Stockholm,
Sweden
--------------------------------------------------------------
Power Lines, Cancer, and Fear
Over the past 18 years, there has been considerable interest in the
possible link between electromagnetic fields and cancer, especially
leukemia.
The story of this highly publicized research has been marked by mystery,
contradiction, and confusion. When something as ubiquitous and
misunderstood as extremely-low-frequency electromagnetic fields is
accused of causing cancer in children, people's reactions may be driven
more by passion than by reason.
Each year in this country about 2000 children are given a diagnosis of
acute lymphoblastic leukemia (ALL), the most common childhood cancer.
Despite the remarkable advances in treatment, ALL still carries a 30
percent mortality. Other than exposure to ionizing radiation, its cause
remains a mystery. ALL is more common among whites and children of
higher socioeconomic class, and for unclear reasons the incidence of ALL
has increased by about 20 percent in the past two decades. (1,2) During
the past 50 years, per capita use of electricity has increased more than
10 times. Some investigators have claimed that living close to major
power lines causes cancer, particularly leukemia in children.
In this issue of the Journal, Linet et al. (3) report the results of a
major study showing that the risk of ALL does not increase with
increasing electromagnetic-field levels in children's homes. This study
has several strengths. It was large, including 629 children with
leukemia and 619 controls, and it included measurements of
electromagnetic fields, made by technicians blinded to the case or
control status of the subjects, both in the houses where the children
had lived and, in 41 percent of cases, in the homes in which their
mothers resided while pregnant. Linet et al. also found no relation
between the risk of ALL and residential wire-code classifications, again
determined by technicians blinded to the children's health status. The
wire-code classifications are important, because several of the earlier
positive studies relied on these proxy indicators rather than on actual
measurements of electromagnetic fields.
This whole saga began when two Denver researchers, puzzled by small
clusters of cancer in children, came to believe that living in close
proximity to high-voltage power lines was a cause of leukemia. (4) The
analysis they published in 1979 was crude and relied on distances from
homes to power lines and on wiring configurations rather than on direct
measures of exposure to electromagnetic fields. They found that the risk
of childhood leukemia was more than doubled among children living near
such power lines, a finding that led to more studies and more concern.
Soon activists and the media began to spread the word that
electromagnetic fields cause cancer.
The hypothesized cause was exposure to extremely-low-frequency magnetic
fields generated by the electrical current in power lines. Physicists
understand these invisible fields well, but most physicians, parents,
and patients do not. The movement of any electrical charge creates a
magnetic field that can be measured. (5) Even the 60-Hz residential
electric current (50 Hz in Europe) creates a very weak oscillating
field, which, like all magnetic fields, penetrates living tissue. These
low-frequency electromagnetic fields are known as nonionizing radiation,
since the amount of energy in them is far below that required to break
molecular bonds such as those in DNA.
One ironic fact about low-frequency electromagnetic fields is that we
live and worry about them within the Earth's static magnetic field of 50
microteslas, which is hundreds of times greater than the oscillating
magnetic field produced by 110/220-V current in houses (0.01 to 0.05
microtesla). (5,6) Even directly under high-voltage transmission lines,
the magnetic field is only about 3 to 10 microteslas, which is less than
that in an electric railway car and much weaker than the magnetic field
close to my head when I use an electric razor (about 60 microteslas).
Although most physicists find it inconceivable that power-line
electromagnetic fields could pose a hazard to health, dozens of
epidemiologic studies have reported weak positive associations between
proximity to high-voltage power lines and the risk of cancer. (6,7) The
negative or equivocal studies did not end the controversy. Fear of
leukemia is a powerful force, and the media response amplified the
perception of electromagnetic fields as a health hazard. In 1989 The New
Yorker published three articles by journalist Paul Brodeur that
described in mesmerizing detail how maverick researchers had discovered
a cause of cancer that the establishment refused to accept. (8,9,10)
Like many of the epidemiologic studies themselves, these widely quoted
articles described biologic mechanisms of action for electromagnetic
fields that were hypothetical, even fanciful. Brodeur went so far as to
claim that the search for the truth about the hazards of electromagnetic
fields was threatened most by the "obfuscation of industry, the
mendacity of the military, and the corruption of ethics that industrial
and military money could purchase
from various members of the medical and scientific community." (8)
Suspicion spread to many other wavelengths on the nonionizing
electromagnetic spectrum, producing fears about occupational exposure to
electricity as well as exposure to microwave appliances, radar,
video-display terminals, and even cellular telephones. Dozens of studies
looked for associations with brain cancer, miscarriages, fetal-growth
retardation, lymphoma, breast cancer, breast cancer in men, lung cancer,
all cancers, immunologic abnormalities, and even changes in the behavior
of animals.
When people hear that a scientific study has implicated something new as
a cause of cancer, they get worried. They get even more worried when the
exposure is called radiation and comes from dangerous-looking
high-voltage power lines controlled by government and industry, which
some distrust deeply. Such exposure seems eerie when people hear that
electromagnetic fields penetrate their homes, their bodies, their
children. The worried citizens took action. Frightened people, including
parents of children with leukemia, undertook their own epidemiologic
studies and fought to get high-power transmission lines moved away from
their children. Congress responded with large direct appropriations for
wider research on the effects of electromagnetic fields. After a large
apparently positive study in Sweden, (7) the Swedish government came
close to mandating the relocation of schools to at least 1000 meters
from large power lines. But cooler heads prevailed once it became clear
that the absolute incremental risk was small at most, the conclusions
were based on a tiny fraction of all Swedish children with leukemia, and
the increase in risk was found only in relation to some estimates of
magnetic fields, not to the actual fields measured in children's homes.
Serious limitations have been pointed out in nearly all the studies of
power lines and cancer. (11,12) These limitations include unblinded
assessment of exposure, difficulty in making direct measurements of the
constantly varying electromagnetic fields, inconsistencies between the
measured levels and the estimates of exposure based on wiring
configurations, recall bias with respect to exposure, post hoc
definitions of exposure categories, and huge numbers of comparisons with
selective emphasis on those that were positive. Both study participation
and residential wire-code categories may be confounded by socioeconomic
factors. Often the number of cases of ALL in the high-exposure
categories has been very small, and controls may not have been truly
comparable. Moreover, all these epidemiologic studies have been
conducted in pursuit of a cause of cancer for which there is no
plausible biologic basis. There is no convincing evidence that exposure
to electromagnetic fields causes cancer in animals, (6) and
electromagnetic fields have no reproducible biologic effects at all,
except at strengths that are far beyond those ever found in people's
homes.
In recent years, several commissions and expert panels have concluded
that there is no convincing evidence that high-voltage power lines are a
health hazard or a cause of cancer. (6,13) And the weight of the better
epidemiologic studies, including that by Linet et al., now supports the
same conclusion. It is sad that hundreds of millions of dollars have
gone into studies that never had much promise of finding a way to
prevent the tragedy of cancer in children. The many inconclusive and
inconsistent studies have generated worry and fear and have given peace
of mind to no one. The 18 years of research have produced considerable
paranoia, but little insight and no prevention. It is time to stop
wasting our research resources. We should redirect them to research that
will be able to discover the true biologic causes of the leukemic clones
that threaten the lives of children.
Edward W. Campion, M.D.
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com