Subject:  ,,EMF,,(H) NCI study/background
Date:     Thu, 10 Jul 1997 121706 -0500 (CDT)
From:     "Roy L. Beavers" <rbeavers@mail.llion.org>
To:       Multiple recipients of list <emf-l@mail.llion.org>
--------------------------------------------------

Hi everybody:

Here's something for your EMF files.....

Guru's thanks to Peny Linke 

Cheerio........

Roy Beavers (EMFguru)
rbeavers@mail.llion.org.........http://www.feb.se/EMF-L/EMF-L.html
...............................It is better to light a single candle ...
than to curse the darkness...............................................

Here's the info from the NCI web site:
National Cancer Institute

EMBARGOED FOR RELEASE
5 pm EDT
Wednesday, July 2, 1997

FOR RESPONSE TO INQUIRIES
NCI Press Office
(301) 496-6641

Press Release

------------------------------------------------------------------------

Study Finds Magnetic Fields Do Not Raise Children's Leukemia Risk

A comprehensive study by researchers from the National Cancer Institute
(NCI) and the Children's Cancer Group (CCG) found no evidence that magnetic
fields (EMFs) in the home increase the risk for the most common form of
childhood cancer.

In this case-control study, the researchers found that, in general,
children who lived in homes with high measured magnetic fields were not
significantly more likely to be diagnosed with acute lymphoblastic leukemia
(ALL) than children living in homes with lower magnetic field levels. Nor
was ALL found to be more likely among those whose homes were classified in
high categories of "wire-code," a surrogate measure of magnetic fields that
is based on the thickness, configuration, and distance from the home of
nearby power lines.

"The results of our study differ from three earlier U.S. studies in that we
found no evidence of a significantly increased risk of ALL among children
whose main residence or residence during pregnancy was classified in the
highest wire code category," said lead investigator Martha S. Linet, M.D.,
of NCI's Radiation Epidemiology Branch. The results are published in the
July 3 issue of the New England Journal of Medicine.

Whether power frequency magnetic field exposures (EMFs) may increase cancer
risk has been a controversial question, and nearly two decades of research
has produced conflicting results. EMFs exist naturally inside the human
body and in the surrounding environment. But stronger fields are produced
by power lines and electric appliances, which have been the focus of most
research. Recent research has focused on magnetic fields, specifically the
60 cycle-per-second (60 hertz) fields produced by alternating current (AC)
in household electrical power.

The first study to suggest a risk from magnetic fields was published in
1979, when researchers reported that children who had died from leukemia or
other cancers were about two to three times more likely than other children
to have lived within 40 meters of a high-current power line. Several other
groups of investigators later described similar findings based on proximity
to power lines. When researchers have actually measured magnetic fields in
children's homes, however, they have not found significantly increased
risks of leukemia or other cancers.

Previous studies on magnetic fields and childhood cancer have had one or
more shortcomings that make interpretation of their results difficult.
These include small numbers of leukemia cases, measurements limited to a
single residence, long intervals between leukemia diagnosis and magnetic
field measurement, and data collectors aware of which children had leukemia
(cases) and which did not (controls).

The NCI/CCG researchers designed their study to overcome these limitations
as much as possible. A large study population covering nine states was
chosen, and measurement technicians were unaware of case or control status.
For most subjects, measurements were made within two years after diagnosis,
and were obtained in both current and former residences. The measurements
covered homes in which the child had lived for at least 70 percent of his
or her life, or 70 percent of the five years immediately before diagnosis
for children age 5 and older.

The researchers compared magnetic field exposures of 638 children with
leukemia and 620 children without leukemia who were similar in age and
race. About 58 percent of the children were under age 5, the age group in
which ALL is most common. The participants lived in Illinois, Indiana,
Iowa, Michigan, Minnesota, New Jersey, Ohio, Pennsylvania, and Wisconsin.

The researchers estimated magnetic field exposures in two different ways:
by measuring fields in current and former homes of the children (including
homes their mothers lived in during the pregnancy) and by assigning wire
codes to the homes. Slightly less than half of all subjects had summary
residential magnetic levels less than 0.065 microtesla (?T), close to 20
percent had levels ranging from 0.065 to 0.099 ?T, 23 percent had levels
ranging from 0.100 to 0.199 ?T, and the remaining 12 percent had levels of
0.200 ?T or higher.

If magnetic fields increased risk for ALL, the researchers would expect
that the higher the measured level of magnetic fields in homes, and the
higher the wire code category, the more ALL cases they would find. But in
general, they did not see either of these patterns. For children living in
homes with magnetic fields measured at 0.2 ?T or above, the researchers
calculated a slightly elevated, but not statistically significant risk for
ALL compared with risk for children living in homes with magnetic fields
below 0.065 ?T. While risk of ALL appeared to be slightly higher among
children residing in homes with high levels, the absence of a consistent
pattern of increasing risk with increasing exposure level suggests that the
slight increase seen could be due to chance.

In addition, the researchers found no relationship between wire code
classification and risk for ALL. Children with ALL were no more likely than
controls to live in homes with high wire-code classification.

The researchers also interviewed mothers of case and control children about
the children's electrical appliance use and the mothers' appliance use
during pregnancy. Results from this part of the study are still being
analyzed and are expected to be published separately in 1998.

"This important study would not have been possible without the close
collaboration and commitment of the physicians, nurses, and researchers of
the Children's Cancer Group, and the cooperation of the families who
participated," said Leslie L. Robison, Ph.D., a co-investigator in the
study and professor of pediatrics at the University of Minnesota,
Minneapolis. The Children's Cancer Group is a multicenter network of
pediatric oncologists and other researchers from 38 institutions and
affiliated hospitals who diagnose and treat approximately 50 percent of
children with cancer in the United States.

The NCI/CCG study is part of a larger CCG investigation of ALL comprising
more than 1,900 ALL cases and 1,900 controls. The larger study, overseen by
Dr. Robison, is designed to evaluate the risk of ALL associated with a wide
range of factors, including maternal diseases and medication use during
pregnancy, childhood diseases, and other exposures such as parental
occupation. Results are expected within the next two years.



FOR MORE INFORMATION: See Questions and Answers About the National Cancer
Institute / Children's Cancer Group Study of Magnetic Fields and Childhood
Leukemia on this website.

NOTE: For more detailed information on EMF and research on possible health
effects, call the National Institute of Environmental Health Sciences'
(NIEHS) Environmental Health Clearinghouse at1-800-NIEHS-94
(1-800-643-4794) to get a copy of the booklet Questions and Answers About
EMF: Electric and Magnetic Fields Associated with the Use of Electric
Power. This publication, produced by NIEHS and the U.S. Department of
Energy, is also available on the World Wide Web at
http://www.niehs.nih.gov/oc/factsheets/emf/emf.htm

National Cancer Institute

July 2, 1997

FOR RESPONSE TO INQURIES
NCI Press Office
(301) 496-6641

Backgrounder

------------------------------------------------------------------------

Questions and Answers About the National Cancer Institute/Children's Cancer
Group Study of Magnetic Fields and Childhood Leukemia

1. Why was the study done?

Acute lymphoblastic leukemia (ALL) is the most common form of cancer in
children, accounting for 70 to 80 percent of all childhood leukemias and
one-third of all childhood cancers in the United States. Only a small
proportion of cases have an identifiable cause. Beginning in 1979, a number
of studies have suggested that magnetic fields (EMFs)* may increase risk
for ALL, while other studies have found no evidence of risk.



2. What have been some problems in studying magnetic fields and childhood
leukemia? What have earlier studies shown about the relationship of
magnetic fields to childhood leukemia?

The possible relationship of magnetic fields to childhood leukemia has been
difficult to study, in part, because there are no known biological effects
that could explain how these exposures might increase risk of leukemia in
children.

Some investigators have reported that children living in homes close to
high tension power lines have a 2- to 3-fold significantly increased risk
of ALL, while other studies have found no evidence of an elevated risk. In
each study where findings indicated statistically significant excess risk,
researchers used surrogate measures of magnetic field exposures such as
"wire codes" to characterize the thickness, configuration, and distance
between the child's residence and nearby power lines. Researchers who have
actually measured magnetic fields in homes have found little or no evidence
of a significant increase in risk.

Many previous studies had one or more shortcomings such as small numbers of
children with leukemia, magnetic field measurements restricted to a single
home regardless of the number of homes each child had resided in, a long
interval between cancer diagnosis and residential magnetic field
measurements, data collectors aware of which children had leukemia and
which did not, and differential residential mobility between cases and
controls. These limitations have made it difficult to interpret results.
The NCI/CCG study was done with the aim of overcoming some of the problems
of earlier studies and providing more definitive answers.



3. Who conducted the NCI/CCG study? How was it done? How many children were
involved?

The National Cancer Institute (NCI) and the Children's Cancer Group (CCG),
a multicenter network of pediatric oncologists and other researchers from
38 institutions and affiliated hospitals in the United States, collaborated
on the study, which was directed by Martha Linet, M.D., of NCI's Radiation
Epidemiology Branch in the Division of Cancer Epidemiology and Genetics.

The NCI/CCG study was a case-control study: The researchers calculated risk
of ALL among 638 children with leukemia (cases) and 620 healthy children
(controls). Eligible participants for the residential magnetic field
exposure assessment were subjects who resided in nine states: Illinois,
Indiana, Iowa, Michigan, Minnesota, New Jersey, Ohio, Pennsylvania, and
Wisconsin. Children who participated as controls were matched to the
children with leukemia for age, race, and telephone area code and exchange.
About 58 percent of the children were under age 5. A detailed description
of the study's methods will be published in the September 1997 issue of the
journal Epidemiology.



4. How were magnetic fields assessed in the study?

The researchers used an electronic meter and sought to measure magnetic
field levels in four rooms in each current and former home of the case and
control children. The meter took readings in the child's bedroom every 30
seconds for 24 hours. In addition, 30-second "spot" measurements were made
in the bedroom, family room, kitchen, and the room the mother slept in when
pregnant with the child. Results of earlier studies by NCI researchers**
showed that combining the measurements from these three to four rooms gives
results similar to those obtained by having children wear a portable meter,
particularly for children less than 9 years old, who made up 84 percent of
those in the study. The researchers also obtained a measurement immediately
outside the front door of each home to be used if the family did not allow
measurements to be taken inside the home. The earlier studies also revealed
that the front-door measurement correlated well with in-home measurements,
and thus could be used if in-home measurements could not be taken because
access within the home was not permitted.

Eligible subjects were included in the study if magnetic field measurements
were obtained in all homes in which the subject had lived for at least 70
percent of his or her lifetime for children under age 5,or at least 70
percent of the five years immediately preceding diagnosis for subjects age
5 and older. The overall measurement determined for each home was assigned
a numerical weight that corresponded to the duration of time the subject
lived in each home. The individual home measurements were then combined to
provide a summary "time-weighted average" magnetic field exposure over each
child's lifetime (or the five years prior to diagnosis for children age 5
and older).

In analyzing the results, the researchers split the data into four groups
based on time-weighted average exposure to magnetic fields, expressed as
microtesla (?T)***. Then they compared the least-exposed group with more
highly exposed groups to determine whether risk rises with increasing level
of exposure.

The researchers also diagramed the thickness, configuration and distance
from the home of nearby power lines, and a computer algorithm used this
information to assign a wire code category to each home (see: Question 2).
Two types of wire code classifications were assigned. Similar to the
results of previous U.S. studies, the measured magnetic field levels in the
NCI/CCG study increased with increasing wire code categories for both wire
code classifications. Although less accurate than in-home measurements as
an estimate of a child's personal exposure, wire codes have been associated
more strongly with childhood cancer than in-home measurements have been in
earlier studies.



5. How does the NCI/CCG study differ from previous studies?

Most earlier studies, particularly those with in-home measurements,
included relatively small numbers of leukemia cases. Small numbers reduce
the reliability of results. The NCI/CCG study included four times as many
children as the next-largest comparable study. In addition, prior studies
often had long intervals, sometimes as long as two or three decades,
between leukemia diagnosis and magnetic field measurement, and lacked
measurements for homes the children lived in for substantial periods of
their lives. In the NCI/CCG study, most measurements were taken within two
years of diagnosis, and measurements covered residences the children lived
in for at least 70 percent of their lives (or 70 percent of the five years
prior to diagnosis for children older than 5). In addition, most earlier
studies have been done in a single city or other small geographic area. The
NCI/CCG study was conducted in homes in both urban and rural areas across
nine states, making it less likely that factors specific to one geographic
area will unduly affect the results.



6. What were the results of the study?

For children living in homes with magnetic fields measured at 0.2 ?T or
above, the researchers calculated a non-significant relative risk for ALL
(estimated as an odds ratio) of 1.24 compared with children living in homes
with magnetic fields below 0.065 ?T. In other words, children who lived in
homes with magnetic fields levels of 0.2 ?T or greater were estimated to
have a slightly (24 percent) but non-significantly higher probability of
developing ALL than children living in homes with levels below 0.065 ?T.
The tendency for risk to be slightly higher among children residing in
homes with high levels was based on small numbers and was not characterized
by a consistent pattern of increasing risk with increasing exposure level.

Similarly, children who lived in high wire-code homes had no higher risk of
ALL compared with those who lived in low wire-code homes (relative risk of
highest to lowest wire code category estimated as odds ratio of 0.88). This
means that those living in homes classified as very high wire code category
had a slightly (12 percent) but non-significantly lower risk than those
living in homes with nearby power lines that were underground or very low
wire code category.



7. What conclusions can be drawn from the results?

The researchers conclude that their results do not support the theory that
residential magnetic fields cause childhood leukemia, particularly at the
levels found in most homes. If high magnetic fields increase risk for ALL,
researchers would expect that the higher the measured levels and wire codes
in homes, the greater the risk of developing ALL. But in general, they did
not see this trend. While the risk of ALL appeared to be slightly higher
among children residing in homes with high measured magnetic field levels,
the absence of a statistically significant and consistent pattern of
increasing risk with increasing exposure level suggests that the excess
could be due to chance. The possibility of an increased risk at high levels
(greater than 0.3 ?T) cannot be entirely ruled out, however. But if this
risk is real, it could explain only a small proportion of ALL cases.



BACKGROUND INFORMATION ON ELECTRIC AND MAGNETIC FIELDS (EMFS) AND ON
CHILDHOOD LEUKEMIA

8. What are EMFs?

Power lines, electrical wiring, and appliances all produce electric and
magnetic fields. EMFs are invisible lines of force that surround any
electrical device. Electric and magnetic fields have different properties
and possibly different ways of causing biological effects. Electric fields
are easily shielded or weakened by conducting objects (for example, trees,
buildings, and human skin), but magnetic fields are not. The strength of
both electric and magnetic fields drops off very sharply within a few feet
or inches of a source, such as an electrical appliance.

The earth itself produces EMFs, mainly in the form of direct current (DC)
static fields. Electric fields are produced by thunderstorm activity in the
atmosphere. Magnetic fields are thought to be produced by electric currents
flowing deep within the earth's molten core.



9. What is power-frequency EMF and how does it compare with other types of
fields?

The electromagnetic spectrum covers an enormous range of frequencies. These
frequencies are expressed in cycles per second (hertz). Electric power (60
hertz in North America, 50 hertz in most other places) is in the
extremely-low-frequency range, which includes frequencies below 3,000
hertz.

The higher the frequency, the shorter the distance between one wave and the
next, and the greater the amount of energy in the field. Microwave
frequency fields, with wavelengths of several inches, have enough energy to
cause heating in conducting material. Still higher frequencies like X-rays
cause ionization or the breaking of molecular bonds, which damages genetic
material. In comparison, power frequency fields have wavelengths of more
than 3,100 miles (5,000 km) and consequently have very low energy levels
that do not cause heating or ionization. However, AC fields do create weak
electric currents in conducting objects, including people and animals.



10. What happens when a person is exposed to EMFs? Why do scientists
disagree about whether EMFs could cause cancer?

EMFs can create weak electric currents in the bodies of people and animals.
This is one reason why there is a potential for EMFs to cause biological
effects. But the amount of this current, even directly beneath a large
transmission line, is extremely small-millionths of an ampere. (An ampere
is a unit of electrical current.) The current is not only too weak to
damage DNA, but is too weak even to penetrate cell membranes and cause
damage inside cells. It is present mostly between the cells.

Currents from 60-hertz EMFs are weaker than natural currents in the body,
such as those from the electrical activity of the brain and heart. Some
scientists argue that it is therefore impossible for EMFs to have any
important effects. Other scientists argue that, just as a trained ear can
pick up a familiar voice or cry in a crowd, so a cell may respond to an
induced current of low intensity even through the background "noise" of the
body's natural currents. Numerous laboratory studies have shown that
biological effects can be caused by exposure to EMFs. In most cases,
however, it is not clear how EMFs produce these effects.

Because 60-hertz EMFs are too weak to damage the DNA of cells, scientists
believe that if EMFs are associated with cancer at all, they must work as
cancer promoters. Promoters are agents that can push a cell with DNA or
genetic damage closer to the uncontrolled cell growth and division that
characterizes cancer.



11. How common is acute lymphoblastic leukemia? Is it treatable?

Of every 1 million children under age 15 in the United States, about 30 are
diagnosed with ALL and about five die from ALL each year. About 1,600
children are expected to be diagnosed with ALL this year. The disease is
most commonly diagnosed in white children under 5 years old. It is twice as
common in white children as in black children, and is slightly more common
in boys than in girls.

ALL is much more treatable now than in the past. Most children with ALL can
now be cured, and about 80 percent of patients under age 15 survive at
least five years after diagnosis, compared with about 1 percent in the
1950s.



12. What are the known risk factors for ALL? What others have been
proposed?

Only a few risk factors are known, although many have been proposed and
studied. Children with Down syndrome have a greatly increased risk of ALL,
reported to be 10 to 40 times the risk of other children. Other, rarer
chromosomal and genetic abnormalities may also increase risk for ALL.
Children whose mothers had diagnostic X-rays during pregnancy are about
oneand-a-half times more likely to have ALL compared with children whose
mothers had no X-rays. Risk factors that have been proposed, but not
proven, include certain birth characteristics such as high birth weight;
medical conditions or drugs affecting delivery; mothers' prior reproductive
problems such as repeated miscarriages; pesticides and other chemicals;
certain viruses; and natural background ionizing radiation.



13. Are other studies of magnetic fields and childhood leukemia under way?
Are studies under way of other risk factors for childhood leukemia?

Population-based studies of residential magnetic fields and childhood
leukemia are under way in Canada and the United Kingdom. The results are
expected within one to two years.

The NCI/CCG investigators also collected information on the use of
electrical appliances by mothers during pregnancy and children after birth.
The data are still being analyzed, with results expected to be published in
1998. The NCI/CCG magnetic field study was part of a larger CCG study of
more than 1,900 children diagnosed with ALL between 1989 and 1993, and
1,900 controls. This ongoing study is designed to evaluate risk of ALL
associated with a wide range of factors, including maternal diseases and
medication use during pregnancy, childhood infectious and other diseases,
parental occupational exposures, prenatal and postnatal environmental
exposures, parental smoking and alcohol use, lifestyle, and genetic
factors. Results are expected in about two years.



FOR MORE INFORMATION: See press release Study Finds Magnetic Fields Do Not
Raise Children's Leukemia Risk

NOTE: For more detailed information on EMF and research on possible health
effects, call the National Institute of Environmental Health Sciences'
(NIEHS) Environmental Health Clearinghouse at 1-800-NIEHS-94
(1-800-643-4794) to get a copy of the booklet Questions and Answers About
EMF: Electric and Magnetic Fields Associated with the Use of Electric
Power. This publication, produced by NIEHS and the U.S. Department of
Energy, is also available on the World Wide Web at
http://www.niehs.nih.gov/oc/factsheets/emf/emf.htm



* Both electric and magnetic fields are present around appliances and power

lines. But recent interest and research have focused on potential health
effects of magnetic fields. This is because studies have found associations
between increased cancer risk and power-line configurations which are more
closely related to magnetic than to electric fields.

** Friedman, D.R. et al. "Childhood Exposures to Magnetic Fields:
Residential Area Measurements Compared to Personal Dosimetry."
Epidemiology, March 1996

Kaune, W.T. et al. "Development of a protocol for assessing time-weighted
average exposures of young children to power-frequency magnetic fields."
Bioelectromagnetics, January 1994

*** 1 ?T=10 milligauss (mG). Some studies have reported measurements in mG.




Archive provided courtesy of WaveGuide, http://www.wave-guide.org
Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html