US Food and Drug Administration (FDA) has taken the unusual step of
contradicting colleagues at an agency within the National Institutes of
Health after they claimed that a study they conducted into the effects of
radio frequency radiation (RFR) showed "clear evidence" of an association
with a form of heart cancer.
from the National Toxicology Program (NTP), part of the National Institute
of Environmental Health Sciences within the National Institutes of Health,
issued a report on
November 1 in which they said that their study clearly showed that male
rats exposed to high levels of RFR developed heart schwannomas, a form of
cancer that is very rare in humans.
also said that there was some evidence to suggest that exposed male rats
were at increased risk of developing tumors in the brain and adrenal
Bucher, PhD, senior scientist at the NTP, said in a release: "We believe
that the link between radio frequency radiation and tumors in male rats is
real, and the external experts agreed."
FDA reacted promptly the same day.
reviewing the study, we disagree, however, with the conclusions of their
final report regarding 'clear evidence' of carcinogenic activity in
rodents exposed to radiofrequency energy," said Jeffrey Shuren, MD, JD,
director of the Center for Devices and Radiological Health at the FDA.
totality of the available scientific evidence continues to not support
adverse health effects in humans caused by exposures at or under the
current radiofrequency energy exposure limits," he continued.
believe the existing safety limits for cell phones remain acceptable for
protecting the public health," the FDA concluded.
Results From Long-term Studies
NTP studies took more than 10 years to complete and cost $430 million.
results were released in February 2018, as reported in
detail at the time by Medscape
Medical News. This latest announcement was
a final report of the findings, disseminated in press releases and a press
studies involved exposing male and female mice and rats to RFR with
modulations that are used in 2G and 3G cell phones. These were the
standard technologies in use at the time the study started (the study was
nominated in May 1999).
levels were far higher than that typically experienced by humans using
cell phones. The lowest level was the maximum permissible exposure for
cell phone users; subsequent levels rose to four times that.
this, Bucher said: "The exposures used in the studies cannot be compared
directly to the exposure that humans experience when using a cell phone."
added: "In our studies, rats and mice received radio frequency radiation
across their whole bodies. By contrast, people are mostly exposed in
specific local tissues close to where they hold the phone."
pointed out that the whole-body exposure performed in the study is
"commonly done" in studies such as these to replicate the effects seen in
animal tissue exposures.
he echoed comments made by the NTP at the release of the draft
results earlier this
year, saying, "These findings should not be applied to human cell phone
the FDA announcement, Shuren emphasized that the study yielded some
"unusual findings," including that exposed male rats lived longer than
unexposed rats, that only the highest energy dosage was significantly
associated with the development of heart schwannomas, and that there was
no true dose response.
will need to consider all of the findings when exploring future human
epidemiological studies," Shuren said.
must remember the study was not designed to test the safety of cell phone
use in humans, so we cannot draw conclusions about the risks of cell phone
use from it," the FDA commented.
statements, however, did not stop the story from taking on a life of its
the United Kingdom, the Daily
Mail covered the
story with the lurid headline, "Cell phones ARE linked to cancer, landmark
made the claim that there was "clear evidence" of a link between heart,
brain, and adrenal gland cancers "front and center," saying that the link
in male rats is "undeniable."
story does acknowledge, however, that the exposures were "much higher"
than those seen in humans and that the evidence was "less clear" for
female rats and mice of both sexes.
scientists warn that the new research suggests that men in particular
should take precautions to minimize the exposure of sensitive areas to
cell phone radiation," the newspaper said.
article notes that the study employed older technologies and that since
then, 3G and 4G technologies have become industry standards.
newer technologies have continued to evolve, it is important to note that
these technologies have not completely replaced the older technologies,"
Bucher is quoted as saying. "In fact, today's phones are very complex in
that they contain several antennas, for Wi-Fi, GPS, 2G/3G bands, etc."
York Times also
reported the NPT study, noting that
the next-generation phones "employ much higher frequencies." They add,
"these radio waves are far less successful at penetrating the bodies of
humans and rats, scientists say."
the numerous caveats that accompany the findings, Bucher said in a
telephone press conference that he has "never been a heavy user of a cell
phone" but has become "a little more aware of my use of cell phones" since
taking part in the studies.
I'm making a short call, I have absolutely no hesitation at all in picking
up the phone and using it in a traditional manner," he added.
I'm on a conference call for an hour or two, I tend to just think about
using earbuds or some other way of increasing the distance between the
cell phone and my body," he said.
B. Miller, MD, PhD, professor emeritus at the Dalla Lana School of Public
Health, University of Toronto, Canada, went further.
Mail quoted him as
saying: "This animal evidence, together with the extensive human evidence,
coupled with the rising incidence of brain cancers in young people in the
US, conclusively confirms that radio frequency radiation is a Category 1
of the Studies
the NPT studies, the animals were housed in bespoke chambers with a
transmitting antenna that radiated RFR fields and rotating stirrers that
generated uniform exposure.
the study, rates and mice were exposed to whole-body RFR. The rats were
exposed at a frequency of 900 MHz; the mice, at a frequency of 1900 MHz.
Two technologies were employed: code division multiple access (CDMA), and
the Global System for Mobile Communications (GSM).
technologies were chosen because CDMA and GSM are commonly used in the
United States and Europe. There are substantial differences in their
signal structure, which the researchers believed may result in different
exposure levels were 1.5 to 6 watts per kilogram for rats and 2.5 to 10
watts per kilogram for mice at periods of 10 minutes on and 10 minutes off
for approximately 9 hours per day.
began in the womb for rats and at 5 to 6 weeks of age for mice. Exposure
continued for up to 2 years, which equates to the majority of their
natural lifespan. Incidence rates of cancer were then compared with
unexposed control animals.
Wyde, PhD, who was the lead toxicologist on the studies, said in a
release: "A major strength of our studies is that we were able to control
exactly how much radio frequency radiation the animals received —
something that's not possible when studying human cell phone use, which
has often relied on questionnaires."
researchers found what they describe as "clear evidence" of an association
between RFR exposure and malignant schwannomas in the hearts of male
also found "some evidence" of an association between RFR exposure and the
development of malignant gliomas and adrenal gland tumors in male rats.
in female rats and in both male and female mice, the evidence as to
whether there was an association between RFR exposure and the development
of cancers was "equivocal."
exposure was associated with lower body weights among newborn rats
and their mothers, particularly exposure to high levels of RFR
during pregnancy and lactation. The animals went on to grow to a
was also observed that lifespan was longer for male rats exposed to RFR
than for unexposed rats, which Wyde suggested "may be explained by an
observed decrease in chronic kidney problems that are often the cause of
death in older rats."
NTP is building smaller exposure chambers for future studies, which will
allow newer technologies to be evaluated in weeks or months, rather than
studies will focus on identifying biomarkers of the potential effects of
RFR exposure, such as DNA damage in exposed tissue.
study was funded by the National Institutes of Health. The investigators
have disclosed no relevant financial relationships.
Institutes of Health. NTP TR 595, Full
text; NTP TR 596, Full
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