At high power levels, RF waves can heat
up water molecules (which is how microwave ovens work). Scientists used
to focus their concerns on the possibility that such heating of human
tissue, which is mostly water, might damage cells.
In fact, the FCC’s
test of cell-phone emissions—which was set in 1996 and which all phones
must pass before being allowed on the market—is based on that effect.
But most experts now aren’t concerned about that possible tissue
heating caused by RF waves. Instead, what’s worrying some scientists are
newer lab studies suggesting that exposure to cell-phone radiation can
have biological effects without raising temperature.
In 2011, researchers at the National Institutes of Health showed that
low-level radiation from an activated cell phone held close to a human
head could change the way certain brain cells functioned, even without
raising body temperature.
The study did not prove that the effect on
brain cells was dangerous, only that radiation from cell phones could
have a direct effect on human tissue.
RF waves from cell phones have also been shown to produce “stress”
proteins in human cells, according to research from Martin Blank, Ph.D.,
a special lecturer in the department of physiology and cellular
biophysics at Columbia University and another signer of the recent
letter to the WHO and U.N.
“These proteins are used for protection,”
Blank says. “The cell is saying that RF is bad for me and it has to do
something about it.”
And just this year, a German study found that RF waves promoted the
growth of brain tumors in mice, again at radiation levels supposedly too
low to raise body temperature.
The
U.S. National Toxicology Program is now running an animal study of its own, exposing rats and mice to low-dose radiation. Results are expected in 2016.
What Do Cancer Studies in Human Populations Show?
The research above describes some lab and
animal studies that looked at how cell-phone radiation might cause
cancer or affect the body in other ways. But we also reviewed studies
that investigated whether cell phones increased brain-cancer risk in
humans.
We focused on five large population studies, plus follow-ups to those
studies, that investigated that question. Together the studies included
more than a million people worldwide, comparing cell-phone users with
nonusers.
Though some findings were reassuring, others do raise concerns.
Specifically, three of the studies—one from Sweden, another from France,
and a third that combined data from 13 countries—suggest a connection
between heavy cell-phone use and gliomas, tumors that are usually
cancerous and often deadly.
One of those studies also hinted at a link
between cell phones and acoustic neuromas (noncancerous tumors), and two
studies hinted at meningiomas, a relatively common but usually not
deadly brain tumor.
Though those findings are worrisome, none of the studies can prove a
connection between cell phones and brain cancer, for several reasons.
For one thing, cell-phone use in certain studies was self-reported, so
it may not be accurate.
In addition, the findings might be influenced by the fact that the
study subjects owned cell phones that were in some cases manufactured
two decades ago. The way we use cell phones and the networks they’re
operated on have also changed since then. Last, cancer can develop
slowly over decades, yet the studies have analyzed data over only about a
five- to 20-year span.
Are Today’s Phones Safer?
Cell-phone designs
have changed a lot since the studies described above were completed.
For example, the antennas—where most of the radiation from cell phones
is emitted—are no longer located outside of phones near the top, closest
to your brain when you talk, but are inside the phone, and they can be
toward the bottom.
As a result, the antenna may not be held against your
head when you’re on the phone. That’s important because when it comes
to cell-phone radiation, every millimeter counts: The strength of
exposure drops dramatically as the distance from your body increases.
Perhaps our best protection is that more people today use phones to text instead of talk, and
headphones and earbuds
are growing in popularity. On the other hand, it’s also true that we
use cell phones much more than we used to, so our overall exposure may
be greater.
So Should I Stop Using My Cell Phone?
No, Consumer Reports does not think that’s necessary. But we do have some concerns.
“The evidence so far doesn’t prove that cell phones cause cancer, and
we definitely need more and better research,” says Michael Hansen,
Ph.D., a senior scientist at Consumer Reports.
“But we feel that the
research does raise enough questions that taking some common-sense
precautions when using your cell phone can make sense.” Specifically, CR
recommends these steps:
- Try to keep the phone away from your head and body. That is
particularly important when the cellular signal is weak—when your phone
has only one bar, for example—because phones may increase their power
then to compensate.
- Text or video call when possible.
- When speaking, use the speaker phone on your device or a hands-free headset.
- Don’t stow your phone in your pants or shirt pocket. Instead, carry it in a bag or use a belt clip.
Warning: Cellphone radiation exposure during
pregnancy impacts fetal brain development and may cause hyperactivity,
Yale School of Medicine researchers say 
