By TARA PARKER-POPE
Stuart Bradford
The debate about cellphone safety was reignited yet again last week
when a panel of the World Heath Organization declared that it was
“possible” the phones could cause cancer.
This is the first time a major health organization has suggested such
a link, and it was promptly disputed by many scientists, who have been
saying for years that there is scant evidence cellphones cause cancer
and that it is biologically implausible to think they could.
So what do we really know about cellphones and health? Here are some answers to common questions about the issue.
What is the source of the latest claim?
The panel, the International Agency for Research on Cancer, acts as
an adviser to the World Health Organization, focusing on environmental
and lifestyle factors that may contribute to cancer.
Since 1971 the agency’s “monographs” program
has evaluated more than 900 such factors, assigning each of them to one
of five classification groups. It has found that 107 are carcinogenic
to humans, including asbestos, estrogen and tobacco, and 59 are “probably carcinogenic,” including the human papillomavirus and night-shift work.
In addition, 266 agents — including certain industrial chemicals,
coffee and now cellphones — are “possibly” carcinogenic. The panel has
been unable to reach a conclusion on 508 agents, calling them “not
classifiable”; these include chlorinated drinking water, fluorescent
lighting and tea.
Only one of more than 900 factors studied — a nylon-manufacturing
chemical found in drinking-water supplies — has been declared “probably
not carcinogenic.”
On what did the panel base its cellphone findings?
Cellphones give off a weak form of energy called nonionizing
radiation, and the panel said it performed an exhaustive review of
numerous studies of this type of radiation in animals and humans.
The human studies all are observational, showing only an association
between cellphone use and cancer, not a causal relationship. Some of the
research suggests links to three types of tumors: cancer of the parotid, a salivary gland near the ear; acoustic neuroma, a tumor that essentially occurs where the ear meets the brain; and glioma, the aggressive brain tumor whose victims have included Senator Edward M. Kennedy.
All these tumors are rare, so even if cellphone use does increase risk, the risk to any individual is still very low.
The largest and longest study of cellphone use is called Interphone, a
vast research effort in 13 countries, including Canada, Israel and
several in Western Europe. The results, published in The International
Journal of Epidemiology last year, found no overall link between
cellphone use and brain tumors. But the investigators reported that
study participants with the highest level of cellphone use had a 40
percent higher risk for glioma.
Another study, in The American Journal of Epidemiology, published
data from Israel finding a 58 percent higher risk of parotid gland
tumors among heavy cellphone users. A Swedish analysis of 16 studies in
the journal Occupational and Environmental Medicine showed a doubling of
risk for acoustic neuroma and glioma after 10 years of heavy cellphone
use.
So it sounds as if the research has, in fact, found
“possible” links between cellphones and cancer. Why do scientists
dispute that?
The research is plagued by methodological problems. Over all, the Interphone study suggested that cellphone users are less likely
to get cancer. Nobody believes that cellphones protect you from cancer,
so the finding is considered an anomaly, attributable to biases and
errors in the data. Critics say you can’t pick and choose. If one
finding must be dismissed because of faulty data, then so must the
others.
Moreover, if cellphones caused brain tumors, we should have seen a
worldwide increase in brain tumors pandemic as the phones became
ubiquitous. That hasn’t happened.
“If you look at brain cancer around the world over 25 years that
cellphones have been in use, there’s no suggestion at all of any
increase in rates,” said Dr. Meir J. Stampfer, a professor at the
Harvard School of Public Health and a consultant to the cellphone
industry. “In science, unlike math, we can’t have absolute certainty,
but in the scheme of things, this is not a health risk I would be
concerned about at all.”
But cellphones do emit radiation. Doesn’t radiation cause cancer?
The nonionizing radiation given off by cellphones is too weak to
break chemical bonds or damage DNA. Scientists have said repeatedly that
there is no known biological mechanism to explain how it might lead to
cancer or other health problems.
That does not entirely close the argument. This year The Journal of
the American Medical Association reported on research from the National
Institutes of Health finding that less than an hour of cellphone use can
speed up brain activity in the area closest to the antenna. The study
offered a hypothetical mechanism for harm from low levels of nonionizing
radiation: Perhaps it sets off free radicals or an inflammatory response in the brain.
What’s the story behind that Internet video showing cellphones popping popcorn?
In the video, four cellphones are pointed at a pile of kernels that
soon begin popping. It has been widely forwarded and accepted as the
real thing, but in fact it’s just a viral marketing campaign by the
maker of Bluetooth headsets.
Speaking of headsets, are Bluetooth earpieces safer than putting a cellphone to the ear?
Bluetooth is a technology that allows electronic devices to
communicate wirelessly. To do so, the device emits very low levels of
radiation. Nobody has conducted research looking at the health effects
of Bluetooth earpieces.
One concern is that even though the device emits less radiation than a
cellphone, it goes directly inside the ear, closer to the brain. Short
of not using a cellphone, the lowest exposure would come from using the
speaker phone or a wired headset or ear buds.
That said, any risk from the electromagnetic fields emitted by a
Bluetooth device is negligible, according to William G. Scanlon,
professor of wireless communications at Queen’s University Belfast in
Northern Ireland. Bluetooth “is so low-power,” he wrote in an e-mail,
that devices using it “would be well down the list of things to avoid
(including anything with WiFi).”
If everyone says the risk is low, what’s all the fuss about?
Despite the reassuring data, it’s important to remember that all of
the humans studied so far began using cellphones as adults. With an
entire generation having now been exposed to cellphones since childhood,
nobody knows the health effect of a lifetime of exposure.
“We’ve hit the point where today’s children are going to use a
cellphone or something like a cellphone for most of their lives,” said
Dr. Jonathan Samet, a professor of preventive medicine
at the University of Southern California and the chairman of the panel
that suggested the cellphone-cancer link. “We do need to understand if
there is a risk of cancer or anything else.”
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