University of Pittsburgh physics professor Eric Swanson doesn't use a cell phone (because he finds them annoying), but he assures us that cell phones cannot cause cancer mainly because cell phone radiation is not known to damage DNA ("Stop Freaking Out About Cell Phones!," Forum, Aug. 3). He is mistaken.
Second, more than a thousand studies find that cell signals can affect the ability of our genes to protect us, impairing responses to stress, heavy metals and toxic chemicals.
Contrary to what Mr. Swanson asserts, cell phones might cause cancer without directly damaging DNA or breaking chemical bonds. This is understood by the 23 renowned cancer biologists who recently signed a cautionary advisory on cell phones.
With half of the world using cell phones, no one seriously suggests that this revolutionary, life-saving tool should be put back into the bottle. But we need to be sure that this essential technology becomes as safe as possible.
It's better to be safe than sorry and to reduce direct exposure to cell phone radiation by using head sets and speakerphones. Meanwhile, electrical engineers can continue to lower the amount of radiation to which we are exposed and we scientists can more fully evaluate the impact of cell phones on public health.
Just last week the Israeli Health Ministry expanded on a previous public advisory by suggesting that children's use of cell phones be limited. This was based on the recent warning to UPMC staff from the highly respected Dr. Ronald B. Herberman, director of the University of Pittsburgh Cancer Institute. Health authorities in England, Germany and France have issued similar warnings.
I agree with Mr. Swanson that neurosurgeons are not necessarily qualified to conduct or opine on statistical studies, but neither are physicists like himself suited to disclaim theories of cancer offered by other scientists.
When DNA is damaged, cells can get signals to grow uncontrollably, which can lead to more than 200 forms of cancer. But sometimes cancer occurs without direct damage to DNA. For instance, when asbestos is inhaled deeply into the lung, it can cause inflammation that triggers cancer several decades later. Prenatal hormonal stimulation can lead to cancer in middle age.
Yes, human studies on cell phone use and cancer are incomplete and inconsistent. But the cell phone industries' own studies show that the cell signal is absorbed deeply into the brains of children, and up to 2 inches into an adult skull. Most cell phone manuals, which are seldom read, recommend keeping the phone an inch from the ear and not directly against the body. Sensible precautions for those concerned about cell phones can be found on the Web sites of the Food and Drug Administration, the National Cancer Institute and the American Cancer Society.
Some studies of populations that have used cell phones for longer periods of time have found a doubled risk of serious brain tumors. Other studies have found subtle disturbances in brain chemistry and possibly lowered sperm count.
In 1990, about 1 in 10 Americans used cell phones for limited periods of time. Nine times more Americans use cell phones today, and for much longer periods. Brain cancer and other possible chronic ailments can take a decade or longer to develop.
The absence of definitive evidence in this instance should not be confused with proof of safety; rather, it reflects the hard realities of the modern world where we introduce new technologies before evaluating their potential impact on our lives.
Good public health practice requires that we take prudent precautions to limit exposure to cell phone radiation. Meanwhile, as engineers continue to refine the technology, research should proceed to clarify whether newer phones pose the same risk as older ones.
The full cooperation of the cell phone industry would help a great deal in pursuing this research.
Dr. Herberman and Dr. Elmer Huerta, the president of the American Cancer Society, have called for the release of encoded records of cell phone use to the National Institutes of Health, the American Cancer Society and independent university scientists for use in their research. Information about individuals already must be provided to the government when someone is suspected of threatening national security. Surely, the health and welfare of our children and grandchildren demand that cell phone companies provide confidentiality-protected cell phone records to independent scientists so that definitive studies can be carried out.
If this is done, within a decade we should know whether the risks found with older-style phones in Sweden and other nations also occur with the newer phones now widely used in the United States and around the world.
Dr. Lennart Hardell is a professor of oncology for University Hospital in Orebro, Sweden, where he has conducted long-term studies of the health effects of cell phone use (email@example.com)
It is both wise and timely to advocate for precautions in the use of both mobile and cordless phones as recently advised by the University of Pittsburgh Cancer Institute. Our research team in Sweden has raised similar concerns about long-term health effects from exposure to microwaves during cell phone use.
The brain has the highest exposure on the side where the phone is held. Furthermore, the brain of a child is more exposed to microwaves than the brain of an adult. The bone is thinner and a smaller brain permits deeper penetration. A recent French study showed that children might be twice as at risk as grown-ups, which is worrying.
Sweden was one of the countries first to adopt wireless technology in the early 1980s. Thus there are now persons who have used mobile and cordless phones long enough to evaluate long-term health effects, primarily the risk for brain tumors.
Our research was conducted for more than 10 years and we were the first to report an increased risk for brain tumors. In follow-up studies we were able to confirm the results.
By now, evaluating all international studies in this area, there is a consistent pattern of a nearly doubled risk for brain tumors (glioma and acoustic neuroma) on the side of the head where a mobile phone has been used for at least 10 years. Glioma is a usually lethal type of brain tumor and acoustic neuroma is a benign tumor on the hearing nerve that can cause tinnitus and ultimately deafness.
Little has so far been studied of long-term health effects from nearby microwave exposure during the use of wireless phones or distant exposure from base stations emitting microwaves. Since virtually whole populations are exposed, even small effects would have large public health implications.
Current emissions from wireless phones do not protect us from brain tumors in the long run. Prudent avoidance of exposure is necessary as we await safer technology.