A study spanning four Scandinavian countries with a population of 16 million people found no increase in brain cancer rates resulting from the use in cell phones.  The results were published at the Journal of the National Cancer Institute.  No statistical differences were found from 1998 to 2003 compared to 1974 to 1998 and this is reportedly consistent with a new U.S. study expected to be published in a few months.  This also matches the results of a Danish study published in 2007 which tracked 420,000 cell phone users in Denmark.

While the skeptics who argue that these studies rely on samples that are too small or cover too short a time span, they are the same people tout statistically insignificant studies that indicate a danger with cell phones based on fewer than 500 people.  But if a sample size of 16 million people is too small, what does that make a study based on 500 people or less?

Some continue to argue that these latest large-scale studies are too short because it takes dozens of years to develop cancer.  It’s true that cancers may take longer than 10 years to develop, but scientists have been studying the effects of radio waves on humans for multiple decades long before the advent of cell phones.  The number of people exposed to close proximity radio transmitters (e.g., amateur radio, commercial, and military radio operators) before the dawn of the cell phone era was significantly lower, but there were still plenty of people to study and the power levels were an order of magnitude higher than modern digital cellular phones.  If there were any cancer danger from radio waves, we would have likely found some problems by now.

The reality is that there is no known process by which radio waves can cause cancer.  The problem is that scientists aren’t marketing experts and they use scary terms like “radiation” to describe electromagnetic fields.  The laymen hears radiation and they think of nuclear subatomic particle radiation like Chernobyl or Hiroshima or they think of ultraviolet solar radiation that causes skin cancer, but these forms of radiation are known to tear through DNA and cause mutations.

Radio wave energy cannot do that and it only causes slight heating in tissue that is difficult to measure.  In the case of a cell phone transmitting 1 watt of energy (even if we assumed beyond worse case where it was completely absorbed by the person) would only heat up a 70 kg person by 0.01 degrees centigrade over the course of an hour which is insignificant compared to the effect of wearing a hat or long instead of short sleeve shirt.  While the heating is more concentrated near the transmitter, one hour is an awful long time for heat in a mostly liquid substance to disperse and dissipate from normal sweating.

The fear of tissue heating is based on some studies which have suggested that tissue heated a few degrees above normal (which is several hundred times more that what a cell phone could ever provide) might accelerate growth in some existing tumor tissue.  But these power levels aren’t nearly comparable and it doesn’t suggest that slight heating is the cause of the tumor.

Ultimately, common sense can go a long way to allay these fears.  No one can seriously suggest that we stop using cell phones and those who have lingering fears should simply use a wired headset or a Bluetooth headset that uses 1000 times less transmit power than the cell phone.  Small children probably don’t need to spend excessive hours talking on a cell phone daily with or without a headset regardless of any potential risks from radio waves, and teenagers seem to prefer text messaging these days.  Prolonged usage of any kind of phone (wireless or wired, children or adult) justifies the use of a headset if only for the sake of good posture and ergonomics.

The reality is that we can’t significantly lower the transmit power of the cell phones unless we’re willing to put low-power cell towers on every street corner.  Increasing cell tower density is certainly a very good idea that will lower radio wave exposure (reduced transmit power) and improve cell phone capacity as well as increase data capacity.  That won’t happen until we see significant increases in mobile Internet adoption and it won’t happen until we get beyond or irrational fears of cell towers which ironically faces opposition from the same people that are demanding lower transmit power from cell phones.

The best course of policy would be to support more and denser deployment of cell towers to lower transmit levels all around and we should continue studying the health effects of cell phones over the long term, but there’s absolutely no reason to panic given the sheer amount of evidence indicating no dangers.  What we don’t need is trial lawyers trying to line their own pockets with pseudoscience because that would ultimately raise prices for consumers, harm the deployment of wireless networks, and harm the economy.