Consider the following mishmash of city creatures interacting in their urban habitat: An elderly woman lifts her reading glasses, squinting as she concentrates on her mobile phone. A young man in a backward Yankees cap bellows into the iPhone plastered to his ear, “Dude, they sold out!” as members of the bookish crowd shoot him annoyed glances. A mother scans the magazine rack, paying scant attention to her child as he—perhaps 4 years old—sits quietly poking at a glowing screen. Everyone is on their cell phone.
Worldwide cell phone subscriptions are likely to surpass five billion subscribers by the end of 2011. In the United States alone, the number has gone from 109.5 million in December 2005 to more than 300 million subscriber connections—almost the entirety of the US population. If a causal link between cell phone radiation and carcinogenicity were established, it would rank as a global pandemic, with tumors of the head and neck taking the spotlight.
Most scientists have been generally dismissive of the connection between cell phones and cancer, usually citing the inability of the radiation to directly mutate DNA to cause or potentiate cancer. But a spate of more recent studies—and the categorization of cell phone radiation as a class 2B carcinogen by World Health Organization (WHO) subsidiary the International Agency for Research on Cancer (IARC)—has clearly given scientists, and the public, more to think about.
The potential link must be kept under a microscope of scrutiny in the years to come, chiefly because brain tumors are relatively rare and generally take many decades to develop.
In the realm of head and neck cancers, the potential development of gliomas, a type of tumor that starts in the brain or spine, are the most troubling. Thought to arise from the brain’s glial cells, the supporting cells of the nervous system, gliomas comprise approximately 80% of primary malignant central nervous system tumors.
In 2008 there were 237,913 new cases of brain tumors in the world, with gliomas accounting for approximately two thirds of those, according to Globocan 2008, an IARC subsidiary of the WHO project that compiles global cancer demographics. The Cancer Brain Tumor Registry of the United States (CBTRUS) listed that primary brain tumors account for approximately 2% of cancers overall. This equates to approximately 35,000 new cases per year in the United States. Considering that glioblastoma multiforme—the worst but most commonly diagnosed primary brain malignancy in adults—has a median survival of one year, even when medicine throws all of its established treatments of surgery, chemo- and radiation therapy at it, and worries begin anew.
What is cell phone radiation?
In order to transmit the data stream when you are making a call, the phone utilizes a radio frequency (RF) carrier which emits an electromagnetic wave. During a call, small alterations in the carrier amplitude determine the amount of RF radiation that could potentially enter the user’s body. “The higher the signal amplitude, the larger the specific absorption rate,” says Dr. Michael E. Knox, an expert in wireless communications and industry professor for electrical and computer engineering at the Polytechnic Institute of New York University, noting that the specific absorption rate (SAR) is a parameter used for evaluating the energy absorption in human tissue. “Phone transmission today is comparable to the analog days,” says Dr. Knox.
In addition, RF frequency radiation is but a sliver of the electromagnetic spectrum (EMS). The EMS contains the entire range of known radiation emissions from the higher frequencies (X-rays and gamma rays) to the lower frequencies (radio waves and microwaves). What’s important is that the spectrum can be divided into two major categories: ionizing and non-ionizing radiation.
Ionizing radiation has the ability to strip electrons from molecular orbit, breaking bonds and potentially allowing mutation to occur. It’s what most people mean when they say the word radiation, and is stigmatized and spotlighted when nuclear power plants fail containment or when Peter Parker gets bitten by a radioactive spider. RF radiation, however, falls into the latter, feebler non-ionizing category, which includes frequencies used for broadcasting FM radio and keeping the buffet food warm via infrared lamps.
Knowing this, the primary stance that scientists take on the link between cell phones and cancer is that RF radiation does not have the technical capability to directly damage and mutate DNA—and most cancers typically have multiple associated mutations. For example, glioblastoma multiforme typically exhibits alterations in places such chromosome 10q, and in genes such as p53 and EGFR. RF radiation’s only known effect on human tissue is to cause the vibration of its molecules, otherwise known as heating.
Why the concern about RF radiation?
Well, first, RF radiation has been shown to actually penetrate the skull and heat the brain. A study published in Physics in Medicine and Biology in 2008 showed that most of the radiation—97-99%, depending on frequency—“appears to be absorbed in the brain hemisphere on the side where the phone is used.” But don’t panic. As Dr. Knox pointed out, the average SAR has an inverse relationship with distance in free space: Double the distance, and the power decreases by a factor of 4. Moreover, brain temperature changes due to absorbed RF radiation were only around 0.1 to 0.2 degrees Celsius—less than the temperature change you endure while slaving away at the gym.
Second, in February 2011, a study was published in the Journal of the American Medical Association which answered the simple question of whether cell phone radiation biologically affects the brain region closest to the phone. The short answer is yes, as they found evidence that exposure for less than an hour “may enhance the excitability of brain tissue” in the regions with the highest exposures, providing evidence that acute cell phone exposure “affects brain metabolic activity.”
Dr. Nora Volkow, the principal investigator, stressed that relevance to carcinogenesis was not the purpose of the experiment, and that the changes in brain activity were small, akin to (and even less than) the amount of change that naturally occurs upon seeing a pigeon flapping about.
But could there be more insidious mechanisms by which non-ionizing radiation might cause or at least abet cancer development? >>*<<