This is a reprint of an article from the Journal of Naturopathic Medicine that was a response to a recent study published in JAMA (Volkow N, Tomasi D, Wang G-J, et al. Effect of cell phone radiofrequency signal exposure on brain glucose metabolism. JAMA. 2011;305(8):808-813).
The bottom line is that cell phone use does indeed appear to enhance brain activity, which can potentially pose risks for cancer or other neurological complications. There are still many unanswered questions with respect to cell phone use and cancer, but this study is further evidence that this issue needs to be addressed and payed attention to:

For years, medical experts and scientists have voiced concerns regarding
the questionable safety of cell phone use, but even with the evidence
mounting, this alluring technology is hard to resist. Humankind’s
increasing use of cell phones, 5 billion users worldwide, necessitates a
thorough, unbiased look at the risks.

The JAMA study documents that cell phone exposure affects the
brain by increasing brain glucose, a known measure of increased brain
activity. Though the study does not offer an explanation of the
underlying mechanism, we do know that in other biological systems of the
body, chronic increase in glucose can have a significant effect on the
local tissues, altering cell and gene function. Notably, the study
refutes the longstanding claim by both the Federal Communications
Commission and the cell phone industry that there are no biological
effects from non-thermal levels of cell phone radiation.

The studies published on cell phone use and the possible health risks (including tumors of the brain, as well as male infertility)
are numerous, and many repudiate any risks. Among the catalogue of
studies, often funded in part by the cell phone industry, a
meta-analysis published in the Journal of Clinical Oncology in 2006, involving 23 case-controlled studies and almost 38,000 participants, concluded there are increased health risks.
Recently a branch of the World Health Organization called The
International Agency for Research on Cancer (IARC) convened 31
scientists from 14 countries, including the United States, and evaluated
peer-reviewed studies regarding the safety of cell phones and issued a
statement that puts exposure to radiofrequency electromagnetic fields
from cell phone use in the same category as lead and car exhaust:
possibly carcinogenic. At what point do we acknowledge that precautions need to be taken? Our
current safety standards regarding cell phones are based on obsolete
research. They certainly don’t take into account the dramatic increase
in number of users, the increase in amount of time spent in use, and the
rise of cell phone use by young people. There not only needs to be
continued investigation into the effects on brain tissues, but also the
consequences of both heavy use and long-term exposure–parameters not yet
studied.

The concept of the precautionary principle encourages policy makers to
make decisions that protect the public from a policy or action that may
be harmful, in the absence of definitive data. In looking at the health
impacts of electromagnetic radiofrequencies from cell phones, the public
needs to be protected from the harm that may be caused by their use. It
calls to mind our history regarding tobacco, when medical professionals
awaited definitive trial data for decades, while millions of
individuals suffered predictable health consequences. By refusing to
acknowledge the possible health risks of cell phone use now, we may be
harming generations to come.

While we continue to gather information, we can counsel our patients on
the many ways to reduce overall electromagnetic radiation exposure:

• Turn cell phones off when not in use. Cell phone emissions are
  occurring whenever the phone is on, whether it is being used or not.
• Avoid cell phone use when the signal is weak. Emissions increase while the phone is searching for a tower.
• Store cell phones away from the body in a purse, backpack, or briefcase.
• Use a protective headset that puts distance between the phone and the brain, with corded earphones if possible.
• Engage in texting in lieu of phone calls.

We can assume there will be continued development of the technology,
including safer phones and safer designs for towers. Ultimately, curbing
cell phone use–using our cell phones for truly important communications
and turning them off when they are not needed–may be the key to
reducing risk.