Cell Phones: An Introduction

Over 35 years ago in 1973, the world’s first call on a portable cellular phone was made. It was an experimental Motorola phone, described as “like a brick” and weighing almost two pounds. Motorola had already revolutionized communications a few times – Neil Armstrong’s famous declaration from the moon was delivered on a Motorola radio – but no one could have imagined how important personal cell phones would turn out to be. It took until 1983 for personal cell phones to reach the market, and each one cost over $3,000. Now, there are 2.5 billion cell phones in use around the world, approximately one phone for every 2.5 people on the planet. In fact, there are more cellular phones than “land line” phones based on traditional wiring. Eight out of ten Americans own cell phones and a growing number are abandoning their land lines every day.

How They Work and Risks of Use

But how do cell phones work? It may seem amazing, but cell phones are basically sophisticated full-duplex radios equipped with low power transmitters. This means that a cell phone is a radio that operates on a variety of frequencies, allowing two users or more to speak at the same time. Cell phone providers use about 800 radio frequencies per city. Each frequency is used only by phones near a given tower, and each tower can reuse each frequency without overlapping. This enables a cell network to provide simultaneous calls for users no matter how far apart. Because cell phones are now so common, they have some risks. Studies have shown that cell phone use in cars contributes to traffic accidents. Do cell phones interfere with medical equipment? Studies indicate mild interference with medical equipment may occur when cell phones are used at close range. Though there are, to date, no confirmed reports of life-threatening cell phone interference at hospitals, the use of cell phones is generally banned as a precaution. Cell phones can also interfere with equipment like cardiac pacemakers and the navigation systems in airplanes.

Is Cell Phone Radiation Dangerous?

Because cell phones give off radiation, medical research continues into whether cell phones are associated with serious health risks. Some studies suggest the possibility that higher incidences of headache and fatigue, as well as diseases like Alzheimer’s and cancer, may be linked to cell phone use. The type of radiation emitted by cell phones is radiofrequency radiation. This radiation allows the cell phone to communicate with signal towers and vice versa. RF radiation is a form of electromagnetic radiation, a low-energy radiation that comes from the interaction of magnetic and electric fields. Unlike the high-intensity radiation given off by something like an x-ray machine, cell phone radiation is non-ionizing radiation. Non-ionizing radiation does not produce heating or other chemical changes in the cells exposed to it. According to the National Cancer Institute, there is no known link between RF radiation in cell phones and cancer. But the issue is still being investigated: even as recently as September 14, 2009, the Senate held hearings to listen to experts on both sides of the issue – with inconclusive results.

What is a Cellular Base Station?

Cellular base stations allow cell phones to interact with traditional phones. Antennas mounted on top of the station's tower allow it to collect signals from cell phones and “beam” them down into the building at the station’s base, which has electrical equipment for creating the necessary connection. The radiation emitted by base station towers is microwave radiation. Microwave radiation is the same kind that’s used – not surprisingly – in microwave ovens to cook food. As with cell phones, microwave radiation is a form of electromagnetic radiation. The FDA regulates how much microwave radiation can “leak” out of consumer products, since high levels of microwave exposure can lead to eye damage and burns. Most people are exposed to base station radiation only in passing, and there are no confirmed risks from this level of radiation. However, manufacturers continue to seek ways to reduce radiation from base stations.

What is a Phone’s Specific Absorption Rate?

Personal cell phones can be used with a number of devices that reduce radiation exposure. To determine whether these devices are necessary, it may be helpful to know a phone’s Specific Absorption Rate. The SAR is a measure of the amount of RF radiation a cell phone user’s body absorbs during use. The FCC considers any phone with a SAR of 1.6 watts per kilogram or below to be safe – no cell phone with radiation above this level can be legally sold in the United States. It is possible to look up the SAR of any given phone by looking for the FCC ID number (usually printed within the battery compartment) and entering this code on the FCC website provided for that purpose.

For more information on selecting and using a cell phone and reducing cell phone risks, see the following Internet resources.

Cellular Phone and Base Station Q&A: This resource from the Health Physics Society provides definitive answers to common questions about cell phone radiation safety and base station safety according to the latest published research.

Cellular Telephone Specific Absorption Rate: An index of SAR information by brand and phone model provided by the Federal Communications Commission. Links to the FCC database where a cell phone’s SAR can be looked up.

Shopping for Cell Phones: The AARP’s in-depth guide for selecting a cell phone for elderly users.

Hearing Aids and Cell Phones: Guide to selecting a hearing aid-compatible cellular phone from the American Speech-Language-Hearing Association.

MobileWorld Glossary: An extensive glossary of hundreds of terms relating to cell phone use.

Cellular Phone Use and Cancer Risk: Information on cell phones and cell phone radiation from the National Cancer Association.

Statement for the Record: Statements of Dr. Robert N. Hoover of the National Cancer Institute at the September, 2009 Senate hearing on cell phones and cancer. Offers detailed remarks and a summary overview of current medical research into cellular phone use versus incidence of brain cancer.

The INTERPHONE Study: Overview of information on an ongoing, international research project coordinated by the World Health Organization studying potential connections between cell phones and cancer.

Devices That May Interfere With Pacemakers: Information from the American Heart Association on devices, including cellular phones, that may interfere with pacemaker operation.

Unsafe At Any Airspeed?: Article from researchers at Carnegie Mellon University discussing the potential risks of cell phone use on aircraft.


Cellular Phone Use: Cellular phone safety tips from the Governor’s Traffic Safety Committee of the state of New York.