How Mobile Phone Radiation Functions

Cell phones naturally emit a small amount of electromagnetic radiation as part of their basic operation. If you're familiar with How Mobile Phones Operate, you already know that they transmit signals through radio waves, which consist of radio-frequency (RF) energy, a type of electromagnetic radiation.

There's ongoing debate in the media about whether cell phones emit sufficient radiation to pose health risks. The primary concern is that mobile phones are often held close to or against the head, exposing the tissue to direct radiation. There is supporting evidence for both perspectives on the issue.

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In this article, we will dive deeper into this debated topic. You'll learn how cell phones produce radiation and how they are evaluated for radiation levels.

Radiation Source

When using a cell phone, a transmitter captures your voice and encodes it onto a continuous sine wave (refer to How Radio Works for a deeper understanding of sound transmission). A sine wave is a type of constantly fluctuating wave that radiates outward from the antenna and oscillates evenly through space. These sine waves are quantified by frequency, which measures the number of oscillations per second. After the sound has been encoded on the sine wave, the transmitter sends it to the antenna, which then broadcasts the signal.

Cell phones are equipped with low-power transmitters. Most car phones use a transmitter with a power of 3 watts, while a handheld cell phone operates on approximately 0.75 to 1 watt of power. The transmitter's location inside the phone can differ by manufacturer, but it's generally situated close to the phone's antenna. The radio waves that carry the encoded signal are composed of electromagnetic radiation, emitted by the antenna. The antenna's role in any radio transmitter is to launch the radio waves into space, and in the case of cell phones, these waves are received by a receiver in the cell-phone tower.

Electromagnetic radiation consists of electric and magnetic energy waves traveling at the speed of light, as defined by the Federal Communications Commission (FCC). This energy spans the electromagnetic spectrum, which includes radiation from extremely low frequency (ELF) to X-rays and gamma rays. Later, you'll explore how these various levels of radiation can impact biological tissue.

When using a cell phone, most people hold it against their heads. In this position, a portion of the radiation is likely absorbed by the human tissue. In the upcoming section, we'll examine why some researchers believe cell phones could be harmful and explore the potential effects of these omnipresent devices.

Potential Health Concerns

In the late 1970s, concerns emerged that magnetic fields from power lines might be linked to leukemia in children. However, later epidemiological studies found no connection between cancer and power lines. A more recent health concern tied to everyday technology involves the potential radiation damage from cell phones. Ongoing studies on this issue continue to show conflicting results.

All cell phones release a certain amount of electromagnetic radiation. Considering how close the phone is to the head, there is a possibility that this radiation could harm some of the 118 million cell-phone users in the United States. The debate among scientists and lawmakers revolves around how much radiation is deemed unsafe and whether long-term exposure to cell-phone radiation could have any lasting effects.

Electromagnetic radiation exists in two forms:

On its website, the FDA states, "the available scientific evidence does not demonstrate any adverse health effects associated with the use of mobile phones." However, this doesn't rule out the potential for harm. According to the FCC, radiation can damage human tissue when exposed to high levels of RF radiation. RF radiation has the ability to heat human tissue, similar to how microwave ovens heat food. Prolonged exposure to RF radiation can damage tissue because the body isn't designed to disperse excessive heat. The eyes are especially vulnerable due to the absence of sufficient blood flow in that region.

The concern with non-ionizing radiation, the type of radiation linked to cell phones, is its potential long-term effects. While it may not cause immediate tissue damage, scientists remain uncertain about whether extended exposure could lead to health issues. This matter is especially pressing today, as more people use cell phones than ever before. In 1994, there were 16 million cell-phone users in the United States. By July 17, 2001, that number had increased to more than 118 million.

Here are some illnesses and conditions that have been potentially linked to cell-phone radiation:

Studies have complicated the issue further. Like most contentious topics, studies yield differing results. Some suggest a connection between cell phones and higher rates of cancer and other health problems, while others report that cell-phone users have no greater risk of cancer than the general population. To date, no study has conclusively proven that cell phones cause these diseases. However, research continues to explore the matter in more detail. For more information on these studies, refer to the links page at the end of this article. ­

At high levels, radio-frequency energy can quickly heat biological tissue, causing damage such as burns, according to a recent report from the U.S. General Accounting Office (GAO), a nonpartisan congressional agency that audits federal programs. The report further stated that mobile phones operate at power levels far below the threshold at which such heating effects could occur. The radiation emitted by these devices is minimal, and the U.S. government sets strict limits on how much radiation a cell phone can release.

In the next section, we will explore how the radiation levels from cell phones are measured.

Radiation Testing Methods

Each cell phone model must undergo testing to meet FCC standards before it can be sold in the U.S. Most of this testing is done by the manufacturers, which raises some concerns about the accuracy of the testing procedures, as noted in a GAO report.

The FCC has set an exposure limit for cell phones based on the overall heating effects of radio-frequency energy. This exposure limit was introduced in 1996, with the FCC releasing voluntary testing guidelines a year later to assist manufacturers in complying with these limits. While the guidelines are not mandatory, other testing methods are permitted once the procedures are reviewed by the FCC.

Radiation levels are measured by the specific absorption rate (SAR), which gauges the amount of radio-frequency energy absorbed by the human body. For a cell phone to obtain an FCC license, its maximum SAR must be under 1.6 watts per kilogram (W/kg). In 2000, the Cellular Telecommunications & Internet Association (CTIA) mandated that manufacturers display radiation levels on phone labels.

Testing procedures are generally consistent, with minor variations. According to a May 2001 GAO report titled 'Research and Regulatory Efforts on Mobile Phone Health Issues,' the process for checking SAR levels involves the following steps:

During testing, the phone’s antenna is extended and retracted to observe any variations in radiation based on the phone’s configuration. The highest SAR reading recorded during these tests must be submitted to the FCC by the manufacturer. Phones are required to have a SAR value under 1.6 W/kg, averaged over 1 gram of fluid.

To check your phone's specific absorption rate (SAR), visit this FCC website. You will need to locate the FCC identification code for your phone, input it in the designated field, and the site will provide the relevant details for your device.

Because there is no universal standard for testing, the FCC must review the specific procedures used by each manufacturer to certify the SAR of every new phone, as stated in the GAO report.

The question of whether cell phones cause significant harm to the human body remains unresolved. Studies offer conflicting results, and while more research may clarify the effects of cell-phone radiation, it is likely to further confuse the public. For now, millions of cell-phone users continue using their devices, accepting whatever risks may exist.