ACS :: Cellular Phones

Cellular (cell) phones first became widely available in the United States in the 1990s, but their use has increased dramatically since then. According to the Cellular Telecommunications & Internet Association, there were an estimated 270 million cell phone subscribers in the United States as of December 2008, representing about 87% of the total population.

Based on the large and still growing number of cell phone users, and the fact that cell phones give off a type of low-energy radiation, some concerns have been raised about the safety of cell phone use. In particular, issues have been raised about whether cell phones might increase the risk of brain tumors or other tumors in the head and neck area.

Cell phones communicate with nearby cell towers through radio frequency (RF) waves, a form of energy located on the electromagnetic spectrum between FM radio waves and microwaves. The RF waves from cell phones, like FM radio waves, microwaves, and visible light, are a form of radiation. But these types of radiation are non-ionizing. They don't have enough energy to directly damage DNA. They are different from types of ionizing radiation such as x-rays and gamma rays, which are known to damage DNA and can cause cancer.

At very high levels, RF waves can heat up body tissues. (This is the basis for how microwave ovens work.) But the levels of energy given off by cell phones are much lower, and studies suggest they aren't able to heat up body tissues.

The RF waves from cell phones come from the antenna, which is part of the body of a hand-held phone. The waves are strongest at the antenna and lose energy as they travel away from the phone. The phone is typically held against the side of the head when in use. The closer the antenna is to the head, the greater a person's expected exposure to RF energy.

Many factors can affect the amount of RF energy to which a person is exposed, including:

Other factors may also affect exposure. For example, older cell phones (analog models) used more energy than newer, digital phones.

The amount of RF energy absorbed from the phone into the user's local tissues is known as the specific absorption rate (SAR). Different cell phones have different SAR levels. Cell phone makers are required to report the SAR level of their product to the Federal Communications Commission (FCC). The upper limit of SAR allowed in the United States is 1.6 watts per kilogram (W/kg) of body weight.

Because cell phones are held near the head when in use, the main concern has been over whether they might cause or contribute to tumors in this area, including:

About 30 studies have looked at possible links between cell phone use and tumors. Most of these studies have focused on brain tumors. Many of these have been case-control studies, in which patients with brain tumors (cases) were compared to people free of brain tumors (controls), in terms of their past use of cell phones.

A large, long-term study following more than 420,000 cell phone users in Denmark between 1982 and 2002 had findings similar to those of the case-control studies. Cell phone use, even for more than 10 years, was not linked with an increased risk of brain tumors or cancer overall, nor was there a link with any brain tumor subtypes or with tumors in any location within the brain. As in the case-control studies, no link was found between brain tumor risk and length of cell phone use, age when a person started using the phone, or type of cell phone used.

Taken as a whole, most studies to date have not found a link between cell phone use and the development of tumors. However, these studies have had some important limitations.

For example, in case-control studies, information about the amount of phone use was largely assessed by asking people to recall their use. People's memories of their cell phone use may not always be dependable.

Perhaps more important is that most studies have not been able to follow people for long periods of time. When tumors form after a known cancer-causing exposure, it usually takes many years (sometimes decades) for a tumor to develop. Because cell phones have been in widespread use for less than 20 years in most countries, it has been hard to study the possible long-term health effects.

Another important concern is that studies have not looked at whether cell phones might have different effects in children, who are now using them much more than in the past. If there are health effects, they might be more pronounced in children because their nervous systems are still developing. And by starting phone use at a younger age, they are also likely to have a much higher total lifetime exposure than people who started using cell phones as adults.

Further research is needed to address these limitations. Several large studies now under way, including the 13-country INTERPHONE study, should help provide clearer answers in the near future.

As noted above, the RF waves given off by cell phones don't have enough energy to damage DNA directly. Because of this, many scientists believe that cell phones aren't able to cause cancer. Most studies done in the lab have supported this theory, finding that RF waves do not cause DNA damage.

A number of scientists have reported that the RF waves from cell phones may have different effects on cells in the lab, some of which could possibly help tumors grow. However, these claims have not been verified by other scientists. Given the widespread use of cell phones, it is important that these claims be carefully tested by other scientists with expertise in this area.

In general, expert agencies agree that most evidence to date does not point to cell phone use increasing the risk of tumors, but that more research is needed to look at possible long-term effects.

According to the Food and Drug Administration (FDA), which regulates the safety of radiation-emitting devices such as cell phones in the United States:

The majority of studies published have failed to show an association between exposure to radiofrequency from a cell phone and health problems.

There is no scientific evidence that proves that wireless phone usage can lead to cancer or a variety of other problems, including headaches, dizziness or memory loss. However, organizations in the United States and overseas are sponsoring research and investigating claims of possible health effects related to the use of wireless telephones.

Although some studies have raised concerns, the scientific research, when taken together, does not indicate a significant association between cell phone use and health effects.

According to the National Toxicology Program (NTP), which is currently conducting studies of the possible health effects of cell phones:

While the weight of the current scientific evidence has not conclusively linked cell phones with any health problems, the NTP and other scientific organizations conclude that additional data are needed.

Although research has not consistently demonstrated a link between cellular telephone use and cancer, scientists still caution that further surveillance is needed before conclusions can be drawn.

The United States Environmental Protection Agency (EPA), National Toxicology Program (NTP), and the International Agency for Research on Cancer (IARC), 3 of the main agencies that classify cancer-causing exposures (carcinogens), have not classified cell phones as to their cancer-causing potential.

Few other health concerns have been raised about cell phone use. One has been whether the RF waves from cell phones might interfere with medical devices such as heart pacemakers. According to the FDA, cell phones should not pose a major risk for the vast majority of pacemaker wearers. Still, people with pacemakers may want to take some simple precautions to help ensure that their cell phones don't cause a problem, such as not putting the phone in a shirt pocket close to the pacemaker.

Several studies have found that people who use cell phones while driving are more likely to be in car accidents. It is not clear that hands-free phones are any safer than hand-held phones when it comes to driving.

Studies now under way should give a clearer picture of the possible health effects of cell phone use in the future. Until then, there are several things that people who are concerned about RF waves can do to limit their exposure.

Use a hands-free device such as a corded or cordless earpiece. Using an earpiece moves the antenna away from the user's head, which decreases the amount of RF waves that reach the head. Corded earpieces emit virtually 0 RF waves (although the phone itself still emits small amounts of RF waves that can reach parts of the body if close enough, such as on the waist or in a pocket). Bluetooth^® earpieces have an SAR value of around 0.001 watts/kg (less than one thousandth the SAR limit for cell phones as set by the FDA and FCC).

Choose a phone with a low SAR value. Different models of phones can give off different levels of RF waves. One way to get information on the SAR level for a specific phone model is to find the FCC identification (ID) number for that model. The FCC ID number is usually somewhere on the phone, sometimes under the battery pack. Once you have the ID number, go to the following Web address: www.fcc.gov/oet/ea/fccid. On this page, you will see instructions for entering the FCC ID number.

Limit your (and your children's) cell phone use. One of the most obvious ways to limit exposure to RF waves from cell phones is to limit how much you use them. You may want to use your cell phone only for shorter conversations, or use it only when a conventional phone is not available. Parents who are concerned about their children's exposure may limit how much time they spend on the phone.

For safety reasons, it is especially important to limit or avoid the use of cell phones while driving.

Cordless phones, commonly used in homes, have base units that are plugged into telephone jacks and wired to a local telephone service. They are not considered "cell" phones. The question of health risks from cordless phones, which operate at about 1/600 the power of cell phones, has not been raised.

In addition to the American Cancer Society, other sources of patient information and support include:

Federal Communications Commission
RF Safety Program, Office of Engineering and Technology
Web site: www.fcc.gov/oet/rfsafety/

* Inclusion on this list does not imply endorsement by the American Cancer Society.

The American Cancer Society is happy to address almost any cancer-related topic. If you have any more questions, please call us at 1-800-227-2345 at any time, 24 hours a day.

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