Cell Phones and Cancer Risk

Key Points

• Cell phones emit radiofrequency energy, a form of non-ionizing electromagnetic radiation, which can be absorbed by tissues closest to where the phone is held.
• The amount of radiofrequency energy a cell phone user is exposed to depends on the technology of the phone, the distance between the phone’s antenna and the user, the extent and type of use, and the user’s distance from cell phone towers.
• Studies thus far have not shown a consistent link between cell phone use and cancers of the brain, nerves, or other tissues of the head or neck. More research is needed because cell phone technology and how people use cell phones have been changing rapidly.

·  Why is there concern that cell phones may cause cancer or other health problems?

There are three main reasons why people are concerned that cell phones (also known as “wireless” or “mobile” telephones) might have the potential to cause certain types of cancer or other health problems:

• Cell phones emit radiofrequency energy (radio waves), a form of non-ionizing radiation. Tissues nearest to where the phone is held can absorb this energy.
• The number of cell phone users has increased rapidly. As of 2010, there were more than 303 million subscribers to cell phone service in the United States, according to the Cellular Telecommunications and Internet Association. This is a nearly threefold increase from the 110 million users in 2000. Globally, the number of cell phone subscriptions is estimated by the International Telecommunications Union to be 5 billion.
• Over time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have increased. Cell phone technology has also undergone substantial changes.

·  What is radiofrequency energy and how does it affect the body?

Radiofrequency energy is a form of electromagnetic radiation. Electromagnetic radiation can be categorized into two types: ionizing (e.g., x-rays, radon, and cosmic rays) and non-ionizing (e.g., radiofrequency and extremely low-frequency or power frequency).

Exposure to ionizing radiation, such as from radiation therapy, is known to increase the risk of cancer. However, although many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens, and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk (1).

The only known biological effect of radiofrequency energy is heating. The ability of microwave ovens to heat food is one example of this effect of radiofrequency energy. Radiofrequency exposure from cell phone use does cause heating; however, it is not sufficient to measurably increase body temperature.

A recent study showed that when people used a cell phone for 50 minutes, brain tissues on the same side of the head as the phone’s antenna metabolized more glucose than did tissues on the opposite side of the brain (2). The researchers noted that the results are preliminary, and possible health outcomes from this increase in glucose metabolism are still unknown.

·  What has research shown about the possible cancer-causing effects of radiofrequency energy?

Although there have been some concerns that radiofrequency energy from cell phones held closely to the head may affect the brain and other tissues, to date there is no evidence from studies of cells, animals, or humans that radiofrequency energy can cause cancer.

It is generally accepted that damage to DNA is necessary for cancer to develop. However, radiofrequency energy, unlike ionizing radiation, does not cause DNA damage in cells, and it has not been found to cause cancer in animals or to enhance the cancer-causing effects of known chemical carcinogens in animals (3–5).

Findings from specific research studies are summarized below:

• The Interphone Study, conducted by a consortium of researchers from 13 countries, is the largest health-related case-control study of use of cell phones and head and neck tumors. Most published analyses from this study have shown no statistically significant increases in brain or central nervous system cancers related to higher amounts of cell phone use. One recent analysis showed a statistically significant, albeit modest, increase in the risk of glioma among the small proportion of study participants who spent the most total time on cell phone calls. However, the researchers considered this finding inconclusive because they felt that the amount of use reported by some respondents was unlikely and because the participants who reported lower levels of use appeared to have a reduced risk of brain cancer (7–9). Another recent study from the group found no relationship between brain tumor locations and regions of the brain that were exposed to the highest level of radiofrequency energy from cell phones (10).
• A cohort study in Denmark linked billing information from more than 358,000 cell phone subscribers with brain tumor incidence data from the Danish Cancer Registry. The analyses found no association between cell phone use and the incidence of glioma, meningioma, or acoustic neuroma, even among people who had been cell phone subscribers for 13 or more years (11–13).
• Early case-control studies in the United States, Europe, and Japan were unable to demonstrate a relationship between cell phone use and glioma or meningioma (14).
• Some case-control studies in Sweden found statistically significant trends of increasing brain cancer risk for the total amount of cell phone use and the years of use among people who began using cell phones before age 20 (15). However, another large, case-control study in Sweden did not find an increased risk of brain cancer among people between the ages of 20 and 69 (16). In addition, the international CEFALO study, which compared children who were diagnosed with brain cancer between ages 7 and 19 with similar children who were not, found no relationship between their cell phone use and risk for brain cancer (17).
• NCI's Surveillance, Epidemiology, and End Results (SEER) Program, which tracks cancer incidence in the United States over time, found no increase in the incidence of brain or other central nervous system cancers between 1987 and 2007, despite the dramatic increase in cell phone use in this country during that time (18, 19). Similarly, incidence data from Denmark, Finland, Norway, and Sweden for the period 1974–2008 revealed no increase in age-adjusted incidence of brain tumors (20, 21). A 2012 study by NCI researchers, which compared observed glioma incidence rates in SEER with projected rates based on risks observed in the Interphone study (8), found that the projected rates were consistent with observed U.S. rates. The researchers also compared the SEER rates with projected rates based on a Swedish study published in 2011 (15). They determined that the projected rates were at least 40 percent higher than, and incompatible with, the actual U.S. rates.
• Studies of workers exposed to radiofrequency energy have shown no evidence of increased risk of brain tumors among U.S. Navy electronics technicians, aviation technicians, or fire control technicians, those working in an electromagnetic pulse test program, plastic-ware workers, cellular phone manufacturing workers, or Navy personnel with a high probability of exposure to radar .

• 1. Where can I find more information about radio frequency energy from my cell phone?

     The FCC provides information about the specific absorption rate (SAR) of cell phones produced and marketed within the last 1 to 2 years. The SAR corresponds with the relative amount of radio frequency energy absorbed by the head of a cell phone user (23). Consumers can access this information using the phone’s FCC ID number, which is usually located on the case of the phone, and the FCC’s ID search form.

  2. What are other sources of radio frequency energy?

     The most common exposures to radiofrequency energy are from telecommunications devices and equipment (1). In the United States, cell phones currently operate in a frequency range of about 1,800 to 2,200 megahertz (MHz) (6). In this range, the electromagnetic radiation produced is in the form of non-ionizing radiofrequency energy.
     Cordless phones (phones that have a base unit connected to the telephone wiring in a house) often operate at radio frequencies similar to those of cell phones; however, since cordless phones have a limited range and require a nearby base, their signals are generally much less powerful than those of cell phones.
     Among other radiofrequency energy sources, AM/FM radios and VHF/UHF televisions operate at lower radio frequencies than cell phones, whereas sources such as radar, satellite stations, magnetic resonance imaging (MRI) devices, industrial equipment, and microwave ovens operate at somewhat higher radio frequencies (1).