Cellular Telephone Use and Cancer - Nat. Cancer Institute

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Fact Sheet 3.72Sunday, March 31, 2002 9:07 PM

Cellular Telephone Use and Cancer - Nat. Cancer

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Cellular Telephone Use and Cancer

 

 

Recently, there has been concern that the use of hand-held cellular

telephones may be linked with an increased risk of cancer. In response to this

concern, and the rapidly rising number of cellular telephone users worldwide,

studies have been conducted to determine whether there is an association between

cellular telephone use and an increased risk of certain types of cancer.

Although the majority of these studies have not supported any such association,

scientists caution that more research needs to be done before conclusions can be

drawn about the risk of cancer from cellular telephones.

 

Concerns About Cellular Telephone Use and Human Health

 

The number of people using cellular telephones has risen dramatically

during the past decade, and is expected to continue increasing. According to the

Cellular Telecommunications Industry Association (CTIA), there are currently

over 110 million wireless telephone users in the United States. This number is

increasing at a rate of about 46,000 new rs per day. Experts estimate

that by 2005 there will be over 1.26 billion wireless telephone users worldwide.

 

The concern about an increased risk of cancer with cellular telephone use

is related to the radiation that the device produces. Like televisions, alarm

systems, computers, and all other electrical devices, cellular telephones emit

electromagnetic radiation. In the United States, cellular telephones operate in

a frequency ranging from about 800 to 2100 megahertz (MHz). In that range, the

radiation produced is in the form of non-ionizing radiofrequency (RF) radiation.

AM/FM radios, VHF/UHF televisions, and cordless telephones operate at lower

radio frequencies than cellular phones; microwave ovens, radar, and

satellite-stations operate at higher radio frequencies. RF radiation is

different from ionizing radiation, which can present a health risk at certain

doses. Ionizing radiation is produced by devices such as x-ray machines. It is

not yet known whether the non-ionizing radiation emitted by cellular telephones

poses a cancer risk. Because so many people use cellular telephones, it is

important to learn whether RF radiation affects human health, and to provide

reassurance if it does not.

 

A cellular telephone user’s level of exposure to RF radiation depends on

several factors. These factors include the amount of cellular telephone traffic,

the quality of the transmission, how far the antenna is extended, and the size

of the handset. A cellular telephone’s main source of RF energy is its antenna.

Therefore, the closer the antenna is to the head, the greater a person’s

expected exposure to RF radiation. The amount of RF radiation absorbed decreases

rapidly with increasing distance between the antenna and the user. The antenna

of hand-held cellular telephones is in the handset, which is typically held

against the side of the head while the phone is in use. The antenna of a car

cellular telephone is mounted on the outside of the car, some distance from the

user. Transportable cellular telephones or “bag phones” have an antenna in a

portable unit separate from the handset. Most of the studies conducted on

cellular telephone use and cancer risk have focused on hand-held models, since

they deliver the most RF radiation to the user.

 

The intensity of RF radiation emitted by cellular telephones also depends

on the power level of the signal sent to and from the nearest base station. A

given geographical region is divided into zones or cells, each of which is

equipped with a base station. When a call is placed from a cellular telephone, a

signal is sent from the antenna of the phone to the nearest base station

antenna. The base station routes the call through a switching center, where the

call can be transferred to another cellular telephone, another base station, or

to the local land-line telephone system. The farther a cellular telephone is

from the base station antenna, the higher the power level needed to maintain the

connection. This distance, in part, determines the amount of RF radiation

exposure to the user.

 

RF radiation can be harmful at high levels because it produces heat. Some

people have speculated that the heat produced by RF radiation from hand-held

cellular telephones may be associated with brain tumors, because the antenna is

held close to the user’s head. However, the heat generated by a cellular

telephone is small in comparison with the large amount of heat generated by RF

radiation in a microwave oven. It is generally agreed that the amount of heat

produced by a cellular telephone is too small to cause cancer.

 

 

Studies of Cellular Telephone Use and Cancer Risk

 

Public concern and limited scientific evidence have prompted several

studies of cellular telephone use and cancer risk. Because hand-held models are

used close to the head, most of these studies have examined the risk of brain

cancer. Researchers have focused on whether the RF radiation emitted by cellular

telephones increases the risk of tumors, and, if so, how this type of radiation

causes cancer.

 

Results of a study from Sweden were published in the July 1999 issue of

the International Journal of Oncology . This study compared cellular telephone

use in a group of 209 individuals who had brain tumors (the case group) with a

group of 425 people without brain cancer (the control group). The study reported

a statistically non-significant increased risk for brain tumors on the side of

the head on which the cellular telephone was used. However, researchers found no

overall increase in the risk for brain tumors with cellular telephone use.

 

A study of 195,775 wireless communications workers was published in the

March 2000 issue of the journal Epidemiology . These workers were exposed to RF

radiation during the manufacturing and testing of cellular telephones. The

results of this study found no association between occupational RF radiation

exposure and cancers of the brain and nervous system, or between RF radiation

exposure and all types of lymphoma and leukemia.

 

A study funded by Wireless Technology Research LLC and the National Cancer

Institute (NCI) was conducted in five academic medical centers in the United

States. The study analyzed the possible link between brain cancer and cellular

telephone use between 1994 and 1998. Results of this study were published in the

December 20, 2000, issue of the Journal of the American Medical Association .

The study compared a group of 469 men and women with brain cancer to a control

group of 422 men and women.

 

Researchers asked the participants how often they used a hand-held

cellular telephone, for how many years they had used one, and what hand they

generally used to hold the phone. The study found that the use of handheld

cellular telephones was unrelated to the risk of brain cancer. However, like the

Swedish study (described above), the researchers found a statistically

non-significant increased risk for brain tumors on the side of the head on which

the cellular telephone was held.

 

The results of another large NCI-funded study of cellular telephones and

brain tumors were published in the January 11, 2001, issue of the New England

Journal of Medicine . The study focused on 782 patients with one of three types

of brain tumors (glioma, meningioma, or acoustic neuroma) at three medical

centers between 1994 and 1998. The control group consisted of 799 patients at

the same hospitals who did not have brain cancer.

 

Researchers interviewed the participants about their hand-held cellular

telephone use, including how long they had used a cellular telephone, the usual

frequency of use, and which hand they normally used to hold the handset. The

researchers did not find an increased risk of brain cancer among cellular

telephone users. The results showed no evidence of increasing risk with

increasing years of use, or average minutes of use per day. The study also found

that brain tumors did not occur more often than expected on the side of the head

on which participants reported using their phone.

 

Because very little is known about the causes of brain tumors, the NCI is

studying a wide range of possible environmental and genetic causes, in addition

to cellular telephone use. Topics under study include a family history of cancer

or other diseases, a personal medical history of certain diseases, dietary

factors, workplace exposure to certain chemicals and electromagnetic fields,

selected home appliances, hair dyes, reproductive history and hormonal

exposures, viruses, exposure to ionizing radiation, and genetic factors. Results

of these studies will be reported in future publications.

 

A small study of mobile telephones and the risk of uveal melanoma, a rare

type of eye cancer, was conducted in Germany. The results of this study were

published in the January 2001 issue of the journal Epidemiology . A total of 118

individuals with uveal melanoma were compared with a control group of 475 people

without this condition. Participants were asked about their exposure to several

sources of electromagnetic radiation, including cellular telephones. Researchers

found that an elevated risk of uveal melanoma was associated with exposure to

electromagnetic radiation. This small study was the first to examine the risk of

uveal melanoma in relation to RF radiation exposure, and it did not measure the

amount of RF radiation exposure in each participant. Future studies may clarify

this hypothesized association.

 

The results of a large study of all cellular telephone users in Denmark

from 1982 through 1995 were published in the February 7, 2001, issue of the

Journal of the National Cancer Institute . Subscriber lists from the two Danish

cellular telephone operating companies identified 420,095 non-corporate cellular

telephone users during that time period. Researchers determined cancer incidence

by linking r data with the Danish Cancer Registry, which is considered

to be a valid and virtually complete record of all cancer cases in Denmark.

Results indicated no increased risk among cellular telephone users of cancers of

the brain or nervous system, leukemia, cancer of the salivary gland, or all

cancers combined. Moreover, there was no evidence for an increasing risk of

cancer with increasing years as a cellular telephone r.

 

 

Conclusions

 

Overall, most of these studies do not support a link between cellular

telephone use and an increased risk of cancer. However, all of the studies have

limitations, and it would be premature to conclude that the use of hand-held

cellular telephones is not associated with cancer. One limitation is the

relatively short amount of time that cellular telephones have been widely

available. Cancers that take a long time to develop would not have been detected

by these studies.

 

Researchers suggest that future studies need to address the effects of

long-term, heavy use of cellular telephones, and the differences between

analogue and digital technologies. Analogue and digital telephones operate at

different frequencies and power levels. Although many of the cellular telephones

tested in recent studies used analogue technology, most cellular telephones

today are based on digital technology.

 

Additional studies of cellular telephone use and cancer risk are under way

in the United States and internationally to address these remaining issues. For

example, the U.S. Food and Drug Administration (FDA), a Federal Government

agency that monitors the safety of wireless phones, and the Cellular

Telecommunications Industry Association (CTIA) are working jointly to evaluate

the health effects of cellular telephone use. They will plan studies to

determine the possible health effects of repeated or long-term exposure to

cellular telephones, and select topics for future research.

 

 

What Consumers Can Do If They Are Concerned About the Health Effects of

Cellular Telephones

 

The FDA has suggested some steps that cellular telephone users can take if

they are concerned about potential health risks, but do not want to give up

their mobile phones:

 

 

1.. Reserve the use of cellular telephones for shorter conversations, or

for when a conventional phone is not available;

 

2.. Switch to a type of mobile phone with a headset to place more

distance between the antenna and the phone user;

 

3.. For use in the car, switch to a mobile phone with the antenna

mounted outside the vehicle.

 

The Federal Communications Commission (FCC) is a Federal Government agency

that regulates interstate and international communications by radio, television,

wire, satellite, and cable. The FCC provides consumers with information on human

exposure to RF radiation from wireless phones and other devices. The

Commission’s Web site, which is located at http://www.fcc.gov/oet/rfsafety on

the Internet, allows consumers to find information about the specific absorption

rate (SAR) of cellular telephones produced and marketed within the last 1 to 2

years. The SAR corresponds to the relative amount of RF energy absorbed into the

head of a cellular telephone user. Consumers can access this information using

the phone’s FCC ID number, which is usually located on the case of the phone.

Instructions for obtaining information about the SAR are available on the FCC’s

Web site.

 

References

 

Hardell L, Nasman A, Pahlson A, Hallquist A, Hansson Mild K. Use of

cellular telephones and the risk for brain tumours: A case-control study.

International Journal of Oncology 1999; 15(1):113–116.

 

Inskip PD, Tarone RE, Hatch EE, et al. Cellular-telephone use and brain

tumors. New England Journal of Medicine 2001; 344(2):79–86.

 

Johansen C, Boice Jr. JD, McLaughlin JK, Olsen JH. Cellular telephones and

cancer: A nationwide cohort study in Denmark. Journal of the National Cancer

Institute 2001; 93(3):203–207.

 

More information about cellular phones. Journal of the National Cancer

Institute 2001; 93(3):172.

 

Morgan RW, Kelsh MA, Zhao K, Exuzides KA, Heringer S, Negrete W.

Radiofrequency exposure and mortality from cancer of the brain and

lymphatic/hematopoietic systems. Epidemiology 2000; 11(2):118–127.

 

Muscat JE, Malkin MG, Thompson S, et al. Handheld cellular telephone use

and risk of brain cancer. Journal of the American Medical Association 2000;

284(23):3001–3007.

 

National Cancer Institute Press Release. Questions and Answers for the

National Cancer Institute Study of Brain Tumors and Use of Cellular Telephones.

December 21, 2000.

http://newscenter.cancer.gov/pressreleases/cellphassoc_qa.html

 

National Cancer Institute Press Release. No Association Found Between

Cellular Phone Use and Risk of Brain Tumors. December 21, 2000.

http://newscenter.cancer.gov/pressreleases/cellphassoc.html

 

Nelson NJ. Recent studies show cell phone use is not associated with

increased cancer risk. Journal of the National Cancer Institute 2001;

93(3):170–172.

 

Nordenberg T. Cell phones and cancer: No clear connection. FDA Consumer

2000; 34(6):19–23.

 

Stang A, Anastassiou G, Ahrens W, Bromen K, Bornfeld N, Jockel KH. The

possible role of radiofrequency radiation in the development of uveal melanoma.

Epidemiology 2001; 12(1):7–12.

 

Trichopoulos D, Adami HO. Cellular telephones and brain tumors. New

England Journal of Medicine 2001; 344(2):133–134.

 

 

 

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