Alcohol is the common term for ethanol or ethyl alcohol, a chemical substance found in alcoholic beverages such as beer, hard cider, malt liquor, wines, and distilled spirits (liquor). Alcohol is produced by the fermentation of sugars and starches by yeast. Alcohol is also found in some medicines, mouthwashes, and household products (including vanilla extract and other flavorings). This fact sheet focuses on cancer risks associated with the consumption of alcoholic beverages.

According to the National Institute on Alcohol Abuse and Alcoholism, a standard alcoholic drink in the United States contains 14.0 grams (0.6 ounces) of pure alcohol. Generally, this amount of pure alcohol is found in:

• 12 ounces of beer
• 8–10 ounces of malt liquor
• 5 ounces of wine
• 1.5 ounces, or a “shot,” of 80-proof distilled spirits (liquor)

These amounts are used by public health experts in developing health guidelines about alcohol consumption and to provide a way for people to compare the amounts of alcohol they consume. However, they may not reflect the typical serving sizes people may encounter in daily life.

According to the federal government’s Dietary Guidelines for Americans, 2020–2025, individuals who do not drink alcohol should not start drinking for any reason. The Dietary Guidelines also recommends that people who drink alcohol do so in moderation by limiting consumption to 2 drinks or less in a day for men and 1 drink or less in a day for women. Heavy alcohol drinking is defined as having 4 or more drinks on any day or 8 or more drinks per week for women and 5 or more drinks on any day or 15 or more drinks per week for men.

There is a strong scientific consensus that alcohol drinking can cause several types of cancer (1, 2). In its Report on Carcinogens, the National Toxicology Program of the US Department of Health and Human Services lists consumption of alcoholic beverages as a known human carcinogen.

The evidence indicates that the more alcohol a person drinks—particularly the more alcohol a person drinks regularly over time—the higher his or her risk of developing an alcohol-associated cancer. Even those who have no more than one drink per day and binge drinkers (those who consume 4 or more drinks for women and 5 or more drinks for men in one sitting) have a modestly increased risk of some cancers (3–7). Based on data from 2009, an estimated 3.5% of cancer deaths in the United States (about 19,500 deaths) were alcohol related (8).

Researchers have hypothesized multiple ways that alcohol may increase the risk of cancer, including

• metabolizing (breaking down) ethanol in alcoholic drinks to acetaldehyde, which is a toxic chemical and a probable human carcinogen; acetaldehyde can damage both DNA (the genetic material that makes up genes) and proteins
• generating reactive oxygen species (chemically reactive molecules that contain oxygen), which can damage DNA, proteins, and lipids (fats) in the body through a process called oxidation
• impairing the body’s ability to break down and absorb a variety of nutrients that may be associated with cancer risk, including vitamin A; nutrients in the vitamin B complex, such as folate; vitamin C; vitamin D; vitamin E; and carotenoids
• increasing blood levels of estrogen, a sex hormone linked to the risk of breast cancer

Alcoholic beverages may also contain a variety of carcinogenic contaminants that are introduced during fermentation and production, such as nitrosamines, asbestos fibers, phenols, and hydrocarbons.

The mechanisms by which alcohol consumption may decrease the risks of some cancers are not understood and may be indirect.

Epidemiologic research shows that people who use both alcohol and tobacco have much greater risks of developing cancers of the oral cavity, pharynx (throat), larynx, and esophagus than people who use either alcohol or tobacco alone. In fact, for oral and pharyngeal cancers, the risks associated with using both alcohol and tobacco are multiplicative; that is, they are greater than would be expected from adding the individual risks associated with alcohol and tobacco together (10, 26).

A person’s risk of alcohol-related cancers is influenced by their genes, specifically the genes that encode enzymes involved in metabolizing (breaking down) alcohol (27).

For example, one way the body metabolizes alcohol is through the activity of an enzyme called alcohol dehydrogenase, or ADH, which converts ethanol into the carcinogenic metabolite acetaldehyde, mainly in the liver. Recent evidence suggests that acetaldehyde production also occurs in the oral cavity and may be influenced by factors such as the oral microbiome (28, 29).

Many individuals of East Asian descent carry a version of the gene for ADH that codes for a “superactive” form of the enzyme. This superactive ADH enzyme speeds the conversion of alcohol (ethanol) to toxic acetaldehyde. Among people of Japanese descent, those who have this form of ADH have a higher risk of pancreatic cancer than those with the more common form of ADH (30).

Another enzyme, called aldehyde dehydrogenase 2 (ALDH2), metabolizes toxic acetaldehyde to nontoxic substances. Some people, particularly those of East Asian descent, carry a variant of the gene for ALDH2 that encodes a defective form of the enzyme. In people who produce the defective enzyme, acetaldehyde builds up when they drink alcohol. The accumulation of acetaldehyde has such unpleasant effects (including facial flushing and heart palpitations) that most people who have inherited the ALDH2 variant are unable to consume large amounts of alcohol and therefore have a low risk of developing alcohol-related cancers. 

However, some individuals with the defective form of ALDH2 can become tolerant to the unpleasant effects of acetaldehyde and consume large amounts of alcohol. Epidemiologic studies have shown that such individuals have a higher risk of alcohol-related esophageal cancer, as well as of head and neck cancers, than individuals with the fully active enzyme who drink comparable amounts of alcohol (31). These increased risks are seen only among people who carry the ALDH2 variant and drink alcohol—they are not observed in people who carry the variant but do not drink alcohol.

The plant secondary compound resveratrol, found in grapes used to make red wine and some other plants, has been investigated for many possible health effects, including cancer prevention. However, researchers have found no association between moderate consumption of red wine and the risk of developing prostate cancer (32) or colorectal cancer (33).

Most of the studies that have examined whether cancer risk declines after a person stops drinking alcohol have focused on head and neck cancers and on esophageal cancer. In general, these studies have found that stopping alcohol consumption is not associated with immediate reductions in cancer risk. The cancer risks eventually decline, although it may take years for the risks of cancer to return to those of never drinkers.

For example, ex-drinkers still had higher risks of oral cavity and pharyngeal cancers than never drinkers even 16 years after they stopped drinking alcohol, although it was lower than before they stopped drinking (34). One study estimated that it would take more than 35 years for the higher risks of laryngeal and pharyngeal cancers associated with alcohol consumption to decrease to the level of never drinkers (35).

As with most questions related to a specific individual’s cancer treatment, it is best for patients to check with their health care team about whether it is safe to drink alcohol during or immediately following chemotherapy treatment. The doctors and nurses administering the treatment will be able to give specific advice about whether it is safe to consume alcohol while undergoing specific cancer treatments.

Because underarm antiperspirants or deodorants are applied near the breast and contain potentially harmful ingredients, several scientists and others have suggested a possible connection between their use and breast cancer (1, 2). However, no scientific evidence links the use of these products to the development of breast cancer.

Aluminum-based compounds are used as the active ingredient in antiperspirants. These compounds form a temporary “plug” within the sweat duct that stops the flow of sweat to the skin’s surface. Some research suggests that aluminum-containing underarm antiperspirants, which are applied frequently and left on the skin near the breast, may be absorbed by the skin and have estrogen-like (hormonal) effects (3).

Because estrogen can promote the growth of breast cancer cells, some scientists have suggested that the aluminum-based compounds in antiperspirants may contribute to the development of breast cancer (3). In addition, it has been suggested that aluminum may have direct activity in breast tissue (4). However, no studies to date have confirmed any substantial adverse effects of aluminum that could contribute to increased breast cancer risks. A 2014 review concluded there was no clear evidence showing that the use of aluminum-containing underarm antiperspirants or cosmetics increases the risk of breast cancer (5).

Some research has focused on parabens, which are preservatives used in some deodorants and antiperspirants that have been shown to mimic the activity of estrogen in the body’s cells (6). It has been reported that parabens are found in breast tumors, but there is no evidence that they cause breast cancer. Although parabens are used in many cosmetic, food, and pharmaceutical products, most deodorants and antiperspirants in the United States do not currently contain parabens.

Only a few studies have investigated a possible relationship between breast cancer and underarm antiperspirants/deodorants. One study, published in 2002, did not show any increase in risk for breast cancer among women who reported using an underarm antiperspirant or deodorant (7). The results also showed no increase in breast cancer risk among women who reported using a blade (nonelectric) razor and an underarm antiperspirant or deodorant, or among women who reported using an underarm antiperspirant or deodorant within 1 hour of shaving with a blade razor. These conclusions were based on interviews with 813 women with breast cancer and 793 women with no history of breast cancer.

A subsequent study, published in 2006, also found no association between antiperspirant use and breast cancer risk, although it included only 54 women with breast cancer and 50 women without breast cancer (8).

A 2003 retrospective cohort study examining the frequency of underarm shaving and antiperspirant/deodorant use among 437 breast cancer survivors (2) reported younger age at breast cancer diagnosis for women who used antiperspirants/deodorants frequently or who started using them together with shaving at an earlier age. Because of the retrospective nature of the study, the results are not conclusive.

Because studies of antiperspirants and deodorants and breast cancer have provided conflicting results, additional research would be needed to determine whether a relationship exists (9).

People who are concerned about their breast cancer risk are encouraged to talk with their doctor.

Information about risk factors for breast cancer is available through NCI’s Cancer Information Service at 1–800–4–CANCER (1–800–422–6237).

At high doses, ionizing radiation can cause immediate damage to a person’s body, including, at very high doses, radiation sickness and death. At lower doses, ionizing radiation can cause health effects such as cardiovascular disease and cataracts, as well as cancer. It causes cancer primarily because it damages DNA, which can lead to cancer-causing gene mutations. 

Children and adolescents can be more sensitive to the cancer-causing effects of ionizing radiation than adults because their bodies are still growing and developing. Also, children and adolescents usually have more years of life following radiation exposure during which cancer may develop.

More information about the health effects of ionizing radiation exposure is available from the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency.

Although the time it takes for the radiation to decrease by half (the half-life) of I-131 is only 8 days, the damage it causes can increase the risk of thyroid cancer for many years after the initial exposure.

A study led by NCI researchers followed more than 12,500 people who were younger than age 18 at the time they were exposed to a range of doses of I-131 (0.65 Gy on average) from the Chernobyl accident (7). A total of 65 new cases of thyroid cancer were found in this population between 1998 and 2007. The researchers found that the higher a person’s dose of I-131, the more likely they were to get thyroid cancer (with each Gy of exposure associated with a doubling of risk). They also found that this risk remained high for at least 30 years (9).
 

Cancer patients who are being treated with systemic chemotherapy or radiation therapy should be evacuated from the area where a nuclear power plant accident has occurred so their medical treatment can continue without interruption. Patients should always keep a record of the treatments they have had in the past and that they may be currently receiving, including the names of any drugs and their doses. These records may be important in the aftermath not only of a nuclear power plant accident but also after other large-scale events that may disrupt medical services, when medical records may be lost.

Local or national authorities may also advise certain people (newborns, infants, children, adolescents, and women who are pregnant) in areas with high I-131 contamination to take potassium iodide (KI) to prevent the accumulation of I-131 in their thyroid. KI should not pose a danger to someone who previously received radiation therapy or chemotherapy. Patients who are actively being treated for cancer and who are advised to take KI should consult with their doctor before taking the medication, so their doctor can evaluate their treatment plan and their health status, including their nutritional status, to determine the safety of KI treatment for them.

Researchers at NCI and elsewhere continue to learn about the cancer risks from ionizing radiation by studying various groups of people, including those who were exposed as a result of the Chernobyl accident, survivors of the atomic bomb explosions in Japan during World War II, and people who were exposed to radiation during medical diagnostic procedures or as part of their job.

• NCI conducts much of this research through the Radiation Epidemiology Branch of the Division of Cancer Epidemiology and Genetics (DCEG). 
• DCEG researchers are carrying out a long-term study of Chernobyl survivors.
• Through DCEG and the Division of Cancer Biology, NCI supports the Chernobyl Tissue Bank, which contains samples from the Chernobyl survivors. These are being used to investigate the effects of radioactive exposure from nuclear power plant accidents.
• NCI collaborates with researchers from Japan’s Radiation Effects Research Foundation to learn about the health effects from the 1945 atomic bomb exposures in that country. This ongoing project is called the Life Span Study.
• NCI works closely with the National Institute of Allergy and Infectious Diseases to support the federal government’s Radiation and Nuclear Countermeasures Program.
• Health professionals can also find information about the medical management of exposed persons during radiation emergencies at the US Department of Health and Human Services’s Radiation Emergency Medical Management website.

Testing is the only way to know if a person’s home has elevated radon levels. Indoor radon levels are affected by the soil composition under and around the house, and the ease with which radon enters the house. Homes that are next door to each other can have different indoor radon levels, making a neighbor’s test result a poor predictor of radon risk. In addition, rain or snow, barometric pressure, and other influences can cause radon levels to vary from month to month or day to day, which is why both short- and long-term tests are available.

Short-term detectors measure radon levels for 2 days to 90 days, depending on the device. Long-term tests determine the average concentration for more than 90 days. Because radon levels can vary from day to day and month to month, a long-term test is a better indicator of the average radon level. Both tests are relatively easy to use and inexpensive. A state or local radon official can explain the differences between testing devices and recommend the most appropriate test for a person’s needs and conditions.

The U.S. Environmental Protection Agency (EPA) recommends taking action to reduce radon in homes that have a radon level at or above 4 picocuries per liter (pCi/L) of air. About 1 in 15 U.S. homes is estimated to have radon levels at or above this EPA action level. Scientists estimate that lung cancer deaths could be reduced by 2 to 4 percent, or about 5,000 deaths, by lowering radon levels in homes exceeding the EPA’s action level.

The EPA has more information about residential radon exposure and what people can do about it in the Consumer’s Guide to Radon Reduction.

Electric and magnetic fields are invisible areas of energy (also called radiation) that are produced by electricity, which is the movement of electrons, or current, through a wire.

An electric field is produced by voltage, which is the pressure used to push the electrons through the wire, much like water being pushed through a pipe. As the voltage increases, the electric field increases in strength. Electric fields are measured in volts per meter (V/m).

A magnetic field results from the flow of current through wires or electrical devices and increases in strength as the current increases. The strength of a magnetic field decreases rapidly with increasing distance from its source. Magnetic fields are measured in microteslas (μT, or millionths of a tesla).

Electric fields are produced whether or not a device is turned on, whereas magnetic fields are produced only when current is flowing, which usually requires a device to be turned on. Power lines produce magnetic fields continuously because current is always flowing through them. Electric fields are easily shielded or weakened by walls and other objects, whereas magnetic fields can pass through buildings, living things, and most other materials.

Electric and magnetic fields together are referred to as electromagnetic fields, or EMFs. The electric and magnetic forces in EMFs are caused by electromagnetic radiation. There are two main categories of EMFs:

• Higher-frequency EMFs, which include x-rays and gamma rays. These EMFs are in the ionizing radiation part of the electromagnetic spectrum and can damage DNA or cells directly.
• Low- to mid-frequency EMFs, which include static fields (electric or magnetic fields that do not vary with time), magnetic fields from electric power lines and appliances, radio waves, microwaves, infrared radiation, and visible light. These EMFs are in the non-ionizing radiation part of the electromagnetic spectrum and are not known to damage DNA or cells directly. Low- to mid-frequency EMFs include extremely low frequency EMFs (ELF-EMFs) and radiofrequency EMFs. ELF-EMFs have frequencies of up to 300 cycles per second, or hertz (Hz), and radiofrequency EMFs range from 3 kilohertz (3 kHz, or 3,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Radiofrequency radiation is measured in watts per meter squared (W/m²).

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There are both natural and human-made sources of non-ionizing EMFs. The earth’s magnetic field, which causes the needle on a compass to point North, is one example of a naturally occurring EMF.

Human-made EMFs fall into both the ELF and radiofrequency categories of non-ionizing part of the electromagnetic spectrum. These EMFs can come from a number of sources. 

Extremely low frequency EMFs (ELF-EMFs). Sources of ELF-EMFs include power lines, electrical wiring, and electrical appliances such as shavers, hair dryers, and electric blankets.

Radiofrequency radiation. The most common sources of radiofrequency radiation are wireless telecommunication devices and equipment, including cell phones, smart meters, and portable wireless devices, such as tablets and laptop computers (1). In the United States, cell phones currently operate in a frequency range of about 1.8 to 2.2 GHz (2). (For more information about cell phones, see the NCI fact sheet Cell Phones and Cancer Risk.)

Other common sources of radiofrequency radiation include:

• Radio and television signals. AM/FM radios and older VHF/UHF televisions operate at lower radiofrequencies than cell phones. Radio signals are AM (amplitude-modulated) or FM (frequency-modulated). AM radio is used for broadcasting over very long distances, whereas FM radio covers more localized areas. AM signals are transmitted from large arrays of antennas that are placed at high elevation on sites that are off limits to the general public because exposures close to the source can be high. Maintenance workers could receive substantial radiofrequency exposures from AM radio antennas, but the general public would not. FM radio antennas and TV broadcasting antennas, which are much smaller than AM antennas, are generally mounted at the top of high towers. Radiofrequency exposures near the base of these towers are below guideline limits (3), so exposure of the general population is very low. Sometimes small local radio and TV antennas are mounted on the top of a building; access to the roof of such buildings is usually controlled.
• Radar, satellite stations, magnetic resonance imaging (MRI) devices, and industrial equipment.These operate at somewhat higher radiofrequencies than cell phones (1).
• Microwave ovens used in homes, which also operate at somewhat higher radiofrequencies than cell phones (1). Microwave ovens are manufactured with effective shielding that has reduced the leakage of radiofrequency radiation from these appliances to barely detectable levels.
• Cordless telephones, which can operate on analogue or DECT (Digital Enhanced Cordless Telecommunications) technology and typically emit radiofrequencies similar to those of cell phones. However, because cordless phones have a limited range and require a nearby base, their signal strengths are generally much lower than those of cell phones (1).
• Cell phone base stations. Antenna towers or base stations, including those for mobile phone networks and for broadcasting for radio and for television, emit various types of radiofrequency energy. Because the majority of individuals in the general population are exposed only intermittently to base stations and broadcast antennas, it is difficult to estimate exposures for a population (4). The strength of these exposures varies based on the population density of the region, the average distance from the source, and the time of day or the day of the week (lower exposures on the weekends or at night) (1). A study that used using personal portable exposure meters to assess exposures to different sources of radiofrequency EMFs among children in Europe found that the single largest contributor to the total radiofrequency EMF exposure was the proximity to base stations (5).

  In general, exposures decrease with increasing distance from the source (6). Exposures among maintenance workers have been found to vary depending on their tasks, the type of antenna, and the location of the worker in relation to the source (1). Cumulative exposures of such workers are very difficult to estimate.

• Televisions and computer screens produce electric and magnetic fields at various frequencies, as well as static electric fields. The liquid crystal displays found in some laptop and desktop computers do not produce substantial electric or magnetic fields. Modern computers have conductive screens that reduce static fields produced by the screen to normal background levels.
• Wireless local area networks, commonly known as Wi-Fi. These are specific types of wireless networking systems and an increasingly common source of radiofrequency radiation. Wireless networks use radio waves to connect Wi-Fi–enabled devices to an access point that is connected to the internet, either physically or through some form of data connection. Most Wi-Fi devices operate at radiofrequencies that are broadly similar to cell phones, typically 2.4 to 2.5 GHz, although in recent years Wi-Fi devices that operate at somewhat higher frequencies (5, 5.3, or 5.8 GHz) have appeared (7). Radiofrequency radiation exposure from Wi-Fi devices is considerably lower than that from cell phones (8). Both sources emit levels of radiofrequency radiation that are far below the guideline of 10 W/m² as specified by the International Commission on Non-Ionizing Radiation Protection (3).
• Digital electric and gas meters, also known as “smart meters.” These devices, which operate at about the same radiofrequencies as cell phones, transmit information on consumption of electricity or gas to utility companies. Smart meters produce very low level fields that sometimes cannot be distinguished from the total background radiofrequency radiation levels inside a home (9).

For household appliances and other devices used in the home that require electricity, magnetic field levels are highest near the source of the field and decrease rapidly the farther away the user is from the source. Magnetic fields drop precipitously at a distance of about 1 foot from most appliances. For computer screens, at a distance of 12–20 inches from the screen that most persons using computers sit, magnetic fields are similarly dramatically lower.

Power lines and electrical appliances that emit non-ionizing EMFs are present everywhere in homes and workplaces. For example, wireless local networks are nearly always “on” and are increasingly commonplace in homes, schools, and many public places.

No mechanism by which ELF-EMFs or radiofrequency radiation could cause cancer has been identified. Unlike high-energy (ionizing) radiation, EMFs in the non-ionizing part of the electromagnetic spectrum cannot damage DNA or cells directly. Some scientists have speculated that ELF-EMFs could cause cancer through other mechanisms, such as by reducing levels of the hormone melatonin. There is some evidence that melatonin may suppress the development of certain tumors.

Studies of animals have not provided any indications that exposure to ELF-EMFs is associated with cancer (10–13). The few high-quality studies in animals have provided no evidence that Wi-Fi is harmful to health (8).

Although there is no known mechanism by which non-ionizing EMFs could damage DNA and cause cancer, even a small increase in risk would be of clinical importance given how widespread exposure to these fields is.

Numerous epidemiologic studies and comprehensive reviews of the scientific literature have evaluated possible associations between exposure to non-ionizing EMFs and risk of cancer in children (13–15). (Magnetic fields are the component of non-ionizing EMFs that are usually studied in relation to their possible health effects.) Most of the research has focused on leukemia and brain tumors, the two most common cancers in children. Studies have examined associations of these cancers with living near power lines, with magnetic fields in the home, and with exposure of parents to high levels of magnetic fields in the workplace. No consistent evidence for an association between any source of non-ionizing EMF and cancer has been found.

Exposure from power lines. Although a study in 1979 pointed to a possible association between living near electric power lines and childhood leukemia (16), more recent studies have had mixed findings (17–25). Most of these studies did not find an association or found one only for those children who lived in homes with very high levels of magnetic fields, which are present in few residences.

Several studies have analyzed the combined data from multiple studies of power line exposure and childhood leukemia:

• A pooled analysis of nine studies reported a twofold increase in risk of childhood leukemia among children with exposures of 0.4 μT or higher. Less than 1% of the children in the studies experienced this level of exposure (26).
• A meta-analysis of 15 studies observed a 1.7-fold increase in childhood leukemia among children with exposures of 0.3 μT or higher. A little more than 3% of children in the studies experienced this level of exposure (27).
• More recently, a pooled analysis of seven studies published after 2000 reported a 1.4-fold increase in childhood leukemia among children with exposures of 0.3 μT or higher. However, less than one half of 1% of the children in the studies experienced this level of exposure (28). 

For the two pooled studies and the meta-analysis, the number of highly exposed children was too small to provide stable estimates of the dose–response relationship. This means that the findings could be interpreted to reflect linear increases in risk, a threshold effect at 0.3 or 0.4 μT, or no significant increase.

The interpretation of the finding of increased childhood leukemia risk among children with the highest exposures (at least 0.3 μT) is unclear.

Exposure from electrical appliances. Another way that children can be exposed to magnetic fields is from household electrical appliances. Although magnetic fields near many electrical appliances are higher than those near power lines, appliances contribute less to a person’s total exposure to magnetic fields because most appliances are used for only short periods of time. And moving even a short distance from most electrical appliances reduces exposure dramatically. Again, studies have not found consistent evidence for an association between the use of household electrical appliances and risk of childhood leukemia (29).

Exposure to Wi-Fi. In view of the widespread use of Wi-Fi in schools, the UK Health Protection Agency (now part of Public Health England) has conducted the largest and most comprehensive measurement studies to assess exposures of children to radiofrequency electromagnetic fields from wireless computer networks (30, 31). This agency concluded that radiofrequency exposures were well below recommended maximum levels and that there was “no reason why Wi-Fi should not continue to be used in schools and in other places” (32). 

A review of the published literature concluded that the few high-quality studies to date provide no evidence of biological effects from Wi-Fi exposures (7).

Exposure from cell phone base stations. Few studies have examined cancer risk in children living close to cell phone base stations or radio or television transmitters. Mobile phone base stations transmit and receive radiofrequency signals to and from mobile phones near the station. None of the studies that estimated exposures on an individual level found an increased risk of pediatric tumors (33–35). 

Parental exposure and risk in offspring. Several studies have examined possible associations between maternal or paternal exposure to high levels of magnetic fields before conception and/or during pregnancy and the risk of cancer in their future children. The results to date have been inconsistent (36, 37). This question requires further evaluation.

Exposure and cancer survival. A few studies have investigated whether magnetic field exposure is associated with prognosis or survival of children with leukemia. Several small retrospective studies of this question have yielded inconsistent results (38–40). An analysis that combined prospective data for more than 3,000 children with acute lymphoid leukemia from eight countries showed that ELF magnetic field exposure was not associated with their survival or risk of relapse (41).

Many studies have examined the association between non-ionizing EMF exposure and cancer in adults, of which few studies have reported evidence of increased risk (1).

Residential exposures. The majority of epidemiologic studies have shown no relationship between breast cancer in women and exposure to extremely low frequency EMFs (ELF-EMFs) in the home (42–45), although a few individual studies have suggested an association; only one reported results that were statistically significant (46).

Workplace exposures to ELF radiation. Several studies conducted in the 1980s and early 1990s reported that people who worked in some electrical occupations that exposed them to ELF radiation (such as power station operators and telephone line workers) had higher-than-expected rates of some types of cancer, particularly leukemia, brain tumors, and male breast cancer (13). Most of the results were based on participants’ job titles and not on actual measurements of their exposures.  More recent studies, including some that considered exposure measurements as well as job titles, have generally not shown an increasing risk of leukemia, brain tumors, or female breast cancer with increasing exposure to magnetic fields at work (46–51).

Workplace exposures to radiofrequency radiation. A limited number of studies have evaluated risks of cancer in workers exposed to radiofrequency radiation. A large study of U.S. Navy personnel found no excess of brain tumors among those with a high probability of exposure to radar (including electronics technicians, aviation technicians, and fire control technicians); however, nonlymphocytic leukemia, particularly acute myeloid leukemia, was increased in electronics technicians in aviation squadrons, but not in Navy personnel in the other job categories (52). A case–control study among U.S. Air Force personnel found the suggestion of an increased risk of brain cancer among personnel who maintained or repaired radiofrequency or microwave-emitting equipment (53). A case–control study found the suggestion of an increased risk of death from brain cancer among men occupationally exposed to microwave and/or radiofrequency radiation, with all of the excess risk among workers in electrical and electronics jobs involving design, manufacture, repair, or installation of electrical or electronics equipment (54). There was no evidence that electrical utility workers who were exposed to pulsed electromagnetic fields produced by power lines were more likely to develop brain tumors or leukemia than the general population (55). Employees of a large manufacturer of wireless communication products were not more likely to die from brain tumors or cancers of the hematopoietic or lymphatic system than the general population (56). A large prospective study among police officers in Great Britain found no evidence for an association between radiofrequency EMF exposure from personal radio use and the risk of all cancers combined (57). A large multinational population-based case–control study found no clear evidence that occupational exposures to radiofrequency radiation are associated with increased risks of glioma or meningioma (58).

In 2002, the International Agency for Research on Cancer (IARC), a component of the World Health Organization, appointed an expert Working Group to review all available evidence on static and extremely low frequency electric and magnetic fields (13). The Working Group classified ELF-EMFs as “possibly carcinogenic to humans,” based on limited evidence from human studies in relation to childhood leukemia. Static electric and magnetic fields and extremely low frequency electric fields were determined “not classifiable as to their carcinogenicity to humans” (13).

In 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks reviewed electromagnetic fields in general, as well as cell phones in particular. It found that, overall, epidemiologic studies of extremely low frequency fields show an increased risk of childhood leukemia with estimated daily average exposures above 0.3 to 0.4 μT, although no mechanisms have been identified and there is no support from experimental studies that explains these findings. It also found that the epidemiologic studies on radiofrequency exposure do not show an increased risk of brain tumors or other cancers of the head and neck region, although the possibility of an association with acoustic neuroma remains open (59).

The National Institute of Environmental Health Sciences (NIEHS) website has information about EMFs and cancer.

The Occupational Safety and Health Administration website has information about workplace exposures to ELF-EMF.

The US Environmental Protection Agency website has information on power lines and other sources of EMF.

The European Commission also has general information on EMF.

The World Health Organization website also has information on EMF.

There are two main reasons why people are concerned that cell (or mobile) phones might have the potential to cause certain types of cancer or other health problems: Cell phones emit radiation (in the form of radiofrequency radiation, or radio waves), and cell phone use is widespread. Even a small increase in cancer risk from cell phones would be of concern given how many people use them.

Brain and central nervous system cancers have been of particular concern because hand-held phones are used close to the head and because ionizing radiation—a higher energy form of radiation than what cell phones emit—has been found to cause some brain cancers. Many different kinds of studies have been carried out to try to investigate whether cell phone use is dangerous to human health.

However, the evidence to date suggests that cell phone use does not cause brain or other kinds of cancer in humans.

Cell phones emit radiation in the radiofrequency region of the electromagnetic spectrum. Second-, third-, and fourth-generation cell phones (2G, 3G, 4G) emit radiofrequency in the frequency range of 0.7–2.7 GHz. Fifth-generation (5G) cell phones are anticipated to use the frequency spectrum up to 80 GHz. 

These frequencies all fall in the nonionizing range of the spectrum, which is low frequency and low energy. The energy is too low to damage DNA. By contrast, ionizing radiation, which includes x-rays, radon, and cosmic rays, is high frequency and high energy. Energy from ionizing radiation can damage DNA. DNA damage can cause changes to genes that may increase the risk of cancer.

The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation. More information about ionizing radiation can be found on the Radiation page.

The human body does absorb energy from devices that emit radiofrequency radiation. The only consistently recognized biological effect of radiofrequency radiation absorption in humans that the general public might encounter is heating to the area of the body where a cell phone is held (e.g., the ear and head). However, that heating is not sufficient to measurably increase core body temperature. There are no other clearly established dangerous health effects on the human body from radiofrequency radiation.

No. Investigators have studied whether the incidence of brain or other central nervous system cancers (that is, the number of new cases of these cancers diagnosed each year) has changed during the time that cell phone use increased dramatically. These studies found:

• stable incidence rates for adult gliomas in the United States (1), Nordic countries (2) and Australia (3) during the past several decades
• stable incidence rates for pediatric brain tumors in the United States during 1993–2013 (4)
• stable incidence rates for acoustic neuroma (5), which are nonmalignant tumors, and meningioma (6), which are usually nonmalignant, among US adults since 2009 

In addition, studies using cancer incidence data have tested different scenarios (simulations) determining whether the incidence trends are in line with various levels of risk as reported in studies of cell phone use and brain tumors between 1979 and 2008 (7, 8). These simulations showed that many risk changes reported in case–control studies were not consistent with incidence data, implying that biases and errors in the study may have distorted the findings.

Because these studies examine cancer incidence trends over time in populations rather than comparing risk in people who do and don’t use cell phones, their ability to observe potential small differences in risk among heavy users or susceptible populations is limited. Observational/epidemiologic studies—including case–control and cohort studies (described below)—are designed to measure individual exposure to cell phone radiation and ascertain specific health outcomes.

Epidemiologic studies use information from several sources, including questionnaires and data from cell phone service providers, to estimate radiofrequency radiation exposure in groups of people. Direct measurements are not yet possible outside of a laboratory setting. Estimates from studies reported to date take into account the following:

• How regularly study participants use cell phones (the number of calls per week or month)
• The age and the year when study participants first used a cell phone and the age and the year of last use (allows calculation of the duration of use and time since the start of use)
• The average number of cell phone calls per day, week, or month (frequency)
• The average length of a typical cell phone call
• The total hours of lifetime use, calculated from the length of typical call times, the frequency of use, and the duration of use

Researchers have carried out several types of population studies to investigate the possibility of a relationship between cell phone use and the risk of tumors, both malignant (cancerous) and nonmalignant (not cancer). Epidemiologic studies (also called observational studies) are research studies in which investigators observe groups of individuals (populations) and collect information about them but do not try to change anything about the groups. 

Two main types of epidemiologic studies—cohort studies and case–control studies—have been used to examine associations between cell phone use and cancer risk. In a case–control study, cell phone use is compared between people who have tumors and people who don’t. In a cohort study, a large group of people who do not have cancer at the beginning of the study is followed over time and tumor development in people who did and didn’t use cell phones is compared. Cohort studies are limited by the fact that they may only be able to look at cell phone subscribers, who are not necessarily the cell phone users.

The tumors that have been investigated in epidemiologic studies include malignant brain tumors, such as gliomas, as well as nonmalignant tumors, such as acoustic neuroma (tumors in the cells of the nerve responsible for hearing that are also known as vestibular schwannomas), meningiomas (usually nonmalignant tumors in the membranes that cover and protect the brain and spinal cord), parotid gland tumors (tumors in the salivary glands), skin cancer, and thyroid gland tumors.

Four large epidemiologic studies have examined the possible association between cell phone use and cancer: Interphone, a case–control study, and three cohort studies, the Danish Study, the Million Women Study, and the Cohort Study on Mobile Phones and Health (COSMOS). The findings of these studies are mixed, but overall, they do not show an association between cell phone use and cancer (9–23).

Interphone Case–Control Study

How the study was done: This is the largest case–control study of cell phone use and the risk of head and neck tumors. It was conducted by a consortium of researchers from 13 countries. The data came from questionnaires that were completed by study participants in Europe, Israel, Canada, Australia, New Zealand, and Japan.

What the study showed: Most published analyses from this study have shown no increases overall in brain or other central nervous system cancers (glioma and meningioma) related to higher amounts of cell phone use. One analysis showed a statistically significant, although small, increase in the risk of glioma among study participants who spent the most total time on cell phone calls. However, for a variety of reasons the researchers considered this finding inconclusive (11–13).

An analysis of data from all 13 countries reported a statistically significant association between intracranial distribution of tumors within the brain and self-reported location of the phone (14). However, the authors of this study noted that it is not possible to draw firm conclusions about cause and effect based on their findings.

An analysis of data from five Northern European countries showed an increased risk of acoustic neuroma in those who had used a cell phone for 10 or more years (15). 

In subsequent analyses of Interphone data, investigators investigated whether tumors were more likely to form in areas of the brain with the highest exposure. One analysis showed no relationship between tumor location and level of radiation (16). However, another found evidence that glioma and, to a lesser extent, meningioma were more likely to develop where exposure was highest (17).

Danish Cohort Study

How the study was done: This cohort study linked billing information from more than 358,000 cell phone subscribers with brain tumor incidence data from the Danish Cancer Registry.

What the study showed: No association was observed 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 (18–20).

Million Women Cohort Study

How the study was done: This prospective cohort study conducted in the United Kingdom used data obtained from questionnaires that were completed by study participants.

What the study showed: Self-reported cell phone use was not associated with an increased risk of glioma, meningioma, or non-central nervous system tumors. Although the original published findings reported an association with an increased risk of acoustic neuroma (21), it was not observed with additional years of follow-up of the cohort (22).

Cohort Study of Mobile Phones and Health (COSMOS)

How the study was done: This large prospective cohort study conducted in Denmark, Finland, Sweden, the Netherlands, and the United Kingdom used data on health, lifestyle, and current and past cell phone use obtained from a questionnaire completed by participants when they joined the study. That information was supplemented with cancer occurrence data obtained from linkage to national cancer registries and cell phone records obtained from mobile network operators. 

What the study showed: Among 264,574 participants with a median follow-up of just over 7 years, the cumulative amount of mobile phone call-time was not associated with the risk of developing glioma, meningioma, or acoustic neuroma (23). No associations with cancer risk were seen in the heaviest mobile phone users or among among those with the longest history of mobile phone use (15 or more years).

Other Epidemiologic Studies

In addition to these four large studies, other, smaller epidemiologic studies have looked for associations between cell phone use and individual cancers in both adults and children. These include:

• Two NCI-sponsored case–control studies, each conducted in multiple US academic medical centers or hospitals between 1994 and 1998 that used data from questionnaires (24) or computer-assisted personal interviews (25). Neither study showed a relationship between cell phone use and the risk of glioma, meningioma, or acoustic neuroma in adults.
• The CERENAT study, another case–control study conducted in multiple areas in France from 2004 to 2006 using data collected in face-to-face interviews using standardized questionnaires (26). This study found no association for either gliomas or meningiomas when comparing adults who were regular cell phone users with non-users. However, the heaviest users had significantly increased risks of both gliomas and meningiomas.
• A pooled analysis of two case–control studies conducted in Sweden that reported 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 (27).
• Another case–control study in Sweden, part of the Interphone pooled studies, did not find an increased risk of brain cancer among long-term cell phone users between the ages of 20 and 69 (28).
• The CEFALO study, an international case–control study of children diagnosed with brain cancer between ages 7 and 19, found no relationship between their cell phone use and risk for brain cancer (29).
• The MOBI-Kids study, a large international case–control study of young people ages 10 to 24 years diagnosed with brain tumors, found no evidence of an association between wireless phone use and the risk of brain tumors (30). 
• A population-based case–control study conducted in Connecticut found no association between cell phone use and the risk of thyroid cancer (31).

Researchers have carried out several kinds of studies to investigate possible effects of cell phone use on the human body. In 2011, two small studies were published that examined brain glucose metabolism in people after they had used cell phones. The results were inconsistent. One study showed increased glucose metabolism in the region of the brain close to the antenna compared with tissues on the opposite side of the brain (32); the other study (33) found reduced glucose metabolism on the side of the brain where the phone was used.

The authors of these studies noted that the results were preliminary and that possible health outcomes from changes in glucose metabolism in humans were unknown. Such inconsistent findings are not uncommon in experimental studies of the physiological effects of radiofrequency electromagnetic radiation in people (11). Some factors that can contribute to inconsistencies across such studies include assumptions used to estimate doses, failure to consider temperature effects, and investigators not being blinded to exposure status.

Another study investigated blood flow in the brain of people exposed to radiofrequency radiation from cell phones and found no evidence of an effect on blood flow in the brain (34).

Early studies involving laboratory animals showed no evidence that radiofrequency radiation increased cancer risk or enhanced the cancer-causing effects of known chemical carcinogens (35–38).

Because of inconsistent findings from epidemiologic studies in humans and the lack of clear data from previous experimental studies in animals, in 1999 the Food and Drug Administration (FDA) nominated radiofrequency radiation exposure associated with cell phone exposures for study in animal models by the US National Toxicology Program (NTP). NTP is an interagency program that coordinates toxicology research and testing across the US Department of Health and Human Services and is headquartered at the National Institute of Environmental Health Sciences, part of NIH.

The NTP studied radiofrequency radiation (2G and 3G frequencies) in rats and mice (39, 40). This large project was conducted in highly specialized labs. The rodents experienced whole-body exposures of 3, 6, or 9 watts per kilogram of body weight for 5 or 7 days per week for 18 hours per day in cycles of 10 minutes on, 10 minutes off. A research overview of the rodent studies, with links to the peer-review summary, is available on the NTP website. The primary outcomes observed were a small number of cancers of Schwann cells in the heart and non-cancerous changes (hyperplasia) in the same tissues for male rats, but not female rats, nor in mice overall.

These experimental findings raise new questions because cancers in the heart are extremely rare in humans. Schwann cells of the heart in rodents are similar to the kind of cells in humans that give rise to acoustic neuromas (also known as vestibular schwannomas), which some studies have suggested are increased in people who reported the heaviest use of cell phones. The NTP plans to continue to study radiofrequency exposure in animal models to provide insights into the biological changes that might explain the outcomes observed in their study.

Another animal study, in which rats were exposed 7 days per week for 19 hours per day to radiofrequency radiation at 0.001, 0.03, and 0.1 watts per kilogram of body weight was reported by investigators at the Italian Ramazzini Institute (41). Among the rats with the highest exposure levels, the researchers noted an increase in heart schwannomas in male rats and nonmalignant Schwann cell growth in the heart in male and female rats. However, key details necessary for interpretation of the results were missing: exposure methods, other standard operating procedures, and nutritional/feeding aspects. The gaps in the report from the study raise questions that have not been resolved.

ICNIRP (an independent nonprofit organization that provides scientific advice and guidance on the health and environmental effects of nonionizing radiation) critically evaluated both studies. It concluded that both followed good laboratory practice, including using more animals than earlier research and exposing the animals to radiofrequency radiation throughout their lifetimes. However, it also identified what it considered major weaknesses in how the studies were conducted and statistically analyzed and concluded that these limitations prevent drawing conclusions about the ability of radiofrequency exposures to cause cancer (42).

A few studies have shown some evidence of statistical association of cell phone use and brain tumor risks in humans, but most studies have found no association. Reasons for these discrepancies include the following:

• Recall bias, which can occur when data about prior habits and exposures are collected from study participants using questionnaires administered after diagnosis of a disease in some of the participants. Study participants who have brain tumors, for example, may remember their cell phone use differently from individuals without brain tumors.
• Inaccurate reporting, which can happen when people say that something has happened more often or less often than it actually did. For example, people may not remember how much they used cell phones in a given time period.
• Morbidity and mortality among study participants who have brain cancer. Gliomas are particularly difficult to study because of their high death rate and the short survival of people who develop these tumors. Patients who survive initial treatment are often impaired, which may affect their responses to questions.
• Participation bias, which can happen when people who are diagnosed with brain tumors are more likely than healthy people (known as controls) to enroll in a research study.
• Changing technology. Older studies evaluated radiofrequency radiation exposure from analog cell phones. Today, cell phones use digital technology, which operates at a different frequency and a lower power level than analog phones, and cellular technology continues to change (43). 
• Exposure assessment limitations. Different studies measure exposure differently, which makes it difficult to compare the results of different studies (44). Investigations of sources and levels of exposure, particularly in children, are ongoing (45).
• Insufficient follow-up of highly exposed populations. It may take a very long time to develop symptoms after exposure to radiofrequency radiation, and current studies may not yet have followed participants long enough.
• Inadequate statistical power and methods to detect very small risks or risks that affect small subgroups of people specifically 
• Chance as an explanation of apparent effects may not have been considered.

The most consistent health risk associated with cell phone use is distracted driving and vehicle accidents (46, 47). Several other potential health effects have been reported with cell phone use. Neurologic effects are of particular concern in young persons. However, studies of memory, learning, and cognitive function have generally produced inconsistent results (48–51).

In 2011, the International Agency for Research on Cancer (IARC), a component of the World Health Organization, appointed an expert working group to review all available evidence on the use of cell phones. The working group classified cell phone use as “possibly carcinogenic to humans,” based on limited evidence from human studies, limited evidence from studies of radiofrequency radiation and cancer in rodents, and inconsistent evidence from mechanistic studies (11).

The working group indicated that, although the human studies were susceptible to bias, the findings could not be dismissed as reflecting bias alone, and that a causal interpretation could not be excluded. The working group noted that any interpretation of the evidence should also consider that the observed associations could reflect chance, bias, or confounding variables rather than an underlying causal effect. In addition, the working group stated that the investigation of brain cancer risk associated with cell phone use poses complex research challenges.

The American Cancer Society’s cell phones page states “It is not clear at this time that RF (radiofrequency) waves from cell phones cause dangerous health effects in people, but studies now being done should give a clearer picture of the possible health effects in the future.” 

The National Institute of Environmental Health Sciences (NIEHS) states that the weight of the current scientific evidence has not conclusively linked cell phone use with any adverse health problems, but more research is needed.

The US Food and Drug Administration (FDA) notes that studies reporting biological changes associated with radiofrequency radiation have failed to be replicated and that the majority of human epidemiologic studies have failed to show a relationship between exposure to radiofrequency radiation from cell phones and health problems. FDA, which originally nominated this exposure for review by the NTP in 1999, issued a statement on the draft NTP reports released in February 2018, saying “based on this current information, we believe the current safety limits for cell phones are acceptable for protecting the public health.” FDA and the Federal Communications Commission (FCC) share responsibility for regulating cell phone technologies.

The US Centers for Disease Control and Prevention (CDC) states that no scientific evidence definitively answers whether cell phone use causes cancer.

The Federal Communications Commission (FCC) concludes that currently no scientific evidence establishes a definite link between wireless device use and cancer or other illnesses.

In 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks concluded that, overall, the epidemiologic studies on cell phone radiofrequency electromagnetic radiation exposure do not show an increased risk of brain tumors or of other cancers of the head and neck region (9). The committee also stated that epidemiologic studies do not indicate increased risk for other malignant diseases, including childhood cancer (9).

There are theoretical considerations as to why the potential health effects of cell phone use should be investigated separately in children. Their nervous systems are still developing and, therefore, more vulnerable to factors that may cause cancer. Their heads are smaller than those of adults and consequently have a greater proportional exposure to radiation emitted by cell phones. And, children have the potential of accumulating more years of cell phone exposure than adults.

Thus far, the data from studies of children with cancer do not suggest that children are at increased risk of developing cancer from cell phone use. The first published analysis came from a large case–control study called CEFALO, which was conducted in Europe. The study included 352 children who were diagnosed with brain tumors between 2004 and 2008 at the ages of 7 to 19 years. They were matched by age, sex, and geographical region with 646 young people randomly selected from population registries. Researchers did not find an association between cell phone use and brain tumor risk by amount of use or by the location of the tumor (29).

The largest case–control study among children, a 14-country study known as MOBI-Kids, included 899 young people ages 10 to 24 years who were diagnosed with brain tumors between 2010 and 2015. They were matched by sex, age, and region with 1,910 young people who were undergoing surgery for appendicitis. Researchers found no evidence of an association between wireless phone use and brain tumors in young people (30).

The National Institutes of Health (NIH), including the National Cancer Institute (NCI), conducts research on cell phone use and the risks of cancer and other diseases.

FDA and FCC share regulatory responsibilities for cell phones. FDA is responsible for testing and evaluating electronic product radiation and providing information for the public about the radiofrequency energy emitted by cell phones. FCC sets limits on the emissions of radiofrequency energy by cell phones and similar wireless products.

The dose of the energy that people absorb from any source of radiation is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight (52). The SAR decreases very quickly as the distance to the exposure source increases. For cell phone users who hold their phones next to their head during voice calls, the highest exposure is to the brain, acoustic nerve, salivary gland, and thyroid.

The FCC provides information about the SAR of cell phones produced and marketed within the previous 1 to 2 years. 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. SARs for older phones can be found by checking the phone settings or by contacting the manufacturer.

FDA has suggested some steps that concerned cell phone users can take to reduce their exposure to radiofrequency radiation:

• Reduce the amount of time spent using your cell phone.
• Use speaker mode, head phones, or ear buds to place more distance between your head and the cell phone.
• Avoid making calls when the signal is weak as this causes cell phones to boost RF transmission power.
• Consider texting rather than talking, but don’t text while you are driving. 

Use of wired or wireless headsets reduces the amount of radiofrequency radiation exposure to the head because the phone is not placed against the head (53). Exposures decline dramatically when cell phones are used hands-free. For example, wireless (Bluetooth) devices (such as headphones and earbuds) use short-range signals that typically transmit radiofrequency waves at power levels 10–400 times lower than cell phones (54).