Power Lines, Electrical Devices, and Extremely Low Frequency Radiation

The electromagnetic spectrum

Types of radiation are often described by how much energy their particles (photons) carry. Radiation exists along a range from very low-energy (low-frequency) radiation to very high-energy (high-frequency) radiation. This range is called the electromagnetic spectrum.

Examples of high-energy radiation include x-rays and gamma rays, as well as some higher energy ultraviolet (UV) rays. These are forms of ionizing radiation, which have enough energy to remove an electron from (ionize) an atom. This can damage the DNA (genes) inside cells, which can sometimes lead to cancer.

What is extremely low frequency (ELF) radiation?

ELF radiation is at the low-energy end of the electromagnetic spectrum and is a type of non-ionizing radiation. Non-ionizing radiation doesn’t have enough energy to directly damage DNA. ELF radiation has even lower energy than other types of non-ionizing radiation, such as radiofrequency radiation and infrared and visible light.

ELF radiation doesn’t damage the DNA in cells the way ionizing radiation does. It is largely thought to be safe. However, experts are studying ELF to see if it could somehow affect cancer risk in other ways.

Electric and magnetic fields

Electromagnetic radiation is made of 2 parts:

• Electric fields are the forces acting on charged particles (parts of atoms), such as electrons or protons, which cause them to move. Electric current is the flow of electrons produced by an electric field.
• A magnetic field is created when charged particles are in motion.

With most types of radiation, the electric and magnetic fields are paired. Because they act as one, they are looked at together as an electromagnetic field (EMF). But with ELF radiation, the magnetic field can exist and act alone, as can the electric field, and the two are often studied separately.

The possible link between EMFs and cancer has been a subject of debate for several decades. It's not clear exactly how non-ionizing EMFs could increase cancer risk. Plus, people are all exposed to different amounts of these fields at different times, so the issue has been hard to study.

Do power lines and other sources of ELF radiation cause cancer?

Concerns that ELF radiation from power lines and other sources might cause health problems, including cancer, have been around for many years.

What expert agencies say

Several national and international agencies study different exposures in the environment to determine if they are carcinogenic. In general, the American Cancer Society (ACS) does not determine whether something should be considered a carcinogen (something that can cause cancer). Instead, ACS looks to other respected organizations for help with this.

Based on animal and human evidence, some expert agencies have evaluated the potential cancer-causing nature of ELF radiation.

• The International Agency for Research on Cancer (IARC)  is part of the World Health Organization (WHO). One of its major goals is to identify causes of cancer. It considers the evidence for ELF magnetic and electric fields separately. IARC has classified ELF magnetic fields as “possibly carcinogenic to humans.” It has classified ELF electric fields as “not classifiable as to their carcinogenicity to humans.”
• The US National Institute of Environmental Health Sciences (NIEHS) describes the scientific evidence suggesting that ELF exposure poses a health risk as “weak”. But the agency notes that ELF can’t be recognized as entirely safe and considers it to be a “possible” human carcinogen.
• The European research group Advanced Research on Interaction Mechanisms of electroMagnetic exposures with Organisms for Risk Assessment (ARIMMORA) has concluded that their studies were consistent with the previously established IARC classification of ELF magnetic fields as “possibly carcinogenic.”

What studies show

Researchers use 2 main types of studies to try to figure out if something causes cancer.

• Lab studies are done using lab animals or cells in lab dishes.
• Studies in people look for patterns over time.

Often, neither type of study provides enough evidence on its own. Experts usually look at both types of studies when trying to figure out if something can cause cancer.

Studies in the lab

Studies have looked at the possible effects of ELF magnetic fields (ELF-MF) on cancer in rats and mice. These studies exposed the animals to magnetic fields much stronger than what people are normally exposed to. Most of these studies have found no increase in the risk of any type of cancer.

One study did show an increased risk of tumors that start in thyroid cells, called C-cells, in male rats at some exposures. This increased risk was not seen in female rats or in mice and was not seen at the highest field strength. These inconsistencies, and the fact that these findings were not seen in the other studies, make it hard for scientists to conclude that the observed increased risk of tumors is from ELF radiation.

Other studies in mice and rats have looked specifically for increases in leukemia and lymphoma as a result of exposure to ELF radiation. Mixed results have been seen. One study noted a small increase in mice getting leukemia, but not rats.

Although there is no clear link between ELF-MF and cancer in animal studies, some evidence from animal and cell-based research shows that ELF-MF may affect living organisms in some ways. For example:

• Some studies suggest that at certain levels of exposure, ELF-MF may affect how information from genes is used for cellular processes.
• Some studies have noted that ELF-MF might stress cells, which could lead to the creation of reactive oxygen species inside the cells.

Results from different studies looking at these ideas have been inconsistent. And many studies have not found that ELF has any biological impact.

Studies in people

Studying the effects of ELF radiation in people can be hard, for many reasons.

Exposure to ELF radiation is very common, so it’s not possible to compare people who have been exposed and those who have not. Instead, studies try to compare people exposed to higher levels versus lower levels.

It is hard to determine how much ELF radiation a person has been exposed to, especially over a long period. The effects of ELF radiation aren’t thought to add up over time. And there is no test that can measure how much exposure a person has had.

Researchers can get a snapshot of ELF exposures in different ways, but none of these are perfect. They can:

• Have a person wear a device that records their exposure levels over hours or days
• Measure the magnetic or electrical field strength in a person’s home or workplace settings
• Estimate exposure based on the wiring configuration of someone’s workplace or home
• Estimate exposure based on how far someone’s home or workplace is from power lines

All these methods, however, result in exposure estimates with a lot of uncertainty. They usually don't account for a person’s ELF exposures while in other places. They also don’t measure ELF exposures in every location where a person has ever lived or worked over their lifetime.

There’s no good way to accurately estimate someone’s long-term exposure, which is most important when looking for possible effects on cancer risk.

Some studies have looked at possible links between ELF exposures in adults and cancer. Most have not found a link, although a small number have suggested a possible link.

Studies in children

• Some studies have looked at a possible link between ELF radiation from magnetic fields in the home and the risk of childhood leukemia. Past studies have had mixed results. A more recent study found no increased risk of leukemia and that the link between leukemia and magnetic fields has declined over time.
• Studies looking at the effect of ELF electric fields on childhood leukemia risk have not found a link.
• Studies evaluating the risk of childhood brain tumors and ELF magnetic fields have mixed results.
• Studies have generally not found any strong links between ELF electric or magnetic fields and other types of childhood cancers.

How are people exposed to ELF radiation?

Generating, transmitting, distributing, and using electricity all expose people to ELF radiation, which can come from power lines, household wiring, or any electrical device. This can include anything from refrigerators and vacuum cleaners to televisions and computer monitors (when they are on). Even electric blankets expose people to ELF radiation.

How much electromagnetic radiation you are exposed to depends on:

• The strength of the EMF
• Your distance from the source of the field
• The length of time you are exposed

The highest exposure occurs when a person is very close to a source putting out a strong field and stays there for a long time.

Can I avoid or limit my exposure to ELF radiation?

It’s not clear that exposure to ELF radiation is harmful. And it’s not possible to avoid all exposure to EMFs. But there are things you can do to lower your exposure if you are concerned.

The NIEHS recommends that people who are concerned about their exposure to EMF and ELF radiation:

• Find out where their major EMF sources are
• Move away from them or limit the time spent near them.

For example, moving even an arm’s length away from a source can dramatically lower exposure to its field.

Power lines

People who are concerned about ELF radiation exposure from high-power electrical lines should keep in mind that the intensity of any exposure goes down notably as you get farther away from the source. On the ground, the strength of the electromagnetic field is highest directly under the power line. As you get farther away, you are exposed to less and less, with the level eventually matching normal home background levels. The electromagnetic field directly under a power line is typically in the range of what you could be exposed to when using certain household appliances.

If you are concerned about your exposure to electromagnetic sources around you (including power lines), you can measure the field strength with a device called a gaussmeter.

To learn more  

The following organizations may offer helpful information.

Environmental Protection Agency (EPA)
Website: www.epa.gov

National Cancer Institute (NCI)
Toll-free number: 1-800-422-6237 (1-800-4-CANCER)
Website: www.cancer.gov

Electromagnetic Fields and Cancer: www.cancer.gov/about-cancer/causes-prevention/risk/radiation/electromagnetic-fields-fact-sheet