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Why men and women with breast cancer should avoid ELFs

By Magda Havas, BSc, PhD

The ELFs in the title do not refer to little green men but rather to extremely low frequency (ELF) electromagnetic fields that are produced when we use electricity.

In 2001, the International Agency for Research on Cancer (IARC) classified low frequency electromagnetic fields as a possible human carcinogen. They based this classification primarily on studies showing that children who lived near power lines had a greater risk of developing leukemia.

However, if you look at the scientific literature, the evidence that ELF fields contribute to breast cancer is much more powerful and convincing than it is for childhood leukemia. For that reason it is important that all people avoid these fields, particularly those with a family history of breast cancer or those recovering from breast cancer.

What does the science show?

Occupational Epidemiological Studies: Scientific studies document a higher rate of breast cancer among both males and females who are occupationally exposed to high electromagnetic fields. This includes electric utility trades, railway workers, engine drivers, welders, as well as telephone installers, repairers, and line workers and possibly textile workers who use industrial sewing machines. The longer the exposure, the greater the risk. The risk seems to be greater for people who are premenopausal and for those with estrogen receptor-positive breast cancer.

In Vitro Studies: Studies with human breast cancer cells (MCF-7) exposed to magnetic fields showed that these cells grew faster when exposed to 12 mG (strength of the magnetic field) than when exposed to 2 mG. Normal physiological concentrations of melatonin reduced the cancer growth, but therapeutic levels of tamoxifen were not nearly as effective when the cells were exposed to the magnetic field.

In Vivo Studies: Studies with laboratory rats showed that fields from 1 to 1000 mG resulted in a greater incidence of tumors, more tumors, larger tumors and a shorter latency period. Interestingly higher magnetic fields (1000 to 5000 mG) showed a beneficial effect indicating that mammary tumors in rats may be sensitive to high magnetic fields just as they are sensitive to ionizing radiation.

What is the mechanism?

The estrogen-melatonin-EMF link has been described by others (see review by Havas 2000) and is a plausible explanation of the mechanism involved. For estrogen receptor-positive breast cancer cells, estrogen is like a fuel that promotes cell growth. One of the concerns for postmenopausal people taking estrogen supplements is that the estrogen may stimulate proliferation of pre-existing breast cancer cells.

When melatonin levels in the body are low, estrogen levels are elevated and this can stimulate breast cancer growth. Light and low frequency EMFs can reduce the melatonin production in the body and that is why light-at-night should also be avoided by those who have estrogen receptor-positive breast cancer. Melatonin is a powerful antioxidant that inhibits the proliferation of cancerous cells. Anything that interferes with melatonin production interferes with the body’s ability to fight cancer and there is evidence that magnetic fields interfere with melatonin production.

The action of tamoxifen, one of the drugs used to treat breast cancer, is impaired in a 12 mG magnetic field. Results have been replicated around the world and extended to other cell lines including human glioma (brain) cells. Exposure to high electromagnetic fields may block the potential of this drug and thus reduce the effectiveness of chemotherapy for breast cancer treatment.

What produces ELFs?

Devices that use or distribute electricity generate low frequency electric and magnetic fields. This includes power lines, transformers, and substations outside the home as well as appliances that you plug into an electrical outlet. Electrical wiring within the home can also be a source of high EMFs.

Older homes that still have knob and tube wiring as well as homes that are improperly wired can generate high magnetic fields (levels above 5 mG). The best way to determine if you are exposed is to measure the magnetic field using a Gauss meter. Inexpensive Gauss meters are available (see info below).

Electric appliances generate two different fields: an electric field and a magnetic field. The electric field is generated as long as an appliance is plugged into an electrical outlet. The magnetic field is generated only when the appliance is turned on and a current is flowing. While both fields have been linked to cancers, the magnetic field is the one that has received the most scientific attention.

The strength of the magnetic field and the amount of time you are exposed are both important parameters when it comes to protecting your health. Hair dryers, power tools, and your electric stove generate high magnetic fields but are used for short periods. Computers, electric alarm clocks near your bed, electric blankets, and the heater in a waterbed, generate low magnetic fields, however you are exposed for longer periods each day.

Your bedroom should have the lowest EM fields since your body is regenerating during the night and you don’t want anything to interfere with that regeneration.

What can you do to minimize your exposure?

  1. Outdoor Source: Don’t buy a home near high voltage transmission lines or a substation. A distance of at least 100 meters from transmission lines is necessary before the fields drop to background levels. Electricity distribution lines on city streets also generate a strong magnetic field. A bedroom on the second floor a few meters away from one of these distribution lines is not an ideal bedroom for anyone and certainly not for someone fighting cancer. In communities where the distribution lines are buried underground, high magnetic fields are measured immediately above these lines and near the box transformers on front lawns. The magnetic field drops off quickly with distance from these sources, so as long as children are not playing on top of these transformers, the magnetic field need not be a serious concern.
  2. Indoor Wiring: If you have an older home or a home with some “homemade” wiring, contact a qualified electrician to check and fix any wiring problems. You can determine this to some extent if you use a gauss meter and measure the magnetic field in the middle of a room. Ideally levels should be below 1 mG. By turning on lights and other appliances if the magnetic field jumps significantly in the middle of a room you may need to have this checked. The electric panel has a high magnetic field that drops significantly within 1 to 2 meters. For this reason the electric panel needs to be kept away from beds and places where people spend hours each day. The magnetic field penetrates walls so a panel on the other side of the wall near your bed is not a good idea.
  3. Appliances: Appliances that emit a high magnetic field are mentioned above. Keep your distance from these appliances as much as possible to minimize exposure. With an electrical blanket, warm up your bed and then unplug the blanket before you go to sleep. This eliminates both the electric field and the magnetic field. Turning the blanket off but leaving it plugged in eliminates only the magnetic field. With an electric clock near your bed, move it far enough away so you cannot turn it off. Better yet, get a wind-up or battery-power clock to wake you up in the morning.
  4. Distance is your best friend when it comes to avoiding magnetic fields. The strength of the magnetic field decreases with distance, so placing a few inches or feet between you and an electric device will decrease your exposure.
  5. On demand switches available. For those whose bedroom has a high magnetic field (greater than 1-2 mG) due to the wiring within the bedroom, you can turn the electricity off to the bedroom room at the electric panel or install an “on-demand” switch that will do this automatically. This allows you to sleep in a low magnetic field environment.
  6. Shielding magnetic fields. It is possible to shield magnetic fields using mu metal, an aluminum alloy but this product is expensive and needs to be done professionally with proper monitoring.
  7. Alternating magnetic fields: According to the Austrian Medical Association (2012) levels of alternating magnetic fields at or below 0.2 mG are within normal limits; between 0.2 and 1 mG are slightly above normal; between 1 and 4 mG are far above normal; and above 4 mG are very far above normal.

Useful resources:

  • Austrian Medical Association, 2012. Guidelines of the Austrian Medical Association for the diagnosis and treatment of EMF-related health problems and illnesses (EMF syndrome). Consensus paper of the Austrian Medical Association’s EMF Working Group.
  • Havas, M. 2000. Biological effects of non-ionizing electromagnetic energy: A critical review of the reports by the US National Research Council and the US National Institute of Environmental Health Sciences as they relate to the broad realm of EMF bioeffects. Environ. Rev. 8: 173-253.
  • WHO, 2002. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Volume 80. Non-ionizing radiation, Part 1: Static and Extremely Low-Frequency (ELF) and Electric and Magnetic Fields, World Health Organization, International Agency for Research on Cancer, IARC Press, Lyon France, 445 pages.
  • Gauss meter: A popular meter to measure the magnetic field that is easy to use is the Trifield meter. It is available at (U.S.) or at (Canada) for about $200.
  • On-demand switches: (Canada)
  • Mu-metal for shielding magnetic fields: (U.S.)
  • Magda Havas is an Associate Professor at Trent University, Peterborough, ON, Canada. for more information visit:

Published: May 14th, 2012