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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?
Published: May 14th, 2012