Study of biological effects of electromagnetic radiation inconclusive

April 17, 1992

By Diane LaMacchia

In recent years, there have been a number of stories in the news about a feared link between electromagnetic radiation and ill health effects.

Last May, for example, the Fresno Bee reported that an elementary school in Fresno, Calif., closed ten of its classrooms because of their proximity to high voltage electrical powerlines.

According to the Fresno Bee, ten teachers or teachers' aides who had taught in the classrooms, located about 110 feet from high voltage powerlines, developed cancer. Health authorities are conducting an epidemiological study.

Epidemiological studies in other areas have suggested that powerline-frequency fields may have adverse health effects. But LBL's Thomas Budinger, who chairs a committee of the Institute of Electrical and Electronics Engineers Inc. (IEEE), to set national safety standards for exposure to electrical and magnetic fields, says none of the 24 epidemiological studies on this subject to date has sufficient statistics to warrant a conclusion of cause and effect.

"For example, the most recent published report shows no relation between oscillating magnetic fields and leukemia prevalence," Budinger says. "What the report did show is a relation between power line configurations and leukemia. To infer magnetic field effects from powerline configurations is not yet science."

Robert Liburdy heads a research effort at LBL to investigate the biological effects of these extremely low frequency electromagnetic fields (EMF/ELFs). LBL's research is focused on how EMFs affect the T-lymphocyte, an immune system cell that can be involved in leukemia.

"We want to know if a normal person will develop an impaired immune system," says Liburdy. "If the immune system is impaired, they may be more susceptible to cancer."

ELF fields, which include those from household appliances, generate nonionizing radiation -- radiation that is not energetic enough to damage DNA directly. If there is a link to cancer, it may be that ELF/EMFs induce alterations in cell-membrane functions involved in cell proliferation and division. Liburdy, Dan Callahan, Margrit Wiesendanger, Theresa Sloma, and Matthew Falk are examining ELF/EMF effects on calcium signalling in the lymphocyte.

When a foreign body binds to the surface of a lymphocyte, a signal is sent to the inside of the cell, and a series of biochemical processes occur. One of the earliest responses is the opening of a channel to let calcium into the cell's interior. This can set off a cascade of biochemical events that lead to an immune response of lymphocyte proliferation.

"Calcium transport (across the cell membrane) is so fundamental," says Liburdy. "The calcium signalling pathway is found in almost every cell. It's involved in mitogenesis (cell division), cell growth, and wound healing."

The researchers saw changes in this cell proliferation when they varied electrical field strength and duration. But they found that cells that are resting, and not activated by antigens, are unaffected by the fields. Those that are activated by antigens responding to the addition of a mitogen -- simulating the cell's coming in contact with a foreign body -- have an altered calcium transport function.

"The activated state is critical to the cell's response to electric and magnetic fields," Liburdy says. Lymphocytes are activated when a person's immune system is fighting disease, so it's possible that a person whose immune system has been stimulated would be more susceptible to ELF fields. The scientists placed rat lymphocytes on annular tissue culture plates -- petri dishes with three wells of progressively smaller radii -- inside a specially fabricated solenoid. A 60-hertz powerline, with the same frequency as typical powerlines in office buildings and houses, generated an oscillating magnetic field with a maximum peak of 200 gauss, to which the cells were exposed for periods varying from five to 60 minutes.

Using calcium 45 isotopes, the scientists were able to observe the movement of calcium across the cell membranes. The cells that were activated, by adding a mitogen, transported calcium more than twice as fast as the others. The speed varied with the strength of the fields, depending on the radius of the wells, according to Faraday's Law.

When a magnetic field encounters tissue, an electrical field is induced inside of it. The strength of this electrical field is determined by the radius of the tissue. Liburdy and his team found that calcium transport is increased or inhibited depending on the strength of the induced electrical field.

"The dose response is non-linear," says Liburdy. "We see enhancement or inhibition depending on the strength of the induced electric fields." The LBL team works with magnetic fields at both low-level environmental and higher-level occupational strengths.

The LBL researchers will continue to probe the mechanisms of ELF field effects, particularly the important role played by the biological status of the cellular system. Collaborating with biophysicist Marcos Maestre, they have begun new studies using fluorescence microscopy to observe single lymphocytes during exposure to ELF fields.

Meanwhile, Budinger says the American National Standards Institute's revised guidelines for industry and government have just been approved for the frequency between three kilohertz (3KHz or 3,000 hertz) and 300 gigahertz (300GHz or 300 billion hertz).

"The IEEE committee responsible for this standard is now engaged in ascertaining guidelines for the range from zero to three kilohertz," Budinger says. "The only reliable data we could accept at present are thresholds for measurable effects -- such as electric shock or electrical neuromuscular stimulation -- from oscillating magnetic fields nearly ten thousand times those encountered in the environment."