Magnetic fields can diminish drug action
by J. Raloff
The low-level electromagnetic
fields present in some North American homes
today can diminish or wipe out a widely prescribed drug's action, at least
in test tubes. Researchers have found that when exposed to such fields, the
drug tamoxifen lost its ability to halt the proliferation of cancer cells
grown in the laboratory. Tamoxifen is a synthetic hormone used to prevent
the recurrence of breast cancer.
findings, reported at a Washington, D.C., meeting sponsored
by the U.S. Public Health Service, also heighten concern that these
electromagnetic fields may be triggering hitherto unrecognized biological
changes in people.
new study is an extension of research that Robert P. Liburdy, a cell
biologist at Lawrence Berkeley (Calif.) National Laboratory, reported on 4
years ago. At that time, he showed that while melatonin, a natural
antioxidant hormone, would inhibit the growth of breast cancer cells
exposed to 2 milligauss (mG) magnetic fields, its activity was essentially
erased when the cells were bathed in a 12 mG field (SN: 7/3/93, p. 10).
Though the average magnetic field
associated with the 60 hertz current in
U.S. homes is 2 mG or lower, it can reach 12 mG in a small share of homes,
such as those with unusual electric wiring. Values range as high as 1,000
mG in some occupational settings. People may also be exposed briefly to 12
mG or higher magnetic fields from electric razors and hair dryers, the
sides of computer monitors, or appliances with large motors, such as
Liburdy and Joan D. Harland, also
at the national lab, have now incubated
one type of breast cancer cell treated with tamoxifen -- at concentrations
typical of those found in the breast cells of women taking the drug -- in
the presence of the same two field strengths.
Untreated cells appeared to grow equally well in each field. The growth
rate of cells treated with tamoxifen fell by 40 percent in the 2 mG
environment but exhibited no drop-off in the 12 mG field. Liburdy told
Science News, "We've shown that you can overcome this field's suppression
of tamoxifen, but to do it you've got to increase the drug dose by up to
and Harland report their findings in Bioelectromagnetics (vol. 18,
At that meeting, Liburdy also described follow-up research on a
second type of breast cancer cell. Again, both melatonin and tamoxifen
inhibited cell growth in a 2 mG environment but failed to do so under the
influence of a 12 mG field.
At a Bioelectromagnetics Society meeting earlier this
presented laboratory data indicating that 12 mG magnetic fields from a
computer monitor, which have a slightly different waveform than those
associated with home wiring or many appliances, also erase the
antiproliferative action of a hormone -- in this case, melatonin.
"As basic science,
this is very interesting stuff," notes Richard Stevens
of the Pacific Northwest National Laboratory in Richland, Wash. Most of the
new experiments were done with the most widely studied line of breast
cancer cells, he notes. Moreover, "the [magnetic] field levels used are
certainly relevant to humans."
While it's far too early to suggest that residential fields
pose a risk to
the efficacy of tamoxifen, Stevens does argue that "this study provides the
rationale for wondering about and investigating such implications."
Carl F. Blackman, a biophysicist with the Environmental Protection Agency
in Research Triangle Park, N.C., has recently confirmed Liburdy's finding
that magnetic fields can suppress melatonin's action and is now probing the
ability of low-level fields to affect the action of tamoxifen. In other
experiments, he finds that electromagnetic fields can affect the
development of nerve cells when concentrations of nerve growth factor are
What all these
studies suggest, he says, is that "in a system that is
stable and unstressed, you may see no effect of these fields. But if you
stimulate it or depress it a little bit" -- with drug treatment or
insufficient growth factors, for example -- "the field may show an effect."
Blackman, C.F., et al. 1996. Independent replication of the 12-mG magnetic
field effect on melatonin and mcf-7 cells in vitro. Eighteenth annual
meeting of the Bioelectromagnetics Society. Victoria, British Columbia.
J.D. and R.P. Liburdy. 1997. Environmental magnetic fields inhibit
the antiproliferative action of tamoxifen and melatonin in a human breast
cancer cell line. Bioelectromagnetics 18.
Liburdy, R.P., et al. 1997. A 12mG (1.2 uTesla) magnetic field inhibits
tamoxifen's oncostatic action in a second human breast cancer cell line:
T47D. Second World Congress for Electricity and Magnetism in Biology and
Medicine. Bologna, Italy.
1995. EMFs on the brain? Science News 147(Jan. 21):44.
Adler, T. 1994. Study reaffirms tamoxifen's dark
side. Science News
Edwards, D. 1988. Cells haywire
in electromagnetic field? Science News
Ezzell, C. 1991. Power-line static. Science News 140(Sept. 28):202.
1994. Do EMFs pose breast cancer risk? Science News 145(June
Raloff, J. 1995. Drug of darkness. Science News 147(May 13):300.
Tamoxifen puts cancer on starvation diet. Science News
______. 1994. Tamoxifen turmoil. Science News 146(Oct. 22):268.
______. 1994. Another
way EMFs might harm tissues. Science News 145(Feb.
______. 1993. EMFs run aground. Science News 144(Aug. 21):124.
______. 1993. .
. . but quenched by ubiquitous hormone. Science News
______. 1992. Tamoxifen quandary. Science News 141(April 25):266.
EPA suspects ELF fields can cause cancer. Science News
K. 1991. Fickle fields: EMFs and epidemiology. Science News
Carl F. Blackman
U.S. Environmental Protection Agency
Mailstop Code 68
Research Triangle Park, NC 27711-2055
Life Sciences Division
Lawrence Berkeley National Laboratory
One Cyclotron Road
Berkeley, CA 94720
Health Division, K4-28
Battelle Pacific Northwest Laboratory
Richland, WA 99352