References:

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.

These 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.

The 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
refrigerators.

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
10-fold."

Liburdy and Harland report their findings in Bioelectromagnetics (vol. 18,
no. 8).

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 year, Liburdy
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
too low.

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."

References:

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.

Harland, 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.