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SEATTLE — University of Washington researchers have found
that prolonged exposure to low-level magnetic fields like those generated by
hair dryers, coffee makers and electric blankets can damage brain cell DNA.
A new study, to be published in the May edition of Environmental
Health Perspectives, found that exposure to a 60-hertz field for
24 hours broke brain-cell DNA strands in rats, and exposure for 48 hours
caused even more DNA damage.
Bioengineering professors Henry Lai and Narendra Singh also found
that continued exposure makes cells self-destruct because they can't repair themselves
— much like findings of a 1995 study conducted at 10 times the intensity for just two hours.
The UW study suggests the effects
are cumulative, meaning duration can be as damaging as intensity.
"In real life, people get this exposure in brief doses — three
minutes of exposure to a blow dryer, five minutes of exposure to an electric razor," Lai said. "We
found that this could add up over time."
Lai and Singh aren't urging people to start drip-drying their hair or
quit using electric alarm clocks.
They do say people need to be aware that low-level magnetic fields
emitted by many electrical devices central to daily life could be harmful.
"People should do what they can to limit their exposure to as
little as possible, especially in relation to electrical appliances that are used very close to the body,"
Lai said.
Traditionally, scientists have believed that low-level electronic
fields could not be harmful because they weren't potent enough to break chemical bonds in cells.
The UW study doesn't completely debunk that theory. It suggests
a more subtle mechanism is at work.
Lai and Singh hypothesize that rather than
causing direct harm, low-level electromagnetic fields spike the amount of free iron within certain cells.
That free iron then undergoes a chemical reaction that releases "free
radicals" or charged atoms that attack cell structures, including DNA, lipids and proteins.
To test that theory, researchers gave some of the rats drugs that
either neutralize free radicals or decrease free iron before exposing the animals to the magnetic field.
The experiment supported their hypothesis, showing that the drugs
prevented brain-cell DNA damage.
Cells undergo wear and tear all the time, so DNA damage in and of
itself isn't cause for alarm.
It becomes a concern when damage increases, because that increases
the likelihood that a mistake will occur in the cellular repair process. That could result in a mutation,
which in turn could cause diseases like cancer.
Some types of DNA damage are easily fixed, such as a break on one
side of DNA's ladder-like double helix. Repairs become more difficult if both sides of the helix are
broken, thus increasing the likelihood of mutation.
Both single- and double-strand breaks were found in the UW study.
The study, which has undergone peer review, is available in the
online edition of Environmental Health Perspectives. The publication is the journal of the National
Institutes of Environmental Health, a branch of the National Institutes of Health.
The study is available online at ehp.niehs.nih.gov/docs/2004/6355/abstract.html
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