low level radiation article

["Michael C. Baker" <mcbaker@LANL.GOV>]

 From USA Today's web site.



Mike









Posted 5/7/2003 9:39 PM



Study: Lowest-level radiation is more damaging than thought

By Dan Vergano, USA TODAY



Radiation may damage living cells at surprisingly low energy levels, 

challenging scientific beliefs about the levels of radiation likely 

to prove deadly.



The study by a team of European researchers found unexpected 

molecular reactions to low-energy radiation that suggests it may play 

a greater role in causing cancers than originally thought. It also 

suggests a possible new route for cancer treatments.



Although ultraviolet rays in sunlight are known to cause skin cancer, 

the health effects of other low-energy, or "non-ionizing," radiation 

from cell phones or electrical wires is a controversial subject.



High-energy radiation, as in X-rays, that damages cells by 

"ionizing," or electrically exciting, molecules is a well-established 

cause of cancer.



In Wednesday's Physical Review Letters journal, physicists led by 

Tilmann Maerk of Austria's University of Innsbruck describe 

experiments on the effects of low-power radiation on chemicals found 

in RNA, the "helper" molecules that cells use to carry out genetic 

instructions.



Using a beam of radiation lower in energy than that used in any 

previously reported experiments - about 1,000 times weaker than the 

dangerous ultra-violet radiation in sunlight and far lower than the 

level at which damage was thought to occur in cells - the team 

discovered fragmentation in the RNA parts. Not strong enough to 

electrify the molecules, the beam instead triggered secondary effects 

that splintered the molecules in a quick chain reaction. Maerk called 

the damage "a big surprise."



The research team told Physics News Update, an Internet publication 

of the American Institute of Physics, that the same low-energy beam 

disrupts a constituent molecule of DNA, the repository of genes in 

cells.



"This work challenges current models of how ionizing radiation 

damages cellular material and thus how (the cell) might be treated," 

says biological physics expert Nigel Mason of London's Open 

University. The chain reaction may target particular sites in cells 

for destruction, he says, suggesting a way of using low-energy 

radiation to kill tumor cells. Doctors already use high-energy 

radiation to kill tumors, but a low-energy dose would not have the 

same harmful side effects.



"The standard view in radiation biology is that most, although not 

all, effects of consequence for human health are produced by ionizing 

radiation," making the finding particularly surprising, says health 

physicist Marco Zaider of Memorial Sloan-Kettering Cancer Center.



Zaider notes the radiation from cell phones and computer screens is 

much lower energy than the radiation described in the report.



The next step is to work with the molecules in water solutions to 

better mimic behavior in cells.

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