[ RadSafe ] DNA can be damaged by very low-energy radiation

Fri Mar 14 12:56:18 CDT 2014

While this may be interesting, if something has reduced you to a puddle of water without skin or even cell membranes to protect your DNA, you have bigger worries than the possibility that someone will shine a laser pointer at you.  No, I take that back; you don't have any worries, including the possibility that someone will shine a laser pointer at you.

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of ROY HERREN
Sent: Friday, March 14, 2014 12:48 AM
To: Radsafe
Subject: [ RadSafe ] DNA can be damaged by very low-energy radiation

PUBLIC RELEASE DATE:14-Mar-2014 Contact: Deepak Mathur atmol1 at tifr.res.in
91-222-278-2736
Tata Institute of Fundamental Research 

DNA can be damaged by very low-energy radiation How safe are 'eye-safe' lasers?
"Very low-energy radiation also damages DNA: how safe are "eye-safe" lasers?"
Damage to DNA by high energy radiation constitutes the most lethal damage occurring at the cellular level. Surprisingly, very low-energy interactions - with OH radicals, for instance - can also induce DNA damage, including double strand breaks. It is known that single strand breaks in the DNA backbone are amenable to repair but most double strand breaks are irreparable. The propensity with which slow OH radicals damage DNA depends on their rotational energy: rotationally "hot" OH is more proficient in causing double breaks. These novel findings are from experiments conducted on DNA in a physiological environment. 
Intense femtosecond laser pulses are propagated through water (in which DNA plasmids are suspended), creating plasma channels within water, resulting in generation, in situ, of electrons and OH radicals. It is shown that use of long laser wavelength light (1350 nm and 2200 nm) ensures only OH-induced damage to DNA is accessed. It is noteworthy that industry presently characterizes as "eye-safe" lasers that emit at wavelengths longer than 1300 nm. 
But it is such wavelengths that are proficient at inducing damage to DNA: how safe is "eye-safe" when DNA in the eye can be readily damaged? 
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Roy Herren
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