UV

["DAVE GILMORE" <DGILMORE@navajo.astate.edu>]

>for the Advancement of Science. "Traditionally, sunscreens have
only blocked the transmission of a kind of ultraviolet light in
sunlight that's known as UV B," Setlow said.  "That's the range of
wavelengths that cause sunburn, or erythema. It's also the kind of
UV that the DNA in our cells absorbs most easily."

"But we have found that another range of wavelengths, collectively
called UV A, may be much more powerful in causing skin cancers
called melanoma," Setlow continued. "Our research shows that about
90 percent of sunlight's melanoma-causing effect may come from UV
A and only 10 percent from UV B." Still, he said, UV B is the
chief cause of other skin cancers besides melanoma.>

What are the wavelength ranges of UVA and UVB?
What absorbs UVA so that it could cause cancer?  Is absorption by DNA 
bimodal?

On the food irradiation topic:  bacteria are defined as being dead 
when they are no longer able to reproduce (eg, DNA damage).  I'm not 
sure how we define life for individual carrot cells or whether we 
want to.



HANDBELL PEOPLE have all gone campan-

David F. Gilmore
Assistant Professor of Environmental Biology   
P.O. Box 599, Dept. of Biological Sciences  
Arkansas State University 
State University, AR 72467
dgilmore@navajo.astate.edu
ph  501-972-3082    fax 501-972-2638