[ RadSafe ] Radioactivity in Granite Countertops NYT had an article on the topic

[parthasarathy k s]

Dear radsafers


A few years ago there were a few articles in newspapers on the radiation levels on the surface of granite counter tops. At least one of them was in the New York Times. "Excess" radiation levels on some geological samples displayed in a British Museum has led to convictions!

In UK , granite containing regions are well known for high background radiation levels.

Regards
Parthasarathy



________________________________
 From: "JPreisig at aol.com" <JPreisig at aol.com>
To: radsafe at health.phys.iit.edu 
Sent: Tuesday, 28 February 2012, 3:16
Subject: Re: [ RadSafe ] Radioactivity in Granite Countertops
 
Dear Stewart Farber,

     Are these gammas from granite wimpy little gammas,  energetically 
speaking, or highly
energetic????

     Is it possible that your friend's granite counter  top has had a layer 
of plastic laminate
applied over top of the granite????

     Joe Preisig



In a message dated 2/27/2012 1:41:57 P.M. Eastern Standard Time,  
SAFarber at optonline.net writes:

Does  anyone know if there some types of granite that contain NO enhanced
levels  of natural radioactivity? This has never been my experience, but I'm
no  geologist.



I've done studies with high-pressure ionization  chambers in many places
showing clearly elevated levels of radioactivity  contained in granite in
construction throughout the Northeastern US as  indicated by elevated gamma
dose rates of 20 micro-R/hr [200 nSv/hr] or  more  [ in close proximity to
granite walls -approx. 1 foot distant]  vs. typical background dose rates  
of
about 8 micro-R/hr [ 80 nSv/hr]  for the area. 



Every HPIC measurement near granite I've made  around Boston [ at the
Christian Science Church, South Station, Bunker Hill  Monument, steps of the
MA Statehouse, granite Colonial era wharf  buildings]  or all around
Westerly, RI [a town where almost every  building is made of granite], or in
NH or Maine, or  the Harrisburg,  PA Capitol granite steps,  has shown about
a doubling of background  dose rate measured with a HPIC a  foot  or so from
the granite  used in construction. 



Another interesting measurement was of a  doubling of background dose rate
near a large piece of Aswan red granite  from Egypt which was used to make a
sarcophagus for a princess many  thousands of  years ago. This ancient
granite ceremonial Egyptian  coffin is currently displayed in front of the
Boston, MA Museum of  Science.



All  granite mentioned  above would show  greatly elevated count rates when
measured on contact with a standard  pancake GM like an Ludlum 44-9 or
HP-360.  



However, a  friend has recently installed granite countertops which shows
background  rad levels on contact. So has my friend purchased "real" granite
with all  the  natural radioactivity it "should" contain or has she been
cheated  of her little bit of residual elevated U-238, Th-232, and  K-40
radioactivity from the Big  Bang?



Thoughts?





Stewart  Farber



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