[ RadSafe ] Radioactivity in Granite Countertops

[Michael E. Kitto]

I have analyzed many granite countertops and published two peer-reviewed
papers (and given some talks) in the last couple of years regarding radon
and gamma-ray emissions from decorative granites (those used inside).  I
found that the vast majority of commercially available granite slabs have
moderate to low amounts of radon and gamma emitters.  Most of the gamma is
from K-40.  There are a few granites that are very radioactive (contain a
substantial amount of U and progeny), but these are imported from Namibia,
Brazil, etc.  I have not found a "hot" one yet that was from the US.

Now, regarding the "granite" with little radioactivity.  There is quite a
market for "synthetic granite", for lack of a better term.  This is quartz,
which contains little K-40 or U decay series, which has been
"reconstituted" to form countertops that are sold as "granite" in the
stores.  For example, Silestone and Cambria.  These are really "clean"
compared to nearly any real granite.

Dan, the Four Seasons granite that I analyzed was quite radioactive and a
radon emitter; in the top five but not the worst I seen.

The most difficult part of the research was convincing people that a gas
(radon) was coming from the granite.  I guess it defied their logic.

The publications are below, or email me if you want a pdf :
”Emanation of Radon from Household Granite” Health Phys. 96(4), 477 (2009).
”Assessment of Gamma-ray Emissions from Natural and Manmade Decorative
Stone” J. Radioanal. Nucl. Chem., Articles 282, 409 (2009).

 Michael Kitto, PhD
 Nuclear Chemistry Laboratory
 NYS DOH


>Message: 11
Date: Mon, 27 Feb 2012 22:46:00 -0700
From: Dan McCarn <hotgreenchile at gmail.com>
Subject: Re: [ RadSafe ] Radioactivity in Granite Countertops NYT had
		 an article on the topic
To: parthasarathy k s <ksparth at yahoo.co.uk>, 		 "The International
		 Radiation Protection (Health Physics) Mailing List"
		 <radsafe at health.phys.iit.edu>
Message-ID:

<CAD=JBaz=sF0cw95EiPnoM6PM7syC8OFSj=2b6hrqmXY4itHW2w at mail.gmail.com>
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Hi Dr. P:

Yes, the New York Times quoted me on the Four Seasons Granite three years
ago (without my knowledge).

Dan ii