[ RadSafe ] Nuc Med pt x-contamination of other people

Stewart Farber SAFarber at optonline.net
Fri Dec 2 12:54:11 CST 2011

Hi all,

Regarding the issue of "cross-contamination" of sorts involving I-131 from
various practices, the following may be of interest to some. David North
mentioned some interesting measurements he made following thyroid ablations
[which typically involves no less than 50 milli-Ci or 1.85E9 Bq of I-131].
He mentioned some positive measurements in some family members including
pets above a detection level of 1/10,000 of the I-131 administration which
would equate to something over 185,000 Bq cross contamination. Concerning
another "cross-contamination" of sorts from a nuclear plant to environmental
media consider the following.

I used to review environmental rad monitoring program data for a number of
nuclear plants in New England including Maine Yankee Nuclear Power Station
--at the time at 900 MW[e] was the largest power plant in New England. The
annual airborne I-131 release limit for this one nuclear station was
coincidentally equal to that activity used in a single thyroid ablation or
50 milli-Ci = 1.85 billion Bq.  At levels slightly above the annual average
allowable airborne  I-131 release rate from Maine Yankee [1.85 E9 Bq/year=
5 E6 Bq/day] we were able to measure I-131 in milk at nearby farms at levels
of a few Bq/Liter [ less than 10 pico-Curies/Liter].

It is likely that with the number of thyroid ablation procedures performed
on people, and animals like cats at many vet centers, that if one made
sensitive environmental measurements near some non-power related facilities
that I-131 activity could be measured even in various environmental media,
including air in the general environment not just in sewage systems or solid
waste of many sorts.

Stewart Farber, MS Public Health
SAFarber at optonline.net

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of North, David
Sent: Friday, December 02, 2011 10:17 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Nuc Med pt x-contamination of other people

I did an investigation of the cross-contamination of household members after
patients were sent home following large doses of I-131 for metastatic
thyroid cancer. I counted the thyroids of 43 people and 7 dogs living with
the patients. Three people and four dogs were positive at the level of about
1/10000 of the administered doses. Most of the dogs were licking the
patients, I think. A couple were definitely too small to drink out of the
toilets! (I submitted this to Health Physics for publication, was asked to
revise it a bit, and then I got REALLY busy clinically. So, I will probably
have to submit it all over again when I can get back to it.)

Anyway, it does happen occasionally, but doesn't seem to involve a lot of

David L. North, Sc.M., DABR
Associate Physicist
Main Building, Rm 317
Rhode Island Hospital
593 Eddy St.
Providence, RI 02903
w: (401)444-5961
f: (401) 444-4446
dnorth at lifespan.org

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