[ RadSafe ] They walk among us

Otto G. Raabe ograabe at ucdavis.edu
Thu Oct 21 12:37:01 CDT 2010

>October 21, 2010

I personally believe that there is some misunderstanding among 
medical and radiation safety professionals about the risks associated 
with I-131 shed by patients after thyroid cancer treatment. The 
guidance given many patients fails to appropriately caution them 
about exposure to others, especially children. Patients receiving mCi 
doses of I-131 can readily expose family members and friends to 
microcurie quantities of I-131 via casual contact and bathroom 
contamination for weeks after treatment, but they typically may be 
told that after 4 days they have no restrictions.

Excellent guidance is found in International Commission on 
Radiological Protection (ICRP) publication 94, "Release of patients 
after therapy with unsealed radionuclides", (Elsevier Press, 2004).

Children can be exposed by skin contact, kissing, or while using a 
contaminated toilet. Intake of only 1 microcurie of I-131 by a child 
can result in a thyroid dose of 13 REM. That is unacceptable from a 
radiation safety perspective and should not be treated casually. 
There is also a meaningful thyroid cancer risk from such an exposure 
(Jacob et al., "Childhood exposure due to the Chernobyl accident and 
thyroid cancer risk....", British Journal of Cancer 80, 1461-1469, 1999)

According to ICRP-94, a patient receiving primary treatment should 
avoid visiting or contacting children or pregnant women for about 
three weeks after treatment, and for about two weeks in the case of 
follow-up treatment,  They should stay home and avoid the public arena as well.

A patient visiting someone could easily contaminate a bathroom in the 
hosts home and children can be exposed even without direct contact 
with the patient.


Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
Phone: (530) 752-7754   FAX: (530) 758-6140

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