Re: radiation is radiation? - I-131

[Richard Smart <R.Smart@unsw.edu.au>]

At 21:00 10/05/2000 -0500, Ruth Weiner wrote:
>Bob's first question raises an interesting point (especially for me since my
>father was an early user of I-131 as a diagnostic tool).  Have there been
>any epidemiological studies of cancer in patients in whom I-131 was used
>diagnostically?  Similarly, have there been studies on patients who have had
>bone scans with Tc-99?
>
>

Yes there have.  I refer you to the paper by Hall, Mattsson and Boice Jr,
"Thyroid cancer after diagnostic administration of Iodine-131" Rad Res 1996
145:86-92

They followed 34,104 patients for up to 40 years.  The mean thyroid dose
was estimated to be 1.1 Gy.  The Standardised Incidence Ratio was 1.35 (95%
CI 1.05-1.71) for thyroid cancer. 

The abstract states " Excess cancers were apparent only among patients
referred because of a suspected thyroid tumour and no increased risk was
seen among those referred for other reasons.  Further the risk was not
related to radiation dose, time since exposure or age at exposure. The
slight excess of thyroid cancer thus appeared to be due to the underlying
thyroid condition and not radiation exposure.  Among those under age 20
years when I-131 was administered, a small excess risk (3 cancers compared
to 1.8 expected) was about 2-10 times lower than that predicted from data
for the A-bomb survivors.  These data suggest that protraction of dose may
result in a lower risk than an acute x-ray exposure of the same total dose."

Hope this helps the discussion

Richard Smart


>-----Original Message-----
>From: Bob Flood <bflood@SLAC.Stanford.EDU>
>To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
>Date: Wednesday, May 10, 2000 4:38 PM
>Subject: Re: radiation is radiation?
>
>
>>>Norm is coming from a perspective that the short 1/2 life products are
>>>the demons - especially I-131 since it insidiously hides away in the
>>>thyroid and he has been given to believe that the thyroid is
>>>particularly radio sensitive and that I-131 and most other short 1/2
>>>lived isotopes are not found in nature.
>>
>>An interesting point that can be subjected to the same kind of sanity check
>>as we've seen in other posts. That "deadly" I-131 secretively released from
>>nuclear plants and causing so much harm and unhappiness is the same stuff
>>that hospitals have been using for thyroid uptake studies on countless
>>people for years. If it's as harmful as the anti's claim, where is the
>>enormous outbreak of thyroid cancer it should have caused? It would most
>>certainly be far to big to hide.
>>
>>Like I've said before, we keep talking about science and they keep talking
>>about religion. The TF Project people are just as certain that every
>>photon's a killer as those people in Salem were about those women being
>>witches. And just like the people of Salem who kept on believing those
>women
>>were witches AFTER the young women who accused them recanted her testimony
>>and admitted she made it all up, the TF Project people aren't going to let
>>any obvious facts get in their way either. To paraphrase, "it's not about
>>trust, it's about faith!" And those who do not believe can expect to be
>>treated like blasphemers.
>>============================
>>Bob Flood
>>Dosimetry Group Leader
>>Stanford Linear Accelerator Center
>>bflood@slac.stanford.edu
>>
>>
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>
>
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Richard Smart PhD
Principal Physicist and Radiation Safety Officer
Nuclear Medicine Department
St. George Hospital
Kogarah
NSW, 2217, Australia
Tel: (61 2) 9350 3129
Fax: (61 2) 9350 3991
email: r.smart@unsw.edu.au
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