Dr Engelbert Buxbaum
(by engelbert_buxbaum from hotmail.com)
Wed Jun 9 10:38:49 EST 2010
In article <4c46dc22-1694-45ea-ab11-
a441674e057a from x21g2000yqa.googlegroups.com>, nick.theodorakis from gmail.com
> On Jun 8, 10:12 am, "Allan Jones" <allan.jo... from gmx.de> wrote:
> > Hi!
> > There is currently a lot of radiation work going on in our lab and i am always worried about people contaminating stuff with small amounts of isotopes the geiger counter does not detect very well (ie tritium, 14c, 35s).
> > Now I have looked into the definition of annual limit on intake and so on and am slightly confused. The ALI values seem extermely high, so does this mean the amounts (a couple of µCi) we use are not particularly dangerous?
> > I do not assume anything is contaminated, but am a worrysome person and some of the people here seem quite relaxed concerning radioactivity. I guess however that back in their days its use was much more common.
> > What do you think?
> As a point of comparison, I once had a medical imaging test in which I
> was injected with 5 mCi (yes, that's milli) of radioactive thallium.
> When I got back to lab, they said, ha ha, let's see if you're
> radioactive, and held a geiger counter up to my chest. If course, I
> made the geiger counter chatter, at which point it seemed they all
> backed away and said, "oh." They kept me away from the x-ray film for
> a couple of weeks.
A colleague of mine had a thyroid scan with Tc, and consequently
blackened out his dosimeter. Created quite a stir with the safety guys,
until the cause was established to be "not work-related". When he
entered the lab, he could make the Geiger-counter needle wrap around its
stop from several meters away.
A couple of years ago a disgrunteled scientist poored 10 mCi of 32-P
into the coffee urn in the common room at a US university. Widely
published in scientific magazines at the time, but none of the exposed
people suffered any ill effect.
PET-scans are done with some 200 mCi (sic!) of 18-F (or at least were
some 20 years ago, when I looked into it). Actual treatment of cancers
is yet a completely different game.
So follow normal safety precautions (ALARA principle), but don't worry
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