[ RadSafe ] Fatalities due to Internal Radioactive Material

james.g.barnes at att.net james.g.barnes at att.net
Mon Nov 27 16:06:44 CST 2006

Hi, Elsa;

You have to be careful with all the prepared internal dose tables and software as they tend to report a dose over 50 years or one year and are modeling dose effects that are stochastic (i.e., chances of contracting cancer) in nature.  What has to be done here is figure out how much dose would have been delivered over about 3 or 4 days, as that would have been the triggering dose that would be needed to deliver a fatal effect from RADIATION (as opposed to a TOXIC effect).  So just the dose that the individual received over the administration of the substance and his death would be pertinent.  NOT a 50-year committed dose, and not an annual dose, for that matter.

My guesstimate is that the threshold for fatal exposure from internal is in the mid-100's to low 1,000's of rad (conservatively; I'll bet it's actually higher).  In this case, it would have to be delivered over about three weeks, and the bulk of it would have to be delivered early in the isotope's retention period.  Additionally, I'm not sure that it is appropriate to take a quality factor correction on the alpha emission, as the QF is for stochastic (i.e., cancer), not determinisitic effects (e.g., blood organ death).  So in that situation, an alpha would be rated purely on the energy it deposited (i.e., you wouldn't multiply by 20).  That suggests it would take a huge amount of material to deliver a fatal dose; particularly one that produced the rapid deterioriation seen in the victim.

The toxic nature of the Po would seem to far outweigh the radiological effects in this situation.

Re: the Goiania event, I think one of the little girls was killed by a combination of external and internal.  I believe the other injuries and fatalities were attributable to the massive external doses.

Jim Barnes

-------------- Original message from "Elsa nimmo" <Elsa.nimmo at varian.com>: -------------- 

> Hi Jim, 
> Thanks for the response! My question was really one of curiosity. We 
> all know about cases of chronic doses due to ingested material (dial 
> painters), but I couldn't think of fatalities due to acute dose of 
> radiation from unsealed internal emitters (in absence of large dose from 
> an external source). 
> But yes, there was that terrible case with the teletherapy source in 
> Goiania, Brazil. 
> Elsa 
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