Re: Tritium and plastic

["Wesley M. Dunn" <WDUNN@brc1.tdh.state.tx.us>]

Jim,

LD 50/30 is generally accepted to be within a range 300-650 rad of 
LET radiation.  The updated Rad Health Handbook references Lushbaugh 
as giving a number of 345 rad LET radiation in one week as LD 50.  It 
also defines LD 50/60 as 500 rad.  I choose 450 just as a ballpark 
number.

Using QAD (Quick and Dirty), I took 1 rad = 1 rem, since the ALI 
(based on ICRP 30) is determined as the intake necessary to provide 
an effective dose of 5 rem.

So the answer to your question is "inference" and "rules o' thumb", 
at least from me.  Al (or others) might have (or time to dig up) 
better references.

However, it should serve to answer the original request: why 
people shouldn't be too worried about up to 25 Ci (the provided 
number....its usually much less) of tritiated gas in an exit sign.

Wes

> Date sent:      Mon, 27 Jan 97 10:40:53 -0600
> Send reply to:  radsafe@romulus.ehs.uiuc.edu
> From:           JMUCKERHEIDE@delphi.com
> To:             Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject:        Re: Tritium and plastic

> Al, Wes, all,
> 
> Based on?  what is the animal data?  
>  
> Regards, Jim Muckerheide
> jmuckerheide@delphi.com
> 
> > Wesley M. Dunn wrote:
> > > 
> > > Well, taking the LD 50/30 as approximately 450 rem (Whole Body Acute
> > > Dose -- probably reasonable with THO with an effective 1/2 life of
> > > about 10 days):
> > > 
> > > ALI (Oral; THO) = 80 mCi = 5 rem
> > > 
> > > LD 50/30 ~7 Ci (single intake)
> > I have used 8 Ci (single intake) as a lethal dose (e.g. LD 50/30).  So
> > we essentially agree.  Al Tschaeche  xat@inel.gov
> > 
> > 
> 
*********************************************************************
Wesley M. Dunn, CHP                        512-834-6688
Deputy Director, Licensing                 512-834-6690 (fax)
(Texas) Bureau of Radiation Control        wdunn@brc1.tdh.state.tx.us
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