Re: I-131 Air Sampling -Reply

[Schoenhofer <schoenho@via.at>]

At 11:22 1996-06-28 -0500, you wrote:
>>Silver zeolite is the medium of choice for iodine sampling primarily
>>because of its low affinity for noble gases; however, activated charcoal
>>should do nicely.  HEPA filtration does not "see" iodine.  HEPA filtration is
>>suitable for particulate radiation, not for gases and vapors.
>
>This is something I have often wondered about.  Implicit in the above
>statement is the assumption that we are talking about iodine vapor.  In the
>real world, does radioiodine react to form a variety of chemical compounds
>and attach to dust particles, etc?
>
>Stay safe, mike (mcnaught@LANL.GOV)
>=============================================================================

Mike,

You need not wonder about the question of the chemical form of iodine - it
is well known, that I-131 may be present in many different chemical forms,
for instance as I2-molecule, as I-ion, as methyl iodide etc. Different
reactor designs produce different ratios of the above mentioned chemical
forms. After a release many different species can be produced by
environmental chemical reactions. After the Chernobyl accident we found,
that the ratio of "molecular iodine", "ionic iodine" and "organic iodine"
varied considerably over time. The proportion of these species attached to
aerosols will vary widely according to different environmental conditions.
Moreover the impact on the population will be totally different -
inhalation, deposition, iodine transferred to milk etc. will be heavily
dependent on the chemical form. As far as I know, the chemical speciation of
radionuclides is something which is not yet accepted as one of the important
factors of transfer of radionuclides from the environment to man. Simply
because too little is known about it!

What I want to express with the above words is, that even if you know
exactly the distribution of iodine in the different species in aerosols, you
will not be able to calculate the transfer and the dose to the population. 

Best regards, 
Franz Schoenhofer 
Federal Institute for Food Control and Research
Kinderspitalg. 15
A-1095 Vienna,
Austria
Schoenhofer
Habichergasse 31/7
A-1160 Wien
Tel./Fax:	+43-1-4955308
Tel.:		+43-664-3380333
e-mail:		schoenho@via.at