[ RadSafe ] Please Critique This Reply by Rosalie Bertell

[Marcel Schouwenburg]

Dear Rosalie Bertell,

What you are referring to in your reply (from the Handbook of Health
Physics and Radiological Health) is based on out dated information from
the previous ICRP-model for the respiratory tract as was published in
ICRP 30, part 3 (1981). This old model indeed did not apply to aerosols
with AMADs less than 0.1 micron.

ICRP not just changed the limit for particle size. They published a
whole new (much improved and extended) model that replaces the model as
published in ICRP 30. The old model had become obsolete and needed to be
replaced by a newer one that a.o. would describe the respiratory tract
in a better way. One of the improvements was that this model can be used
for a broader range of particles than the old one.

So, the model was replaced and not the limit. The first Gulf War has,
imho, nothing to do with this. The old model just had to be replaced
since it was becoming obsolete (as currently also is happening with the
model for the gastro intestinal tract that will be replaced by the
HAT-model).

With kind regards,

Marcel Schouwenburg
Head / Lecturer Training Centre Delft, Health Physicist, expert level 2
RadSafe Moderator & Listowner
National Centre for Radiation Protection (Dutch abbr. NCSV)

Delft University of Technology
Faculty of Applied Sciences / Reactor Institute Delft
Mekelweg 15
NL - 2629 JB  DELFT
The Netherlands
T: +31 (0)15 27 86575
F: +31 (0)15 27 81717
M: +31 (0)6 419 83 145
E: m.schouwenburg at tudelft.nl

On Wed, 2007-02-21 at 11:56 -0500, Rosalie Bertell wrote:
> Dear Mr. Marcel Schouwenburg,
> 
>  
> 
> Thank you for this reference. My source was the Handbook of Health
> Physics and Radiological Health, Third Edition, Edited by Bernard
> Schleien, Lester A. Slaback, Jr. and Brian Kent Birky, Lippincott
> Williams and Wilkins, Philadelphia,1998.  on page 12-13, it is stated:
> 
> “The model is intended for use with aerosol with AMADs between 0.2 and
> 10 micron and with geometric standard deviation less than 4.5.
> Provisional estimates of deposition further extending the size range
> are given in the dashed lines of Figure12.3. ….. The model does not
> apply to aerosols with AMADs less than 01. micron. (Courtesy ICRP from
> Publication  54, 1987)”.
> 
>  
> 
> Could you please explain why ICRP 66 (1994) changed this limit. This
> should have been promulgated by 1998. My understanding is that when
> particles are of AMADs less than 0.1 micron they behave like a gas.
> They freely enter through the cell walls, the lung-blood barrier, the
> blood brain barrier and cross the placenta. The other major problem is
> that are too small for the kidney filter. Was this decision made after
> the first Gulf War for some reason?
> 
>  
> 
> Dr. Rosalie Bertell
>