[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: irradiated mail
I would think the distribution of dose would be quite different between a beta irradiator and a gamma
device. This is purely intuitive, not based on any personal experience with the processes involved, or
any measurements performed. However, with an electron beam irradiator in order to deliver sufficient dose
to the internals of larger envelopes/packages or a pallet of letters passing thru a machine [since I
think they irradiate bundled material], the surface dose would certainly be far higher that that at the
center. By analogy, I recall seeing test data on the 0.5 mm monel metal encapsulated 50 mg Ra-226
nasopharyngeal irradiator used to treat no fewer than 500,000 young children in the US for enlarged
adenoids acccording to the CDC. This nasal radium irradition [NRI} "treatment" relied primarily on the
energetic betas exiting the source to shrink adenoids. In this case the surface/contact dose [first mm]
was on the order of 10000 rads while the depth at 1 cm in tissue was on the order of 100 rads [100 times
lower]. This much higher ratio of surface beta dose in mail irradiation could produce chemical reactions
on any plastic shrink wrap or the plasticizers that might be used in their formulation [??] covering
bundles of mail [or in chemical residues in paper as posited by Ruth]. A gamma irradiator using an
energetic gamma ray would produce much more even dose in delivering any given dose to all parts of a
pallet of mail. Just thoughts to ponder.
Stewart Farber, MSPH
farbersa@optonline.net
=======
8/29/02 4:17:07 AM, William V Lipton <liptonw@DTEENERGY.COM> wrote:
>My understanding is that virtually all of the dose from gamma irradiation is
>produced by the secondary electrons. In that case, how would gamma irradiation
>produce different effects than beta or electron beam irradiation?
>
>The opinions expressed are strictly mine.
>It's not about dose, it's about trust.
>Curies forever.
>
>Bill Lipton
>liptonw@dteenergy.com
>
>Muckerheide wrote:
>
>> Jim,
>>
>> As noted, e-beams, not gammas. E-beams are "politically-correct" vs.
>> radioisotopes/radioactivity.
>>
>> Another fool's errand pushed by ignorance by "authorities" and "marketing"
>> playing on anti-radiation perceptions.
>>
>> Regards, Jim
>>
>> on 8/28/02 6:00 PM, Jim Hardeman at Jim_Hardeman@dnr.state.ga.us wrote:
>>
>> > Ruth -
>> >
>> > Based on what I saw about the "irradiation machines", I think you're probably
>> > looking at electron beams rather than gamma or X-rays. I would suspect the
>> > reaction of electrons w/ the organic sulfides would be similar to that of
>> > alphas.
>> >
>> > I've heard stories (that's the best I can characterize them) of the clear
>> > plastic windows on irradiated envelopes being browned / charred, other
>> > plastics (floppy disks, CD's, etc.) being "melted" or deformed. To my mind the
>> > chemical reactions in irradiated plastics are as likely, if not more likely,
>> > to be responsible for the production of "irritants" as the irradiation of
>> > paper ... assuming for the sake of argument, of course, that some sort of
>> > irritants are actually produced by the irradiation process.
>> >
>> > For what it's worth, when I was working on the Radiation Sterilizers, Inc.
>> > (RSI) cleanup here in Decatur, GA seemingly a lifetime ago (it was only 1988),
>> > we were working with paper products, predominantly cardboard boxes, that had
>> > been sterilized with gamma doses in the megarad range ... and we handled those
>> > products with no ill effects. Now granted, we were surveying them for
>> > contamination, so we did have latex gloves, etc. ... so that may not be a
>> > valid data point ... but in the thousands of person-hours that we worked with
>> > these products, I don't recall anybody saying anything about any sort of
>> > irritant.
>> >
>> > My $0.02 worth ...
>> >
>> > Jim Hardeman
>> > Jim_Hardeman@dnr.state.ga.us
>
>
>************************************************************************
>You are currently subscribed to the Radsafe mailing list. To unsubscribe,
>send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
>radsafe" (no quote marks) in the body of the e-mail, with no subject line.
>You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/
>
>
************************************************************************
You are currently subscribed to the Radsafe mailing list. To unsubscribe,
send an e-mail to Majordomo@list.vanderbilt.edu Put the text "unsubscribe
radsafe" (no quote marks) in the body of the e-mail, with no subject line.
You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/