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RE: New York Times - Red Meat Irradiation Rules
Phil and Radsafers,
The question regarding preference of one technique over another, is highly
debated by suppliers of both techniques. The issue is tied to the ability
of said technique to deliver the "legal dose" to the product in an
efficient, effective, and confirm-able manner. The maximum dose permitted
under 21 CFR § 179 is 4.5 kGys for fresh meat, and 7.0 kGys for frozen meat.
The minimum dose continues to be debated, but a multi-log reduction of
E-coli H57:O157 may require a dose of 2.0 to 2.5 kGys. Thus the total
deliverable dose range may be 2.0 to 4.5 kGys for fresh meat; and 2.0 to 7.0
kGys for frozen meat. Now comes the technique mechanical/operational
discussion.
Cobalt 60 gamma facilities are currently designed with a max to min ratio
ranging from 2 to 4, depending upon the target width of the product being
processed. The greater the target width, the greater the dose max/min
ratio... obvious to most scientists, mathematicians and irradiator
operators; but not so obvious to people sitting on the periphery.
(An analogy would be the temperature spread of preparing a turkey vs.
preparing a pork chop. The internal turkey temperature may only reach 180
to 190° F, whereas the external temperature may approach 375°F; a single
pork chop on the other hand might only have a 15 or 20°F variance because of
its relative thin target depth).
Electron beam operators will tell you that they can operate within smaller
max/min ratios, but this is only valid if the product depth is small, i.e.
several centimeters. Thus meat packers (companies) who wish to irradiate
"finished" product in cartons measuring in the 2 to 3 cubic feet range, may
have difficulty processing product with an Electron beam system because of
its inherent limitations of depth of target. This is not to say that
Electron beam is not a technique of choice. My point is that both systems
are of value. The selection is determined by the need of the packer to
process finished or in-situ product - whether this be in final cartons or
via a conveyor where you process the patties prior to carton packing.
This being said, the issue of equipment may now impact the decision. The
construction of either a Cobalt 60 or an Electron beam system, excluding the
building and land, may be in the $5 to 10 million range, depending upon the
features and sophistication of the conveyance system. (Like buying a car
... power windows, CD player, moon roof, etc.) All systems have three key
components: irradiation cell (typically a concrete chamber); mechanical
conveyance equipment; and a source (Cobalt 60, Cesium 137, or Electron
beam). In all three cases; elaborate, redundant safety systems are included
and are a must. The price variance from one system to another is the
throughput capability of the system, the labor saving conveyor handling
system, and the sophistication of the computer controlled tracking system.
All systems will (can) do the job; selecting and installing a system that is
sufficiently efficient to ultimately be cost competitive is fundamental.
In response to the statement about "source disposal" let me assure you and
all Radsafers, that the delivery, installation, tracking and return of
radioactive sources by large scale irradiators is a highly controlled,
highly regulated, tightly focused activity. Each facility is duly licensed
by the US NRC or state regulating agencies. Obtaining and being granted a
"radioactive license" is no small task, and is not for the feint of heart.
And lastly, all major suppliers of radioactive materials (i.e. Cobalt 60)
agree to accept returned, low-level pencils. Their choice is either to
dispose of said pencil, recharge said pencils (very expensive) or
re-encapsulate said pencils into another usable format for alternate uses of
low-energy sources. If the food manufacturer uses a contract irradiation
facility, the total activity of the facility is not an issue for the food
manufacturer; it is the responsibility of the licensee and his supplier.
Sorry to be so long winded about this topic, but while many profess to know
about the commercial use of Cobalt 60 or Electron beam, there are only a
handful of such facilities in the US capable of processing foods, and I felt
that as an operator and RSO of such a facility that you would appreciate the
comments of someone with "hands-on" experience.
Thomas Mates
General Manager and facility RSO
SteriGenics International
714-259-0611
thomasm@tustin.sterigenics.com
The above comments are my own, and are not to be construed to be those of my
company or its assigns.
-----Original Message-----
From: 7pe@ornl.gov [SMTP:7pe@ornl.gov]
Sent: Friday, February 12, 1999 11:14 AM
To: Multiple recipients of list
Subject: RE: New York Times - Red Meat Irradiation Rules
Radsafers,
Is there any opinion out there (loaded question!) as to which
type(s) of
irradiation is preferable over another? My understanding is that
the gamma
sources used in some facilities are of high curie content and that
there
may be less logistical problems (source disposal) by favoring
another
source of the irradiation (some type of radiation generating device
like an
accelerator?).
Perhaps some constructive input to industry and the public could
come from
recommending one process over another for food irradiation.
This is an area I know little about, but am asked questions about it
from
time to time.
Thanks,
Phil Egidi
ORNL/GJ
7pe@ornl.gov
>
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