RENSE.COM


Evidence For CWD/Mad Cow/TSEs
In The Environment

flounder@wt.net
1-29-3

Hello Jeff and Patricia,
 
I hope you don't mind me butting in again, but I see
you are also worried about TSEs and the Environment,
and rightly so. I have done research on this for the
past few years, so I wish to share this data with you.
 
Your story:
 
Admission Of Possible CWD/BSE Contaminated Ground
 
From Patricia Doyle, PhD
http://www.rense.com/general33/contam.htm
 
Now, please let me add my 2 cents worth of support to
this...
 
CWD/TSEs & ENVIRONMENT CONTAMINATION
 
I believe it to be very irresponsible to dispose
of clinical/sub-clinial cases of CWD or any animal
with TSEs in landfills...
 
TSS
 
Aguzzi warns of CWD danger
 
The TSE family of diseases also includes chronic wasting disease (CWD)
in deer, a condition that has spread in the US in recent years (Nature
416, 569; 2002). Speaking at the Days of Molecular Medicine conference
in La Jolla in March, prion expert Adriano Aguzzi issued a strong
warning against underestimating this form of TSE.
 
"For more than a decade, the US has by-and-large considered mad cows
to be an exquisitely European problem. The perceived need to protect
US citizens from this alien threat has even prompted the deferral of
blood donors from Europe," he said. "Yet the threat-from-within
posed by CWD needs careful consideration, since the evidence that CWD
is less dangerous to humans than BSE is less-than-complete. Aguzzi
went on to point out that CWD is arguably the most mysterious of all
prion diseases.
 
"Its horizontal spread among the wild population is exceedingly
efficient, and appears to have reached a prevalence unprecedented even
by BSE in the UK at its peak. The pathogenesis of CWD, therefore,
deserves a vigorous research effort. Europeans also need to think
about this problem, and it would be timely and appropriate to increase
CWD surveillance in Europe too." Aguzzi has secured funding from the
National Institutes of Health to investigate CWD, and the effort will
be lead by Christina Sigurdson in his department at the University of
Zurich. KAREN BIRMINGHAM, LONDON
 
This quote from Dr. Gambetti is especially significant since he is the
rather cautious TSE researcher under contract with the Centers for Disease
Control to examine the brains of individuals who have died of CJD.
-----------------
 
Pierluigi Gambetti, director of the National Prion Disease Pathology
Surveillance Center at Case Western Reserve University in Cleveland,
said all deer should be tested for chronic wasting disease before any
processing is done.
 
"There is no way around it," he said. "Nobody should touch that meat
unless it has been tested."
 
http://www.ledger-enquirer.com/mld/...ion/3954298.htm
 
 
TSEs And The Environment
 
The LANCET
Volume 351, Number 9110 18 April 1998
 
BSE: the final resting place
 
How to dispose of dangerous waste is a question that has vexed the human
race for hundreds of years. The answer has usually been to get it out of
sight--burn it or bury it. In Periclean Athens, victims of the plague
were incinerated in funeral pyres; in 14th century Venice, a law
stipulated that Black Death corpses should be buried to a minimum depth
of 5 feet; and now, as the 20th century draws to a close, we are
challenged by everything from industrial mercury to the smouldering
reactors of decommissioned atomic submarines.
 
The Irish Department of Agriculture will convene an expert panel on
April 27-29 to discuss the disposal of tissues from animals with bovine
spongiform encephalopathy (BSE). Proper disposal of tissues from
infected cattle has implications for both human and animal safety.
Safety for human beings is an issue because there is now unassailable if
still indirect evidence that BSE causes infections in man in the form of
"new variant" Creutzfeld-Jakob disease (nvCJD).1-3 Safety for animals is
also an issue because BSE-affected cattle could possibly transmit
disease to species other than cattle, including sheep, the species that
was almost surely the unwitting source of the BSE epidemic.
 
The first matter to consider is the distribution of infectivity in the
bodies of infected animals. The brain (and more generally, the central
nervous system) is the primary target in all transmissible spongiform
encephalopathies (TSE), and it contains by far the highest concentration
of the infectious agent. In naturally occuring disease, infectivity may
reach levels of up to about one million lethal doses per gram of brain
tissue, whether the disease be kuru, CJD, scrapie, or BSE. The
infectious agent in BSE-infected cattle has so far been found only in
brain, spinal cord, cervical and thoracic dorsal root ganglia,
trigeminal ganglia, distal ileum, and bone marrow.4 However, the much
more widespread distribution of low levels of infectivity in human
beings with kuru or CJD, and in sheep and goats with scrapie, suggests
that caution is advisable in prematurely dismissing as harmless other
tissues of BSE-infected cattle.
 
A second consideration relates to the routes by which TSE infection can
occur. Decades of accumulated data, both natural and experimental, have
shown clearly that the most efficient method of infection is by direct
penetration of the central nervous system; penetration of peripheral
sites is less likely to transmit disease. Infection can also occur by
the oral route, and the ingestion of as little as 1 g of BSE brain
tissue can transmit disease to other cattle.5 Infection by the
respiratory route does not occur (an important consideration with
respect to incineration), and venereal infection either does not occur
or is too rare to be detected.
 
How can tissue infectivity be destroyed before disposal? The agents that
cause TSE have been known almost since their discovery to have awesome
resistance to methods that quickly and easily inactivate most other
pathogens. Irradiation, chemicals, and heat are the three commonest
inactivating techniques. Irradiation has proved entirely ineffective,
and only a handful of a long catalogue of chemicals have produced more
than modest reduction in infectivity. The most active of these are
concentrated solutions of sodium hypochlorite (bleach) or sodium
hydroxide (lye). As for heat, even though the agent shares with most
other pathogens the feature of being more effectively damaged by wet
heat than by dry heat, boiling has little effect, and steam heat under
pressure (autoclaving) at temperatures of 121ºC is not always
sterilising. To date, the most effective heat kill requires exposure of
infectious material to steam heat at 134ºC for 1 h in a porous-load
autoclave.6 Exposure to dry heat even at temperatures of up to 360ºC for
1 h may leave a small amount of residual infectivity.7 The standard
method of incineration, heating to about 1000ºC for at least several
seconds, has been assumed to achieve total sterilisation, but needs
experimental verification in the light of suggestions that rendered
tissue waste might find some useful purpose as a source of heating fuel.
 
Thus, TSE agents are very resistant to virtually every imaginable method
of inactivation, and those methods found to be most effective may, in
one test or another, fail to sterilise. It seems that even when most
infectious particles succumb to an inactivating process, there may
remain a small subpopulation of particles that exhibit an extraordinary
capacity to withstand inactivation, and that, with appropriate testing,
will be found to retain the ability to transmit disease. Also, almost
all available inactivation data have come from research studies done
under carefully controlled laboratory conditions, and it is always
difficult to translate these conditions to the world of commerce. Even
when the data are applied in the commercial process, the repetitive
nature of the process requires vigilance in quality control and
inspection to ensure adherence to its regulations.
 
The final issue that must be addressed is the "lifespan" of the
infectious agent after disposal if it has been only incompletely
inactivated beforehand. Given the extraordinary resistance of the agent
to decontamination measures, the epidemiological and experimental
evidence indicating that TSE agents may endure in nature for a long time
should come as no surprise. The first real clue to this possibility came
from the Icelandic observation that healthy sheep contracted scrapie
when they grazed on pastures that had lain unused for 3 years after
having been grazed by scrapie-infected sheep.8
 
Support for this observation was obtained from an experiment in which
scrapie-infected brain material was mixed with soil, placed in a
container, and then allowed to "weather" in a semi-interred state for 3
years.9 A small amount of residual infectivity was detected in the
contaminated soil, and most of the infectivity remained in the topmost
layers of soil, where the tissue had originally been placed--in other
words, there had been no significant leaching of infectivity to deeper
soil layers.
 
It is therefore plausible for surface or subsurface disposal of
TSE-contaminated tissue or carcasses to result in long-lasting soil
infectivity. Uncovered landfills are a favourite feeding site for
seagulls, which could disperse the infectivity.10 Other animals might do
likewise, and if the landfill site were later used for herbivore
grazing, or tilled as arable land, the potential for disease
transmission might remain. A further question concerns the risk of
contamination of the surrounding water table, or even surface
waste-water channels, by effluents and discarded solid waste from
treatment plants.
 
A reasonable conclusion from existing data is that there is a potential
for human infection to result from environmental contamination by
BSE-infected tissue residues. The potential cannot be quantified because
of the huge number of uncertainties and assumptions that attend each
stage of the disposal process.
 
On the positive side, spongiform encephalopathy can be said to be not
easily transmissible. Although the level of infectivity to which
creatures are exposed is not known, it is probably very low, since sheep
that die from scrapie, cattle that die from BSE, and human beings who
die from nvCJD represent only a small proportion of their respective
exposed populations.
 
Whatever risk exists is therefore extremely small, but not zero, hence
all practical steps that might reduce the risk to the smallest
acceptable level must be considered. What is practical and what is
acceptable are concepts that will be hammered out on the anvil of
politics: scientific input, such as it is, already waits in the forge. A
fairly obvious recommendation, based on the science, would be that all
material that is actually or potentially contaminated by BSE, whether
whole carcasses, rendered solids, or waste effluents, should be exposed
to lye and thoroughly incinerated under strictly inspected conditions.
Another is that the residue is buried in landfills to a depth that would
minimise any subsequent animal or human exposure, in areas that would
not intersect with any potable water-table source. Certainly, it has
been, and will continue to be, necessary in many instances to accept
less than the ideal.
 
Paul Brown
 
Laboratory of Central Nervous System Studies, National Institute of
Neurological Disorders and Stroke, Bethesda, MD 20892, USA
 
1 Will RG, Ironside JW, Zeidler M, et al. A new variant of
Creutzfeldt-Jakob disease in the UK. Lancet 1996; 347: 921-25 [PubMed].
 
2 Bruce M, Will RG, Ironside JW, et al. Transmissions to mice indicate
that 'new variant' CJD is caused by the BSE agent. Nature 1997: 389:
498-501.
 
3 Collinge J, Sidle KCL, Heads J, Ironside J, Hill AF. Molecular
analysis of prion strain variation and the aetiology of 'new variant'
CJD. Nature 1996; 383: 685-90 [PubMed].
 
4 Wells GAH, Hawkins SAC, Green RB, et al. Preliminary observations on
the pathogenesis of experimental bovine spongiform encephalopathy (BSE):
an update. Vet Rec 1998; 142: 103-06 [PubMed].
 
5 Collee JG, Bradley R. BSE: a decade on--part 2. Lancet 1997; 349:
715-21 [PubMed].
 
6 Taylor DM. Exposure to, and inactivation of, the unconventional agents
that cause transmissible degenerative encephalopathies. In: Baker HF,
Ridley RM, eds. Methods in molecular medicine: prion diseases. Totawa
NJ: Humana Press, 1996: 105-18.
 
7 Brown P, Liberski PP, Wolff A, Gajdusek DC. Resistance of scrapie
infectivity to steam autoclaving after formaldehyde fixation and limited
survival after ashing at 360°C: practical and theoretical implications,
J Infect Dis 1990; 161: 467-72 [PubMed].
 
8 Palsson PA. Rida (scrapie) in Iceland and its epidemiology. In:
Prusiner SB, Hadlow WJ, eds. Slow transmissible diseases of the nervous
system, vol I. New York: Academic Press, 1979: 357-66.
 
9 Brown P, Gajdusek DC. Survival of scrapie virus after 3 years'
interment. Lancet 1991; 337; 269-70.
 
10 Scrimgoeur EM, Brown P, Monaghan P. Disposal of rendered specified
offal. Vet Rec 1996; 139: 219-20 [PubMed].
 
http://www.thelancet.com/newlancet/sub/issues/vol351no9110/body.commentary1146.html
 
snip...
 
88. Natural decay: Infectivity persists for a long time in the
environment. A study by Palsson in 1979 showed how scrapie was
contracted by healthy sheep, after they had grazed on
land which had previously been grazed by scrapie-infected sheep, even
though the land had lain fallow for three years before the healthy sheep
were introduced. Brown also quoted an early experiment of his own
(1991), where he had buried scrapie-infected hamster brain and found
that he could still detect substantial infectivity three years later
near where the material had been placed. 89. Potential environmental
routes of infection: Brown discusses the various possible
scenarios, including surface or subsurface deposits of TSE-contaminated
material, which would lead to a build-up of long-lasting infectivity.
Birds feeding on animal remains (such as gulls visiting landfill sites)
could disperse infectivity. Other animals could become vectors if they
later grazed on contaminated land. "A further question concerns
the risk of contamination of the surrounding water table or even surface
water channels, by effluents and discarded solid wastes from treatment
plants. A reasonable conclusion is that there is a potential for human
infection to result from environmental contamination by BSE-infected
tissue residues. The potential cannot be quantified because of the huge
numbers of uncertainties and assumptions that attend each stage of the
disposal process". These comments, from a long established authority on
TSEs, closely echo my own statements which were based on a recent
examination of all the evidence. 90. Susceptibility: It is likely that
transmissibility of the disease to humans in vivo is probably low,
because sheep that die from scrapie and cattle that die from BSE are
probably a small fraction of the exposed population. However, no
definitive data are available.
 
91. Recommendations for disposal procedures: Brown recommends that
material which is actually or potentially contaminated by BSE should be:
1) exposed to caustic soda; 2) thoroughly incinerated under carefully
inspected conditions; and 3) that any residue should be buried in
landfill, to a depth which would minimise any subsequent animal or
human exposure, in areas that would not intersect with any potable
water-table source.
 
92. This review and recommendations from Brown have particular
importance. Brown is one of the world's foremost authorities on TSEs and
is a senior researcher in the US National Institutes of Health (NIH). It
is notable that such a respected authority is forthright in
acknowledging the existence of potential risks, and in identifying the
appropriate measures necessary to safeguard public health.
Paper by SM Cousens, L Linsell, PG Smith, Dr M Chandrakumar, JW
Wilesmith, RSG Knight, M Zeidler, G Stewart, RG Will, "Geographical
distribution of variant CJD in the UK (excluding Northern Ireland)".
Lancet 353:18-21, 2 nd January 1999 93. The above paper {Appendix 41
(02/01/99)} (J/L/353/18) examined the possibility that patients with
vCJD (variant CJD) might live closer to rendering factories than would
be expected by chance. All 26 cases of vCJD in the UK with onset up to
31 st August 1998 were studied. The incubation period of vCJD is not
known but by analogy with other human TSEs could lie within the range
5-25 years. If vCJD had arisen by exposure to rendering products, such
exposure might plausibly have occurred 8-10 years before the
onset of symptoms. The authors were able to obtain the addresses of all
rendering plants in the UK which were in production in 1988. For each
case of vCJD, the distance from the place of residence on 1st January
1998 to the nearest rendering plant was calculated
 
snip...
 
http://www.bseinquiry.gov.uk/files/ws/s019b.pdf
 
Infectivity surviving ashing to 600*C is (in my opinion) degradable but infective.
based on Bown & Gajdusek, (1991), landfill and burial may be assumed to
have a reduction factor of 98% (i.e. a factor of 50) over 3 years.
CJD-infected brain-tissue remained infectious after storing at
room-temperature for 22 months (Tateishi et al, 1988). Scrapie agent is
known to remain viable after at least 30 months of desiccation (Wilson
et al, 1950). and pastures that had been grazed by scrapie-infected
sheep still appeared to be contaminated with scrapie agent three years
after they were last occupied by sheep (Palsson, 1979).
 
http://europa.eu.int/comm/food/fs/sc/ssc/out58_en.pdf
 
PAUL BROWN SCRAPIE SOIL TEST
 
http://www.bseinquiry.gov.uk/files/sc/seac07/tab03.pdf
 
Some unofficial information from a source on the inside looking out -
 
Confidential!!!!
 
As early as 1992-3 there had been long studies conducted on small
pastures containing scrapie infected sheep at the sheep research station
associated with the Neuropathogenesis Unit in Edinburgh, Scotland.
Whether these are documented...I don't know. But personal recounts both
heard and recorded in a daily journal indicate that leaving the pastures
free and replacing the topsoil completely at least 2 feet of thickness
each year for SEVEN years....and then when very clean (proven scrapie
free) sheep were placed on these small pastures.... the new sheep also
broke out with scrapie and passed it to offspring. I am not sure that TSE
contaminated ground could ever be free of the agent!!
A very frightening revelation!!!
 
----------
 
You can take that with however many grains of salt you wish, and
we can debate these issues all day long, but the bottom line,
this is not rocket-science, all one has to do is some
experiments and case studies. But for the life of me,
I don't know what they are waiting on?
 
Kind regards,
 
Terry S. Singeltary Sr.
Bacliff, Texas USA
 
More here:
 
http://www.bseinquiry.gov.uk/files/ws/s018.pdf
 
INCINERATION TEMPS
 
Requirements include:
 
a. after burning to the range of 800 to 1000*C to eliminate smell;
 
well heck, this is just typical public relations fear factor control.
do you actually think they would spend the extra costs for fuel,
for such extreme heat, just to eliminate smell, when they spread
manure all over your veg's. i think not. what they really meant were
any _TSE agents_.
 
b. Gas scrubbing to eliminate smoke -- though steam may be omitted;
 
c. Stacks to be fitted with grit arreaters;
 
snip...
 
1.2 Visual Imact
 
It is considered that the requirement for any carcase incinerator
disign would be to ensure that the operations relating to the reception,
storage and decepitation of diseased carcasses must not be publicly
visible and that any part of a carcase could not be removed or
interfered with by animals or birds.
 
full text;
 
http://www.bseinquiry.gov.uk/files/yb/1989/04/03006001.pdf
 
New studies on the heat resistance of hamster-adapted scrapie agent:
Threshold survival after ashing at 600°C suggests an inorganic template
of replication
 
Paul Brown*, [dagger ] , Edward H. Rau [Dagger ] , Bruce K. Johnson*,
Alfred E. Bacote*, Clarence J. Gibbs Jr.*, and D. Carleton Gajdusek§
 
* Laboratory of Central Nervous System Studies, National Institute of
Neurological Disorders and Stroke, and [Dagger ] Environmental
Protection Branch, Division of Safety, Office of Research Services,
National Institutes of Health, Bethesda, MD 20892; and § Institut Alfred
Fessard, Centre National de la Recherche Scientifique, 91198 Gif sur
Yvette, France
 
Contributed by D. Carleton Gajdusek, December 22, 1999
 
Abstract
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
 
One-gram samples from a pool of crude brain tissue from hamsters
infected with the 263K strain of hamster-adapted scrapie agent were
placed in covered quartz-glass crucibles and exposed for either 5 or 15
min to dry heat at temperatures ranging from 150°C to 1,000°C. Residual
infectivity in the treated samples was assayed by the intracerebral
inoculation of dilution series into healthy weanling hamsters, which
were observed for 10 months; disease transmissions were verified by
Western blot testing for proteinase-resistant protein in brains from
clinically positive hamsters. Unheated control tissue contained 9.9
log10LD50/g tissue; after exposure to 150°C, titers equaled or exceeded
6 log10LD50/g, and after exposure to 300°C, titers equaled or exceeded 4
log10LD50/g. Exposure to 600°C completely ashed the brain samples,
which, when reconstituted with saline to their original weights,
transmitted disease to 5 of 35 inoculated hamsters. No transmissions
occurred after exposure to 1,000°C. These results suggest that an
inorganic molecular template with a decomposition point near 600°C is
capable of nucleating the biological replication of the scrapie agent.
 
transmissible spongiform encephalopathy | scrapie | prion | medical
waste | incineration
 
Introduction
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
 
The infectious agents responsible for transmissible spongiform
encephalopathy (TSE) are notoriously resistant to most physical and
chemical methods used for inactivating pathogens, including heat. It has
long been recognized, for example, that boiling is ineffective and that
higher temperatures are most efficient when combined with steam under
pressure (i.e., autoclaving). As a means of decontamination, dry heat is
used only at the extremely high temperatures achieved during
incineration, usually in excess of 600°C. It has been assumed, without
proof, that incineration totally inactivates the agents of TSE, whether
of human or animal origin. It also has been assumed that the replication
of these agents is a strictly biological process (1), although the
notion of a "virus" nucleant of an inorganic molecular cast of the
infectious [beta ] -pleated peptide also has been advanced (2). In this
paper, we address these issues by means of dry heat inactivation studies.
 
snip...
 
GUTTING DEER/ELK AND THOSE THIN GLOVES;
 
Distribution of prion protein in the ileal Peyer's patch of scrapie-free
lambs and lambs naturally and experimentally exposed to the scrapie agent
 
Ragna Heggeb'z1, Charles McL. Press1, Gjermund Gunnes1, Kai Inge Lie1,
Michael A. Tranulis2, Martha Ulvund3, Martin H. Groschup4 and Thor
Landsverk1
 
Department of Morphology, Genetics and Aquatic Biology1 and Department
of Biochemistry, Physiology and Nutrition2, Norwegian School of
Veterinary Science, PO Box 8146 Dep., N-0033, Oslo, Norway
Department of Sheep and Goat Research, Norwegian School of Veterinary
Science, Kyrkjevegen 332/334, 4300 Sandnes, Norway3
Federal Research Centre for Virus Diseases of Animals, Paul-Ehrlich-Str.
28, 72076 TÃbingen, Germany4
 
Author for correspondence: Charles Press. Fax +47 22964764. e-mail
Charles.Press@veths.no
 
A sensitive immunohistochemical procedure was used to investigate the
presence of prion protein (PrP) in the ileal Peyer?s patch of
PrP-genotyped lambs, including scrapie-free lambs and lambs naturally
and experimentally exposed to the scrapie agent. The tyramide signal
amplification system was used to enhance the sensitivity of conventional
immunohistochemical procedures to show that PrP was widely distributed
in the enteric nervous plexus supplying the gut wall. In scrapie-free
lambs, PrP was also detected in scattered cells in the lamina propria
and in the dome and interfollicular areas of the Peyer?s patch. In the
follicles, staining for PrP was mainly confined to the capsule and cells
associated with vascular structures in the light central zone. In lambs
naturally exposed to the scrapie agent, staining was prominent in the
dome and neck region of the follicles and was also found to be
associated with the follicle-associated epithelium. Similar observations
were made in lambs that had received a single oral dose of
scrapie-infected brain material from sheep with a homologous and
heterologous PrP genotype 1 and 5 weeks previously. These studies show
that the ileal Peyer?s patch in young sheep may be an important site of
uptake of the scrapie agent and that the biology of this major
gut-associated lymphoid tissue may influence the susceptibility to oral
infection in sheep. Furthermore, these studies suggest that homology or
heterology between PrP genotypes or the presence of PrP genotypes seldom
associated with disease does not impede uptake of PrP.
======================================================
 
BSE, KURU, DENTAL AND ___CUT ABRASIONS___ from gutting a deer
perhaps;
 
snip...
 
Since there was a suggestion that kuru had been transmitted
through the gums and/or gum abrasions...
 
snip...
 
http://www.bseinquiry.gov.uk/files/yb/1989/04/17005001.pdf
 
[PDF]BSE INQUIRY Statement of behalf of the Environment Agency ...
File Format: PDF/Adobe Acrobat - View as HTML
... his Statement of March 1998 to the BSE Inquiry ... systems subject
to regular or intermittent
contamination by rapid movement of recharge water ...
www.bse.org.uk/files/ws/s490.pdf
 
http://www.bseinquiry.gov.uk/files/ws/s490.pdf
 
BSE INQUIRY
 
Statement of behalf of the Environment Agency
Concerning Thruxted Mill
By
Mr C. P. Young
Principal Hydrogeologist, Soil Waste and Groundwater Group
WRc plc; Medmenham, Bucks
 
http://www.bseinquiry.gov.uk/files/ws/s490.pdf
 
Very important to those hunters looking for healthy
deer/elk to eat...TSS
 
MRC-43-00 [ ] [Text only version of this site] [Print this page]
Issued: Monday, 28 August 2000
NEW EVIDENCE OF SUB-CLINICAL PRION INFECTION: IMPORTANT RESEARCH
FINDINGS RELEVANT TO CJD AND BSE
 
A team of researchers led by Professor John Collinge at the Medical
Research Council Prion Unit1 report today in the Proceedings of the
National Academy of Sciences, on new evidence for the existence of a
'sub-clinical' form of BSE in mice which was unknown until now.
 
The scientists took a closer look at what is known as the 'species
barrier' - the main protective factor which limits the ability of
prions2 to jump from one species to infect another. They found the mice
had a 'sub-clinical' form of disease where they carried high levels of
infectivity but did not develop the clinical disease during their normal
lifespan. The idea that individuals can carry a disease and show no
clinical symptoms is not new. It is commonly seen in conventional
infectious diseases.
 
Researchers tried to infect laboratory mice with hamster prions3 called
Sc237 and found that the mice showed no apparent signs of disease.
However, on closer inspection they found that the mice had high levels
of mouse prions in their brains. This was surprising because it has
always been assumed that hamster prions could not cause the disease in
mice, even when injected directly into the brain.
 
In addition the researchers showed that this new sub-clinical infection
could be easily passed on when injected into healthy mice and hamsters.
 
The height of the species barrier varies widely between different
combinations of animals and also varies with the type or strain of
prions. While some barriers are quite small (for instance BSE easily
infects mice), other combinations of strain and species show a seemingly
impenetrable barrier. Traditionally, the particular barrier studied here
was assumed to be robust.
 
Professor John Collinge said: "These results have a number of important
implications. They suggest that we should re-think how we measure
species barriers in the laboratory, and that we should not assume that
just because one species appears resistant to a strain of prions they
have been exposed to, that they do not silently carry the infection.
This research raises the possibility, which has been mentioned before,
that apparently healthy cattle could harbour, but never show signs of, BSE.
 
"This is a timely and unexpected result, increasing what we know about
prion disease. These new findings have important implications for those
researching prion disease, those responsible for preventing infected
material getting into the food chain and for those considering how best
to safeguard health and reduce the risk that theoretically, prion
disease could be contracted through medical and surgical procedures."
 
ISSUED FRIDAY 25 AUGUST UNDER EMBARGO. PLEASE NOTE THAT THE EMBARGO IS
SET BY THE JOURNAL.
 
FOR FURTHER INFORMATION CONTACT THE MRC PRESS OFFICE ON 020 7637 6011
(OFFICE HOURS) OR 07818 428297 OR 0385 774357 (OUT-OF-OFFICE-HOURS) OR
PROFESSOR JOHN COLLINGE ON 020 7594 3760. PLEASE NOTE THAT OWING TO
TRAVEL COMMITMENTS PROFESSOR COLLINGE WILL ONLY BE AVAILABLE UNTIL 16.30
ON FRIDAY 25 AUGUST AND CONTACTABLE AGAIN ON MONDAY 28 AUGUST VIA THE
MRC PRESS OFFICE. DR ANDREW HILL (A CO-AUTHOR ON THE PAPER) FROM THE
DEPARTMENT OF PATHOLOGY AT THE UNIVERSITY OF MELBOURNE WILL BE AVAILABLE
ON 00 61 3 8344 3995 (DURING OFFICE HOURS) OR 00 61 3 9443 0009
(OUT-OF-OFFICE HOURS). PLEASE NOTE THAT AUSTRALIA IS TEN HOURS AHEAD OF
UK TIME.
 
NOTES FOR EDITORS
 
Professor Collinge is a consultant neurologist and Director of the newly
formed MRC Prion Unit based at The Imperial College School of Medicine
at St Mary's Hospital. He is also a member of the UK Government's
Spongiform Encephalopathy Advisory Committee (SEAC). The MRC prion unit
is was set up in 1999, and its work includes molecular genetic studies
of human prion disease and transgenic modelling of human prion diseases.
 
Prions are unique infectious agents that cause fatal brain diseases such
as Creutzfeldt-Jakob disease (CJD) in humans and scrapie and BSE (mad
cow disease) in animals. In some circumstances prions from one species
of animals can infect another and it is clear that BSE has done this to
cause the disease variant CJD in the UK and France. It remains unclear
how large an epidemic of variant CJD will occur over the years ahead.
 
The strain of prion used here to infect the mice is the Sc237 strain
(also known as 263K) which infects hamsters, and until now was assumed
not to infect mice.
 
This research was funded by the Medical Research Council and Wellcome Trust.
 
The Medical Research Council (MRC) is a national organisation funded by
the UK tax-payer. Its business is medical research aimed at improving
human health; everyone stands to benefit from the outputs. The research
it supports and the scientists it trains meet the needs of the health
services, the pharmaceutical and other health-related industries and the
academic world. MRC has funded work which has led to some of the most
significant discoveries and achievements in medicine in the UK. About
half of the MRC's expenditure of £345 million is invested in over 50 of
its Institutes and Units, where it employs its own research staff. The
remaining half goes in the form of grant support and training awards to
individuals and teams in universities and medical schools.
 
The Wellcome Trust is the world's largest medical research charity with
a spend of some £600 million in the current financial year 1999/2000.
The Wellcome Trust supports more than 5,000 researchers, at 400
locations, in 42 different countries to promote and foster research with
the aim of improving human and animal health. As well as funding major
initiatives in the public understanding of science, the Wellcome Trust
is the country's leading supporter of research into the history of medicine.
 
©2002 Medical Research Council
Data Protection policy | Contact the MRC
=========================================
 
Subject: OPINION ON THE USE OF BURIAL FOR DEALING WITH ANIMAL CARCASSES AND OTHER ANIMAL MATERIALS THAT MIGHT CONTAIN BSE/TSE
Date: Wed, 22 Jan 2003 14:58:53 -0600
From: "Terry S. Singeltary Sr." <flounder@WT.NET>
Reply-To: Bovine Spongiform Encephalopathy <BSE-L@uni-karlsruhe.de>
To: BSE-L@uni-karlsruhe.de
 
######## Bovine Spongiform Encephalopathy <BSE-L@UNI-KARLSRUHE.DE> #########
 
C:\WINNT\Profiles\bredagi.000\Desktop\Burial_OPINION_0301_OPINION_FINAL.doc
EUROPEAN COMMISSION
HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL
Directorate C - Scientific Opinions
C1 - Follow-up and dissemination of scientific opinions
OPINION ON
THE USE OF BURIAL FOR DEALING WITH ANIMAL
CARCASSES AND OTHER ANIMAL MATERIALS THAT
MIGHT CONTAIN BSE/TSE
ADOPTED BY THE
SCIENTIFIC STEERING COMMITTEE
MEETING OF 16-17 JANUARY 2003
1
OPINION
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to advice on the examples of conditions under which
safe burial of potentially TSE-infected (animal) materials can be
achieved. The details of the SSC's evaluation are provided in the
attached report. The SSC concludes as follows:
(1) The term "burial" includes a diversity of disposal conditions.
Although burial is widely used for disposal of waste the degradation
process essential for BSE/TSE infectivity reduction is very difficult to
control. The extent to which such an infectivity reduction can occur as
a consequence of burial is poorly characterised.
It would appear to be a slow process in various circumstances.
(2) A number of concerns have been identified including potential for
groundwater contamination, dispersal/transmission by
birds/animals/insects, accidental uncovering by man.
(3) In the absence of any new data the SSC confirms its previous opinion
that animal material which could possibly be contaminated with BSE/TSEs,
burial poses a risk except under highly controlled conditions (e.g.,
controlled landfill). The SSC reiterates the consideration made in its
opinion of 24-25 June 1999 on "Fallen Stock"1. The limited capacity for
destruction of animal wastes in certain countries or regions in the
first place justifies the installation of the required facilities; it
should not be used as a justification for unsafe disposal practices such
as burial. However, the SSC recognises that for certain situations or
places or for certain diseases (including animals killed and recycled or
disposed of as a measure to control notifiable diseases), the available
rendering or incinerator or disposal capacity within a region or country
could be a limiting factor in the control of a disease. Thus if hundreds
or even millions of animals need to be rendered after killing or if the
transport of a material to a rendering or disposal plant proved to be
impractical, an appropriate case by case risk assessment2 should be
carried out before deciding upon the most appropriate way of disposal.
In principle, the risk is expected to be the lower for small
incinerators3 as compared to burial. As such decisions in practice may
have to be taken at very short notice, risk management scenarios
according to various possible risks should be prepared in advance to
allow for a rapid decision when the need arises.
 
1 Scientific Opinion on The risks of non conventional transmissible
agents, conventional infectious agents or other hazards such as toxic
substances entering the human food or animal feed chains via raw
material from fallen stock and dead animals (including also: ruminants,
pigs, poultry, fish, wild/exotic/zoo animals, fur animals, cats,
laboratory animals and fish) or via condemned materials.
Adopted By the Scientific Steering Committee at its meeting of 24-25
June 1999. (and re-edited at its meeting of 22-23 July 1999).
2 See also the relevant sections and footnotes on risk assessment in the
report accompanying the SSC opinion of 24-25 June 1999.
3 See SSC opinion of 16-17 January 2003 on the use of small incinerators
for BSE risk reduction.
2
 
THE USE OF BURIAL FOR DEALING WITH CARCASSES AND OTHER MATERIALS THAT
MIGHT CONTAIN BSE/TSE
REPORT
 
1. MANDATE
 
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to advice on the examples of conditions under which
safe burial of potentially TSE-infected animal materials can be
achieved. The SSC appointed Prof.J.Bridges as rapporteur. His report was
discussed and amended by the TSE/BSE ad hoc Group at its meeting of 9
January 2003 and by the SSC at its meeting of 16-17 January 2003.
 
2. GENERAL CONSIDERATIONS
 
"Burial" covers a range of disposal situations ranging from the practice
of burying animals on farms and other premises in a relatively shallow
trench (with or without treatment such as lining) to deep disposal to a
lined and professionally managed landfill site (SSC 2001).
Buried organic material is normally decomposed by microbial and chemical
processes. However this is not a process amenable to control measures.
As noted by the SSC "Opinion on Fallen Stock" (SSC 25th June 1999) there
is little reliable information on the extent and rate of infectivity
reduction of BSE/TSEs following burial. An old paper by Brown and
Gajdusek 1991 assumed a reduction of 98% over 3 years. However it is
noted that the rate of degradation of materials following burial can
vary very considerably between sites. This is not surprising because the
degradation process is strongly influenced by factors such as water
content of the site, temperature inside the site, nature of adsorptive
"material" present etc. The previous SSC opinion noted that BSE/TSEs
appear to be resistant to degradation when stored at room temperature
over several years. It also raised concerns that mites could serve as a
vector and/or reservoir for the infected scrapie material.
Burial sites may have a thriving animal population. Uncovering of risk
material that is not deeply buried is therefore possible.
The SSC in its opinion of 28th-29th June 2001 set out a framework for
assessing the risk from different waste disposal processes. These
criteria may be applied to
burial as follows:
 
(1) Characterisation of the risk materials involved.
 
Unlike many other waste disposal options there are no technical or
economic factors that would limit the nature of the material that can be
disposed of by burial. Moreover in many cases the location of burial
sites is uncertain. The potential for transmission of BSE/TSEs for SRM
that is buried near the surface is also poorly characterised.3
 
(2) Risk reduction.
 
The extent to which the infectivity is reduced is likely to vary
substantially according to the nature of the site depth of burial
whether pre-treatment by burning or through the addition of lime is used
etc. There appears to be no scientific basis at present for the
prediction of the rate of loss of infectivity. In the absence of such
data, as a worst case, it has to be assumed that over a three-five year
period the loss of infectivity may be slight. In principle on a
well-managed fully contained landfill the risks from infective material
can approach zero. However this requires rigorous management over many
years. This is difficult to guarantee.
 
(3) Degree to Which the Risks can be Contained
 
The principal concerns are:
 
* Prevention of access to the SRM by animals that could result in the
transmission (directly or indirectly) of the BSE/TSE.
 
* Penetration of prions into the leachate/groundwater. It is noted that
on some landfill sites leachate is sprayed into the air to facilitate
oxidation of some organic components. Such a practice could in principle
lead to dispersal of BSE/TSEs. It is also noted that it is not uncommon
for landfill sites to be re-engineered to increase their stability, gas
and leachate flow and/or total capacity. If this re-engineering involved
an area where previous burial of BSE/TSE contaminated material had taken
place and additional risk could accrue. The possibility of contaminated
material being dug up in shallow and unmarked burial sites on farms etc
constitutes a considerably greater risk.
 
3. FURTHER INVESTIGATIONS
 
Research is needed on specific aspects of the behaviour of prion like
molecules in controlled landfills i.e.:
 
* Potential for adsorption to other material present in the waste that
might limit their mobility.
 
* Principal factors influencing rates of degradation.
 
* Effectiveness of encasement in cement in controlling/reducing the risk.
 
4. CONCLUSION
 
In the absence of new evidence the opinion of the SSC "Opinion on Fallen
Stock" (SSC 25th June 1999) must be endorsed strongly that land burial
of all animals and material derived from them for which there is a
possibility that they could incorporate BSE/TSEs poses a significant
risk. Only in exceptional circumstances where there could be a
considerable delay in implementing a safe means of disposal
should burial of such materials be considered. Guidelines should be made
available to aid on burial site selection.
 
http://europa.eu.int/comm/food/fs/sc/ssc/out309_en.pdf
 
C:\WINNT\Profiles\bredagi.000\Desktop\Burning_OPINION_0301_OPINION_FINAL.doc
 
EUROPEAN COMMISSION
HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL
Directorate C - Scientific Opinions
C1 - Follow-up and dissemination of scientific opinions
 
OPINION ON
 
OPEN BURNING OF POTENTIALLY TSE-INFECTED ANIMAL
MATERIALS
 
ADOPTED BY THE
SCIENTIFIC STEERING COMMITTEE
AT ITS MEETING OF 16-17 JANUARY 2003
 
2
OPINION
 
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to advice on the examples of conditions under which
safe burning of potentially TSE-infected (animal) materials can be
achieved. The details of the SSC's evaluation are provided in the
attached report. The SSC concludes as follows:
 
(1) "Burning" covers a wide variety of combustion conditions. This
opinion is concerned with the process of open burning e.g. bonfires.
 
(2) There are serious concerns regarding the use of open burning for the
destruction of pathogen contaminated animal waste, particularly for
waste which may be contaminated with relatively heat stable pathogens.
Issues include: the potentially very high variability of the pathogen
inactivation, the nature of the gaseous and particulate emissions, and
the risks from the residual ash.
 
(3) The SSC recommends that open burning is only considered for pathogen
destruction under exceptional circumstances following a specific risk
assessment. In the case of animal waste possibly contaminated with
BSE/TSE in view of the uncertainty of the risk open burning should be
considered a risk. Suitable monitoring methods for TSE contamination of
both air and ash are needed. Protocols for safe burning in emergency
situations need to be established. The SSC reiterates the consideration
made in its opinion of 24-25 June 1999 on "Fallen Stock"1. The limited
capacity for destruction of animal wastes in certain countries or
regions in the first place justifies the installation of the required
facilities; it should not be used as a justification for unsafe disposal
practices such as burial. However, the SSC recognises that for certain
situations or places or for certain diseases (including animals
killed and recycled or disposed of as a measure to control notifiable
diseases), the available rendering or incinerator or disposal capacity
within a region or country could be a limiting factor in the control of
a disease. Thus if hundreds or even millions of animals need to be
rendered after killing or if the transport of a material to a rendering
or disposal plant proved to be impractical, an appropriate case by case
risk assessment2 should be carried out before deciding upon the most
appropriate way of disposal. In principle, the risk is expected to be
the lower for small incinerators3 as compared to open burning. As
such decisions in practice may have to be taken at very short notice,
risk management scenarios according to various possible risks should be
prepared in advance to allow for a rapid decision when the need arises.
1 Scientific Opinion on The risks of non conventional transmissible
agents, conventional infectious agents or other hazards such as toxic
substances entering the human food or animal feed chains via raw
material from fallen stock and dead animals (including also: ruminants,
pigs, poultry, fish, wild/exotic/zoo animals, fur animals, cats,
laboratory animals and fish) or via condemned materials.
Adopted By the Scientific Steering Committee at its meeting of 24-25
June 1999. (and re-edited at its meeting of 22-23 July 1999).
2 See also the relevant sections and footnotes on risk assessment in the
report accompanying the SSC opinion of 24-25 June 1999.
3 See SSC opinion of 16-17 January 2003 on the use of small incinerators
for BSE risk reduction.
3
 
OPEN BURNING OF POTENTIALLY TSE-INFECTED ANIMAL MATERIALS
REPORT
 
1. MANDATE
 
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to advice on the examples of conditions under which
safe burning of potentially TSE-infected animal materials can be
achieved. The SSC appointed Prof.J.Bridges as rapporteur. His report was
discussed and amended by the TSE/BSE ad hoc Group at its meeting of 9
January 2003 and by the SSC at its meeting of 16-17 January 2003.
 
2. GENERAL CONSIDERATIONS
 
Burning is a combustion process to which a range of control measures may
be applied to contain emissions and to ensure the completeness of the
degradation process for organic matter. Depending on the source (waste)
material the burning process may or may not require addition of other
energy sources. Incineration/pyrolysis are contained combustion
processes are contained combustion processes and therefore have the
potential for a high level of control.
(However see opinion on small incinerators). At the other end of the
control spectrum is open burning; such as bonfires.
Typically combustion of animal waste requires the addition of a high
calorific fuel in order to initiate (and for some materials to sustain)
the process. It is recognised that open burning of animal waste is a
very cheap and convenient method of disposal. However uncontained
burning has a number of problems in terms of the potential risks involved:
 
(1) In the open burning situation a range of temperatures will be
encountered. It is difficult therefore to ensure complete combustion of
the animal waste. If the waste is contaminated with pathogens there will
remain considerable uncertainty as to the degree of their inactivation.
 
(2) Gaseous and particulate emissions to the atmosphere will occur and
consequently worker and public exposure is likely. There is very little
data to indicate whether or not some pathogens could be dispersed to air
as a consequence of open burning.
 
(3) The supporting/secondary fuel may be a source of contamination
itself. For example in the recent foot and mouth disease outbreak in the
UK timbers were used at some sites that were heavily contaminated with
pentachlorophenol.
 
(4) The residual ash must be considered to be a risk source. Its safe
disposal needs to be assured (see opinion on small incinerators) to
prevent human and animal contact and protect from groundwater
contamination. While careful selection of burning sites can reduce the
risks open burning should only be considered in emergency situations.
For each such emergency situation a specific risk assessment should be
conducted which must include the risk 4 from the pathogen of immediate
concern but also other pathogens that might be present.
 
3. RISK ASSESSMENT OF OPEN BURNING FOR BSE
 
The SSC, at its meeting of 28th-29th June 2001, recommended "a framework
for the assessment of the risk from different options for the safe
disposal or use of meat and bone meal (MBM) and other products which
might be contaminated with TSEs and other materials. Applying the
framework to the practice of open burning, the following conclusions can
be drawn:
 
3.1. Nature of the materials handled
Potentially a wide variety of materials can be used provided suitable
secondary fuel is available. The burning process is very simple in
principle and difficult in practice to regulate effectively.
 
3.2. Risk reduction due to open burning There is no reliable data to
indicate the extent of risk reduction that could be achieved by open
burning. It is reasonable however to assume that overall it
will be rather less effective in reducing the infectivity of BSE/TSE
than wellconducted incineration. Moreover the reproducibility of the
risk reduction is likely to be very variable even at a single location.
 
3.3. Airborne emissions and residue ash The composition of airborne
emissions and residue ash is rarely monitored. From a risk assessment
viewpoint particular attention needs to be given to the potential for
the airborne dispersal of relatively heat stable pathogens as a
consequence of open burning. In the absence of reliable data both
airborne emissions and residual ash must be considered to constitute a
significant risk if animal waste that might be contaminated with TSEs is
being burnt.
 
4. FURTHER INVESTIGATION
 
Research is needed particularly on:
* The potential for airborne dispersal of relatively heat stable pathogens.
* Methodologies to improve the efficacy of the combustion process to
ensure the inactivation of pathogen contaminated animal waste.
 
5. CONCLUSION
 
Open burning potentially represents a significant risk where the animal
waste has the possibility of being contaminated with BSEs/TSEs. Suitable
monitoring methods for TSE contamination of both air and ash are needed.
Protocols for safe burning in emergency situations need to be established.
 
http://europa.eu.int/comm/food/fs/sc/ssc/out310_en.pdf
 
C:\WINNT\Profiles\bredagi.000\Desktop\Incinerator_OPINION_0301_FINAL.doc
 
EUROPEAN COMMISSION
HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL
 
Directorate C - Scientific Opinions
C1 - Follow-up and dissemination of scientific opinions
OPINION ON
 
THE USE OF SMALL INCINERATORS FOR BSE RISK REDUCTION
 
SCIENTIFIC STEERING COMMITTEE
MEETING OF 16-17 JANUARY 2003
 
2
OPINION
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to (i) evaluate a risk assessment1 prepared for the
UK's Spongiform Encephalopathy Advisory Committee (SEAC), on the
potential risk arising from the use of small incinerators to dispose of
specified risk materials and (ii) to advise on the safety
with regard to TSE risks of the use of such small incinerators.
 
The details of the SSC's evaluation are provided in the attached report.
The SSC concludes as follows:
 
(i) The SSC, at its meeting of 28th -29th June 2001, recommended "a
framework for the assessment of the risk from different options for the
safe disposal or use of meat and bone meal (MBM) and other products
which might be contaminated with TSEs and other materials." This
framework comprised five components:
 
(1) Identification and characterisation of the risk materials involved,
the possible means for their transmission and potential at risk groups.
 
(2) The risk reduction achieved by the particular process.
 
(3) The degree to which the risks can be contained under both normal and
emergency operating conditions. This inevitably includes consideration
of the effectiveness of control measures.
 
(4) Identification of interdependent processes for example transport,
storage, loading of any TSE related risk materials.
 
(5) The intended end-use of the products for example disposal, recycling
etc. The risk assessment prepared for SEAC focuses on the risks involved
steps 1 and 2 in respect of BSE/TSEs only and is based on a visit to 10
incinerators out of a total of 263 in the UK of which 60% had after
burners. The risk assessment is also using a number of assumptions and
data that may be valid for certain incinerator types under certain
conditions, but are not necessarily applicable either for all types of
materials to be disposed of, or to the whole range of types of small
incinerators in use the EU and the UK.
 
(ii) Small incinerators are widely used to meet the needs of local
communities. These incinerators vary greatly in their design, nature of
use and performance characteristics and the quality of their management.
As a consequence of this variability there are many uncertainties in
identifying risks posed by small incinerators that are used to treat SRM
materials and each type should eventually receive its own assessment.
Also, general operating and control criteria should be established for
 
1 DNV Consulting (Det Norske Veritas), 2001. Risk assessment of SRM
incinerators. Prepared for the UK Ministry of Agriculture, Fisheries and
Food. Revision 2 of the Draft report, February 2001. 24
pages. 3
 
Potential risk sources arising from the incineration process include:
gaseous emissions and residual ash. Research is currently ongoing
mimicking incineration of TSE-infected brain tissue to assess the
infectivity clearance level under various scenarios2. However, there are
no final reported measurements that enable the risk to be assessed from
either the emissions or the ash from small incinerators. It has
been argued that the protein content of the ash is a reasonable
surrogate measure of the degree of risk deduction caused by the
incineration process. This assumption is questionable in view of the
resistance to heat of prions as compared to other proteins. Protein
measurements in ash are however probably a useful general
measure of the overall efficiency and reproducibility of the
incineration process. Results in the aforementioned report1 indicate a
large degree of variability in performance among the small incinerators
in the UK that have been evaluated. It is anticipated that small
incinerators, used by other Member States will also show a
considerable variation in performance. In evaluating the risk of small
incinerators, consideration should be given to the risk of potential
contamination of the ash and of the gaseous emissions.
In the absence of generally accepted and enforced performance standards
for small incinerators handling SRMs each such facility therefore needs
to be the subject of a specific risk assessment. The SSC considers that
the standards set up by the new Waste Incinerator Directive (2000/76/EC)
and in its opinion of June 1999 on waste disposal should serve as
guidance. In the absence of reliable data on the possible residual
infectivity of the ash, it should be disposed of, i.e., in controlled
landfills as described in the SSC opinion of June 1999 on safe disposal
of waste. The SSC finally wishes to emphasise the need for suitable
monitoring methods in order that risks can be assessed readily for
individual types of small incinerators.
2 P.Brown, pers.comm., December 2002. Publication in progress.4
 
THE USE OF SMALL INCINERATORS FOR BSE RISK REDUCTION
REPORT
 
1. MANDATE
 
On 17 May 2002, the Scientific Steering Committee (SSC) was invited by
Commission Services to (i) evaluate a risk assessment3 prepared for the
UK's Spongiform Encephalopathy Advisory Committee (SEAC), on the
potential risk arising from the use of small incinerators to dispose of
specified risk materials and (ii) to advise on the safety with regard to
TSE risks of the use of such small incinerators.
 
The SSC appointed Prof. J. Bridges as rapporteur. His report was discussed
and amended by the TSE/BSE ad hoc Group at its meeting of 9 January 2003
and by the SSC at its meeting of 16-17 January 2003.
 
2. CURRENT LEGISLATIVE FRAMEWORK
 
Until 2000, small incinerators were exempt from the emission limits set
by the EC for MSW and hazardous waste incinerators with throughputs
greater than 50 kg/hour. An "incineration plant" is defined by the new
Incineration of Waste Directive (2000/76/EC) as "any stationary or
mobile technical equipment dedicated to the thermal treatment of waste
with or without recovery of the combustion heat generated". This
definition would appear to exclude open burning of waste. The
new Directive, which must be transposed into the legislation of each
Member State by December 2002, replaces a range of previous directives
on incineration. It applies to all new incinerator installations from
December 28th 2002 and all existing installations from December 28th
2005. The principal aim of the Directive is to prevent and/or limit
negative environmental effects due to emissions into air, soil,
surface and ground water and the resulting risks to human health from
the incineration and co-incineration of waste. It covers many aspects
from a requirement for afterburners to airborne emission limits and
criteria for the composition of residual ash. Previous EC legislation
has exempted small incinerators (i.e. those operating at less than 50 kg
per hour). The Waste Incinerator Directive (WID) (2000) allows such
small incinerators to be exempt from licensing at the national level
however they will still be subjected to the same onerous
requirements of the WID as larger incinerators.
 
In the UK it is proposed that in future incinerators dealing with
non-hazardous waste but with a throughput of less than 1 tonne per hour
will be regulated by local authorities whereas those with a larger
throughput will be regulated by the national authority. It is possible
that different regulatory mechanisms may result in differences in the
rigour with which the new standards are enforced. The position
on the disposal of animal waste is complicated. Animal carcass
incineration use not covered by the WID and therefore the existing
regulatory framework (90/66/EEC which covers animal and public health
requirements to ensure destruction of pathogens) will continue to be
applied. A new Animal By-Products Regulation
 
3 DNV Consulting (Det Norske Veritas), 2001. Risk assessment of SRM
incinerators. Prepared for the UK Ministry of Agriculture, Fisheries and
Food. Revision 2 of the Draft report, February 2001. 24
pages.
5
 
(ABPR) will apply in Member States during the first part of 2003. The
relationship to WID has been included in the ABPR. It is important that
it does not result in less strict standards being applied for animal
carcass incineration. In contrast to whole carcasses WID will apply to
the burning of meat and bone meal, tallow or other material (even if
they burn animal carcasses too). Additional specific directives will
continue to apply to waste that could be contaminated with BSE/TSEs.
(96/449/EC)
 
3. CURRENT USE OF SMALL INCINERATORS TO DISPOSE OF ANIMAL WASTE
Small incinerators are used for a variety of purposes and in a range of
locations among Member States. Many are located alongside small
abattoirs, knackers, hunt kennels, or laboratories. Thus they meet the
needs of relatively small communities. Across Member States these small
incinerators include a variety of designs and operating conditions (as
indicated above in principle they will probably be required
to meet specific standards for emissions and for the composition of the
residual ash by December 28th 2005).
In the UK there are indications (see DNV Report 2001) that a
considerable quantity of SRM which would have previously been sent for
rendering is now being incinerated directly in small incinerators. Thus
evaluation of the risks from such incinerators is of increasing importance.
 
4. RISK ASSESSMENT FOR SMALL INCINERATORS
 
The SSC, at its meeting of 28th -29th June 2001, recommended "a
framework for the assessment of the risk from different options for the
safe disposal or use of meat and bone meal (MBM) and other products
which might be contaminated with TSEs and other materials.
This framework comprised five components:
 
(1) Identification and characterisation of the risk materials involved,
the possible means for their transmission and potential at risk groups.
 
(2) The risk reduction achieved by the particular process.
 
(3) The degree to which the risks can be contained under both normal and
emergency operating conditions. This inevitably includes consideration
of the effectiveness of control measures.
 
(4) Identification of interdependent processes for example transport,
storage, loading of any TSE related risk materials.
 
(5) The intended end-use of the products for example disposal, recycling
etc. Recently a report has been prepared by DNV consulting (2001) for
the UK Ministry of Agriculture, Fisheries and Food (now known as DEFRA)
that assesses the risks from small incinerators in the UK that receive
SRMs. This report focuses on the risks involved steps 1 and 2 in respect
of BSE/TSEs only. 10 incinerators out of a total of 263 in the UK were
visited of which 60% had after burners.
 
(1) Nature of the materials handled.
 
The DNV report 2001 starts with the assumption that "the materials
incinerated at small abattoirs will be mainly SRM and bones from animals
that are fit for human consumption. It may also include material from
animals failed by meat inspectors. The likelihood of there being an animal
6 with significant BSE infectivity is very small and certainly much less
than for the fallen stock handled by hunt kennels and knackers4. For
this reason the study has concentrated on the latter type of operation".
The Report notes that "the material handled by both knacker and hunt
kennels is highly variable and difficult to characterise". In terms of
input the key factors to consider are:
 
* The number of adult bovines processed and the proportion of these
carcasses that are likely to be infected.
 
* The extent of infectivity (in terms of human oral Infectious Units)
that may occur (average and worst case).
 
In the DNV (2001) risk assessment only the BSE risk from processing
bovine SRMs was considered. For quantitative risk assessment purposes
the mean value of the oral ID50 for cattle was taken as 0.1 gram. A
range of values was taken to cover uncertainty in the inter-species
barrier from 104 to 1 (as recommended by the SSC 2000). In order to
assess the likelihood that a particular carcass could be infected, UK
and Swiss monitoring data was used. An incidence rate based on Prionics
test findings of between 0.013 and 0.0025 was calculated. The DNV Report
notes that prevalence rates are progressively reducing from these
1998/99 figures. Finally the report concludes that the SRM from an
infected bovine could contribute 700 Infectious Units.
 
(2) Risk reduction due to incineration
 
Once a carcass/SRM has been introduced into a small incinerator there
are two main sources for the potential release of BSE infectivity
 
(a) Airborne emissions
(b) Residual ash
 
There is no direct data on the TSE levels that may occur in those two
media. The SSC however is aware of currently ongoing heat studies
mimicking various incineration conditions and scenarios and aiming at
assessing the TSE clearance efficacy of these processes (P.Brown,
pers.comm., 16.01.03) on both the residual ash and the trapped emission
gases. In the absence of final data from such experiments for individual
(small) incinerator types, the DNV Report (2001) assumes that
measurement of the total protein content of ash is a relevant surrogate
for BSE/TSE material. Protein content is a useful indicator of the
general performance of an incinerator. However it is much more
problematic whether it is also a valid marker for possible BSE/TSE
contamination as it known that BSE/TSE are relatively heat resistant as
compared to other proteins. Failure to detect certain amino acids
present in prions is encouraging but the sensitivity limits
for amino acids are relatively poor for reassurance purposes. Equally
important, the data provided in the DNV report shows moderate split sample
4 It may be mentioned that this assumption may be valid for the UK as a
whole, but note necessarily for all other Member States. 7
variation but often substantial inter sampling variation (up to 600
fold). This indicates a wide span of performance standards among the
small SRM incinerators in the UK and most likely across the whole of the
EU. Typically performance was substantially poorer than is the case for
larger incinerators. Unburned material is not uncommonly noted in the
ash from small incinerators. If the reduction in protein content due to
incineration is accepted as a valid indicator, typical infectivity
reduction can be calculated to be of the order of 1600 (DNV Report
2001). Incinerators are known to emit particulate matter from their
stacks. Larger incinerators have much higher stacks to facilitate
disposal of emissions, they also have gas cleaning equipment to minimise
the emission of particulate matter, metals and acidic gases. Small
incinerators generally do not have any gas cleaning equipment. It can be
speculated (as in the DNV Report 2001) that unburned materials (and
therefore potentially infections is much less likely to be emitted in
the form of particulate matter than burnt material.
Nonetheless there is no data to support this assumption.
 
(3) Other considerations.
 
(a) Disposal of ash.
 
In the case of small incinerators ash is often dispersed of locally to a
trench, which is typically neither lined, nor is the residue buried
deeply. In contrast for larger incinerators in the UK ash is normally
disposed of to a contained landfill. The risk from disposal to a trench
is difficult to gauge in the absence of reliable data on the possible
infectivity of the ash.
 
(b) Management factors.
 
Almost inevitably the level of expertise available for the management
of small incinerators is highly variable because few such facilities can
afford to employ specialists in incineration. This is also likely to be
often the case for the inspectors as well. While such considerations
cannot formally be taken into account in a risk assessment, they are
not the less relevant factors that need to be considered in assessing
the risk from a particular plant.
 
(c) Benchmarking.
 
The DNV 2001 risk assessment relies greatly on the assumption that
BSE/TSE contaminated material is very unlikely to be processed.
The Report seeks to compare the risks from a small incinerator with
that from large SRM incinerators which the author had assessed
previously (DNV, 1997). It identifies that the risk is four-five -fold
less from a typical small incinerator because the scale of activities is
much lower. However it is noted that the amount of experimental
data to back this conclusion is extremely limited and does not take
into account either risks from the residual ash or any consequences of
a substantially lower stack height limiting the dilution of the emitted
particulate and gaseous matter. 8
 
5. FURTHER INVESTIGATIONS
 
In view of the uncertainty regarding the risks due to BSE/TSE
contamination of the fly and bottom ash and airborne emissions it is
recommended that further research is conducted to identify the residual
risks (along with attendant uncertainties) from the burial of ash
(without further treatment,) in uncontained sites. It is essential that
suitable monitoring methods are developed.
 
6. LITERATURE
 
EC (European Commission), 1999. Opinion on The risks of non conventional
transmissible agents, conventional infectious agents or other hazards
such as toxic substances entering the human food or animal feed chains
via raw material from fallen stock and dead animals (including also:
ruminants, pigs, poultry, fish, wild/exotic/zoo animals, fur animals,
cats, laboratory animals and fish) or via condemned materials. Adopted
By the Scientific Steering Committee at its meeting of 24-25 June 1999
and re-edited at its meeting of 22-23 July 1999. DNV Consulting (Det
Norske Veritas), 1997. Risks from disposing of BSE infected cattle in
animal carcass incinerators. Report prepared for the UK Environment
Agency. DNV Consulting (Det Norske Veritas), 2001. Risk assessment of
SRM incinerators. Prepared for the UK Ministry of Agriculture, Fisheries
and Food. Revision 2 of the Draft report, February 2001. 24 pages.
SEAC (Spongiform Encephalopathy Advisory Committee, UK), 2001. Public
summary of the SEAC meeting of 25 April 2001.
 
http://europa.eu.int/comm/food/fs/sc/ssc/out311_en.pdf
 
TSS
 
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Terry S. Singeltary Sr.
P.O. Box 42
Bacliff, Texas USA 77518
<flounder@wt.net>
 
CJD WATCH
 
http://www.fortunecity.com/healthclub/cpr/349/part1cjd.htm
 
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http://disc.server.com/Indices/167318.html
 
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http://www.vegsource.com/talk/madcow/index.html
 
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