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CWD Best Management

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cedardell

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I have been extremely concerned about the spread of CWD in our area of Northern Illinois. Some time in the past on this website I read a post about Montana's mobile incinerator for the complete destruction and vaporization of road kills. Does anyone know where the specs or plans for the construction of one of these things exists? We are in desperate need of one because our department of ag and health insist on leaving the road kills lay to feed cyotes. We even had a case where humans picked up a road kill to eat that had been uthanized by a vet. The news media blared about that for weeks trying to warn about the danger of eating it. Still no change of policy. We have all kinds of dead animals both wild and domestic being dumped in our ditches. This makes them just a few feet from our cattle.
 

flounder

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hello cedardell,


this might help you out.........




J A N U A R Y 2 0 0 5 T A H C R E P O R T
A P P E N D I X 3 . 6 . 5
GENERAL GUIDELINES
FOR THE DISPOSAL OF CARCASSES



http://www.aphis.usda.gov/NCIE/oie/pdf_files/tahc-carcass-disp-jan05.pdf




NDA, in consultation with NDEQ and NGPC, will investigate alternative methods
of disposing cervid carcasses that may have been exposed to CWD, including the
use of mobile air curtain incinerators. If deemed feasible and appropriate, said
equipment will be purchased as funds are available and locations for operating
said incinerator will be selected after consultation with NDEQ.




http://www.ngpc.state.ne.us/wildlife/guides/cwd/management.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





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." <[email protected]>
Reply-To: Bovine Spongiform Encephalopathy <[email protected]>
To: [email protected]

######## Bovine Spongiform Encephalopathy <[email protected]> #########

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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flounder

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BUT NEVER FORGET;


Gerald Wells: Report of the Visit to USA, April-May 1989

snip...

The general opinion of those present was that BSE, as an
overt disease phenomenon, _could exist in the USA, but if it did,
it was very rare. The need for improved and specific surveillance
methods to detect it as recognised...

snip...

It is clear that USDA have little information and _no_ regulatory
responsibility for rendering plants in the US...

snip...

3. Prof. A. Robertson gave a brief account of BSE. The US approach
was to accord it a _very low profile indeed_. Dr. A Thiermann showed
the picture in the ''Independent'' with cattle being incinerated and thought
this was a fanatical incident to be _avoided_ in the US _at all costs_...

snip...


http://www.bseinquiry.gov.uk/files/mb/m11b/tab01.pdf


TSS
 

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