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From: TSS (216-119-128-77.ipset8.wt.net)
Subject: Re: Proposal to stop CWD testing in Colorado
Date: November 20, 2003 at 9:29 am PST

In Reply to: Proposal to stop CWD testing in Colorado posted by Kay L. on November 20, 2003 at 8:48 am:

my opinion; ''totally insane''! they still have really no idea what
the real existance of CWD is in any given area with the limited
testing down to date, even though it is far greater in what they are
testing in USA cattle for TSEs. They simply do not know whether
to bury or burn, so I guess they just decide to stop all together,
stick there head in the sand, and hope it just goes away. BOY, are
they in for a big surprise. something of interest below;

11/7/03 DRAFT

EPA Region 8 Recommended Approach for Treatment and Disposal of Waste
Potentially Contaminated with Chronic Wasting Disease (CWD)

Introduction

This document is intended to summarize the relevant EPA authorities
applicable to disposal of wastes that may be contaminated with chronic
wasting disease (CWD) and to provide information regarding effective
inactivation and disposal techniques for waste from infected animals. It is
intended as an initial framework for the network of federal, state, and
local agencies within Region 8 that must make decisions regarding CWD in the
near term. Practicable steps are presented that will protect the
environment and the health of deer and elk populations while the state of
the science concerning CWD develops and more definitive information becomes
available.[1]

This document contains interim recommendations, which we expect to modify as
we continue to learn more about CWD. We are working with other federal
agencies to develop additional information about the treatment and disposal
of waste potentially contaminated with CWD.[2] We have also established a
group of state government senior level policy officials (senior policy
group) to assist and advise us as we carry out our responsibilities
regarding CWD. Finally, the American Association of Veterinary Laboratory
Diagnosticians (AAVLD) is considering guidelines for TSE contaminated waste
disposal that offer disposal guidance from working laboratory professionals.
Upon completion, the AAVLD guidelines should be considered along with this
paper.

Our immediate focus is on laboratory wastes potentially contaminated with
CWD. One of the main established areas for CWD in wild populations is
within Region 8, and a large number of tissue samples from deer and elk
harvested from wild populations as well as captive deer and elk are likely
to be tested for CWD in Region 8 laboratories. Although the percentage of
deer and elk with CWD may be low, and surveillance or testing laboratories
do not create additional material contaminated with CWD, the surveillance
and testing programs have the potential to discharge and recycle the CWD
agent back into the natural environment. EPA recognizes and supports the
need for the surveillance and testing programs and related research. Our
intent is to reduce potential risks from CWD-contaminated wastes associated
with laboratory testing and thereby support the continuation, and, as
necessary, expansion of these programs.

Importantly, no implication for unique risk from CWD should be drawn from
this approach. Many of the same scientific concerns are relevant to
discharges of laboratory waste potentially contaminated with other animal
transmissible spongiform encephalopathy (TSE) agents. While our immediate
focus is on CWD, laboratories should consider similar practices when the
presence of other TSEs is suspected. We will consult the senior policy
group regarding our approach to other types of TSEs.

Chronic Wasting Disease (CWD)

CWD occurs in North American deer (Odocoileus hemionus and Odocoileus
virginianus) and Rocky Mountain elk (Cervus elaphus nelsoni). CWD is one of
several TSEs (Collinge 2001). The scientific literature focusing
specifically on CWD is somewhat limited. For that reason, this document
also uses experimental information on other TSE diseases as the basis for
general conclusions about the biology of CWD.

Prions

Current thought is that CWD and other TSEs are caused by prions:
self-propagating, protein-based particles lacking nucleic acids (Prusiner
1982; Prusiner 1993; Aguzzi and Weissman 1997; Prusiner 1997). Prions are
thought to be composed of an abnormal form of a normal cellular protein,[3]
although this is not proven (Chesebro 1998).

TSE agents are very resistant to traditional waste treatment and
decontamination methods. Common methods of waste treatment in sewage
treatment plants, or publicly owned treatment works (POTWs), and septic
systems, as well as landfilling and composting, are ineffective at
completely inactivating TSE agents (Prusiner 1982; Bellinger-Kawahara et al.
1987; Manuelidis 1997; Taylor 2000; Taylor 2001). However, these methods
may achieve partial inactivation, to varying degrees. One TSE agent is
known to survive for extended periods of time in the environment (Palsson
1979; Brown and Gajdusek 1991). No practical chemical tests are currently
available for measuring the presence or concentrations of TSE agents in
water, soil, or biosolids from POTWs or septic systems.

Concerns about CWD-Contaminated Waste Material

EPA is concerned that disposal of CWD-contaminated wastes from testing
laboratories that handle material from deer and elk potentially affected
with CWD could result in more widespread distribution of the CWD agent in
the environment. To minimize exposure potential, EPA Region 8 recommends
reasonable protective practices based on currently available information as
we implement our regulatory responsibilities.

Disposal Options

A variety of suitable options for disposal of TSE-contaminated materials are
available. Each option will be discussed below. Importantly, consultation
with state and local authorities is strongly recommended prior to any
disposal activity.

Landfilling

Program Requirements

The states are mainly responsible for regulating landfills in Region 8. All
Region 8 states have received program approval from EPA under the Resource
Conservation and Recovery Act (RCRA), Subtitle D by adopting required
regulations for Municipal Solid Waste Landfills. EPA has regulatory
authority under RCRA’s 7003 Imminent and Substantial Endangerment provision,
which covers all solid wastes. However, EPA’s primary role for solid and
hazardous wastes is to provide technical assistance to states for solid
waste issues.

Each state’s standards for Municipal Solid Waste Landfills may include
leachate management, liner systems (clay, synthetic, or combination),
groundwater monitoring, and daily cover of wastes. States vary in how they
apply their definition of infectious waste, which could affect the standards
associated with collection, handling and disposal of waste that can include
tissue, body parts, heads and carcasses of CWD-affected animals. All Region
8 states, with the exception of Wyoming, have adopted their own infectious
or medical waste regulations

Recommended Practices

Disposal of potentially CWD-contaminated solid material is acceptable in a
state-permitted municipal solid waste landfill that is in full compliance
with state and federal environmental regulations. Proper landfilling
provides substantial capacity and lower cost compared to other disposal
methods. The design, construction, location and operation of landfills
vary, which may affect the fate and transport of TSE agents within a
landfill. Owners or operators of landfills have the ability to accept or
reject these wastes. When landfilling is chosen as a disposal option,
consultation with state and local authorities and the waste management
industry is recommended.

Incineration

Program Requirements

The Clean Air Act (CAA) provides the authority to EPA to regulate sources of
air pollution. Under the CAA, EPA sets limits on the amount of a specific
pollutant allowed in the ambient air and establishes regulations for
specified categories of air pollution sources. State and local agencies do
much of the work to implement and enforce the CAA. EPA has an oversight
role in permitting stationary sources located in state and local
jurisdictions, reviewing permitting actions to ensure that all CAA
requirements are being met, and providing technical and regulatory support
to the state authorities.

Criteria pollutants (Ozone, particulate matter, nitrogen dioxide, sulfur
dioxide, carbon monoxide, and lead), and hazardous air pollutants (HAPs)
such as Benzene, Toluene, and Xylene, are potential incinerator emissions
regulated by the CAA and 40 CFR Part 50. The applicability of a given
federal and/or state regulation to an incinerator depends on the type of
waste being burned. Incinerators that burn CWD-contaminated carcasses are
considered pathological waste incinerators.[4] While EPA has promulgated
federal regulations for other types of solid waste incinerators, federal
regulations have not yet been promulgated for pathological waste
incinerators. EPA’s current plan is to promulgate regulations for
pathological waste incinerators, as well as other solid waste incinerators
not already regulated, by November 15, 2005. At this time, only state
regulations that may exist for pathological waste incinerators and
state-specific requirements apply.

Inherent in any combustion process is the potential for emissions. In
general, high temperature incineration in a multi-chamber controlled air
system provides an opportunity for complete combustion of the solid waste
resulting in the mitigation of criteria and HAP pollutants, as well as odor
and smoke, where applicable. In addition, air pollution control
technologies used in conjunction with incineration, such as gas scrubbers
and good combustion practices, have proven effective.

Recommended Practices

Incineration is considered an effective method for disposal of
TSE-contaminated wastes (WHO 1999). Properly run incinerators operating
above 600o C (preferably closer to 1000o C) provide assurance of
environmental safety (Brown, personal communication). Incineration has been
the method of choice for the reduction of most pathological waste, such as
human and animal tissues that have been identified as carrying a biological
pathogen. Human crematoriums, veterinary labs and clinics, and humane
societies are the most common users of high temperature pathological
incineration. The incinerators used are usually multiple chamber
designs.[5] The Industrial Combustion Coordinated Rulemaking (ICCR)
Federal Advisory Committee[6] recommends that good combustion practices be
adopted when burning pathological waste. Specifically one second retention
times in the secondary chamber and minimum secondary chamber temperatures of
1,600º to 1,800º F (871º to 982º C). In addition, the Committee recommends
the use of combustion temperature controls. Incinerator ash may be disposed
of in state-permitted municipal solid waste landfills. For specific
information regarding research on incineration temperatures and TSE agent
deactivation see Appendix 2.

Air curtain incinerators[7] may not be completely effective for treatment of
pathological waste, however, this technology will likely result in a
significant reduction in the level of TSE infectivity (though not complete
inactivation). With wet wastes, such as CWD-contaminated carcasses,
temperatures within the pit can fluctuate and dip below recommended
temperatures due to inherent operational limitations, so complete combustion
may be difficult to achieve. In addition, production of those pollutants
regulated by the CAA and/or state regulations such as criteria and HAP
pollutants, odor, and opacity, may increase when the air curtain is broken.

Discharge to Sewage Treatment Plants (POTWs)

Regulatory Requirements

The Pretreatment Program, as authorized under the Clean Water Act (CWA) and
40 CFR Part 403, has multiple objectives. These include minimizing or
preventing pollutants from entering receiving waters, preventing
interference with POTW operations, making sure that worker health and safety
are not adversely affected, and ensuring that process biosolids can be
recycled or reclaimed. EPA, authorized states, and POTWs have the authority
to regulate discharges to POTWs through implementation of pretreatment
standards and requirements.

No treatment process at a POTW effectively inactivates the CWD agent. There
is currently no method to determine the concentration of the CWD agent in
wastewater being discharged to POTWs or in any waste stream leaving the
POTW. Until suitable methods to detect and measure the CWD agent are
developed, EPA recommends using practices designed to minimize CWD agent
release from POTWs into the environment.

The recycling and beneficial reuse of biosolids are among EPA’s objectives
under the CWA and represent a major activity on the part of POTWs. Limited
research indicates that one TSE agent partitions primarily with the solids
(Brown and Gajdusek 1991), suggesting that the highest concentrations of the
TSE agent would be found in the biosolids. Biosolids are typically applied
to food and feed crops, as well as rangeland. Some biosolids are composted
and sold to private citizens as well as businesses. Biosolids produced from
discharge of CWD-contaminated waste might be distributed outside the
established areas of CWD. While lower concentrations of the CWD agent would
be expected in the effluent of POTWs than in the biosolids, it is not known
whether the CWD agent may attach to solids in colloidal suspensions.

Recommended Practices

Dischargers should contact EPA, an authorized state, or their local POTW
officials for more specific information about discharges of facility wastes
to POTWs. EPA intends to issue detailed guidelines for POTWs describing
conditions or best management practices for laboratories to minimize the
potential discharge of waste contaminated with CWD. These practices may then
be incorporated into a permit, enabling the POTWs to accept the discharge
from the laboratories.

If laboratories discharge to a POTW, permit conditions will require them to
implement reasonable management practices to minimize the release of waste
potentially contaminated with CWD. Potentially CWD-contaminated solid
waste, infectious tissues, carcasses, absorbent material, disposable
clothing, etc. should be removed from the waste stream before discharge to a
POTW. Drains should be screened to trap tissue fragments and solids that
may be in the waste stream. Receptacles should be placed to catch fluid
from animal carcasses examined on necropsy tables or suspended over necropsy
floors. Absorbent, disposable material may be used on tables or bench tops
to collect and remove tissues. Once these practices are implemented,
minimized discharge of fluid waste with low infectivity, such as blood and
wash water generated from a necropsy procedure, will be acceptable.

All potentially CWD-contaminated material that is collected should be 1)
treated to inactivate CWD agent by decontamination procedures, 2) processed
through alkaline hydrolysis, 3) properly incinerated, or 4) disposed of in
landfills, as permitted by local, state, or federal law. Appropriate
chemical solutions should be applied to inactivate CWD agents that may
remain on contaminated surfaces, including necropsy floors. Inactivation of
CWD agents on solid surfaces should be completed to the optimum extent
before the resulting wastewater is discharged to POTWs or septic systems.
Because of the pollutant properties of the chemicals and formulations used
in the inactivation of the CWD agent, a laboratory may have to provide some
level of treatment prior to discharge to a POTW or septic system.

Alkaline Hydrolysis

In some laboratories, pretreatment of wastes by alkaline hydrolysis is used
to inactivate the CWD agent before discharge to POTWs or septic systems
(Taylor 2001). Alkaline hydrolysis involves the use of a concentrated
alkaline solution (one molar sodium or potassium hydroxide) along with
temperatures over 300º F (149º C) and high pressures (approximately five
bars) for a period of six hours to ensure that tissues and proteins
(including PrP-res) are hydrolyzed or digested in a vessel similar to a
large stainless steel pressure cooker. The hydrolysis system is generally
computer controlled and may be operated at one, two or three cycles per day.
The loading capacity for these systems varies from as little as 80 pounds
per cycle, up to 7000 pounds per cycle. The discharge from this process
produces a very dense “soup” that is high in biochemical oxygen demand and
solids. Other parameters to consider may include total dissolved solids,
pH, temperature, and chemical specific pollutants. The final pH may meet
POTW discharge limits on pH without further adjustment, although
laboratories should check to ensure the final pH is in compliance with local
limitations. EPA and the POTWs have not identified any significant
concentrations of toxic pollutants of concern in the discharge. A
dehydrator system may be installed that reduces the waste stream from the
alkaline hydrolysis treatment to a very small amount of dry material that
can be disposed of as a solid waste in landfills. Disadvantages to the use
of alkaline hydrolysis digestion are high installation and operating costs.

Discharge to Septic Systems

Regulatory Requirements

The Underground Injection Control (UIC) Program, created under the authority
of the Safe Drinking Water Act, is a preventative program with the goal of
protecting existing and future underground sources of drinking water.
Shallow disposal systems that discharge certain types of fluids into the
subsurface are known as Class V wells. These disposal systems can include
septic systems receiving waste fluids other than sanitary waste only, or any
other conduit to the subsurface by which fluids are released to ground
water. EPA and authorized states have authority to regulate discharge of
CWD-contaminated wastes to Class V wells through the permitting process.

Class V wells that have the potential to contaminate or degrade ground water
are required by permit conditions to monitor the concentrations of
contaminants of concern in waste fluids being released into the subsurface.
However, there are some contaminants, such as the CWD agent, for which
monitoring is not feasible. In these cases, EPA recommends a protective
approach to minimize the amount of these contaminants released into the
environment.

Because there is no method currently available to quantify concentrations of
TSE agents in fluids or septic system sludges, UIC permit requirements for
waste streams that potentially include CWD will specify practices to
minimize the volume of CWD-contaminated wastes entering the waste stream.
Because TSE agents may be expected to partition to septic tank sludge,
permit requirements will also include practices for disposal of septic
system sludge in a manner that protects the environment, such as proper
incineration, alkaline hydrolysis, or disposal in a suitable landfill after
the sludge has been dehydrated.

Recommended Practices

Management practices for minimizing CWD waste discharged to septic systems
are basically the same as those that apply to POTWs. Alkaline hydrolysis
may also be considered. In addition, laboratories must ensure that any
materials discharged, such as the inactivation chemicals, do not adversely
affect or destroy the septic system and that the septic system continues to
function properly.

Cleaning Contaminated Surfaces

Program Requirements

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), any
chemical that is intended to prevent, destroy, repel or mitigate any pest
must either be registered as a pesticide product or exempted prior to its
sale or distribution in the United States. The processes for obtaining
registrations or exemptions are described in EPA’s regulations (40 CFR
152-180). The applicant for registration or exemption is responsible for
providing the data necessary for EPA to conduct an assessment of the
potential risks and benefits of a pesticide product and to determine that no
unreasonable adverse effects will occur from the pesticide product’s
proposed use. There are no EPA registered products approved for
inactivation of TSE agents from contaminated surfaces, but a few products
are under consideration that may be efficacious in these situations. EPA is
expediting its assessment and emergency review process for at least one of
the products.

Recommended Practices

Various guidelines exist for facilities that handle material contaminated by
TSEs, such as operating rooms (World Health Organization 1999, Sehulster and
Chinn, in press), autopsy rooms (Crain 1996, Sehulster and Chinn, in press),
research laboratories, and mortuaries (World Health Organization 1999). All
guidelines recommend treatments to inactivate TSE agents on contaminated
surfaces or instruments and procedures for either handling waste material as
infectious waste or for treating liquid and solid wastes prior to discharge
or disposal.

Recommendations of the Centers for Disease Control and Prevention (Sehulster
and Chinn, in press) for treatment of surfaces contaminated by human TSE
agents specify use of a sodium hypochlorite solution containing
approximately 10,000-20,000 parts per million of available chlorine
(dilutions of 1:5 to 1:3 by volume, respectively, of household chlorine
bleach) after removing tissue from the surfaces. The contact time should be
between 30 minutes and one hour. Chlorine bleach is not stable once diluted
and may not provide the appropriate concentration necessary for inactivation
if it has remained on the shelf for extended periods of time. Chlorine has
a very aggressive toxic effect on treatment processes in POTWs and septic
systems, and an acceptable discharge concentration should be determined for
the facility.

A study by scientists from the National Institutes of Health (Ernst and
Race, 1993) reported that inactivation of a TSE agent from hamster brain is
achievable by the use of a nine percent or greater solution for 30 minutes
of an aqueous acid phenolic inactivation agent that contains (by percent
weight) o-benzyl-p-chlorophenol (6.4%), p-tertiary-amylphenol (3.0%),
o-phenyl-phenol (0.5%), hexylene glycol (4.0%), glycolic acid (12.6%),
isopropanol (8.0%), and water. Inactivation of the TSE agent on instruments
and small, nondisposable items can be accomplished by soaking in a one
percent solution of the aqueous acid phenolic inactivation agent for 16
hours. Components of the solution may exert various toxic effects on POTWs
and septic systems. Because the solution has a pH level less than five,
facilities using this material must ensure that wastewater meets applicable
requirements for pH prior to discharge.

Chemical inactivation treatments have not been validated for large pieces of
tissue. Solids should be removed from surfaces, including necropsy floors,
prior to treatment or removed from the waste stream prior to discharge.
Because the relative humidity may be low in the work areas, surfaces treated
with inactivation solutions should not be allowed to dry. Continued
applications during the treatment time may be necessary. In addition, where
water pools or contaminated materials dry on surfaces, longer treatment
times may be required. Where material has dried on surfaces, scrubbing may
be required to ensure that the material receives adequate treatment.

[1] This paper does not create any new regulations or guidance, but rather
is a summary of existing authorities.

[2] Other federal agencies with significant roles in CWD management and
control are the Animal and Plant Health Inspection Service, USDA; the Food
and Drug Administration; and the Centers for Disease Control and Prevention.
In addition, state wildlife agencies are responsible for determining game
management strategies in response to CWD. We will rely on an interagency
working group to develop approaches to address related issues regarding TSE
agent decontamination. This working group includes representatives from
federal agencies with responsibilities related to CWD and TSEs.

[3] Prions are abnormal, suspected disease-causing forms of normal proteins
that are naturally produced in mammalian cells. The normal form of the
protein is referred to as PrPC (Prion Protein Cellular) or PrP-sen (Prion
Protein Protease Sensitive). The abnormal, disease-causing forms occur when
the normal cellular protein (PrPC) becomes folded in an abnormal way,
resulting in resistance to normal cellular breakdown processes. The
abnormal form is referred to as PrP-res (Prion Protein Protease Resistant)
or PrPSc (Prion Protein Scrapie). By definition, a prion is “a small
proteinaceous infectious particle which resists deactivation by procedures
that modify nucleic acids,” and, therefore, throughout the context of this
document, the term prion will refer to the abnormal, disease-causing form
only.

[4] Pathological waste is waste material consisting of only human or animal
remains, anatomical parts and/or tissue, the bags/containers used to collect
and transport the waste material, and animal bedding, if applicable (from
the Hospital/Medical/Infectious Waste Incineration (HMIWI) regulations at 40
CFR Part 60, Subpart Ec). CWD-contaminated waste does not meet the EPA
definition for infectious waste in the HMIWI regulations because there have
been no proven incidents of CWD transmission to humans. Therefore,
incinerators handling CWD-contaminated waste do not have to meet HMIWI
requirements.

[5] Multiple chamber incinerators are incinerators with at least two or more
refractory-lined combustion chambers (primary and secondary) in series
physically separated by refractory walls, interconnected by gas passages,
and employing adequate design parameters necessary for maximum combustion of
waste materials. Design parameters include maintenance of adequate
combustion temperatures, excess air, complete turbulent mixing, and adequate
time for exposure to combustion temperatures. In dual chamber incinerators,
the waste is initially ignited in the primary chamber where drying and
decomposition are achieved. The partial combustion products then pass into
an afterburning secondary chamber at increased temperatures and adequate
retention times to complete the combustion reactions.

[6] The ICCR Coordinating Committee was established by the EPA under the
Federal Advisory Committee Act in September, 1996. The Committee developed
recommendations for consideration by the EPA in the development of
regulations for stationary combustion source categories including
non-hazardous waste incinerators. The Regulatory Alternatives Paper dated
September 8, 1998 includes these recommendations. See the ICCR Internet web
page at http://www.epa.gov/ttn/atw/iccr/cc/septrec.pdf.

[7] In air curtain incinerators, high velocity air is blown across the upper
portion of a single combustion chamber in which waste and fuel is loaded.
The curtain of air created by this process traps unburned particles under
the curtain in the high temperature zone where temperatures can reach 1,832º
F (1,000º C) or higher.

For Further Information

Please contact: John Larson at 303-312-6030 or Suzanne Stevenson at
303-312-6122 for general information; Dr. Wendy O’Brien at 303-312-6712 for
information regarding risks of CWD; and Judy Wong 303-312-6260 about best
management practices for laboratories that handle CWD-contaminated waste
material.

References

Aguzzi A and Weissman C (1997) Prion research: the next frontiers. Nature
389:795-798.

Bellinger-Kawahara C, Diener TO, McKinley MP, Groth DF, Smith DR, Prusiner
SB (1987) Purified scrapie prions resist inactivation by procedures that
hydrolyze, modify, or shear nucleic acids. Virology 160:271-274.

Brown P and Gajdusek DC (1991) Survival of scrapie virus after 3 years’
interment. Lancet 337:269-270.

Brown P, Rau EH, Johnson BK, Bacote AE, Gibbs CJ Jr., Gajdusek DC (2000) New
studies on the heat resistance of hamster-adapted scrapie agent: Threshold
survival after ashing at 600° C suggests an inorganic template of
replication. Proceedings of the National Academy of Sciences 97:3418-3421.

Brown P (2003) Personal communication. September 15, 2003.

Chesebro B (1998) BSE and prions: uncertainties about the agent. Science
279:42-43.

Collinge J (2001) Prion diseases of humans and animals: Their causes and
molecular basis. Annual Review of Neuroscience 24:519-540.

Crain BJ (1996) Creutzfeldt-Jakob Disease: Safety tips for anatomic studies
of possible CJD. CAP Today January 1996.

Det Norske Veritas (DNV) (1997) Risks from Disposing of BSE Infected Cattle
in Animal Carcase Incinerators. Study carried out for the UK Environment
Agency. 50 pp.

Ernst DR and Race RE (1993) Comparative analysis of scrapie agent
inactivation methods. Journal of Virological Methods 41:193-202.

Manuelidis L (1997) Decontamination of Creutzfeldt-Jakob disease and other
transmissible agents. Journal of Neurovirology 3:62-65.

Palsson PA (1979) Rida (scrapie) in Iceland and its epidemiology. In:
Prusiner SB, Hadlow WJ (Eds.) Slow transmissible diseases of the nervous
system, Vol. I. Academic Press, New York NY; pp. 357-366.

Prusiner SB (1982) Novel proteinaceous infectious particles cause scrapie.
Science 216:136-144.

Prusiner SB (1993) Genetic and infectious prion diseases. Archives of
Neurology 30:1129-1153.

Prusiner SB (1997) Prion diseases and the BSE crisis. Science 278:245-251.

Rau E (2003) Preliminary Results: Infectivity of Air Emissions and Residues
for Simulated Incineration of Scrapie Tissues. Presentation at the Food and
Drug Administration Transmissible Spongiform Encephalopathy Advisory
Committee meeting on July 17, 2003 in Bethesda, MD.

Sehulster L and Chinn RYW (In press) Guideline for Environmental Infection
Control in Health-Care Facilities - Recommendations of CDC and the
Healthcare Infection Control Practices Advisory Committee (HICPAC).

Taylor DM, McConnell I, Fernie K (1996) The effect of dry heat on ME7 strain
of mouse-passaged scrapie agent. Journal of General Virology 77:3161-3164.

Taylor DM (2000) Inactivation of transmissible degenerative encephalopathy
agents: a review. The Veterinary Journal 159:10-17.

Taylor DM (2001) Resistance of transmissible spongiform encephalopathy
agents to decontamination. Contributions to Microbiology 7:58-67.

Taylor DM (2001) Equipment marketed by Waste Reduction Europe Ltd. to
destroy animal carcases and tissues by hot alkaline hydrolysis: An
assessment of the capacity of the process to reliably inactivate BSE-like
agents. David Taylor Assessment January 2001.
http://www.wreurope.net/response/taylor2001.htm.

World Health Organization (1999) WHO Infection Control Guidelines for
Transmissible Spongiform Encephalopathies. Report of a WHO consultation
Geneva Switzerland, 23 – 26 March 1999. 38 pp.

Appendix 1

Best Management Practices for Disposal of TSE Agent Wastes

Landfilling

· Consult with state and local authorities and the waste management
industry.
· Use state-permitted municipal solid waste landfills in full compliance
with state and federal environmental regulations.

Incineration

· Use proper high temperature incineration.
· Consult with state and local authorities.
· Retain materials in the secondary chamber for one second with minimum
secondary chamber temperatures of 1,600º to 1,800º F (871º to 982º C).
· Use combustion temperature controls.
· Use air pollution control technologies in conjunction with incineration.

Discharge to Sewage Treatment Plants or Publicly Owned Treatment Works
(POTWs)

· Contact EPA, an authorized state, or local POTW officials for more
specific information about discharges of facility wastes to POTWs.
· Implement reasonable waste minimization practices to reduce the amount of
CWD-contaminated waste generated.
· Remove potentially CWD-contaminated solid waste, infectious tissues,
carcasses, absorbent material, disposable clothing, etc. from the waste
stream before discharge to a POTW.
· Place screens over drains to trap tissue fragments and solids that may be
in the waste stream.
· Place receptacles to catch fluid from animal carcasses examined on
necropsy tables or suspended over necropsy floors.
· Use absorbent, disposable material on tables or bench tops to collect and
remove tissues.
· Treat CWD-contaminated material that is removed from the waste stream to
inactivate the CWD agent by suitable inactivation chemicals
OR
Process through alkaline hydrolysis
OR
Dispose of all CWD-contaminated material that is collected by proper
incineration or in state-permitted landfills.
· Treat all surfaces that may have been in contact with CWD-contaminated
wastes with an inactivation agent before rinsing these surfaces and allowing
rinse water to enter any drains.
· Treat or neutralize inactivation chemicals, as necessary, to meet
applicable regulatory requirements.

Discharge to Septic Systems

· Follow best management practices for discharges to POTWs.
· Ensure discharged material, such as inactivation solution, does not
adversely affect or destroy the septic system and that it continues to
function properly.

Cleaning Contaminated Surfaces

· Follow guidelines recommended by experts to inactivate TSE agents on
contaminated surfaces or instruments.
1. Sodium hypochlorite solution containing approximately 10,000-20,000 parts
per million of available chlorine for 30–60 minutes.
OR
2. Nine percent or greater solution of an aqueous acid phenolic inactivation
agent that contains (by percent weight) o-benzyl-p-chlorophenol (6.4%),
p-tertiary-amylphenol (3.0%), o-phenyl-phenol (0.5%), hexylene glycol
(4.0%), glycolic acid (12.6%), isopropanol (8.0%), and water for 30 minutes.
OR
3. For instruments and other small nondisposable items, soak in a one
percent solution of the aqueous acid phenolic inactivation agent for 16
hours
AND
4. Inactivation solutions should not be allowed to dry
5. Solids should be removed from surfaces prior to treatment or removed from
the waste stream prior to discharge.

Appendix 2

Incineration Temperatures and TSE Agent Deactivation

Note: The following research indicates that temperatures below those
recommended in this paper may be effective in deactivating TSE/CWD agents.
Recommended levels from the body of this document (1600° to 1800° F) are due
to additional considerations that apply to incineration of all materials.

Research studies conclude that TSE agents may be inactivated by dry heat at
392° F (200° C) for
60 minutes, (Taylor et al.1996), or by incineration at a temperature at or
above 1,562º F (850° C) for at least 2 seconds (Det Norske Veritas 1997).
Recent research (Brown et al. 2000; Rau 2003) suggests that the operating
temperature should be greater than 1,112° F (600° C). While one experiment
at 1,112° F (600° C) for five minutes showed no residual infectivity after
treatment of hamster brain tissue containing a TSE agent, another experiment
showed low levels of residual infectivity when the brain homogenate was
treated at the same temperature for 15 minutes. The authors suggest that
the apparent inconsistency in their data indicates that infectivity was near
the point of extinction at this temperature. This work has been repeated
with consistent results (Rau 2003). Rau also found no residual infectivity
in emission condensate following treatment at 1,112° F (600° C) or 1,832º F
(1,000° C). More definitive studies on incinerator heat-inactivation of TSE
agents are needed.


7/23/03 DRAFT

EPA Region 8 Recommended Approach for Treatment and Disposal of Waste
Potentially Contaminated Chronic Wasting Disease Prions

Executive Summary

This document is intended to summarize briefly what is known about chronic
wasting disease (CWD), the relevant EPA authorities applicable to disposal
of CWD-affected wastes, and current information regarding effective
inactivation and disposal techniques for waste from infected animals. It is
intended as an initial framework for the network of federal, state and local
agencies within Region 8 that must make decisions regarding CWD-related
wastes in the near term. Reasonable steps are presented that will provide
environmental protection while the state of the science concerning CWD
develops and more definitive information becomes available.[1]

We expect to modify this information as we continue to learn more about CWD.
Our approach will be updated as federal agencies, operating in close
coordination through the national CWD/TSE Decontamination Working Group,
develop additional information on, and requirements for, treatment and
disposal of waste potentially contaminated with CWD prions.[2] In
addition, EPA Region 8 has established a regional group of state senior
policy officials to advise the Regional Administrator along with subordinate
workgroups with broad representation to continue to examine these issues, to
share new information as it becomes available, and to recommend
modifications of management practices to treat and dispose of waste
potentially contaminated with CWD prions for this Region.

Our immediate focus is on laboratory wastes potentially contaminated with
CWD prions. This is because of the relative prevalence of CWD within Region
8 and the potential for the deer and elk surveillance and testing programs
to unintentionally concentrate CWD prions. We recognize and support the
need for the surveillance and testing programs. Our intent is to mitigate
any potential risks from laboratory testing and thereby support the
continuation, and, if necessary, expansion of these programs. It is
important to note that no implication of unique risk from CWD prions should
be drawn from this approach.

Background

Chronic wasting disease (CWD)

CWD occurs in North American deer and Rocky Mountain elk and has been
detected within EPA Region 8 in wild populations in Colorado, South Dakota,
Utah, and Wyoming and in game farms in Colorado, Montana, and South Dakota.
Outside Region 8, wild populations affected with CWD have been identified in
Illinois, Nebraska, New Mexico, Wisconsin, and Canada, and CWD positive
captive animals have been identified in Kansas, Minnesota, Nebraska,
Oklahoma, Wisconsin, and Canada (Animal Plant Health Inspection Service
2002; Williams and Miller 2002; Colorado Division of Wildlife 2003;United
States Geological Survey 2003). CWD is one of several transmissible
spongiform encephalopathies (TSEs), which also include bovine spongiform
encephalopathy (BSE) in cattle, scrapie in sheep and goats, and
Creutzfeldt-Jakob disease (CJD) and variant CJD in humans (Belay 1999;
Collinge 2001; DeArmond and Bouzamondo 2002).

CWD and other TSEs are degenerative diseases of the nervous system
characterized by microscopic spongelike holes or “vacuoles” that form in the
brain (Hadlow 1961; Hadlow et al. 1980; Williams and Young 1980; Hadlow et
al. 1982; Wells et al. 1989; Williams and Young 1993;Wells and Wildsmith
1995; Spraker et al. 1997; Wood et al. 1997; Almond 1998; Belay 1999; Hamir
et al. 2001; Belay and Schonberger 2002; DeArmond and Bouzamondo 2002;
Spraker et al. 2002). Current thought is that TSEs are caused by prions:
self-propagating, protein-based particles lacking nucleic acids (Prusiner
1982; Prusiner 1993; Aguzzi and Weissmann 1997; Prusiner 1997). Like other
TSEs, CWD is fatal, although the incubation period may be several years
(Williams and Young 1992; Williams and Miller 2002). Clinical signs of CWD
in affected deer or elk may include depression, emaciation, behavioral
changes, teeth grinding, drooping of the head and ears, and increased
salivation, urination, or water consumption (Sohn et al. 2002; Williams and
Miller 2002). There is no effective treatment or vaccine available. While a
tonsillar biopsy test in live animals is available (Miller and Williams
2002; Wild et al. 2002), it is applicable to deer but not elk. Although
tonsillar biopsy is considered a valuable research tool, a variety of
factors limit its broad application in wild populations. Individual animals
must be captured, sedated, sampled, and held until test results are
available, and obtaining tonsil samples from live deer is more expensive
than testing animals harvested by hunters. The Colorado Division of
Wildlife is currently assessing the tonsillar biopsy technique as a
practical adjunct management tool under field conditions. Until their
evaluation is complete, the tonsillar biopsy method will be considered as
experimental and used for management purposes only (Colorado Division of
Wildlife 2003).

Prions

Prions are composed of an abnormal form of normal cellular protein.[3]
Unlike bacteria and viruses, prions do not contain genetic material.
However, like viruses and bacteria, prions are infectious and replicate in
host tissues. Prions cause the normal cellular protein to convert to the
abnormal or prion form (Prusiner et al. 1990; Caughey and Raymond 1991; Pan
et al. 1993; Huang et al. 1994; Aguzzi and Weissmann 1997; Prusiner 1997;
Telling et al. 1996; Collinge 2001). In animals affected with CWD, prions
are found mainly in the brain, spinal cord, lymph nodes, spleen, tonsils,
and eyes (Williams and Miller 2002), and they have also been detected in the
pancreas and adrenal gland (Sigurdson et al. 2001). In experimental studies
with mice, scrapie prions have been observed in muscle tissue (Bosque et al.
2002), and evidence from laboratory studies indicates that prions have been
found in blood (Tateishi 1980; Kuroda et al. 1983; Manuelidis et al. 1985;
Tateishi 1985; Belay 1999; Houston et al. 2000; Bons et al. 2002). Prions
are very resistant to traditional disinfection methods. Common methods of
waste treatment, including digestion, composting, and rendering, are
ineffective at completely inactivating prions (Prusiner 1982;
Bellinger-Kawahara et al. 1987; Manuelidis 1997; Taylor 2000; Taylor 2001).
Prions can survive for extended periods of time in the environment (Palsson
1979; Brown and Gajdusek 1991). No analytical tests are currently available
for measuring prion concentrations in water or soil.

Transmissibility

Researchers are not certain how CWD is transmitted, but research indicates
it is probably transmitted among deer and elk through oral exposure
(Sigurdson et al. 1999; Sigurdson et al. 2001; Williams and Miller 2002).
CWD may be spread directly by animal-to-animal contact or indirectly through
environmental contamination from urine, feces, or other sources (Miller et
al. 1998; Williams and Miller 2002). The concentration or dose of CWD
prions and duration of exposure needed to cause disease in deer and elk is
unknown. Notably, there are no documented cases of CWD in humans or
domestic animals, but it is unknown whether this situation will change in
the future because all forms of TSEs are experimentally transmissible (World
Health Organization 1999).

There are no reported cases of CWD transmission to humans. No cases of
variant CJD resulting from exposure to either CWD prions or scrapie prions
from sheep have been identified, although variant CJD has developed in
individuals who ate meat from cattle with BSE (Bruce et al. 1994;Will et al.
1996; Bruce et al. 1997; Hill et al. 1997; Scott et al. 1999). Laboratory
research has shown that the CWD prion can convert the normal protein found
in humans and other animals to the abnormal prion form (Raymond et al.
2000). However, the relevance of this information is not known in terms of
predicting transmissibility between species.

No cases of CWD transmission to cattle in the environment have been
reported. In experimental studies, cattle exposed orally to CWD-affected
deer brain or living in close contact with CWD-affected deer have not
developed symptoms of CWD (Hamir et al. 2001). Studies have demonstrated
that the CWD prion can cause wasting disease in cattle by directly injecting
CWD-affected deer brain into the brains of cattle (Hamir et al. 2001), but
the relevance of these results is not known because direct injection into
the brain represents an unnatural route of transmission.

Pathways to the environment

Prion contamination in the environment may potentially occur by several
pathways other than from contaminated excretions from affected animals.
Prions in waste material from CWD testing or game processing facilities may
be present in discharges to septic systems, publicly owned treatment works
(POTWs) or sewers, or in leachate from landfills, potentially contaminating
ground water or surface water. Limited data suggest that prions do not
readily leach from contaminated soil and may partition primarily in solid
phases (Brown and Gajdusek 1991) and, therefore, would not be expected to
partition in high concentrations in water. Biosolids or compost from waste
treatment facilities may contaminate soil when spread on cropland or grazing
land if the material contains prions that have not been inactivated.

Concerns about CWD Waste Material

Because of the uncertainties and lack of information regarding the
detection, transport, fate and persistence of prions in the environment and
how CWD is transmitted, in combination with the lack of effective methods
for prevention or treatment, it is prudent to limit exposure of humans,
cattle and other livestock to CWD. This conclusion is consistent with the
Centers for Disease Control and Prevention’s (CDC) commentary, “No disease
in humans or other animals has been attributed to CWD, but the potential for
disease cannot be ruled out” (Schonberger 2003), and the November 12, 2002,
US Food and Drug Administration (FDA) decision, “…the Agency will not permit
material from Chronic Wasting Disease (CWD)-positive animals… to be used as
an ingredient in feed for any animal species” (US Food and Drug
Administration 2002).

EPA is concerned that disposal of CWD-contaminated wastes from testing
laboratories, meat processors, or other facilities that handle material from
deer and elk potentially affected with CWD could result in more widespread
distribution of CWD prions in the environment. To minimize exposure
potential, EPA Region 8 will use the available information and reasonable
protective practices as we implement our regulatory responsibilities for
underground injection control (i.e., for discharges to “industrial” septic
systems) and industrial pretreatment (i.e., for discharges to wastewater
treatment plants) to effectively manage disposal of potentially
CWD-contaminated wastes or tissues. We will also work closely with federal,
state and local agencies within Region 8 that have related responsibilities.

Current Disposal Methods and Related Regulatory Authorities

Current disposal methods include discharge to Publicly Owned Treatment Works
(POTWs), discharge to septic systems, incineration and landfilling. In some
cases, pretreatment of wastes by alkaline hydrolysis occurs before discharge
to POTWs. In general, the discharge of waste to septic systems or POTWs may
impact the treatment system, environment and human health in different ways.
Some disposal systems may be more sensitive to certain pollutants than
others. It is the discharger’s responsibility to contact the permitting
authority and obtain the specific conditions and limitations that apply to
its discharge.

Discharge to POTWs

The objectives of the Pretreatment Program, authorized under the Clean Water
Act, are to prevent discharges to a POTW that may cause pollutants to enter
receiving waters, interfere with POTW operations, adversely affect worker
health and safety, or interfere with the ability to recycle or reclaim
biosolids. EPA, authorized states and POTWs have the authority to regulate
discharges to POTWs. This program is preventative, in that it requires
actions to prevent contaminants from being released into sewer systems that
may impact the wastewater treatment system, human health, or the
environment. Because of potential environmental effects (i.e. further
exposure of deer and elk from potential concentration and dissemination of
CWD prions), discharge of CWD-contaminated waste should be minimized.
CWD-contaminated wastes include all solid material and infectious tissue
derived from animals, tissue cultures, or other sources that may contain
prions associated with CWD, including deer and elk that exhibit clinical
symptoms, all deer and elk from endemic areas identified by the state, and
harvested animals that require testing according to state regulations.
Discharge of urine, feces, and blood derived from animals with CWD should be
reduced to the extent feasible.

There is currently no method to determine the concentration of CWD prions in
wastewater being discharged to POTWs or in any waste stream leaving the
POTW. Until such tools are developed, EPA must approach control of
effluents through the use of treatment technology and other practices
designed to restrict prion release from POTWs into the environment.

Three main waste streams leave POTWs. They are air emissions, effluent
discharged to surface waters of the United States, and biosolids produced as
a result of solids removal at the POTWs. There is no treatment process at a
POTW that would be effective against CWD prions. Limited research suggests
that prions partition primarily with the solids (Brown and Gajdusek 1991),
so the highest concentrations would likely be found in the biosolids. Fewer
prions would be expected in the effluent of POTWs, although prions may be
attached to solids in colloidal suspensions. Prions would not be expected
to be present in air emissions from POTWs.

Biosolids are typically applied to food and feed crops, as well as
rangeland. The recycling and beneficial reuse of biosolids is one of EPA’s
objectives under the Clean Water Act and a major activity on the part of
POTWs. In Region 8 states, land application is economically feasible
because of the vast amounts of open space and arid climate. Biosolids are a
valuable nutrient supplement to many of these clay or nutrient-poor soils.
Some biosolids are composted and sold to private citizens as well as
businesses.

Dischargers should contact EPA, an authorized state, or their local POTW
officials for more specific information about discharges of facility wastes
to POTWs.

Discharge to Septic Systems

The Underground Injection Control (UIC) Program, created under the authority
of the Safe Drinking Water Act, is a preventative program with the goal of
protecting existing and future underground sources of drinking water.
Shallow disposal systems that discharge certain types of fluids into the
subsurface, are known as Class V wells. These disposal systems can include
septic systems receiving waste fluids other than sanitary waste only, or any
other conduit to the subsurface by which fluids are released to ground
water. Class V wells that have the potential to contaminate or degrade
ground water are required by permit conditions to monitor the concentrations
of contaminants of concern in waste fluids being released into the
subsurface. However, there are some contaminants, such as CWD prions, for
which monitoring is not feasible. EPA and authorized states have authority
to regulate discharge of CWD-contaminated wastes to Class V wells through
the permitting process. In these cases, EPA must take a protective approach
to minimize the amount of these contaminants released into the environment.

Because there is no method currently available to quantify concentrations of
prions in fluids or septic system sludges, UIC permit requirements for waste
streams that potentially include CWD prions will specify practices to
minimize the volume of CWD contaminated wastes entering the waste stream.
Because limited data suggest that prions do not readily leach from
contaminated soil (Brown and Gajdusek 1991), and therefore may be expected
to partition septic tank sludge, permit requirements will also include
practices for disposal of septic system sludge in a manner that protects the
environment.

Incineration

The Clean Air Act (CAA) provides the authority to EPA to regulate sources of
air pollution. Under the CAA, EPA sets limits on how much of a specific
pollutant can be in the ambient air and establishes regulations for
specified categories of air pollution sources. State and local agencies do
much of the work to implement and enforce the CAA once State Implementation
Plans (SIPs) have been approved or federal authority has been delegated by
EPA. EPA has an oversight role in permitting stationary sources located in
state and local jurisdictions, approving SIPs, reviewing permitting actions
to ensure that all CAA requirements are being met, and providing technical
and regulatory support to the state authorities.

Criteria pollutants and hazardous air pollutants (HAPs) are potential
incinerator emissions regulated by the CAA (CAA Sections 108,109 and 112(b)
and CFR Part 50). However, the applicability of a given federal and /or
state regulation to an incinerator is contingent upon the type of waste
being burned. Incinerators that burn CWD contaminated carcasses are
considered pathological waste incinerators.[4] While EPA has promulgated
federal regulations for other types of solid waste incinerators, federal
regulations have not yet been promulgated for pathological waste
incinerators. EPA plans to promulgate regulations for pathological waste
incinerators, as well as other solid waste incinerators not already
regulated, by November 15, 2005. At this time, only state regulations that
may exist for pathological waste incinerators and state specific SIP
requirements apply.

Landfilling

All Region 8 states have received program approval from EPA under the
Resource Conservation and Recovery Act (RCRA), Subtitle D by adopting
required regulations for Municipal Solid Waste Landfills. EPA has
regulatory authority under RCRA’s 7003 Imminent and Substantial Endangerment
provision, which covers all solid wastes. However, the primary role in the
Solid and Hazardous Waste Program is to provide technical assistance to
states for solid waste issues.

Each state’s standards for Municipal Solid Waste Landfills may include
leachate management, liner systems (clay, synthetic, or combination),
groundwater monitoring, and daily cover of wastes. States vary in how they
apply their definition of infectious waste, which could affect the standards
associated with collection, handling and disposal of waste that can include
tissue, body parts, heads and carcasses of CWD-affected animals. All Region
8 states, with the exception of Wyoming, have adopted their own infectious
or medical waste regulations.

There are many unanswered questions regarding landfilling of potentially
CWD-contaminated wastes. Some of these questions include how to monitor for
CWD prions, fate and transport of the prions through the landfill, the
possible inactivation of the CWD prion through inherent landfill biological
processes, and how to remediate if the prions exit the landfill. EPA is
beginning an initial study of some of these questions and is seeking
opportunities to expand this work.

Interim Practices

Overview

The preferred practices for managing waste material and tissue that may
contain prions from animals that are potentially affected with CWD include
treatments to inactivate the prions, whenever practicable. For tissues or
solids contaminated with CWD, effective treatment is achieved through high
temperature incineration or alkaline hydrolysis. These treatment
technologies are being installed at a number of locations.

Facilities should implement reasonable management practices to minimize the
release of waste potentially contaminated with CWD prions. Potentially
CWD-contaminated solid material, including tissues, carcasses, manure,
absorbent material, disposable clothing, etc. should be removed from the
waste stream before discharge to a publicly owned treatment works (POTW) or
septic system. Ideally, this material should be transferred to an
appropriate location for incineration or alkaline hydrolysis. Similarly,
sediment and solids that are removed from septic systems, which contain
potentially CWD-contaminated wastes, ideally should be inactivated by
incineration or alkaline hydrolysis.

When inactivation is not practicable, the alternative practice for disposal
of potentially CWD-contaminated solid material is landfilling in a
state-permitted municipal solid waste landfill.

Contaminated surfaces should be treated with inactivation agent solutions to
inactivate CWD prions. The inactivation agent should be neutralized or
treated appropriately before discharge to avoid toxic effects on POTWs or
septic systems.

Figure 1 illustrates how these treatment technologies might be applied
before discharge into a sewer or a septic system. They are typically used
for entire waste streams and tissues where CWD prion contamination is known
or suspected.

High Temperature Incineration

Incineration has been the method of choice for the reduction of most
pathological waste, such as human and animal tissues that have been
identified as carrying a biological pathogen. High temperature incineration
is defined by the following considerations.

Human crematoriums, veterinary labs and clinics, and humane societies are
the most common users of high temperature pathological incineration. The
incinerators used are usually multiple chamber designs.[5] The Industrial
Combustion Coordinated Rulemaking (ICCR) Federal Advisory Committee[6]
recommends good combustion practices be adopted when burning pathological
waste, including 1 second retention times in the secondary chamber and
minimum secondary chamber temperature of 1600º to 1800º F (871º to 982º C).
In addition, the Committee recommends the use of combustion temperature
controls. Incinerator ash may be disposed of in state permitted municipal
solid waste landfills.

Regarding incineration of prions, research indicates that scrapie
contaminated hamster brain tissue exposed to 1,112° F (600° C) for 5 minutes
showed no infectivity, but infectivity was detected in the material when
exposed to the same temperature for 15 minutes, indicating that the agent
may not be fully inactivated at this temperature (Brown et al. 2000). The
authors suggest that this apparent inconsistency shows that infectivity was
near the point of extinction at this temperature. In the same study,
treatment at 1,832º F (1,000° C) for 5 minutes was associated with complete
elimination of infectivity. The authors caution that only the ashed
residue was assayed for infectivity, but not the combustion emissions. In
addition, prion contaminated material may not be completely inactivated in
the secondary chamber of typical incinerators because the retention times
are only a few seconds. Ash removed from the incinerator without being
exposed to sufficiently high temperatures and retention times in the
secondary chamber may contain residual infectivity. Additional experiments
are underway to evaluate prion inactivation in ash and emissions under
conditions similar to those of medical waste incinerators. A study by Det
Norske Veritas (DNV 1997) concluded that incineration may be considered a
safe way to dispose of TSE contaminated material if primary and secondary
combustion chambers assure that the material is exposed to a temperature at
or above 1,562º F (850° C) for at least 2 seconds and the equipment has
efficient controls to remove particles from flue gas. Taylor et al. (1996)
found no infectivity associated with scrapie contaminated mouse brain tissue
with exposure to dry heat at 392º F (200° C) for 60 minutes.

Some consideration has been made with regard to the use of air curtain
incinerators for the reduction of pathological waste.[7] However, this
mode of incineration may not be completely effective. With wet wastes, such
as CWD contaminated carcasses, temperatures within the pit can fluctuate and
dip below recommended temperatures due to lack of waste mixing and
inadequate airflow within the pit. Incomplete combustion of CWD waste
raises concerns that some prions will not be destroyed and could escape with
fly ash into the environment. In addition, those pollutants regulated by
the CAA and/or state regulations such as criteria and HAP pollutants, odor,
and opacity, may increase due to the air curtain being broken when
additional fuel and carcasses are loaded during the burn.

Inherent in any combustion process is the potential for emissions. However,
high temperature incineration in a multi-chamber controlled air system
provides an opportunity for complete combustion of the solid waste feed
resulting in the mitigation of criteria and HAP pollutants, as well as odor
and smoke, where applicable. In addition, air pollution control
technologies, such as gas scrubbers, and good combustion practices have
proven effective.

Alkaline Hydrolysis

Alkaline hydrolysis involves the use of a concentrated alkaline solution (1
molar sodium or potassium hydroxide) along with temperatures over 300º F
(149º C) and high pressures (approximately 5 bars) for a period of 6 hours
to ensure that tissues and proteins (including prions) are hydrolyzed or
digested. The vessel in which this process occurs is best described as a
large stainless steel pressure cooker. The unit is generally computer
controlled and may be operated at one, two or three cycles per day. The
loading capacity for these units varies. Units are available that can
handle from as little as 80 pounds per cycle or run, up to 7000 pounds per
cycle. The discharge from this process produces a very dense “soup” that is
high in biochemical oxygen demand and total suspended solids. The final pH
may meet the discharge limits on pH without further adjustment, although
POTWs should check to ensure the final pH is in compliance with local
limitations. EPA and the POTWs have not identified any significant
concentrations of toxic pollutants of concern in the discharge.

An example in Region 8 where alkaline hydrolysis digestion is being
implemented is at the diagnostic laboratory at the Colorado State University
(CSU) Veterinary Teaching Hospital, Diagnostic Laboratory. This laboratory
houses a “dedicated” prion laboratory, with all wastes being routed to final
alkaline hydrolysis treatment. This laboratory has been permitted by the
city of Fort Collins to discharge to the POTW. The CSU staff has developed
and installed a dehydrator system that reduces the waste stream from the
alkaline hydrolysis treatment to a very small amount of dry material that
can be disposed of as a solid waste.

Cleaning Contaminated Surfaces

Various guidelines exist for facilities that handle material contaminated by
TSEs, such as operating rooms (World Health Organization 1999, Sehulster and
Chinn, in press), autopsy rooms (Crain 1996, Sehulster and Chinn, in press),
research laboratories, and mortuaries (World Health Organization 1999). All
guidelines recommend treatments to inactivate prions on contaminated
surfaces or instruments and procedures for either handling waste material as
infectious waste or for treating liquid and solid wastes prior to discharge
or disposal.

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), any
chemical that is intended to prevent, destroy, repel or mitigate any pest
must either be registered as a pesticide product (FIFRA Section 3) or
exempted (FIFRA Section 18) prior to its sale or distribution in the United
States. The processes for obtaining registrations or exemptions are
described in EPA’s regulations (40 CFR 152-180) as well as on the web page
(www.epa.gov/pesticides). Basically, it is incumbent on the applicant for
registration or exemption to provide the data necessary for EPA to conduct
an assessment of the potential risks and benefits of a pesticide product and
to determine that no unreasonable adverse effects will occur from the
pesticide product’s proposed use. There are a few products under
consideration that may be efficacious in these situations and EPA is
expediting its assessment and emergency review process under Section 18 of
FIFRA for the products.

Treatments have not been validated for large pieces of tissue. Solids
should be removed from surfaces prior to treatment or removed from the waste
stream prior to discharge. The facility should use a fine mesh screen made
of nylon or similar material over the drains to remove tissues (after
surface treatment of the floors and tables). Use of a galvanized screen
should be avoided because an unacceptable level of zinc in the discharge
might potentially result. Absorbent bench top coverings may also be used to
collect and remove tissues. Inactivation of prions on solid surfaces should
be completed to the maximum extent possible before the resulting wastewater
is discharged.

Landfilling

The alternative practice for disposal of potentially CWD-contaminated solid
material is landfilling in a state-permitted municipal solid waste landfill
that is in full compliance with state and federal environmental regulations
and has no environmentally significant release from the facility.
Recirculating or bioreactor landfills should be excluded from accepting
these types of wastes. Proper landfilling is an acceptable alternative
practice and provides substantial capacity and lower cost compared to other
disposal methods, but offers no immediate inactivation of CWD prions and
raises questions about potential environmental contamination in the future.
Also, the design, construction, location and operation of landfills vary,
which may affect the fate and transport of prions within a landfill. Owners
or operators of landfills have the ability to accept or reject these wastes
based on a number of different economic, management, and environmental
factors. When landfilling is chosen as an option, consultation with state
and local authorities and the waste management industry, including the
landfills and POTWs, is essential. EPA Region 8 will continue to work with
our state and federal partners to evaluate the effectiveness of landfilling
as an alternative practice.

FIGURE 1
Potential Approach for Controlling Discharges to POTWs and Septic Systems
(not shown in text version)

[1] This paper does not create any new regulations or guidance, but rather
is a summary of existing authorities.

[2] Other federal agencies with significant roles in CWD management and
control are the Animal and Plant Health Inspection Service, USDA; the Food
and Drug Administration; and the Centers for Disease Control and Prevention.
In addition, state wildlife agencies are responsible for determining game
management strategies in response to CWD. We will rely on the CWD/TSE
National Working Group to develop approaches to address related issues
regarding prion decontamination.

[3] Prions are abnormal, disease-causing forms of normal proteins that are
naturally produced in mammalian cells. The normal form of the protein is
referred to as PrPC (Prion Protein Cellular). The abnormal, disease-causing
forms occur when the normal cellular protein (PrPC ) becomes folded in an
abnormal way, resulting in resistance to normal breakdown processes. The
abnormal form is referred to as PrPRes (Prion Protein Resistant). By
definition, a prion is “a small proteinaceous infectious particle which
resists deactivation by procedures that modify nucleic acids,” and,
therefore, throughout the context of this document, the term prion will
refer to the abnormal, disease-causing form only.

[4] Pathological waste is waste material consisting of only human or animal
remains, anatomical parts and/or tissue, the bags/containers used to collect
and transport the waste material, and animal bedding, if applicable (from
the Hospital/Medical/Infectious Waste Incineration (HMIWI) regulations at 40
CFR Part 60, Subpart Ec). CWD contaminated waste does not meet the EPA
definition for infectious waste in the HMIWI regulations because there have
been no incidents of CWD transmission to humans.

[5] Multiple chamber incinerators are incinerators with at least two or more
refractory-lined combustion chambers (primary and secondary) in series
physically separated by refractory walls, interconnected by gas passages,
and employing adequate design parameters necessary for maximum combustion of
waste materials. Design parameters include maintenance of adequate
combustion temperatures, excess air, complete turbulent mixing, and adequate
time for exposure to combustion temperatures. In dual chamber incinerators,
the waste is initially ignited in the primary chamber where drying and
decomposition are achieved. The partial combustion products then pass into
an afterburning secondary chamber at increased temperatures and adequate
retention times to complete the combustion reactions.

[6] The ICCR Coordinating Committee was established by the EPA under the
Federal Advisory Committee Act in September, 1996. The Committee developed
recommendations for consideration by the EPA in the development of
regulations for stationary combustion source categories including
non-hazardous waste incinerators. The Regulatory Alternatives Paper dated
September 8, 1998 includes these recommendations. See the ICCR Internet web
page at http://www.epa.gov/ttn/atw/iccr/cc/septrec.pdf.

[7] In air curtain incinerators, high velocity air is blown across the upper
portion of a single combustion chamber in which waste and fuel is loaded.
The curtain of air created by this process traps unburned particles under
the curtain in the high temperature zone where temperatures can reach 1,832º
F (1,000º C) or higher.

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-----Original Message-----
From: Terry S. Singeltary Sr. [mailto:flounder@wt.net]
Sent: Friday, November 14, 2003 11:56 AM
To:
Subject: Re: CWD disposal recommendations

snip...END///






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