re-oxtail soup
>>> Maybe the Japs like oxtail soup as much as I do. It better not be BSE infected. Food safety is always paramount. Profits should never be allowed to trump food safety. It seems that we can not trust the USDA under Johannes on that one (Quite personally, I think it is the Ag. chair committee heads that get packer funding that are the problem; public policy being run by private interests). What other things can we not trust him on? SH, do you care to coment? <<<
well, your in luck;-) the federal Gov. says it is safe to eat. they guarantee it with the USDA stamp of approval$ don't you feel safe?
personally though, i would not write that in stone just yet, once these more sensitive testing come to market. accumulation, amplification, transmission, threshold to clinical disease?
What are Specified Risk Materials?
Specified Risk Materials (SRMs) include the brain, skull, eyes trigeminal ganglia, spinal cord, vertebral column (excluding the vertebrae of the tail, the transverse processes of the thoracic and lumbar vertebrae, and the wings of the sacrum) and dorsal root ganglia of cattle 30 months of age and older. SRMs also include the tonsils and distal ileum of all cattle. However, in order to ensure that the distal ileum is removed, the entire small intestine shall be removed.
http://www.fsis.usda.gov/Fact_Sheets/FSIS_Further_Strengthens_Protections_Against_BSE/index.asp
UPDATE OF THE OPINION ON
TSE INFECTIVITY DISTRIBUTION IN RUMINANT TISSUES
INITIALLY ADOPTED BY
THE SCIENTIFIC STEERING COMMITTEE
AT ITS MEETING OF 10-11 JANUARY 2002
AND AMENDED AT ITS MEETING OF 7-8 NOVEMBER 2002
following the submission of (1) a risk assessment by the German Federal Ministry of
Consumer Protection, food and Agriculture and (2) new scientific evidence
regarding BSE infectivity distribution in tonsils
http://europa.eu.int/comm/food/fs/sc/ssc/out296_en.pdf
OPINION AND REPORT
ASSESSMENT OF THE HUMAN BSE RISK POSED BY
BOVINE VERTEBRAL COLUMN
INCLUDING DORSAL ROOT GANGLIA.
ADOPTED BY THE SCIENTIFIC STEERING COMMITTEE
AT ITS MEETING OF 16 MAY 2002
http://europa.eu.int/comm/food/fs/sc/ssc/out264_en.pdf
##################### Bovine Spongiform Encephalopathy #####################
From: TSS ()
Subject: PrPSc distribution of a natural case of bovine spongiform encephalopathy
Date: August 8, 2005 at 12:28 pm PST
PrPSc distribution of a natural case of bovine
spongiform encephalopathy
Yoshifumi Iwamaru, Yuka Okubo, Tamako Ikeda, Hiroko Hayashi, Mori-
kazu Imamura, Takashi Yokoyama and Morikazu Shinagawa
Priori Disease Research Center, National Institute of Animal Health, 3-1-5
Kannondai, Tsukuba 305-0856 Japan
[email protected]
Abstract
Bovine spongiform encephalopathy (BSE) is a disease of cattle that causes
progressive neurodegeneration of the central nervous system. Infectivity
of BSE agent is accompanied with an abnormal isoform of prion protein
(PrPSc).
The specified risk materials (SRM) are tissues potentially carrying BSE
infectivity. The following tissues are designated as SRM in Japan: the
skull including the brain and eyes but excluding the glossa and the masse-
ter muscle, the vertebral column excluding the vertebrae of the tail, spinal
cord, distal illeum. For a risk management step, the use of SRM in both
animal feed or human food has been prohibited. However, detailed
PrPSc distribution remains obscure in BSE cattle and it has caused con-
troversies about definitions of SRM. Therefore we have examined PrPSc
distribution in a BSE cattle by Western blotting to reassess definitions of
SRM.
The 11th BSE case in Japan was detected in fallen stock surveillance.
The carcass was stocked in the refrigerator. For the detection of PrPSc,
200 mg of tissue samples were homogenized. Following collagenase
treatment, samples were digested with proteinase K. After digestion,
PrPSc was precipitated by sodium phosphotungstate (PTA). The pellets
were subjected to Western blotting using the standard procedure.
Anti-prion protein monoclonal antibody (mAb) T2 conjugated horseradish
peroxidase was used for the detection of PrPSc.
PrPSc was detected in brain, spinal cord, dorsal root ganglia, trigeminal
ganglia, sublingual ganglion, retina. In addition, PrPSc was also detected
in the peripheral nerves (sciatic nerve, tibial nerve, vagus nerve).
Our results suggest that the currently accepted definitions of SRM in
BSE cattle may need to be reexamined.
179
T. Kitamoto (Ed.)
PRIONS
Food and Drug Safety
================
OXTAIL (rich in peripheral nerves).
i will try to keep this short;
PRELIMINARY ANALYSIS OF INTERIM FINAL RULES AND AN
INTERPRETIVE RULE TO PREVENT THE BSE AGENT FROM
ENTERING THE U.S. FOOD SUPPLY
I. Summary
In response to finding a cow in Washington State positive for Bovine Spongiform
Encephalopathy (BSE) on December 23, 2003, FSIS has taken emergency actions to
protect public health. These actions include: designating certain high-risk tissues as
specified risk materials (SRMs) and prohibiting the use of such materials for human food;
requiring the condemnation of non-ambulatory disabled cattle presented for slaughter and
use in human food applications; not awarding the mark of inspection on cattle tested for
BSE under the Animal and Plant Health Inspection Service (APHIS) surveillance
program until the test results are received and the results are reported to be negative for
BSE; ensuring that advanced meat recovery (AMR) systems do not process SRMs and
that boneless "meat" does not contain central nervous system (CNS)–type tissues or
excess levels of bone solids and bone marrow; and prohibiting the use of certain stunning
methods. These actions are all science-based measures intended to further minimize
potential human exposure to the BSE agent through the consumption of beef and beef
food products.
The extent of the economic impact of the BSE finding on the livestock sector and
meat processing industry depends on domestic and foreign consumer attitudes toward the
safety of the U.S. beef supply and how beef consumption habits might change given this
new situation. Consumer attitudes may vary depending on 1) whether the single case of a
cow with BSE were imported or of domestic origin, 2) the extent of the disease, and 3)
how many cattle infected with BSE were taken out of the national beef herd. The finding
2
of a single cow with BSE originating from a shipment of imported cattle from Canada
has had a negative impact on the U.S. cattle sector, largely as a result of decreased export
demand. The measures prescribed by the SRM interim final rule provide greater
assurances to both domestic and foreign consumers that the U.S. beef supply is safe.
As will be shown in the analysis later in this document the total annual cost of the
FSIS actions related to the SRM and AMR interim final rules is estimated at $110.3 to
$149.1 million. The total cost of the SRM interim final rule is estimated at $99.9 to
$136.6 million. The primary impacts of the SRM interim final rule are the exclusion of
SRMs from use in the human food supply ($35.6 to $36.7 million); the prohibition on
non-ambulatory disabled cattle ($35.6 to $71.3 million); and modifications of HACCP
plan/procedures, sanitation SOPs, or other pre-requisite programs and record keeping
requirements ($27.6 million).
The annual total cost of the AMR interim final rule is estimated at $10.7 to $12.5
million. The primary impacts of the AMR interim final rule are restrictions on
incorporating certain non-meat components in AMR products ($4.4 to $5.6 million);
testing AMR product for iron, protein, and CNS-type tissues ($4.7 to $6.2 million); and
revisions to HACCP and other plans, and bookkeeping requirements ($1.0 to $1.3
million).1 Most values are reported as averages for the analysis. Some values however
are reported at the 5th and 95th percentiles of the distribution.
1 The cost impact analysis of the SRM and AMR Interim Final rules is based on a probabilistic model
developed by FSIS, excluding the prohibition on non-ambulatory disabled cattle from the food supply (p.
28) and HACCP plan development, record keeping, and verification (p.33). The cost impacts of these
regulatory measures are based on the deterministic values cited in the text of the analysis.
3
The annual cost of additional inspection, testing, and surveillance by FSIS is
estimated at $3 million2. This estimate does not include the impact of FSIS measures on
programs administered by other USDA agencies. Nor does it include the impacts of
changes in the programs of these agencies on FSIS program costs. These impacts are
difficult to estimate at this time due to uncertainty about the provisions of the programs
that may be implemented by other USDA agencies.3 The action related to the prohibition
on certain stunning devices is not expected to have any cost impacts as these devices are
no longer in use.
The aggregate beef price impacts of the measures contained in the SRM and
AMR interim final rules are not expected to be significant.4 The measures affecting the
removal of SRMs from the human food supply, excluding the condemnation of nonambulatory
cattle presented for slaughter, may have a minimal impact on consumer beef
prices. Price impacts are expected to be primarily limited to products derived from beef
small intestines such as sausages with natural casings and trepas for which substitutes are
limited. Substitutes are available for other by-products, largely from cattle less than 30
months of age, although prices will likely be somewhat higher. For example, the
prohibition on bone-in beef cuts from cattle 30 months of age and older will raise the
2 United States Department of Agriculture, 2005, Explanatory Notes for the Committee on Appropriations,
Volume 1, page 14-14.
3 The impacts of the test and hold provision depend on the level of surveillance testing for BSE that will be
conducted by the APHIS on cattle presented for slaughter at federally-and state-inspected establishments.
Because non-ambulatory disabled cattle are prohibited for use in human food, APHIS surveillance testing
for BSE may shift toward locations other than federally inspected establishments and thereby minimize the
impacts of the new FSIS test and hold policy on establishments that slaughter cattle. However, a more
extensive BSE surveillance program that focuses on all cattle 30 months of age and older may increase
testing at these establishments, and consequently the impact of the test and hold provisions.
4 FSIS is collecting additional information on cost impacts of the SRM and AMR interim final rules that
may not be fully reflected in the current analysis. When this information is available, it will be used with
existing information to estimate the beef price impacts, disaggregated by major market categories. This
analysis, conducted by RTI, International, along with information from public comment; will be
incorporated into the final regulatory impact analysis.
4
prices of these cuts from younger cattle. The removal of non-ambulatory cattle from the
food supply is not expected to have a significant impact on beef prices given the very
small share of beef supply affected (0.1 percent).
The costs associated with regulatory measures affecting the segregation and
disposal of SRMs, and changes in process control practices including plan development
and record keeping are not significant from an industry perspective. Consequently, the
resulting impacts on beef and beef products, and both beef and pork AMR products
are not expected to be significant.
Anecdotal information suggests that prices received for cattle 30 months of age
and older are being significantly discounted from prices for cattle of equivalent grade that
are less than 30 months. The amount of the discount may reflect a combination of costs
due to product loss, segregation, SRM removal and disposal, and other related processing
control costs. These impacts could be significant for cattle producers. The Agency
requests comment on the effect of the SRM interim final rule provisions on cattle
marketing practices and prices.
The following is a preliminary analysis of the major impacts of the measures
contained in the SRM and AMR interim final rules. The Agency is seeking comment
from the public on the types and magnitude of the impacts resulting from the SRM and
AMR interim final rule measures to ensure that the final regulatory impact analysis is
comprehensive.
II. Cattle and Meat Processing Industry.
The United States has the largest fed-cattle industry in the world, and is the
world's largest producer of beef, primarily high-quality grain-fed beef, for domestic and
5
export markets. Beef production in 2003 is estimated at 26.3 billion pounds from an
annual slaughter of about 36 million cattle. Gross farm income from cattle and calf
production totaled $44.1 billion in 20035. U.S. exports of beef, veal, and beef variety
meats in 2003 were 2.6 billion pounds valued at $3.8 billion according to the most recent
estimates.
In 2003, 98.7 percent of all cattle were slaughtered for food and processed in
federally-inspected establishments.6 About 80 percent of the cattle slaughtered at
federally- inspected establishments are estimated to be less than 30 months of age. The
remaining 20 percent are cows, bulls, or stags and some steers and heifers that are
estimated to be 30 months of age and older7. FSIS seeks comments on the age
distribution of cattle sent to slaughter and, in particular, reliable information on the age
distribution of cattle slaughtered at establishments that specialize in market or fed cattle.
In 2003, cattle were processed for dress or further processing in an estimated
4,033 establishments that are federally- and State-inspected. Of the 4,033 establishments,
FSIS estimates that about 84 percent or 3,388 were establishments that typically dealt
with SRMs during carcass dressing, meat-cut fabrication, or further processing of
carcasses or parts of carcasses. The remaining 16 percent, or 645, were establishments
that did not receive SRMs of any type, or only received parts of beef carcasses derived
5 U.S. Department of Agriculture, Economic Research Service, released on February 6, 2004 at ERS
website: http://www.ers.usda.gov/briefing/farmincome/ See the following for more detailed information:
http://www.ers.usda.gov/data/farmincome/finfidmu.htm
6 U. S. Department of Agriculture, Food Safety and Inspection Service. Animal Disposition and Reporting
System, 2003.
7 FSIS has found that some first-calf cows, and some juvenile (not mature) and mature bulls that go to
slaughter may be less than 30 months of age. Furthermore, FSIS has found that some steers and heifers that
go to slaughter may be 30 months of age and older. These steers and heifers have been fed primarily grass
pasture or forage crops while growing and then finished for grading on grain. Also, heifers that have failed
to conceive in the breeding season, or have lost their calves, have been removed from cattle herds. These
older heifers, that have already matured, have been placed in feedlots where the heifers have been finished
for grading on grain. These practices affect the share of meat slaughter and processing establishments
which may have to modify their practices in response to the proposed measures.
6
from cattle 30 months of age and older that did not include the vertebrae (e.g. boxed
boneless trimmings for further processing). Furthermore, of the 3,388 establishment that
typically dealt with SRMs, approximately 888 (26 percent) are State-inspected
establishments and about 2,500 (74 percent) are federally-inspected establishments. Of
these 3,388 establishments, about 2,128 (62.8 percent) were establishments that are
classified by FSIS as "very small." About 1,203 (35.5 percent) of the establishments
were classified as "small." The remaining 57 establishments (1.7 percent) were classified
as "large." 8 These 57 large establishments slaughter or further process more than 94
percent of the cattle. All of the large establishments are federally-inspected. The 1,203
small establishments slaughter and process about 5 percent of the cattle. The 200 largest
establishments slaughter or process about 98 percent of the cattle9.
In 2003, about 56 establishments used AMR systems to produce beef and pork
AMR products. AMR products derived from beef vertebrae were produced in about 30
establishments. Pork AMR products derived from pork vertebrae were produced in about
22 establishments. One establishment produced both beef and pork AMR products
derived from vertebrae. At least four establishments produced beef or pork AMR
products derived from non-vertebral bones. About 17 AMR establishments were small
establishments, and the remaining were large. At least one establishment processed beef
vertebrae from its operations and the operations of another establishment. About three
AMR establishments only fabricated cuts or processed carcasses or parts of carcasses.
8 The size classifications used by FSIS for very small, small, and large establishments are defined as
establishments with fewer than 10, between 10 and 499, and 500 or more employees, respectively.
9 U.S. Department of Agriculture. Animal Disposition and Reporting System, FSIS. 2003.
III. Scientific Findings
In April 1998, USDA commissioned the Harvard School of Public Health, Center
for Risk Analysis, to conduct an analysis and evaluation of the current measures
implemented by the U.S. government to prevent the introduction and spread of BSE in
the United States and to reduce the potential human exposure to the BSE agent. The
Harvard risk assessment reviewed available scientific information related to BSE and
other Transmissible Spongiform Encephalopathies (TSEs), assessed pathways by which
BSE could potentially occur in the United States, and identified measures that could be
taken to protect human and animal health.10
The Harvard BSE risk assessment concluded that if introduced, BSE is extremely
unlikely to become established in the United States and that should BSE enter the United
States, only a small amount of potentially infective tissue would likely reach the human
food supply and be available for human consumption. The Harvard study identified three
pathways or practices that could contribute most to either increased human exposure to
the BSE agent or to the spread of BSE should it be introduced. The three pathways are:
• Noncompliance with FDA regulations prohibiting the use of certain proteins in
feed for cattle and other ruminants;
• Rendering of animals that die on the farm and use (through illegal diversion or
cross-contamination) of the rendered product in ruminant feed;
• Inclusion of high-risk tissue from cattle, such as brain and spinal cord, in edible
products.
The Harvard study concluded that, ... (more on the Harvard BSe risk assessment later, no need to go further here...TSS)
snip........
Under the measures announced by FSIS on January 12, 2004, the spinal cord is
required to be removed from the vertebral column of cattle 30 months of age and older.
In addition, the vertebral column from cattle 30 months of age and older cannot be used
for AMR systems. Thus, unless there is inadvertent use of this material in AMR systems
or if cattle are not properly aged, components of the vertebral column may become
incorporated into edible food, including steaks, meat from AMR systems, and edible
rendered products. FSIS does not believe that the oxtail, used primarily for soups, is a
source of potential infectivity because neither the spinal cord nor the DRG are present in
the portion of the vertebral process that defines the tail area.
http://www.fsis.usda.gov/OPPDE/rdad/FRPubs/03-025N/BSE_Analysis.pdf
THIS document is worth reading if you have not read it.
THE federal Gov. uses the Harvard BSE risk assessment as the 'GOLD STANDARD'
to dispute every scientist in the world that disputes anything they say.
MIND you the Harvard BSE risk ass. was partially funded by the very
industry it was assessing. this is the assessment of that study by TSE scientist.
ABOUT 132 pages;
October 31, 2002
Review of the Evaluation of the
Potential for Bovine Spongiform
Encephalopathy in the United States
Conducted by the Harvard Center for Risk Analysis,
Harvard School of Public Health and Center for
Computational Epidemiology, College of Veterinary
Medicine, Tuskegee University
Final Report
Prepared for
U.S. Department of Agriculture
Food Safety and Inspection Service
Office of Public Health and Science
Prepared by
RTI
Health, Social, and Economics Research
Research Triangle Park, NC 27709
RTI Project Number 07182.024
snip...
3.2 HAVE THE DATA BEEN CORRECTLY
INTERPRETED AND EMPHASIZED?
1) The H-T BSE study authors have done their best to
incorporate the existing data in their estimates of the parameters
selected for inclusion in the model. Not much hard data exist that
could be used directly for setting parameter values. Therefore, the
authors used indirect data to justify logical arguments for setting a
parameter to a particular range of values. The authors may have
included some factors in their model simply because some indirect
data could be found.
The reviewers had concerns that the importance of some parameters
has been overestimated and others underestimated.
2) A rather optimistic choice was made in case of doubt or
insufficient hard evidence or data. These concerns relate to overall
model weaknesses in the general comments section. In the
summary section, on Pages 98 and 99, several of the main issues
that involve assumptions that cannot be verified with confidence are
discussed, and several of them could serve as perfect examples of
what has been argued here, that optimistic choices for favorable
3-4
Section 3 Identification of Data and Critical Evaluation of Evidence
outcome or reassuring nuances are presented (e.g., the
implementation rates, the remote chance that an infected animal
had been imported from the UK).
Reviewers commented on the import of MBM.
3) The UK export statistics mention a shipment of 20 tons to
the U.S. in 1989. Such a quantity was enough to spark the Swiss
epidemic. This part of import risk was considered negligible
probably because the U.S. authorities could not corroborate this
figure. The statement (Page 22, second paragraph, last sentence)
that overseas shipping of MBM was economically noncompetitive
seems questionable because at least for the period when MBM was
almost available for free in the UK, it did get all the way to South-
East Asia in large quantities. Figures from Southern State
Cooperative of recent years are moot in this respect.
A reviewer also commented on the import of live cattle from the
UK.
4) Because the USDA reported that about half of the animals
imported in the risk period did not really enter the food chain, these
were considered to carry no risk (Section 3.4.3). The report does
not provide details or evidence to support this statement. Other
arguments regarding the potential risk of import of live cattle from
the UK, such as animals not being from a BSE-infected farm, and
BSE not being a recognized disease (Page iii, last paragraph), are
questionable. Admittedly, not many were imported at the peak of
the risk period.
5) With respect to rendering (Table 3-3, Page 61), two log
reduction for atmospheric continuous rendering with added fat is
optimistic. Also there is a doubt about the statement on Page 25
(Appendix 1, second paragraph, last sentence) that addition of fat
increases the inactivation.
6) In Section 3.1.2.3 on stunning, it is assumed for the base
case that air-injected stunning is not used in the U.S., based on
conversations with involved persons (Page 55, first paragraph,
seventh line). However, it seems that the model is based on
unlikely events such as air-injected stunning. Therefore, the model
may be limited and may become obsolete. In Section 3.1.2.4 (Page
56, second paragraph, last sentence), the assumption that stunners
3-5
Review of the Evaluation of the Potential for Bovine Spongiform
Encephalopathy in the United States Final Report
not using air injection never cause contamination of the blood
(during exsanguination) with brain material needs to be modified.
7) The remark in Section 4.5 in the last line on Page 99 does
not sound very scientific: exposure could not have been
substantial because we did not see many cases, having in mind the
German experience. About the level of achieved surveillance, more
will follow.
8) In Section 2.3.9.1 on plate waste, it is said to mainly contain
vegetable material (third paragraph, second sentence), and
vegetable protein must be added to give it the correct nutritional
value. The major question is why one would not add mammalian
protein here instead of vegetable?
9) A reviewer commented on ProbPassAM (Section 2.1.1,
Appendix 1, Page 9). If it is their intent, the authors should specify
that ProbPassAM is the probability that a BSE-infected animal, not
just an animal, passes AM inspection. The authors state that the
probability of an animal passing AM inspection is age dependent.
They provide the references that were used to derive these
estimates. Because BSE evolves slowly, their argument that BSE in
older animals is more likely to be detected makes sense, but the
age-dependent variation is for animals without clinical signs. Thus,
the probabilities really represent the age-dependant chance
occurrence that an infected animal passes. Variations in
probabilities for the three age categories are minute (to third
decimal, Appendix 1, Section 3.1.1, Page 38). The authors do not
specify variation in ProbPassAM in animals with clinical signs by
the actual clinical signs, where variation in the probability among
animals is likely to be higher than variation among age categories.
Therefore, it appears that in one instance the parameter is
overestimated and in the other underestimated.
What is important from an inspection point of view is to pay greater
attention to early signs of disease. The probabilities also do not
reflect improvements in detection over the 20-year time span. If the
0.10 probability chosen by the authors is an average probability of
passing infected animals with early signs and animals with late
signs, perhaps it is appropriate. If it represents the probability of
passing an infected animal in the later stages of disease, then the
3-6
Section 3 Identification of Data and Critical Evaluation of Evidence
Figure 3-1. Forrester
(rate/state) Diagram to
Depict Relationships
between Population
Parameters
estimate is probably high, because the neurological signs would be
obvious to an inspector.
10) Reviewers commented on the cattle population parameters
(Appendix 3A). The output tables list epidemic statistics such as the
numbers of cattle infected and the numbers infected exhibiting
clinical signs. It appears that cattle population parameters were
included in the model to simulate epidemic statistics, which is also
suggested in Figure 3-1 of the H-T BSE study report. Cattle
population parameters specified in the H-T BSE study report are
ProbBirth, ProbDeath, and InitSize. From an epidemiological point
of view, these variables can be used to estimate the size of the
national herd, which can define cattle at risk, and transmission of
prions, for instance between cow and calf, which can define spread.
However, the authors do not define clearly how the population
parameters affect the output. That is, the mathematical
relationships, if there are any, among the population parameters.
Figure 3-1 in the H-T BSE report is not sufficient in describing the
relationships. The authors do not report the density-dependent
process used. They might consider using Forrester (rate/state)
diagrams to depict the relationships in an easy to understand figure.
For instance, a simple way to convey to the reader the factors that
affect the size of the cattle population might be as shown in
Figure 3-1.
Population Birth
Rate
0.0833
at Time t
Death
Rate
A rate that increases the population and a rate that decreases the
population determine the size of the herd at a point in time. Then
the authors can elaborate. For instance, the rate of increase is
affected by the current age-specific size of the population at time t-1
and the birth rate. The rate at which the population decreases is
affected by the death/slaughter rate. The number culled for slaughter
(and other factors) affects the death rate.
3-7
Review of the Evaluation of the Potential for Bovine Spongiform
Encephalopathy in the United States Final Report
In Table 3.4.1, the natural death rate is age-specific (Appendix 1,
Page 45). It should be reported that the unit for age is months, and
that the values tabulated are for beef cattle. Overall, the units of
measurement should be included in all tables. Throughout the
report, the stage of production is not considered. For instance, the
death rate is different for stocker cattle on pasture than for feedlot
cattle and varies seasonally and geographically and certainly by
producer. When should details such as these be included in the
model and when should they be excluded? More rationale should
be given for the variables selected and for those omitted.
Population parameters were important in the Great Britain outbreak
because destroying infected animals served to reduce the incidence
rate and disease spread. It is unclear how the population
parameters are used in this model.
11) About maternal transmission, one reviewer noted the
following. The parameters beginCalving and endCalving, the
beginning and ending age when cows give birth, are defined in
Appendix 1, Pages 10 and 11. They are included presumably to
estimate maternal transmission of prions to offspring or perhaps to
determine the period at which transmission could occur. However,
the actual relationship among the variables is not described.
Therefore, one would have to examine the computer code to
understand the relationships. Again, the authors might consider
depicting the relationship as shown in Figure 3-2.
ProbTrans is a probability that a new born calf becomes infected
if the mother is infected and the mother has lived through at least a
fixed fraction of her incubation period and its value is 0.1
(Appendix 1, Section 2.2.2, Page 10). The fixed fraction is specified
by parameter and its value is 0.833
(Appendix 1, Section 3.1.7.3, Page 76). Therefore, it appears that
probTrans is a conditional probability that can take on one of the
two values, which might be depicted by a Warnier-Orr diagram that
the authors could use as a means of making the relationship easier
for the reader to understand:
3-8
Section 3 Identification of Data and Critical Evaluation of Evidence
Figure 3-2. Forrester
Diagram to Depict
Relationships for
Begincalving and
Endcalving
Rate
BSE
Calves
BSE
Mom
Transmit
(ProbTrans)
Moms
Time
since
infected
[Fraction of incubation period > 0.833] {ProbTrans = 10%
[Fraction of incubation period < 0.833] {ProbTrans = 0%
If the condition within the square brackets [ ] is true, then the
assignment to the right of the curly brace { is made. Also, the
authors need to specify if the fraction is >0.833 or ?0.833.
12) Apparently, the incubation period for BSE is assigned a value
between 0 and >130 months according to the probability
distribution ClinicalDate (Appendix 1, Pages 73-76). It is
assumed that although the table indicates >130 months, the highest
value actually used was 130.
13) A few assumptions are based on data extrapolated from
dairy cattle and beef cattle or other animals. Do the results sum
over all types of cattle?
14) The number of cattle among which blood meal from a single
slaughtered animal is divided is estimated as described in Section
2.3.1 (Appendix 1, Page 11). Apparently, the blood collected from
individual animals at slaughter establishments is pooled. The
authors calculate the expected amount of blood meal consumed by
a dairy cow to determine the number of animals (88) fed by a single
4,000 lb batch of blood meal. It is not clear how this number is
used along with estimates of blood meal consumption (Table 3.3.3,
Appendix 1, Page 39) by each bovine type, gender, and age
combination to estimate the number of cattle infected by blood.
Also, the value for the number of animals fed by a single batch of
3-9
Review of the Evaluation of the Potential for Bovine Spongiform
Encephalopathy in the United States Final Report
blood meal is reported as 88 in Appendix 1, on Pages 11 and 23,
but 89 in Appendix I, Page 66. Which of these two numbers is
correct? Because the units in the output tables (Appendix 3A) are
not given, it can only be a guess that the value for blood (in mode of
infection) represents cattle numbers infected by blood.
15) One reviewer commented on the lack of emphasis on
exposure routes. It is generally accepted that the highest risk for BSE
is from
Z import of live cattle or MBM from a country with BSE;
Z an internal processing system that is incapable of reducing
infectivity below a certain threshold level (mainly the
rendering system); and
Z exposure of ruminants to the end products of the second
way (be it purposely or accidental, by cross-contamination).
Although it is commendable that all possible routes and potential
risks are addressed, the emphasis could have been placed more on
the above limited number of priority routes, instead of dwelling on
sometimes highly theoretical routes. In other words, some of the
reported unlikely infection routes are easily dismissed by the model
with a simple statement, whereas others are investigated to a
surprisingly deep level. This comment is also related to the general
comment on complexity and level of detail.
The study apparently treats the scrapie transmission (Section 2.3.3,
Page 23) and the spontaneous BSE case (Section 2.3.1, Page 21) at
the same level as the above listed priority routes. Below we provide
an example of this inconsistency with what is considered major
risks.
It is stated that from 750,000 up to 2.5 million animals are imported
annually from Mexico and Canada (Section 2.3.2.3, Page 22).
However, the H-T BSE study report does not address what happens
in Mexico in terms of MBM exposure. In general, the report says it
was extremely unlikely that those animals posed a risk of
introducing BSE in the U.S. Perhaps the imported animals do not
pose any risk, but what if they had been fed contaminated starter
ratios as calves in Mexico? Even if such animals would not live
until patent clinical stages, they can introduce infectivity into the
system. The Scientific Study Committee (SCC) concluded that this
was an area for consideration (or concern) in the case of the U.S.
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Section 3 Identification of Data and Critical Evaluation of Evidence
16) The third paragraph on Page iii discusses the risk presented
by the 334 animals brought into the U.S. from the UK between
1980 and 1989. The text states: These animals were imported as
breeding stock, not as beef or dairy breeding animals. This fact is
likely to have reduced their potential for exposure to BSE before
their export from the UK (fifth line). There is a misunderstanding
here as discussed below.
The cattle exported from the UK have carried a greater risk of being
infected by BSE than the other members of their natal cohorts that
were not exported. An assessment based solely on the incidence in
the home-based remnant of the cohort can therefore be misleading.
The reason for this elevated risk is because the exported animals are
more likely to have received commercial concentrate feed,
especially beef breeds that had a much lower exposure to feedstuffs
containing MBM. One reason for this was to ensure that they were
in the best physical condition. Examples of this apparent differential
risk for exported animals are the animals of the Saler breed, which
was exported to Canada, and animals exported to Denmark and
Germany. More generally, at the beginning of the clinical
epidemic, pedigree dairy herds were disproportionally represented.
Their exposure to MBM was relatively greater than for other
commercial herds, because of showing animals and general
traditions of managing such herds. Unfortunately a proportion of
the early affected pedigree herds was the source of Friesian heifers
for export to Portugal to restock after the Contagious Bovine
Pleuropneumonia (CBPP) outbreak there.
17) The second paragraph in Section 2.1.1 on Page 6 describes
transmission of TSE disease in the case of sheep-borne scrapie. It is
stated that TSE transmission has been inked to the use of vaccines.
There is not much evidence that a relatively crudely prepared
louping ill vaccine has been associated with transmission. The
evidence from the Italian outbreak is far from conclusive.
18) It would have been more correct if at least experimentally
was inserted after transmitted in the second sentence of the
second paragraph of Section 2.1.2.
19) With reference to Anderson et al. (1996), it is stated in
Section 2.1.3, third paragraph, that the susceptibility of animals
peaks at 1.31 years of age and then decreases based on back
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calculation of the BSE model. There not only is a slight
misunderstanding of the Anderson paper, but also an error in this
paper that unfortunately has never been amended.
The peak susceptibility quoted is not derived by a back calculation.
However, it is derived from a research institutes cattle herd that had
a very unusual feeding profile and this is the error. In Great
Britain, exposure to feedstuffs containing MBM is relatively rare
between 6 months of age and approximately 2 years when heifers
start to calve. This error is perpetuated in the Woolhouse and
Anderson (1997) paper, which is not a separate investigation (i.e.,
both papers are part of the same investigation). Moreover, it has not
been possible to determine the profile of age-dependent
susceptibility and whether it does occur. This would require a
laboratory-based study because the natural feeding pattern
throughout the first 2 years of the life of cattle in Great Britain
precludes the necessary epidemiological analysis of this putative
age-dependent susceptibility.
The synthesis of the current evidence on this aspect is important to
the risk assessment. If there is an age-dependent susceptibility it is
not absolute. That is, all ages are susceptible. The age at which
cattle are exposed orally and parentally to the BSE agent in
experimental challenges in Great Britain has been 4 months. This is
the age at which calves would have achieved their maximum intake
of commercial concentrate feedstuffs under Great Britain conditions.
The results from the British attack rate study, involving oral exposure
to varying amounts of brain tissue from terminal cases of BSE, has
resulted in an incubation period/age at clinical onset distribution
similar to that observed in naturally occurring cases. The
epidemiological evidence from the epidemic in Great Britain is that
age at exposure does not influence the incubation period.
In the ninth line of the third paragraph, it is hypothesized that agerelated
susceptibility is associated with permeability of the intestine
to large protein. A reference to the hypothesis is required because
the change in permeability of the bovine intestine with age does not
explain the apparent age-dependent susceptibility. The quoted
changes occur too early after birth.
In the second paragraph on Page 12, findings from the attack rate
experiments are discussed for the dose of BSE agent. The
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Section 3 Identification of Data and Critical Evaluation of Evidence
researchers should have made themselves aware of the attack rate
study conducted in Great Britain. The lowest dose in the original
study (a follow-up study using lower doses is in progress) was 1g.
The results of this study should have been included here. There
appears to be some confusion here and therefore a concern that the
researchers may not have made the best use of the research results
available, which is a trap generally advised against in terms of
interpretation and use of the results of the bovine pathogenesis
study. Essentially, the researchers have assumed that all of the
animals in the pathogenesis study, exposed to 100g brain orally,
had an incubation period of 36 months. This is not true and
probably arises from a lack of synthesis of the results from these two
studies; the attack rate study, although initiated at the same time as
the pathogenesis study, was the scoping study for the latter. The
problem is that in the attack rate study the 10 animals were exposed
to 100g brain orally. However, the same exposure dose used in the
pathogenesis study had incubation periods that ranged from 33 to
61 months. It is not correct to assume that all of the pathogenesis
study animals had the same relatively short incubation period.
Therefore, the proportional calculation described in Section 2.10.1,
Appendix 1 will produce conservative estimates of infectivity and
underestimate this value.
20) Section 2.2.1 describes scrapie in sheep as one of the
possible causes of the BSE epidemic in the UK. The section is a
little muddled in that it starts discussing transmission of sheep
scrapie between sheep and then goes on to the sheep scrapie origin.
The latter is a little simplistic and half-hearted. Again, this section is
a little short on primary references and reviews of considerations of
the origin, for example Kimberlin (1997). The comment on the
feeding of concentrates to calves not taking place other than in
Great Britain except Australia (Page 14, last sentence) is not true.
The EU-sponsored Great Britain exercise clearly indicated that the
feeding of concentrates containing MBM to calves was not restricted
to Great Britain/UK. Thus, there is a misquotation regarding the
feeding of concentrates to calves, which needs to be corrected to
make accurate international comparisons. Finally, the last sentence
of Section 2.2.1 could be misinterpreted by the uninformed to mean
that cattle are not susceptible to oral exposure to sheep scrapie.
This is not true.
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21) Section 2.2.2 discusses sporadic BSE as one of the possible
causes for the UK epidemic. The first sentence of this section is
rather vague and conflicting. Is this referring to relativity to all other
countries or just to the U.S.? The evidence suggests that this is only
true for the U.S. Occurrence of sporadic BSE according to age of
cattle is discussed in the second paragraph. The age distributions of
the UK animals are specifically mentioned. However, other
European countries certainly have dairy cow populations with
similar age distributions, which needs to be considered here.
22) As discussed in Section 2.2.3, toxic agents and other
hypotheses as a possible cause of the BSE epidemic in the UK are
discussed here. The other hypotheses may not deserve any great
attention in such a risk assessment. They could have been
dismissed either by reference to reviews by others such as the
Spongiform Encephalopathy Advisory Committee (SEAC) in Great
Britain or by the EUs SSC. As it stands, it is misleading. For
example, the Organophosphate Pesticides hypothesis has not
been a singular hypothesis. It has changed significantly throughout
the epidemic by its protagonist. Also, in the last sentence in the first
paragraph of Section 2.2.3.2, it is stated that resulting conditions
from copper deficiency had signs and pathological changes similar
to those of BSE, which is not true. Section 2.2.3.5 discusses
pituitary hormones, but the fact that transmission via hormones
derived from bovine pituitaries was considered in the original
epidemiological study has been ignored.
23) As discussed in Section 2.3.7.1, there is a theoretical risk
that cattle could be exposed to a TSE from porcine-derived protein.
One of the two potential sources of this exposure can be a natural
TSE that infects pigs. Section 2.3.7.1 discusses infectivity in pigs
due to TSE infection. BSE in pigs, as a clinical disease or subclinical
infection, has been a concern worldwide. They were clearly of
potential importance in Great Britain because of the inclusion rate
of MBM. In simple terms pigs could represent an effective sump
for the BSE agent, in which the BSE agent is effectively removed
from the feed system, or at the other extreme they could represent a
means of amplification.
The evidence from Great Britain could have perhaps been used to
strengthen this section. This is so specifically for the last part of the
second paragraph and the third paragraph on Page 29. Some
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Section 3 Identification of Data and Critical Evaluation of Evidence
evidence indicates that subclinical infection is not a problem in
pigs, and this is not presented. Also, some evidence shows that
clinical disease in pigs has not occurred in the pig population in
Great Britain. This has probably got lost in various reports.
However, if one assumes that the incubation period in pigs is the
same as that for BSE in cattle and the surveillance for neurological
disease in pigs in Great Britain is equally effective for such disease
in cattle, then the number of expected cases in the pig population in
Great Britain can be tens of thousands. On the first assumption
there is no evidence to dismiss it. On the second assumption,
evidence indicates that the surveillance of disease, including
neurological disease, in pigs is more effective than in cattle in Great
Britain.
BSE in pigs was detected by a neuropathologist whose specialism
was neurological disease in pigs. Also, during the BSE epidemic
outbreaks of neurological disease in pigs in Great Britain were
detected, brought to the attention of MAFF scientists, and
investigated. The main point is that the third paragraph on Page 29
has a touch of innumeracy. The percentage of pigs slaughtered at
less than 6 months of age is not an important statistic compared to
the number of pigs that reach a potentially susceptible age (~5
years), and this is what the analysis of the pig population referred to
above was concerned with. There is really no evidence that pigs
are important in the epidemiology of BSE, but quoting percentages
rather than absolute numbers is not helpful in such an important risk
assessment.
24) Actions taken in the UK to check BSE are described in
Section 2.4.2, Page 37. The fifth sentence (line 7) indicates that the
ban on specific bovine offal (SBO) as ingredients in feed stuff helps
to identify tissues with the highest infectivity. It should be indicated
that these high risk tissues were identified as a result of research on
sheep scrapie. This sentence also could be more fully referenced.
The last sentence of the paragraph is more accurate if it is moved to
be the penultimate sentence. Because by 1997 the additional ban
on the use of mammalian-derived protein in 1996 could not
possibly have had any effect on the clinical incidence.
To make the second paragraph more realistic, it may be noted that
the SBO ban, with respect to the human food supply, was
introduced in 1989 because of the knowledge that when the
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Review of the Evaluation of the Potential for Bovine Spongiform
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scrapie agent successfully crosses to another species, it can have
altered transmission characteristics with respect to other species.
Also, the tissues listed as the SBOs, such as brain and spinal cord
from cattle older than 6 months, are incomplete.
The chronology of events that is suggested in the third paragraph is
not correct. The national surveillance for Creutzfeldt-Jakob Disease
(CJD) was formally instigated in May 1990, which is clear from the
CJD Surveillance Units website. In Table 2-2, the chronology of
BSE-regulated actions in the UK contains errors. For example, there
was no selective culling in 1990, and spinal cord in animals older
than 6 months was included in the original SBO ban. There are
perhaps some other important exclusions even though this is a
summary table. For a detailed chronology, refer to the six monthly
progress report on the BSE epidemic published by the Ministry of
Agriculture, Fisheries, and Food (MAFF) (now the Department for
Environment, Food, and Rural Affairs or DEFRA), which is available
on their web site.
The two measures to prevent the BSE epidemic described in the last
two paragraphs of this section are confused as different bans. The
reality was that in March 1996, the SEACs recommendation was for
the deboning of carcasses of animals older than 30 months of age
together with the removal of all obvious lymphatic and nervous
tissues. This was not possible because of an insufficient number of
deboning plants. The political decision was therefore made, at the
Prime Ministerial level, to remove all animals over 30 months old
from the human chain. The ban on bone-in-beef was introduced as
a precautionary measure as a result of the later results from the BSE
pathogenesis study (in cattle) conducted in Great Britain that
suggested that infectivity may be present in dorsal root ganglia.
25) In Section 2.4.5, BSE surveillance in the U.S. was evaluated.
The section reads as if there is a little complacency about the
surveillance for BSE, and CJD/vCJD in the U.S. A more critical
evaluation appears to be appropriate. There have clearly been a
number of problems with surveillance for clinical BSE. The first is
the general level of surveillance in the U.S. and other countries.
The second is the fact that at low incidence BSE is clearly a difficult
disease to identify because of its more behavioral, rather than
neurological, clinical presentation in at least the early clinical phase
and the rather variable clinical signs. Thirdly, a concentration on
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Section 3 Identification of Data and Critical Evaluation of Evidence
suspect rabies cases has not proved to be very effective within
continental Europe; this is mainly because rabies is endemic in the
less cattle-dense areas and such surveillance (on its own) can
therefore exclude a significant proportion of the cattle population.
Fourthly, downer cows are probably not the best targets for BSE
surveillance.
The time frame of the BSE risk assessment work is not clear. The
executive summary indicates a starting year of 1998 and the
scientific references section contains some papers published in May
2001. An improved awareness of the extent and magnitude of the
incidence of BSE in EU member states in continental Europe
emerged towards the end of 2000. Any comment on the omission
of what has been learned or stressed from this additional
surveillance in Europe, arising from the use of the more rapid and
economical tests described in Section 2.4.1, may be misplaced.
However, two related aspects emerge. The first is that testing
animals at slaughter improves quite dramatically our knowledge on
the incidence of BSE in countries with a low incidence of clinical
BSE and therefore a relatively poor awareness of the intricacies of
the clinical picture. Secondly, targeting surveillance to the more
general category of fallen stock/casualty slaughter animals, rather
than just downer cows is a much more effective method.
A comparison of surveillance for CJD/vCJD in the U.S. with that in
the UK and the more widely based EU funded surveillance project
would have been helpful because there do seem to be some
differences. A lack of change in the observed incidence of CJD in
the U.S. could be interpreted as providing evidence of no increased
intensity in surveillance. This comment is made in light of the
findings from those countries that have participated in the
international project on CJD surveillance.
snip...
http://www.fsis.usda.gov/oa/topics/BSE_Peer_Review.pdf
Harvard SUPPRESSED PEER review assessment October 31, 2002
http://www.fsis.usda.gov/oa/topics/BSE_Peer_Review.pdf
RB $ Oxtail removal
http://www.bseinquiry.gov.uk/files/yb/1990/02/06002001.pdf
45.4 I sought advice from Dr Kimberlin on the inclusion of pancreas, rennet and oxtail in the
proposed offal ban [YB 89/4.5/1.1]. I responded to MAFF having spoken to Dr Kimberlin
and other experts at the recent research committee [YB 89/4.13/2.1-2.3]. I advised that the
offal prohibited for use should include brains, spinal cord, thymus and intestines but not
rennet. I did not recommend that pancreas, oxtail or liver should be included although I
pointed out that the level of suspicion about their infection was somewhat higher than with,
say, steak.
http://www.bseinquiry.gov.uk/files/ws/s115.pdf
http://www.bseinquiry.gov.uk/files/yb/1989/04/05003001.pdf
http://www.bseinquiry.gov.uk/files/yb/1989/04/13002001.pdf
26. On 3rd November, 1995 Mr Strang received a minute from Mr Render which briefed me
on a number of key points that I needed for a meeting that I was to have with Dr Calman
on 7th November, 1995 (exhibit 17). (YB 95/11.03/2.1-2.7) The minute recorded Dr
Calman's main concerns which were: enforcement of the SBO controls; the incidence of
BABs; and the incidence of CJD in cattle farmers.
27. On 7th November, 1995 I met with Dr Calman, Dr Metters (the Deputy Chief Medical
Officer) and other colleagues. The meeting is recorded in a minute from Mr Strang of 9th
November, 1995 (exhibit 18). (YB 95/11.09/1.1-1.3) At the meeting, I stressed that
MAFF were taking BSE very seriously, and that I welcomed the opportunity to discuss
the issue with the DoH. Dr Calman said that he was concerned, because he thought that
we did not understand the origins of BSE well enough. He said that he was less confident
now than he had been a year ago that things were moving in the right direction. Having
expressed these concerns, he said that much of the science itself was reassuring, and that
work done by Dr Collinge with mouse assays had so far suggested that BSE might not be
transmissible to humans, although this was as yet unconfirmed. He felt, however, that
other developments were less encouraging. We discussed the results of the CJD
surveillance unit, based on much more sophisticated data than in other countries, which
Dr Calman said were worrying, since four cases of CJD in farmers had all occurred in
producers with dairy herds which had had BSE. He was also concerned about the
increased incidence of CJD in young people.
snip......
http://www.bseinquiry.gov.uk/files/ws/s327.pdf
45. On 20th November, 1995 Mr Meldrum sent a minute to Mr Strang (exhibit 24). (YB
95/11.20/12.1-12.6) The minute was to update me in relation to some BSE research
results. I was invited to note these latest research findings and it was suggested that I
should announce them by means of a Parliamentary Question. Mr Meldrum
recommended that no new action needed to be taken in response to these results. In the
minute he said that we had, for a number of years, been carrying out experiments to see
which tissues from cattle clinically affected with BSE could transmit that infectivity. A
large number of different tissues had been tested, most proving negative. However, recent
results had shown that the retina and the terminal spinal cord could transmit BSE
infectivity. Mr Meldrum said that neither result was surprising as both tissues were part
of the central nervous system, which we already knew was the main source of infectivity.
Mr Meldrum said that, as the entire spinal cord, including the terminal region, had been
an SBO since the 1989 Regulations, there was no need to take any further action.
Although the results on the terminal spinal cord could prompt questions about the safety
of oxtails, Mr Meldrum said there was in fact no problem, as the spinal cord does not
extend into the tail. There was also now available four results from animals killed at or
before 14 months old after being experimentally exposed to BSE. These results showed
that infectivity was present in the distal ileum of calves from six months old post
exposure onwards. No other tissue had shown any infectivity up to 14 months old,
including the brain and spinal cord, which were known to harbour infectivity in clinically
affected animals. These results supported the six month age rule for most SBOs.
http://www.bseinquiry.gov.uk/files/ws/s327.pdf
Oxtail Sales
Lord Tebbit asked Her Majesty's Government:
Why it is illegal to sell oxtails for the making of soup but legal to sell soup made from oxtails.[HL1596]
The Parliamentary Secretary, Ministry of Agriculture, Fisheries and Food (Lord Donoughue): The Beef Bones Regulations 1997 prohibit the sale of oxtails to consumers for the making of soup because of the possible risk of BSE infectivity from bone marrow reported by the Spongiform Encephalopathy Advisory Committee (SEAC) in December 1997. However, the commercial manufacture of oxtail soup may continue, provided the oxtail meat which it utilises is removed from the tail by a process which leaves the bones intact, thus preventing the release of bone marrow into the soup. The bones must then be discarded and disposed of in accordance with the regulations.
6 May 1998 : Column WA73
http://www.parliament.the-stationery-office.co.uk/pa/ld199798/ldhansrd/vo980506/text/80506w01.htm
TSS :???:
