Bovine Spongiform Encephalopathy; Minimal-Risk Regions; Importation of Live Bovines and Products Derived From Bovines, 53314-53379 [07-4595]

Agencies

• DEPARTMENT OF AGRICULTURE
• Animal and Plant Health Inspection Service

[Federal Register Volume 72, Number 180 (Tuesday, September 18, 2007)]
[Rules and Regulations]
[Pages 53314-53379]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-4595]



[[Page 53313]]

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Part III





Department of Agriculture





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Animal and Plant Health Inspection Service



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9 CFR Parts 93, 94, 95, and 96



Bovine Spongiform Encephalopathy; Minimal-Risk Regions; Importation of 
Live Bovines and Products Derived From Bovines; Final Rule

Federal Register / Vol. 72, No. 180 / Tuesday, September 18, 2007 / 
Rules and Regulations

[[Page 53314]]


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DEPARTMENT OF AGRICULTURE

Animal and Plant Health Inspection Service

9 CFR Parts 93, 94, 95, and 96

[Docket No. APHIS-2006-0041]
RIN 0579-AC01


Bovine Spongiform Encephalopathy; Minimal-Risk Regions; 
Importation of Live Bovines and Products Derived From Bovines

AGENCY: Animal and Plant Health Inspection Service, USDA.

ACTION: Final rule.

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SUMMARY: We are amending the regulations regarding the importation of 
animals and animal products to establish conditions for the importation 
of the following commodities from regions that present a minimal risk 
of introducing bovine spongiform encephalopathy into the United States: 
Live bovines for any use born on or after a date determined by the 
Animal and Plant Health Inspection Service to be the date of effective 
enforcement of a ruminant-to-ruminant feed ban in the region of export; 
blood and blood products derived from bovines; and casings and part of 
the small intestine derived from bovines. We are making these 
amendments after conducting a risk assessment and comprehensive 
evaluation of the issues and concluding that such bovines and bovine 
products can be safely imported under the conditions described in this 
rule. This document also removes the delay in applicability of certain 
provisions of a final rule published in January 2005.

DATES: Effective Date: November 19, 2007.

FOR FURTHER INFORMATION CONTACT: For information regarding ruminant 
products, contact Dr. Karen James-Preston, Director, Technical Trade 
Services, Animal Products, National Center for Import and Export, VS, 
APHIS, 4700 River Road Unit 38, Riverdale, MD 20737-1231; (301) 734-
4356.
    For information concerning live ruminants, contact Dr. Lee Ann 
Thomas, Director, Technical Trade Services, Animals, Organisms and 
Vectors, and Select Agents, National Center for Import and Export, VS, 
APHIS, 4700 River Road Unit 38, Riverdale, MD 20737-1231; (301) 734-
4935.
    For other information concerning this proposed rule, contact Dr. 
Lisa Ferguson, Senior Staff Veterinarian, National Center for Animal 
Health Programs, VS, APHIS, 4700 River Road Unit 43, Riverdale, MD 
20737-1231; (301) 734-6954.

SUPPLEMENTARY INFORMATION:

Purpose

    This document makes final a proposed rule that the Animal and Plant 
Health Inspection Service (APHIS) of the U.S. Department of Agriculture 
(USDA or the Department) published in the Federal Register on January 
9, 2007 (72 FR 1101-1129, Docket No. APHIS-2006-0041). Additionally, it 
removes the delay of applicability of certain provisions of a final 
rule APHIS published in January 2005. The removal of delay is discussed 
below under the heading ``Removal of Partial Delay of Applicability of 
Provisions of January 2005 Final Rule.''
    In our January 2007 proposed rule, we proposed to amend the 
regulations in 9 CFR parts 93, 94, 95, and 96 to establish conditions 
for the importation of the following commodities from regions that 
present a minimal risk of introducing bovine spongiform encephalopathy 
(BSE) into the United States: Live bovines for any use born on or after 
a date determined by APHIS to be the date of effective enforcement of a 
ruminant-to-ruminant feed ban in the region of export; blood and blood 
products derived from bovines; and casings and part of the small 
intestine derived from bovines.
    In this document, we respond to public comments received on the 
proposed rule and its underlying risk assessment and other supporting 
analyses. Additionally, we discuss below the history of APHIS 
rulemaking related to BSE minimal-risk regions.

Background

    APHIS regulates the importation of animals and animal products into 
the United States to guard against the introduction of animal diseases. 
The regulations in 9 CFR parts 93, 94, 95, and 96 (referred to below as 
the regulations) govern the importation of certain animals, birds, 
poultry, meat, other animal products and byproducts, hay, and straw 
into the United States in order to prevent the introduction of various 
animal diseases, including BSE, a chronic degenerative disease 
affecting the central nervous system of cattle.
    With some exceptions, APHIS' regulations prohibit or restrict the 
importation of live ruminants and certain ruminant products and 
byproducts from the following three categories of regions with regard 
to BSE: (1) Those regions in which BSE is known to exist (listed in 
Sec.  94.18(a)(1) of the regulations); (2) those regions that present 
an undue risk of introducing BSE into the United States because their 
import requirements are less restrictive than those that would be 
acceptable for import into the United States and/or because the regions 
have inadequate surveillance (listed in Sec.  94.18(a)(2) of the 
regulations); and (3) those regions that present a minimal risk of 
introducing BSE into the United States via live ruminants and ruminant 
products and byproducts (listed in Sec.  94.18(a)(3) of the 
regulations).

Chronology of Federal Register Publications Regarding BSE Minimal-Risk 
Regions

    We added the Sec.  94.18(a)(3) category (BSE minimal-risk regions) 
to the regulations in a final rule published in the Federal Register on 
January 4, 2005 (70 FR 459-553, Docket No. 03-080-3). In the final 
rule, we specified which commodities may be imported from BSE minimal-
risk regions and under what conditions, and recognized Canada as a BSE 
minimal-risk region. (At this time, Canada is the only recognized BSE 
minimal-risk region.)
    The January 2005 final rule was based on a proposed rule we 
published in the Federal Register on November 4, 2003 (68 FR 62386-
62405, Docket No. 03-080-1). On December 25, 2003, less than 2 weeks 
before the close of the comment period for our proposed rule, a case of 
BSE in a dairy cow of Canadian origin in Washington State was verified 
by an international reference laboratory.
    In response to comments from the public requesting an extension of 
the comment period and in order to give the public an additional 
opportunity to comment on the proposed rule in light of this 
development, on March 8, 2004, we published a document in the Federal 
Register (69 FR 10633-10636, Docket No. 03-080-2) reopening the comment 
period.
    On January 4, 2005, along with the final rule, we published in the 
Federal Register a notice (70 FR 554, Docket No. 03-080-4) announcing 
the availability of, and requesting comments on, a final environmental 
assessment (EA) regarding the potential impact on the quality of the 
human environment due to the importation of ruminants and ruminant 
products and byproducts from Canada under the conditions specified in 
the final rule. On January 21, 2005, we published in the Federal 
Register a notice (70 FR 3183-3184, Docket No. 03-080-5) announcing the 
availability of a corrected version of the EA for public review and 
comment. On April 8, 2005, we published in the Federal Register a 
finding (70 FR 18252-18262, Docket No. 03-080-7) that the provisions of 
the final rule would not

[[Page 53315]]

have a significant impact on the quality of the human environment.
    On March 11, 2005, we published a document in the Federal Register 
that gave notice that the Secretary of Agriculture was delaying until 
further notice the implementation of certain provisions of the final 
rule with regard to certain commodities (70 FR 12112-12113, Docket No. 
03-080-6).
    On November 28, 2005, we published in the Federal Register an 
interim rule (70 FR 71213-71218, Docket No. 03-080-8) that amended 
certain provisions established by the January 2005 final rule. The 
interim rule broadened the list of who is authorized to break seals on 
conveyances and allows transloading under supervision of products 
transiting the United States.
    On March 14, 2006, we published in the Federal Register a technical 
amendment (71 FR 12994-12998, Docket No. 03-080-9) that clarified our 
intent with regard to certain provisions in the January 2005 final rule 
and corrected several inconsistencies within the rule.
    On August 9, 2006, we published in the Federal Register a proposed 
rule (71 FR 45439-45444, Docket No. APHIS-2006-0026) that proposed to 
amend the provisions established by the January 2005 final rule by 
removing several restrictions regarding the identification of animals 
and the processing of ruminant materials from BSE minimal-risk regions, 
and by relieving BSE-based restrictions on hide-derived gelatin from 
BSE minimal-risk regions. We solicited comments concerning our proposal 
for 60 days ending October 10, 2006. On November 9, 2006, we published 
a document in the Federal Register (71 FR 65758-65759, Docket No. 
APHIS-2006-0026) reopening and extended the comment period until 
November 24, 2006. We received a total of 10 comments by that date. We 
are considering the issues raised by the commenters and will address 
them in a separate rulemaking document.

Scope of the January 2005 Final Rule

    The regulations established by the January 2005 final rule and 
subsequent amendments have allowed the importation from BSE minimal-
risk regions of live bovines that are under 30 months of age when 
imported and when slaughtered and that have been subject to a ruminant 
feed ban equivalent to that in place in the United States.
    We did not attempt, for that rulemaking, to assess the BSE risk 
associated with the importation of live bovines 30 months of age or 
older from a BSE minimal-risk region. Our March 8, 2004, document that 
reopened the comment period on the November 2003 proposed rule stated 
that APHIS was evaluating the appropriate approach with regard to the 
importation of live animals 30 months of age or older from BSE minimal-
risk regions, and would address that issue in a supplemental rulemaking 
proposal in the Federal Register. The provisions in our January 9, 
2007, proposed rule regarding live bovines were the result of that 
evaluation.
    The regulations established by the January 2005 final rule also 
provided for the importation of the following commodities derived from 
bovines of any age: (1) Meat, meat food products, and meat byproducts; 
(2) whole or half carcasses; (3) offal; (4) tallow composed of less 
than 0.15 percent insoluble impurities that are not otherwise eligible 
for importation under Sec.  95.4(a)(1)(i) of the regulations; and (5) 
gelatin derived from bones of bovines that is not otherwise eligible 
for importation under Sec.  94.18(c) of the regulations.
    The January 2005 final rule and subsequent amendments did not 
change the regulations concerning the importation of blood and blood 
products from regions listed in Sec.  94.18(a); the requirements for 
the importation of blood and blood products from BSE minimal-risk 
regions remain the same as the requirements for importation of blood 
and blood products from other regions listed in Sec.  94.18(a)--only 
serum and serum albumin have been eligible for importation. The January 
2005 final rule also did not change the regulations concerning the 
importation of bovine casings (defined as intestines, stomachs, 
esophagi, and urinary bladders) from regions listed in Sec.  94.18(a); 
the requirements for the importation of bovine casings from BSE 
minimal-risk regions remain the same as the requirements for 
importation of bovine casings from other regions listed in Sec.  
94.18(a)--only bovine stomachs are eligible for importation.
    The January 2005 final rule and subsequent amendments allowed trade 
to resume in many, but not all, of the commodities that had been 
prohibited importation from Canada following detection of a BSE-
infected cow in Canada in May 2003. Following our January 2005 final 
rule, we continued to consider the BSE risk associated with older 
bovines and other bovine products from BSE minimal-risk regions--and 
Canada in particular--including bovine blood and blood products, bovine 
small intestine other than the distal ileum, and bovine casings, and 
included provisions in our January 2007 proposed rule for the 
importation of those commodities.\1\
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    \1\ The regulations regarding BSE minimal-risk regions apply to 
bison as well as cattle. In Sec. Sec.  93.400, 94.0, and 95.1 of the 
regulations, bovine is defined as Bos taurus, Bos indicus, and Bison 
bison. Although the research and other data cited in this rulemaking 
refer to bovines other than bison (i.e., to ``cattle''), there is no 
evidence to indicate that the BSE susceptibility of bison differs 
from that of cattle. We therefore assume that our conclusions based 
on cattle-specific evidence discussed in this rulemaking are also 
applicable to bison. Given that no cases of BSE have been detected 
in bison, this is likely a conservative assumption. The provisions 
of this rule apply to bovines as defined in the regulations, which 
include bison.
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Peer Review of APHIS' Risk Assessment

    As part of this rulemaking, APHIS conducted an assessment that 
evaluated the animal health risk to the United States of BSE--i.e., the 
likelihood of establishment and the potential impacts of cases that may 
occur even without establishment--as a result of importing the bovine 
commodities considered in this rule (APHIS 2006b). Our assessment 
concluded that, over the 20 years of the analysis, the BSE risk to the 
United States is negligible. We made the risk assessment available for 
public review and comment at the time the proposed rule was published.
    In addition to making the risk assessment available for review and 
comment by the general public, we requested an external, formal, 
independent peer review of the assessment by recognized experts in the 
field, consistent with guidelines of the U.S. Office of Management and 
Budget (OMB 2004). The objective of the peer review was to determine 
whether the risk assessment was scientifically sound, transparent, and 
consistent with international standards (e.g., those by the OIE); the 
application of external assessments or models was appropriate; and the 
assumptions were justified, supported and reasonable. Comments 
submitted by the public on the proposed rule were submitted to the peer 
reviewers for their consideration. The peer review process was 
coordinated by an independent private contractor.
    The full peer review report may be viewed at https://
www.aphis.usda.gov/peer_review/peer_review_agenda.shtml. 
Additionally, we have included below, under the heading ``Final Report 
from Peer Review of APHIS' Risk Assessment and Responses to Peer 
Reviewer Questions and Recommendations,'' APHIS' responses to reviewer 
comments that we consider representative of the content-related 
questions and recommendations of the report, and our response to those 
questions and recommendations. In summary, the

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reviewers found that the methods used in the risk assessment were 
scientifically rigorous in terms of using existing literature and 
models appropriately and making sound assumptions and that the risk 
assessment itself adhered to international risk assessment standards. 
The reviewers also agreed with the conclusion that the likelihood of 
establishment of BSE in the U.S. cattle population is negligible.
    In addition to being supportive of the methods, evidence, and 
conclusions presented by APHIS in the risk assessment, the reviewers 
made several useful suggestions for its improvement. We made several 
clarifications and updates in consideration of these comments. While we 
expect that the changes improve the transparency and accuracy of the 
document, they do not alter our conclusion that the risk to the United 
States of BSE--i.e., the likelihood of establishment and the potential 
impacts of cases that may occur even without establishment--resulting 
from the changes outlined in the proposed rule is negligible.

Removal of Partial Delay of Applicability of Provisions of January 2005 
Final Rule

    Our January 2005 final rule made eligible for importation from 
Canada meat that is derived from bovines slaughtered in BSE minimal-
risk regions, as well as certain other specified commodities derived 
from such bovines, provided certain specified risk-mitigating 
conditions have been met. The risk analysis we conducted for that 
rulemaking indicated a low BSE risk from such commodities derived from 
bovines of any age if certain conditions are met (APHIS 2004). These 
conditions include the removal of those tissues considered at 
particular risk of containing the BSE agent in infected animals 
(specified risk materials, or SRMs). In that rulemaking, we discussed 
regulatory requirements implemented by FSIS in 2004 that banned SRMs 
from the human food supply in the United States, and we stated that the 
Canadian Government had established similar safeguards in Canada.
    Consequently, we provided that meat, meat byproducts, meat food 
products, and offal derived from bovines are eligible for importation 
from BSE minimal-risk regions if the following conditions, as well as 
all other applicable requirements of the regulations, are met:
     The commodity is derived from bovines that have been 
subject to a ruminant feed ban equivalent to the requirements 
established by the U.S. Food and Drug Administration at 21 CFR 
589.2000;
     The commodity is derived from bovines for which an air-
injected stunning process was not used at slaughter; and
     The SRMs and small intestine of the bovines from which the 
commodity was derived were removed at slaughter.
    Additionally we provided that tallow composed of less than 0.15 
percent insoluble impurities that is not otherwise eligible for 
importation under 9 CFR 95.4(a)(1)(i), and gelatin derived from bones 
of bovines that is not otherwise eligible for importation under 9 CFR 
94.18(c) are eligible for importation from BSE minimal-risk regions, 
provided certain specified conditions are met.
    In the economic analysis we conducted for the January 2005 final 
rule, we evaluated the potential economic effects of implementing that 
rulemaking, including implementation of the provisions allowing the 
importation of meat and other commodities derived from bovines 
slaughtered in BSE minimal-risk regions (APHIS 2004a).
    In March 2005, APHIS published a document in the Federal Register 
that, pursuant to an announcement by the Secretary of Agriculture on 
February 9, 2005, delayed the applicability of the provisions in our 
January 2005 final rule as they apply to the importation from Canada of 
the following commodities when derived from bovines 30 months of age or 
older when slaughtered: (1) Meat, meat food products, and meat 
byproducts other than liver; (2) whole or half carcasses; (3) offal; 
(4) tallow composed of less than 0.15 percent insoluble impurities that 
is not otherwise eligible for importation under 9 CFR 95.4(a)(1)(i); 
and (5) gelatin derived from bones of bovines that is not otherwise 
eligible for importation under 9 CFR 94.18(c).
    In his February 9, 2005, announcement, the Secretary stated that 
because ongoing investigations into recent finds of BSE in Canada in 
animals over 30 months of age were not complete, he felt it prudent to 
delay the effective date for allowing imports of meat from bovines 30 
months of age and over. He also indicated that the delay of 
applicability would address concerns that the January 2005 final rule 
allowed the importation of beef from bovines 30 months of age or older, 
while continuing to prohibit the importation of live cattle 30 months 
of age or older for processing in the United States. The Secretary 
stated that the Department would consider and develop a plan--based on 
the latest scientific information and with the protection of public and 
animal health as the highest priority--to allow imports of live bovines 
30 months of age or older as well as beef from animals 30 months of age 
and older.
    Since the date of the partial delay of applicability of our January 
2005 final rule, we have obtained additional information regarding all 
aspects of the issues that prompted the delay of applicability and have 
conducted additional analyses in line with the plan as described. The 
risk assessment for this final rule demonstrates the negligible BSE 
risk from the importation of additional classes of live cattle, 
including those 30 months of age or older. This includes acknowledging 
the potential risk pathway that could be available if the SRMs from 
infected imported cattle entered the ruminant feed supply in 
contravention of current feed regulations. The negligible risk from the 
importation of live older cattle therefore gives further support to the 
conclusion of the risk analysis conducted for our January 2005 final 
rule regarding meat and meat products derived from bovines of any age 
in BSE minimal-risk regions. Specifically, the risk is even lower for 
the importation of meat and meat products, as the SRMs will be removed 
in accordance with the regulations, than for live bovines.
    Therefore, this document will remove the partial delay of 
applicability of the January 2005 final rule. The removal of the 
partial delay of applicability will become effective on the date that 
the other provisions of this document become applicable. Including the 
removal of the partial delay of applicability in this final rule and 
making it effective along with the other provisions of this rule will 
enable APHIS to more efficiently communicate the necessary 
implementation instructions to U.S. Customs and Border Protection and 
to APHIS field personnel. Additionally, it will provide commercial 
entities more flexibility in carrying out import planning based on the 
relative economic merits of importing live bovines or meat and other 
products derived from bovines.
    Because, for reasons of efficiency for APHIS and the regulated 
community, the Secretary has decided to remove the delay in 
applicability as part of this document, we looked at the economic 
effects of doing so in combination with allowing the importation of 
bovines born on or after March 1, 1999. Although we previously analyzed 
the economic effects of allowing the importation of meat and other 
products derived from bovines 30 months of age

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or older, the economic analysis for this rule provides an updated 
analysis.

Public Comments on the January 2007 Proposed Rule

    We solicited comments concerning our January 2007 proposal for 60 
days ending March 12, 2007. We received close to 400 comments by that 
date. The commenters included cattle industry and farm bureau 
associations, consumer groups, representatives of the Canadian 
Government and other foreign countries, State Departments of 
Agriculture, food processing companies, individual cattle producers, 
and other members of the public.

Subjects of Comments Received

    A number of commenters supported the rule and recommended no 
changes to the proposed provisions. Other commenters supported the rule 
in general but recommended certain changes or actions. Other comments 
consisted only of recommended changes, objections to the rule in 
general or to specific provisions, or requests for clarification. We 
discuss below by topic the issues raised by commenters and our response 
to those comments.

General Opposition to Imports

    Issue: A number of commenters expressed general opposition to the 
importation of any bovines or bovine products from BSE minimal-risk 
regions.
    Response: It appears to us that these commenters are not addressing 
just our January 2007 proposed rule, but, rather, also the January 2005 
final rule that recognized the category of BSE minimal-risk regions and 
established conditions for the importation of certain ruminants and 
ruminant products from such regions.
    As we discussed in the January 2005 final rule, the comprehensive 
analysis and evaluation we conducted for that rulemaking led to the 
conclusion that the conditions specified in that rule for the 
importation of ruminants and ruminant products from BSE minimal-risk 
regions would be effective and would therefore protect against the 
introduction of BSE into the United States. Our January 2007 proposed 
rule considered expansion of the types of commodities allowed 
importation from BSE minimal-risk regions, based on an evaluation of 
the risk (i.e., the likelihood of establishment and the potential 
impacts of cases that may occur even without establishment) of 
importing from Canada live animals, blood and blood products, and the 
small intestine excluding distal ileum.) Given the determination of 
negligible BSE risk associated with the provisions of this final rule, 
and the findings associated with our 2005 final rule, there is no 
scientific basis for increasing restrictions from those already in 
effect or being established in this rule.
    Issue: A number of commenters expressed opposition, without further 
explanation, to the importation from BSE minimal-risk regions of live 
bovines 30 months of age or older and to the importation of products 
derived from such bovines.
    Response: We discussed in our January 2007 proposed rule the 
rationale for our proposal to allow the importation, under certain 
conditions, of live bovines 30 months or older from BSE minimal-risk 
regions. We discussed further the assessment of the disease risk of 
allowing such imports that we conducted before issuing our proposal. It 
is not clear to us which factors in our risk assessment or discussion 
of rationale were being addressed by those commenters who expressed 
general opposition to the importation of live bovines 30 months of age 
or older. We continue to consider the BSE risk from importing live 
bovines under the conditions specified in this rule to be negligible.
    Issue: Several commenters who expressed opposition to the proposed 
rule expressed concern that the agent that causes BSE has yet to be 
fully characterized. The commenters stated that what we know about BSE 
is mostly supposition, which should be a compelling reason not to allow 
the importation of cattle from a region of known BSE outbreaks. One 
commenter stated that research recently conducted at Yale University 
suggests that one of the agents that activates BSE may be viral, which, 
according to the commenter, implies that a feed ban is effective only 
when the virus is not present or active.
    Response: As one of the commenters noted, some researchers 
(Manuelidis et al., 2007) suggest that diseases characterized as 
transmissible spongiform encephalopathies (TSEs), such as BSE, may be 
caused by viruses, although, at this point, no infection-specific 
nucleic acids have been identified.
    Experimental data and epidemiological studies strongly suggest that 
contaminated feed containing ruminant proteins derived from infected 
animals was the source of the epidemic, and that the epidemic was 
perpetuated through the use of these materials in ruminant feed. APHIS 
considers that regardless of the characteristics of the BSE causal 
agent, it is clear that the epidemic was sustained and amplified by the 
recycling of BSE infected cattle into cattle feed. Despite the 
difficulty in definitively determining the causal agent of BSE, risk 
factors for transmission of the agent have been identified. The 
identification and characterization of these risk factors through 
epidemiological and experimental study have allowed the development of 
effective mitigations to prevent BSE spread. The development and 
demonstrated effectiveness of those mitigations does not require 
identification of the agent itself. We consider mitigation measures 
that address the risk factors for BSE to be effective regardless of the 
precise nature of the BSE agent.

Prevalence of BSE in Canada

    Although the provisions of this rule apply to any region recognized 
by APHIS as a BSE minimal-risk region, at present APHIS recognizes only 
one country, Canada, as such a region. Therefore, in evaluating the BSE 
risk of implementing this rule, we conducted an assessment of the risk 
of importing bovines and bovine products from Canada under the 
provisions of our proposed rule (APHIS 2006b). In our risk assessment, 
we laid out the likely risk pathway (i.e., a series of occurrences or 
steps necessary for disease to enter and become established).
    In conducting our risk assessment, one of the factors we took into 
account was the prevalence of BSE in Canada, since prevalence is one 
factor that affects the likelihood of a BSE-infected bovine being 
imported into the United States. We received a number of comments from 
the public that addressed our estimate of the prevalence of BSE in 
Canada. Although some of the comments supported our estimate of BSE 
prevalence in Canada, in general the commenters maintained that such 
prevalence is either higher than we estimated, may be increasing, or is 
uncertain, or that our methods of estimating it were flawed. The 
methodology we used to arrive at such estimates is discussed in detail 
in our risk assessment. However, to provide some context for the issues 
raised by commenters and discussed below, we summarize here the models 
that we used in conducting our assessment.
    The number of BSE cases detected through surveillance understates 
the disease prevalence because exposed animals may be incubating 
disease and carrying infectious material in their tissues without 
presenting clinical symptoms. Like many transmissible spongiform 
encephalopathies (TSEs),

[[Page 53318]]

BSE has an incubation period of several years. Therefore, the disease 
is not detectable in its early stages with current technology. 
Moreover, surveillance will miss a proportion of detectable cases. 
Therefore, we applied statistical methods to the available 
epidemiologic and surveillance data to estimate, with attendant 
uncertainty, the prevalence of BSE in Canada.
    We used two related, but distinct, methods to estimate BSE 
prevalence in Canada: the BSurvE model and the Bayesian Birth Cohort 
(BBC) model. Given its international prominence, we used the European 
Union (EU) BSurvE model (Wilesmith et al., 2004, 2005), recently 
developed for the purpose of estimating BSE prevalence in national 
herds. The BSurvE model is noteworthy for its sound epidemiologic 
structure, including stratifying cattle by age and cause of death 
(i.e., healthy slaughter, fallen stock, casualty slaughter, or clinical 
suspect) and accounting for the relative likelihood of detecting BSE in 
various strata (EFSA 2004). The BSurvE model structure calculates BSE 
surveillance point values (random sample size equivalents) represented 
by targeted Canadian sampling of certain groups of cattle in which BSE 
cases are more likely to be detected. This approach allows for the 
inclusion of infected, but undetected, cases (such as young animals in 
the early stages of incubation) in the estimate, which would be ignored 
by conventional methods.
    The other prevalence estimation model that we used is the BBC 
model. This model uses the BSurvE model structure and incorporates 
additional information. Unlike BSurvE, the BBC model adopts a Bayesian 
statistical framework to incorporate prior information about the 
decreased incidence of BSE observed in animals born after a feed ban 
equivalent to the initial ruminant-to-ruminant feed ban introduced in 
the United Kingdom in 1988.
    Issue: One commenter stated that BSE has become ``firmly 
established'' in Canada.
    Response: We disagree with the comment, which we consider to 
erroneously equate disease presence, which may be transient, with 
disease establishment. In epidemiology, an infectious disease has 
become established in a population when the disease is perpetuated in 
the population without the need for reintroduction from an external 
source. For example, OIE's sister agency, the international Commission 
on Phytosanitary Measures (CPM) defines plant pest establishment as 
``the perpetuation, for the foreseeable future, of a nonindigenous 
biological agent within an area after entry'' (CPM 2001). With the 
implementation and continuation of a feed ban in Canada, all evidence 
points toward eventual eradication, rather than perpetuation of BSE in 
that country.
    Issue: One commenter stated that, since the time APHIS published 
its January 2005 final rule classifying Canada as a BSE minimal-risk 
region, the Agency has presented no new evidence that would support 
allowing the importation from Canada of the additional commodities 
discussed in the proposed rule. In fact, stated the commenter, evidence 
points to Canada having a higher prevalence of BSE than APHIS had 
previously determined.
    Response: As discussed in our January 2007 proposed rule, we 
revisited our earlier conclusions and policies by conducting a rigorous 
risk assessment based on current available scientific knowledge of the 
disease. We used peer reviewed risk assessment models in our analysis 
to estimate the prevalence of the disease in Canada and to analyze the 
likelihood of BSE establishment in the United States and the potential 
impacts of cases that may occur even without establishment as a result 
of the importation into the United States of the bovine commodities 
considered in this rule. The risk assessment itself was peer reviewed 
by experts in the field. As noted above, the reviewers agreed with the 
conclusion that the risk of establishment of BSE in the U.S. cattle 
population is negligible and noted that several assumptions in the risk 
assessment actually over-estimate the risk, so the overall finding that 
the BSE risk is negligible is reasonable. Based on the results of the 
risk assessment, we concluded that we could safely import Canadian 
cattle born on or after March 1, 1999, blood and blood products, and 
small intestines, excluding the distal ileum.
    Issue: Several commenters raised questions about the ability to 
statistically determine BSE prevalence ``trends'' in Canada, but 
reached different conclusions. Some commenters stated that the 
trajectory of BSE prevalence in Canada cannot be determined by 
available surveillance data and that, therefore, BSE prevalence in 
Canada may be increasing. On the other hand, another commenter 
requested that APHIS make clear that, despite the Agency's use of the 
BSurvE Prevalence B estimate, prevalence should not be assumed constant 
over time. The commenter requested that APHIS emphasize that lack of 
statistical evidence that prevalence varies from cohort to cohort is 
likely the result of inadequate statistical power,\2\ and that, 
nevertheless, BSE prevalence in Canada is most likely decreasing.
---------------------------------------------------------------------------

    \2\ The power of a statistical test is the probability of 
rejecting the null hypothesis when it is false. The power depends on 
the test level of significance, the magnitude of effect under the 
alternative hypothesis, sample size, and variability in the 
population. Rice (1988, pp.361-364) describes the calculation of 
statistical power for comparing two independent samples.
---------------------------------------------------------------------------

    Response: In our risk assessment for this rule, we acknowledge 
that, given the rarity of BSE cases in Canada, the surveillance data 
are unlikely to provide adequate statistical power to detect any trend. 
However, as discussed in the risk assessment, we consider it likely 
that the prevalence of BSE in Canada will decrease over time. With so 
few total BSE cases observed in Canada, the statistical power to detect 
differences in prevalence between cohorts is low. The peer reviewers of 
our risk assessment concur with our conclusion. (RTI 2007, pp. 6-26, 6-
27).
    Issue: One commenter estimated the Canadian BSE prevalence to be 
6.4 cases per million cattle. Further, the commenter stated that this 
prevalence estimate is smaller than the risk estimate provided by one 
of APHIS' own risk assessments for a more pessimistic value of the 
misfeeding rate. The commenter suggested that this discrepancy reflects 
optimistic modeling assumptions in APHIS' risk assessment.
    Response: We disagree with the commenter's analysis. Although the 
commenter's alternative prevalence estimate, based on a simple 
extrapolation method, falls within the 90 percent confidence interval 
\3\ of APHIS' BSurvE Prevalence B estimate (2.4 to 6.8 cases per 
million adult cattle) with an expected value of 3.9 per million case 
per million adult cattle (APHIS 2006c, table 5), it is based on 
different assumptions. Based on an analysis of BSE testing in the EU in 
2001 and 2002, the commenter's prevalence estimate assumes that 
targeted ``risk cattle'' are only 10 times more likely to test positive 
for BSE than non-targeted routinely slaughtered cattle. Considering the 
BSE testing conducted in the EU during 2001-2004 (EC 2005a, table 3, p. 
23), cattle in the

[[Page 53319]]

European BSE risk animals category (emergency slaughter, clinical 
suspects, and fallen stock) are 22 times more likely to test BSE 
positive than cattle in the healthy slaughter category. Using the 
commenter's simple extrapolation method and these more up-to-date data 
on BSE test positive ratio, the resulting BSE prevalence estimate would 
be 2.9 per million cattle. Although actually lower than the expected 
value for the BSurvE estimate, this value also falls within the 90 
percent confidence interval of the Agency's BSurvE Prevalence B 
estimate, described above. APHIS calculated both the BSurvE Prevalence 
B estimate and the Bayesian Birth Cohort (BBC) prevalence estimate, but 
judged the latter to better characterize the BSE prevalence in Canada 
over the next 20 years, due to the expected downward pressure exerted 
on the disease by a feed ban.
---------------------------------------------------------------------------

    \3\ A confidence interval is a statistical range with a 
specified probability that a given parameter lies within the range. 
For example, the 90 percent confidence interval of a distribution 
indicates the range of values that we are 90 percent certain include 
the parameter value of interest. It extends from the 5th percentile, 
or 5 percent confidence level, at the low end of the distribution of 
the 95th percentile, or 95 percent confidence level at the high end 
of the distribution. Similarly, a 95 percent confidence interval 
would extend from the2.5 percent confidence level to the 97.5 
percent confidence level.
---------------------------------------------------------------------------

    With regard to the commenter's suggestion of a discrepancy, the 
commenter provides no specific reference to ``the risk estimate 
provided by one of APHIS' own risk assessments,'' but appears to refer 
to the main body of the 2005 report of Cohen and Gray (available at 
https://www.fsis.usda.gov/PDF/BSE_Risk_Assess_Report_2005.pdf), 
which was prepared for the USDA's Food Safety and Inspection Service 
(FSIS). Cohen and Gray (2005) do not estimate Canadian BSE prevalence, 
but rather the effect of introducing 500 BSE-infected cattle into the 
United States, and the pessimistic misfeeding assumption estimates that 
introduction would result in an expected 2,600 new cases over 20 years. 
There is no discrepancy because this aspect of the Cohen and Gray 2005 
report is not relevant to our estimate of Canadian BSE prevalence.
    Issue: Based on APHIS'' statements that animals are infected within 
their first year, and that feed produced prior to the feed ban would 
not be available for longer than a year, one commenter stated that 
additional undetected infected animals must have existed and been 
rendered in order to provide infectivity to detected cases. Therefore, 
stated the commenter, adding in these ``undetected'' animals raises the 
number of Canada's known and measurable BSE cases rises from 10 to 14, 
and APHIS' estimate of BSE prevalence in Canada based on 10 animals is 
low.
    Response: We disagree with the commenter's analysis and conclusion, 
which assumes that we did not take into account the possibility of 
undetected cases of BSE in arriving at our prevalence estimate. APHIS' 
estimate of the prevalence of BSE in Canada was adjusted to account for 
cases that would not be tested and for false negative test results. 
Also, although the bulk of feed will be consumed within a year after it 
is produced, residual infectivity may remain in the feed supply chain 
for an extended period. For example, examination of BSE cases in 
animals born in the United Kingdom after the 1996 ``reinforced feed 
ban'' suggests that these animals may have been infected from the 
persistence of the BSE agent in residual feed in storage bins (SEAC 
2005).
    Issue: One commenter suggested that it is likely that Canada has 
numerous cattle over 30 months of age that are presently incubating the 
BSE disease, rather than just a few (4.1) as suggested by APHIS.
    Response: The estimate of 4.1 BSE-infected animals in the standing 
Canadian adult cattle population was based on the expected BSE 
prevalence in Canada under the BBC model. Using the estimated 
prevalence under BSurvE Prevalence B resulted in an estimate of 23.2 
BSE-infected animals in the standing Canadian adult cattle population. 
Although, quantitatively, our risk assessment did not assume a decline 
in BSE prevalence over the next 20 years, we qualitatively consider 
such a decline to be likely because of continued compliance with the 
feed ban. Therefore, in assessing the BSE risk associated with imports 
from Canada over the next 20 years, we consider the result of the BBC 
model to be the more applicable prevalence estimate for use in our 
quantitative exposure model.
    Issue: One commenter indicated that although it is unclear whether 
the APHIS estimates of Canadian BSE prevalence included the BSE case 
confirmed on August 23, 2006, the APHIS estimates certainly do not take 
into account the case confirmed on February 7, 2007.
    Response: We estimated Canadian BSE prevalence based on a 7-year 
surveillance period through August 15, 2006. This surveillance period 
included the detection of nine BSE cases of Canadian origin reported 
through August 2006. Through surveillance conducted from August 16, 
2006, through April 2007, Canada detected one BSE case born in 2000 and 
another born in 2001 (CFIA 2007). The BSE prevalence estimation methods 
used by APHIS (2006a) require detailed data to stratify tested cattle 
by age and cause of death (healthy slaughter, fallen stock, casualty 
slaughter, or clinical suspect) that are unavailable for the more 
recent surveillance period. However, we can assess the sensitivity of 
our previous Canadian BSE prevalence estimates by adding the two 
additional cases without changing the BSE surveillance points 
accumulated by Canada during the 7-year surveillance period through 
August 15, 2006 (APHIS 2006a, table 4). \4\ This approach results in a 
revised table of BSurvE points and BSE cases by birth year cohort that 
reflects a total of 11 BSE cases of Canadian origin reported through 
April 2007 (APHIS 2007, table i).
---------------------------------------------------------------------------

    \4\ In the BsurveE model, specific ``point values'' are assigned 
to each test sample, based on the surveillance stream or 
subpopulation of animals from which it was collected, as well as the 
likelihood of detecting infected cattle in that subpopulation. A 
sample from the specific surveillance subpopulation where BSE is 
most likely to be detected--i.e., a middle adult clinical suspect--
provides the most surveillance points. Conversely, a sample from the 
subpopulation where BSE is least likely to be detected--generally 
routine slaughter--provides the least points.
---------------------------------------------------------------------------

    Using the same methods described in USDA's estimate of BSE 
prevalence in Canada (APHIS 2006c), we obtain updated Canadian BSE 
prevalence estimates:
     BSurvE Prevalence B: 90 percent confidence interval = 3.0-
8.0 cases per million adult cattle
     Bayesian Birth Cohort (BBC, Winbugs): 90 percent 
confidence interval = 0.47-1.2 cases per million adult cattle
    Because the updated confidence intervals contain the previous 
expected value estimates of 0.68 per million (BBC) and 3.9 per million 
(BSurvE Prevalence B) (APHIS 2006c), we conclude that the prevalence 
estimate is not sensitive to the addition of the two additional BSE 
cases discovered in Canada in August 2006 and February 2007.
    Issue: One commenter stated that APHIS' expectation that the 
prevalence of BSE in Canada will continue to decline from its present 
minimal level does not acknowledge that the prevalence of BSE in Canada 
right now is very uncertain. The commenter's independent estimate of 
the current Canadian BSE prevalence is ``on the order of 4-6 per 
million.''
    Response: APHIS' risk assessment addresses the uncertainty in the 
prevalence of BSE in Canada by considering estimates that differ by 
more than a factor of five (APHIS 2006b). The BBC prevalence estimate 
has an expected value of 0.68 cases per million adult cattle.\5\ The 
BSurvE Prevalence B estimate has an expected value of 3.9 per million. 
The

[[Page 53320]]

commenter's own method of estimation--``on the order of 4-6 per 
million----provides an estimate on the same order of magnitude as the 
BSurvE Prevalence B estimate of current prevalence. In either case, 
prevalence is extremely low.
---------------------------------------------------------------------------

    \5\ The BBC model provides a more precise estimate of BSE 
prevalence in Canada by combining the epidemiologic theory and 
application of surveillance data underlying the BSurvE model with 
additional information about the effect of the feed ban on 
prevalence.
---------------------------------------------------------------------------

    Issue: One commenter stated that, although APHIS estimates that BSE 
prevalence in Canada is about 6.8 or more times greater than in the 
United States (0.68 vs. 0.1 per million), this does not adjust for the 
important fact that the first BSE case in the United States was 
imported from Canada.
    Response: The APHIS October 2006 estimate of BSE prevalence in 
Canada is based on the nine BSE cases of Canadian origin that had been 
confirmed in North America as of August 23, 2006. This total includes a 
case of BSE that was confirmed in Washington State on December 25, 2003 
(APHIS 2006c, p. 1). The estimate of BSE prevalence in the United 
States excludes this case.
    Issue: One commenter stated that the calculation of BSE prevalence 
in Canada used in APHIS' risk assessment excluded the European-born 
case detected in 1993.
    Response: The 1993 Canadian BSE case of European origin was likely 
part of the original exogenous source of BSE infectivity introduced 
into Canada that caused the subsequent generation of indigenous cases. 
Imported cases of BSE reflect an exposure to the disease that occurred 
elsewhere, and, therefore, are not generally included in estimates of 
prevalence that reflect native exposure. Similarly, when APHIS 
estimated the prevalence of BSE in the United States, the BSE-infected 
cow of Canadian origin that was detected in Washington State in 
December 2003 was excluded from the analysis, because it was an 
imported animal. In addition, as noted in APHIS' estimation of BSE 
prevalence in Canada (APHIS 2006c, p. 5), in accordance with OIE 
guidelines (which indicate that surveillance points totals taken into 
account in assessing a country's BSE risk be accumulated over a maximum 
of 7 consecutive years), the estimated prevalence of BSE in Canada is 
based on surveillance data accumulated over a 7-year period beginning 
August 16, 1999. The 1993 case predates the OIE 7-year period.
    Issue: One commenter indicated that APHIS should not take action on 
the proposal until real surveillance data (not model-based predictions) 
show that the BSE problem has abated. The commenter stated further that 
denying Canada's BSE problem, or assuming it away with unvalidated and 
incorrect risk modeling assumptions, does not responsibly manage BSE 
risks to the United States.
    Response: We disagree with the commenter. In low BSE prevalence 
populations such as Canada, surveillance at levels that meet or even 
greatly exceed OIE guidelines provide insufficient statistical power to 
reliably detect changes in BSE prevalence over time. In other words, 
starting with a very low number of infected animals makes it very 
difficult to statistically demonstrate decreases in that number, even 
when testing a relatively large number of animals.
    The OIE Guidelines for BSE Surveillance (Type A) call for countries 
to accumulate 300,000 BSE surveillance points over 7 consecutive years 
in order to detect with 95 percent confidence a prevalence level of at 
least one case of BSE per 100,000 animals (OIE 2006, Appendix 3.8.4).
    To illustrate the comparative difficulty in demonstrating trends in 
low versus high prevalence populations, consider two hypothetical 
countries that have accumulated 1 million BSE surveillance points for 
each of two cohorts: Animals born before and animals born after the 
introduction of a ruminant-to-ruminant feed ban. Under this scenario, 
sampling levels in both countries far exceed the OIE guidelines. 
Assume, however, that the two countries differ with respect to their 
initial prevalence--i.e., the initial prevalence in ``Country A'' is 1 
infected animal per 10,000 animals, while that in ``Country B'' is 1 
infected animal per 100,000 animals.
    For a given surveillance level, the statistical power of a 
hypothesis test can be evaluated as a function of the supposed change 
in BSE prevalence between cohort 1 (pre-feed ban) and cohort 2 (post-
feed ban). The conventional minimum statistical power criterion is 80 
percent. In other words, the probability that a statistical analysis 
will detect a true difference across groups should be at least 80 
percent. The conventional significance level is 5 percent, meaning that 
we would conclude that a result was nonrandom if it were 5 percent or 
less likely to occur by chance alone. In our hypothetical scenario, the 
power of the surveillance in the country with higher prevalence, 
Country A, to detect a 50 percent decline in BSE prevalence is 98 
percent. In comparison, the power of the surveillance in the lower 
prevalence Country B to detect a 50 percent decline in BSE prevalence 
is only 25 percent. In other words, if the Country B feed ban actually 
led to a 50 percent decline in BSE prevalence and the equivalent of 2 
million random samples were collected (6.7 times the level under the 
OIE guidelines), there would still be a 75 percent chance of concluding 
that the prevalence was unchanged from its initial level of 1 infected 
animal per 100,000 animals.
    An important implication of the low statistical power of sampling 
in low prevalence populations is that BSE surveillance data are 
unlikely to provide a purely statistical basis for making a 
determination about the date when a specific intervention (e.g., a 
ruminant-to-ruminant feed ban) becomes effective, even when large 
amounts of surveillance data are available. For example, according to 
the OIE (2007a), the annual incidence of reported BSE cases in the 
Netherlands dropped from 13.2 to 0.8 per million adult cattle from 
2001-2005.\6\ Despite the EU BSE surveillance requirements for testing 
all risk animals over 24 months of age and all healthy slaughter cattle 
over 30 months of age, Figure 1 shows that application of the BSurvE 
(Prevalence A) model to Netherlands BSE surveillance data does not 
yield sufficient statistical power to draw clear distinctions among 
birth year cohorts as prevalence declines (Figure 1).
---------------------------------------------------------------------------

    \6\ The OIE Terrestrial Animal Code (Chapter 1.1.1., Article 
1.1.1.1) defines incidence as ``the number of new cases or outbreaks 
of a disease that occur in a population at risk in a particular 
geographical area within a defined time interval (OIE 2006b).''

---------------------------------------------------------------------------

[[Page 53321]]

[GRAPHIC] [TIFF OMITTED] TR18SE07.023

    Note that, in figure 1, there is a decrease in estimated prevalence 
between 1998 birth-year cohorts and 1999 birth-year cohorts, while, at 
the same time, there is an increase in the upper confidence limit. This 
apparent paradox is indicative of another shortcoming of relying on 
surveillance data alone to determine whether BSE prevalence has been 
reduced. Because fewer animals from the most recent birth year cohorts 
are tested when sent to slaughter, uncertainty about the prevalence in 
the most recent cohorts is much greater than in older cohorts. 
Furthermore, the lower likelihood of detecting BSE in young infected 
animals means that the young animals that are tested contribute 
relatively little to reducing uncertainty in the true (as opposed to 
apparent) BSE prevalence. These two sources of uncertainty in young 
birth cohorts (low numbers of animals tested, and little value in the 
surveillance data that are gathered from them) cause an asymmetrical 
increase in the upper limit of the confidence interval compared to the 
lower confidence limit. This effect on the upper confidence limit on 
BSE prevalence is most pronounced for the most recent birth year 
cohorts which are less likely to be tested and will not have lived long 
enough to manifest BSE, even if they have been infected. Wilesmith et 
al. (2004, figure 3) further illustrates this same concept.
    Consequently, if the effectiveness of a country's safeguards 
against BSE amplification were determined strictly by setting a 
tolerance for the upper confidence limit on BSE prevalence associated 
with the ``real surveillance data,'' one might reach the incorrect 
conclusion that prevalence is increasing, when in actuality, the result 
is simply due to testing fewer and younger animals in the most recent 
birth year cohorts. Finally, relying solely on surveillance data fails 
to account for under reporting of disease due to the lack of diagnostic 
sensitivity to detect BSE at an early stage of disease. By accounting 
for the possibility of false negative test results, epidemiologic 
models such as BSurvE are recognized as providing a more accurate 
estimate of true BSE prevalence than the apparent prevalence measured 
by surveillance data alone.
    Issue: One commenter stated that the output from the BSurvE model 
used by Canada in 2005 grossly underestimated Canada's 2006 and 2007 
BSE prevalence and, therefore, the BSurvE model is unreliable for 
estimating Canada's BSE prevalence. The commenter stated further that, 
at the minimum, APHIS should determine the erroneous inputs that 
resulted in the failed prediction in 2005 and correct them.
    Response: In the risk assessment conducted for this rulemaking, 
APHIS used its own prevalence estimate, not that of the Canadian Food 
Inspection Agency's (CFIA's) 2006 prevalence estimate, which was not 
based on BSurvE, but on a modified version that appears similar to the 
APHIS BBC model. The commenter cites CFIA's Assessment of the North 
American BSE Cases Diagnosed from 2003-2005 (Part II), which states 
that ``when the BSurvE model was recently applied to Canada's 
statistics and adjusted to account for the effectiveness of the 1997 
feed ban (based on experiences with the 1988 feed ban in the United 
Kingdom), the resulting prediction was that it could be expected that 
three infected animals remain within the national herd'' (CFIA 2006, p. 
13).
    APHIS' estimation of BSE prevalence in Canada (APHIS 2006c) is that 
the expected prevalence values under the BBC and BSurvE Prevalence B 
models correspond to an expected number of BSE-infected animals in the 
standing Canadian adult cattle population of 4.1 and 23.2, 
respectively. APHIS further explains that it is important to note that 
this range of prevalence estimates represents uncertainty and not 
variability. BSE-infected animals are recruited into and exit from the 
adult cattle population over time, but at a given point in time, the 
number of infected animals in the population is a fixed but uncertain 
value.
    Assuming the overall probability of infection remains constant over 
time, the actual number of infected cattle in the population at any 
given point in time would still vary randomly about the mean. This 
variability is incorporated in the model supporting the exposure 
assessment for live bovines by means of the Poisson variability 
distribution. Assuming a fixed mean prevalence of 4.1 and 23.2 BSE 
infected animals in the standing adult cattle population in Canada, the 
95th percentile of the Poisson distribution are 7 and 31 BSE-infected 
animals in any given year, respectively. We note that these numbers are 
greater than the

[[Page 53322]]

five BSE cases detected in Canada in 2006, which means that the 
greatest number of Canadian BSE cases identified in a single 
surveillance year is lower than even the 95th percentile of 
distribution.
    Issue: One commenter stated that, if the United States were finding 
BSE cases at the same rate as in Canada, this would translate into 
roughly 40 BSE cases detected in the United States since January 2006, 
which would be regarded as a large number. The commenter stated further 
that, at this time, the BSE situation in Canada does not appear to be 
improving.
    Response: We do not agree with the commenter. The commenter's 
conclusion appears to be based on a cursory estimate and does not 
provide an accurate comparison of BSE cases detected in Canada with a 
comparable number that would have been detected in the United States, 
given the larger U.S. cattle population. The commenter's comparison 
fails to take into account other years of surveillance, as well as the 
age and surveillance stream of tested animals. These data are extremely 
important for estimating BSE prevalence. A comparison based solely on 
the number of detected cases ignores infected animals with unapparent 
or undetected infections.
    Table 1 provides a direct comparison of the estimated BSE 
prevalence in the current standing adult cattle population of the 
United States and Canada, respectively, using identical estimation 
methods (APHIS 2006a; 2006c).

Table 1.--Comparison of Estimated BSE Prevalence in the Current Standing
               Adult Cattle Population of U.S. and Canada
------------------------------------------------------------------------
                                     BSE Prevalence Estimation Method
                                ----------------------------------------
            Country               BSurvE  prevalence
                                          B                   BBC
------------------------------------------------------------------------
                                              Expected value
------------------------------------------------------------------------
US.............................  0.18 x 10-6........  0.10 x 10-6
Canada.........................  3.9 x 10-6.........  0.68 x 10-6
------------------------------------------------------------------------

    Despite the higher estimated BSE prevalence in the current standing 
adult cattle population in Canada compared to the prevalence of BSE in 
the standing adult cattle population in the United States, APHIS finds 
that, because of the extremely low BSE prevalence in Canada and the 
high levels of BSE controls in both Canada and the United States, the 
risk to the United States (i.e., the likelihood of establishment of BSE 
in the United States and the potential impacts of cases that may occur 
even without establishment) as a result of importing from Canada the 
bovine commodities considered in this rule is negligible (APHIS 2006b). 
Furthermore, as stated in our risk assessment, we expect that the 
prevalence of BSE in Canada will decrease continuously over the next 
several years. Peer reviewers of our risk assessment agreed (RTI 2007).
    Issue: One commenter stated that Canada's ratio of positive cases 
per 10,000 cattle tested exceeds the ratio of 22 of the 25 EU-member 
countries; that only the ratios for the United Kingdom, Portugal, and 
Spain exceed Canada's 2006 ratio. The commenter noted further that even 
the countries of Ireland, Germany, and France, each of which are 
considered to have had widespread BSE exposure, have a lower ratio for 
positive cases detected per 10,000 head tested than does Canada. 
Another commenter stated that Canada's BSE prevalence is higher than 
that for Denmark, Belgium, and Austria, and is comparable to the rate 
in Germany. This commenter, who estimated the Canadian BSE prevalence 
to be 6.4 cases per million cattle, stated further that no one 
considers countries with a reported BSE rate of 1 to 2 cases per 
million animals (e.g., Denmark, Belgium and Austria) to have a minimal 
BSE risk, and that Canada is not a BSE minimal-risk region in any 
ordinary sense.
    Response: The commenters' statements ignore important differences 
in BSE surveillance and cattle populations among countries, and a 
comparison based simply on the proportion of positive cases per number 
of cattle tested is inconsistent with the prevalence estimate approach 
taken by one of the commenters, as well as the prevalence estimate used 
by APHIS. Although calculating the proportion of infected animals 
detected per number of tested animals can serve as a useful tool, 
depending on the purpose for the calculation, it is not an estimate of 
prevalence. Rather, prevalence is defined as the number of infected 
animals in the total population at a given point in time. On the other 
hand, the calculation conducted by the commenter who referred to the 
ratio of positive cases per 10,000 cattle tested is similar to that 
conducted by the U.S. Department of Health and Human Services, Centers 
for Disease Control and Prevention (CDC). In May 2007, using data 
similar to that analyzed by APHIS for this rulemaking, CDC calculated 
the proportion of Canadian-born BSE cases identified by Canadian 
authorities in relation to the total number of animals tested in that 
country. CDC then made a like calculation regarding BSE cases in U.S.-
born cattle and compared the Canadian and U.S. results (CDC 2007). 
Unlike the estimate used by APHIS in the risk assessment for this rule, 
the CDC calculation is not an estimate of the prevalence of BSE in 
Canada, nor of the prevalence in the United States. Although the type 
of calculations conducted by CDC can be useful in comparing relative 
proportions of BSE detections per number of cattle tested, they do not, 
as noted above, constitute an estimate of prevalence.
    The number of disease detections per total number of animals tested 
can be influenced by the criteria used for choosing animals for 
testing. For instance, Canada, like the United States, conducts 
targeted BSE surveillance, sampling those animals where disease is most 
likely to be detected if present. In contrast, EU countries routinely 
test large numbers of healthy animals at slaughter. Approximately 80 
percent of cattle tested for BSE in the EU during 2001-2004 were 
healthy slaughtered animals, but ``risk animals'' were 22 times more 
likely to test positive (EC 2005a). One study (Giovannini et al., 2005) 
estimates the true prevalence of BSE infection in several EU countries. 
Based on BSE test