- The Food Safety Consortium Newsletter
- Vol. 11, No. 3
- Summer 2001
- * Striking the Pathogens and Keeping Them
- * FSC Annual
Meeting Planned at ISU
- * USDA Unveils
New Food Safety Web Site; FSC Projects Included
- * Advice to Processors:
Don't Rely on the Models -- Test the Real Thing
- * Report From
- * Global Trade
Should Prompt World Food Safety Effort
- * New Opportunities
Seen for Chemical Spray
- * New Agri Secretary
Seeks Cooperative Approach to Food Safety
- * Papers and
- * Food Safety
- Striking the Pathogens and Keeping Them Down
- When poultry processors prepare their
products as ready-to-eat, there is more at stake than just a
tasty meal. The cooking process is also intended to kill pathogenic
Listeria and Salmonella bacteria. But processors
need to keep a close eye on the product. Sometimes a few of the
bacteria are not dead, but just injured and recuperating.
In research experiments for the Food Safety Consortium, Rong
Murphy of the University of Arkansas biological and agricultural
engineering faculty found that cooking the poultry at low humidity
levels enables more Salmonella to survive than when cooked
at high humidity.
But the solution isn't as simple as just raising the humidity.
"It depends on the type of product," Murphy said. "For
some types, you have to cook it at low humidity. Some kinds of
products, such as fried products, are processed at low humidity.
Grilled products can be cooked at high humidity."
Injured pathogens can come back and survive at levels strong
enough to endanger consumers. "Most of the time it takes
three or four days to start having growth for heat-injured cells,"
The cooking process can make a difference. Murphy explained that
frying for a long time may not kill all the bacteria. But frying
for a short time and then switching to convection cooking will
likely kill all pathogens.
"That's why we conduct studies on different processes to
see what type of pathogens are susceptible to what type of heat,"
Murphy's studies found that processed patties grew Salmonella
and Listeria at lower rates when stored in a vacuum than
when stored in air. Although vacuum packaging reduced growth
levels, the procedure didn't kill the bacteria entirely.
"Even though the products are packaged, the bacteria can
still survive under low oxygen conditions," Murphy said.
"Vacuum packaging itself is not going to kill them."
The poultry industry is interested in the research and its implications
for cooking procedures after processing. Murphy noted that the
processors want to control quality as much as possible at the
plant before shipping out the product.
Murphy's project tested the process to determine at what temperature
pathogens become inactivated in chicken patties while heat slowly
rises and humidity levels vary in an air convection oven.
Commercial processors, she explained, use both high and low levels
of humidity. "That's their traditional practice, mainly
from the quality and flavor viewpoint. We don't try to change
their process. We try to evaluate it from a food safety viewpoint
as to which point you should control."
The research has found that longer cooking times ensured that
the necessary internal temperatures - 160 degrees Fahrenheit
- were reached to ensure safety, but those longer times also
result in increased processing costs and decreased product yield.
"We found that with some products cooking could cause 1
to 2 percent yield less for every 3 degrees Fahrenheit, depending
on the process," Murphy said. "One company is interested
in this point because it cooks nearly to 200 degrees and they
lost a lot of yield."
Losing even small percentages worth of yield can be quite costly
if a company operates a billion-dollar business, Murphy noted.
Overcooking can cook more water out of the product, which cannot
be added back in after processing.
The company that consulted with Murphy is using results of the
study to determine how to improve yield as well as ensure food
safety. "You can lose a lot of money without better process
- FSC Annual Meeting Planned at ISU
- The Food Safety Consortium will hold its
annual meeting Sept. 16-18 at Iowa State University in Ames.
In addition to the usual schedule of presentations by FSC researchers,
this year's meeting will feature a symposium on risk and risk
The main segment of the annual meeting, intended primarily for
FSC researchers and graduate students, will be held Sept. 16
and 17 at The Hotel at Gateway Center in Ames. A reception and
poster session is planned for 6 to 7:30 p.m. Sept. 16. A full
day of progress reports presented by FSC researchers and a continuation
of the poster session will take place from 8 a.m. to 5 p.m. Sept.
The FSC symposium will be held from 8 a.m. to noon Sept. 18 at
the Scheman Building on the ISU campus. The symposium is open
to non-FSC personnel for a $275 registration fee. Speakers for
the symposium will include Anna Lammerding of Health Canada,
Doug Powell of the University of Guelph, Canada and Alice Johnson
of the National Food Processors Association.
To register for the symposium, contact Val Evans at ISU at email@example.com
or 515-294 3305.
- USDA Unveils New Food Safety Web Site; FSC Projects
The U.S. Department of Agriculture has launched a new Web site
aimed at providing a database of food safety research projects
to the research community and the general public. The Web
site provides detailed information on food safety research projects,
spending, and accomplishments by federal agencies, along with
links to other important food safety research information.
"This Web site is a tool that researchers and policy makers
can use to examine research needs and priorities in food safety,"
said Agriculture Secretary Ann M. Veneman. "The goal is
to measure the progress of our food safety research and
continue efforts to educate the public about these important
The searchable database provides information on nearly 500 food
safety research projects - including those of the Food Safety
Consortium - dating from 1998 to the present. The database also
includes research done or funded by the USDA Agricultural Research
Service; USDA Cooperative State Research, Education, and Extension
Service and the U.S. Department of Health and Human Services'
Food and Drug Administration.
Also on the Web site are program and planning information, as
well as various food safety reports, food safety news and information
and more than 100 links to Web-based food safety research information
provided by U.S. and foreign governments, and educational and
The new Web site was created by the Food Safety Research Information
Office at USDA's National Agricultural Library with information
from related government food safety agencies. The National Agricultural
Library, part of the Agricultural Research Service, is the world's
largest and most accessible agricultural research library, and
the principal resource in the United States for information about
food, agriculture, and natural resources.
- Advice to Processors:
Don't Rely on the Models -- Test the Real Thing
- Cooking pork sausage brings up the practical
question of how much heat is necessary to ensure product safety
and maintain sensory quality. Food processors consider factors
such as the cost and the effectiveness of heat in killing pathogenic
bacteria and its effects on taste.
Processors need to run their own tests to find out the answers
to these questions because models won't necessarily tell the
true story about the microbial destruction in meat. Iowa State
University's Food Safety Consortium unit examined the effects
of phosphates on pork processing and found that one uniform treatment
does not fit all scenarios.
Scientists have developed models that are designed to predict
the extent of heat destruction of certain foodborne pathogens
as affected by environmental factors such as phosphates. Phosphates
increase pork's water-holding capacity and improve safety by
making Listeria monocytogenes less resistant to heat and
more susceptible to destruction.
The behavior of foodborne microorganisms can be estimated by
evaluating their growth or destruction in broth cultures or other
model food systems. However, exceptions occur when an additional
significant factor is present in the food but not in the model
For example, a relatively high fat content or phosphate level
in ground pork could make a model unreliable for predicting the
microbial safety or shelf life of pork sausage if the model lacks
the same levels of fat or phosphate.
"Data on pathogen destruction from the use of model systems
should just serve as a general guideline for processors to follow,"
said Aubrey Mendonca, a Food Safety Consortium researcher on
ISU's food science faculty. "But we always tell them to
validate, validate, validate."
Mendonca and a graduate research assistant, Makuba Lihono, looked
at the effect of a phosphate, sodium acid pyrophosphate (SPP),
on the heat destruction of Listeria monocytogenes in a
model system involving pork slurry, a mixture of pork with peptone
water. They also ran the same test using fresh ground pork. The
research team inoculated the pork samples with Listeria monocytogenes
and heated them at temperatures ranging from 55 to 62.5 degrees
"In the presence of SPP, the heat resistance of Listeria
monocytogenes decreases greatly in the model system that
used pork slurry," Mendonca said. "But we could not
repeat these results in the fresh ground pork. We realized that
fresh meat has some enzymes that degrade into orthophosphates,
which have little or no antimicrobial activity. We demonstrated
that the degradation of SPP by natural phosphates in fresh ground
pork contributes to its ineffectiveness against Listeria monocytogenes."
Although the U.S. Department of Agriculture has developed predictive
models, it agrees that processors should validate predictions
from models by running tests with their own meat product. "The
model system can never provide the exact conditions of a meat
product, no matter how hard we try," said Mendonca. "There
are some factors in meat that will not be present in a model
system. Validation involves comparing results from tests in actual
meat products with predictions from models."
Predictive models, when validated, can be useful in indicating
when a food product might spoil or under what conditions foodborne
pathogens such as Listeria monocytogenes might pose a
health risk to consumers.
Processors often want to know what cooking temperature is best
for killing pathogens without negatively affecting palatability,
flavor and texture of the meat product. By using salt, phosphates,
lactate and certain other ingredients, a processor can put enough
stress on the organisms so that less heat is required to kill
them. Lower heat means lower production costs.
Mendonca noted that there are other options for killing pathogens
while allowing for lower cooking temperatures, such as irradiation
although the procedure is still not in wide use. But following
too many options can affect the product in ways that might make
it less attractive to the consumer.
"Many times in sausage making you will add phosphates to
increase product yield and protect flavor, but phosphates are
not added primarily as an antimicrobial", Mendonca said.
"So we've got to rely more on adequate heating of the product
to ensure microbial safety."
- Report From the Coordinator
- By Gregory J. Weidemann
- Consumers across the nation are becoming
more aware of food safety issues and their own role in keeping
contamination out of the food supply. The U.S. Department of
Agriculture Food Safety and Inspection
Service found that to be the case in a recent survey of focus
groups in four cities.
That's something for scientists, administrators, businesses and
government officials to keep in mind among what we call the "food
safety community." The problems that the food safety community
confronts regularly are not just matters for shop talk among
ourselves. These topics involve the general public and they are
listening to the discussion.
"People are more aware of pathogens, more aware of dangers,"
says Susan Conley, director of food safety education for FSIS.
"They have confidence in themselves and in the food supply.
They feel they know how to handle food. This is a new and different
attitude. They are sure of themselves and sure of the food -
even when they are sometimes wrong."
The Food Safety Consortium devotes a portion of its research
to these direct consumer issues. A look at our projects shows
the interest across our three member universities. At Arkansas,
a team is exploring levels of consumers' acceptance of irradiated
poultry. At Kansas State, research has demonstrated the importance
of using oven thermometers to determine the internal temperature
and doneness of cooked meat. Iowa State has launched a web site
with food safety lessons for consumers and for food service personnel.
The FSIS survey is a good example of the need for research scientists
in industry and academia to stay in touch with consumer concerns.
The reason for the most basic of our research is to improve the
safety of the food on our plates at home and when dining out.
Whether we explore the procedures at the production and processing
stages or at the distribution and consumption levels, our researchers
have an abundance of issues to consider.
The subject of food safety's wide-ranging issues provides a good
opportunity to put in a plug for this year's annual meeting of
the Food Safety Consortium. Details about the event are published
elsewhere in this issue. The meeting - Sept. 16-18 at Iowa State
University in Ames - will cover the spectrum of our organization's
research projects, with segments of the meeting separately emphasizing
risk assessment, control and intervention strategies and sampling
protocols methodology. A forum on the final morning of the meeting
will feature guest speakers discussing risk communication.
The annual meeting is an example of communication among our scholars
that plants ideas and generates additional research in the future.
Our work should give the consumers of this nation confidence
that no one in the food safety community is resting on past laurels.
Global Trade Should Prompt World Food Safety Effort,
WHO Official Says
- The world needs new food safety rules
because increased global food trade means health problems can
spread rapidly from country to country, a World Health Organization
official said in July.
The Associated Press reported that Gro Harlem Brundtland, director-general
of the WHO, told the Codex Alimentarius Commission, "The
globalization of the world's food supply means the globalization
of public health concerns. It is more and more difficult to solve
food safety problems in one country without international collaboration."
The 165-nation commission, which meets every two years, is considering
guidelines on bacteria control, pesticide levels in food, and
biotech safety. The commission is a joint body of WHO and the
U.N. Food and Agricultural Organization and met for a week in
Brundtland said that high-profile outbreaks were only part of
the problem, and that around one-third of the population of industrialized
countries suffer from a foodborne disease every year. "Around
2 million children die every year from diarrhea in developing
countries because of bad food and water," he said.
Brundtland also said that few developing countries have food
safety systems, but more of them were trading with industrialized
nations, so it is in their interest to adopt safety measures
to protect both their own population and the populations of their
- New Opportunities Seen for Chemical Spray
- Meat processors may soon have another
tool at their disposal for reducing pathogenic bacteria. Tests
at Kansas State University have shown that spraying a chemical
on frankfurters and pork carcasses reduces pathogenic bacteria
more effectively than water washing.
Acidified sodium chlorite reduced Listeria monocytogenes
when applied to frankfurters in the processing plant, with reductions
increasing as exposure time to the chemical was increased. Also,
acidified sodium chlorite reduced the levels of E. coli
and Salmonella when applied to pork carcasses during processing
Harshavardhan Thippareddi, a Food Safety Consortium researcher
in the KSU animal sciences and industry department, explained
that hot dogs usually have organisms loosely attached that are
called plactonic cells. "Just regular washing with pressurized
water and any similar treatments will remove some of the microbial
cells from the surface. When we use acidified sodium chlorite
we had better reductions compared to the washings with water
or even dipping in water."
Thippareddi said the KSU research showed that the chemical treatment
is effective on ready-to-eat meat products because the surface
is cooked. The treatment is also effective on animal carcasses,
he said, because the presence of organic material does not inactivate
Thippareddi predicted that the process would be picked up by
industry for frankfurters in perhaps a year or two. "I think
we will have some optimized conditions where we could use this
technology in industry," he said. "It is being used
only in the poultry industry now. The beef processing industry
is conducting validation tests of it."
Before the process is further developed for industrial use, Thippareddi's
research team suggests studies to evaluate the chemical treatment's
effect on sensory attributes such as color and flavor. No problems
have been confirmed from visual observation, but there have been
slight changes apparent.
For pork carcasses, organic acid rinses such as lactic acid or
acetic acid are the predominant treatment in the processing plants.
Acidified sodium chlorite is used in poultry processing, Thippareddi
said. In all cases, he expects acidified sodium chlorite to become
the most popular because of its superior performance.
"The advantage is that you can incorporate that with some
minimal changes in the capital investment into the present organic
acid rinse," he said.
Thippareddi said the next step would be to conduct in-plant validations
of the procedures for pork carcasses that his team has tested
on campus, similar to the in-plant validations already under
way in beef carcass processing plants.
Future research may cover ways to extend these antimicrobial
treatments to ground beef trim. "We are looking at a research
project where we can evaluate the effects of acidified sodium
chlorite, hot water and organic acid rinses for the beef trim
that is supposed to go to ground beef manufacturers," Thippareddi
said. "USDA regulations do not allow those treatments now
because of the added water. When you do these washes you inevitably
add some moisture to the product.
"In the future, USDA might come up with something that says
if you are using these procedures as antimicrobial treatments
then you would be able to use them."
- New Agri Secretary Seeks Cooperative Approach to
- These are excerpts from a speech delivered
by Agriculture Secretary Ann M. Veneman in April to the Food
Safety Summit in Washington.
Through the Food Safety Inspection Service, USDA is responsible
for ensuring the safety of the nation's meat, poultry and egg
supplies. It's an important responsibility, and one that we take
very seriously. ...
USDA's commitment to food safety remains strong.
In fact, the president's proposed budget provides funding for
no fewer than 7,600 meat and poultry inspectors - without imposing
user fees of any kind. And the total funding proposed for the
Food Safety Inspection Service in FY 2002 is $716 million, an
increase of $21 million over the 2001 level.
Our priorities at USDA regarding food safety fall into six categories.
First, we must begin with an understanding that the food chain
has fundamentally changed over the past few decades. ...
When we look at the state of the food economy, we can clearly
see that for any new policy to be successful and effective, it
will have to be made with input and cooperation from every link
in the food chain. This is especially true of food safety. Only
a cooperative approach that integrates research, public health
regulation, and education can lead to the formulation of effective
policy that meets everyone's needs.
Second, we must work to ensure that all food safety policies
are based on sound scientific principles.
Speculative or incomplete scientific research may be good for
grabbing headlines, but it's a terrible basis for policy and
regulation. That's why it is so important for those who conduct
scientific research on behalf of the public to ensure that research
is sound and reliable.
And it's just as important - if not more so - for those of us
who oversee research and make policy based on its findings to
accept only scientific studies that live up to the highest standards
of methodological integrity. ...
Third, we must continue to educate the public about all aspects
of food safety, from the testing we do at USDA, to safe handling
practices for consumers.
People are naturally quite concerned about the safety of the
food they eat. And while the general public cannot be expected
to become food safety experts, it is certainly possible for them
to understand the basic issues. A well educated public is better
prepared to assess the validity of claims they may hear in the
media, and to reject false or misleading information. And a well
educated public will hold more realistic views of the safety
of the food supply, and therefore be more confident in the food
they buy and eat. ...
I want to mention one example of a successful public education
effort before I move on. As you may have noticed, the "Fight
BAC!" and "Thermy" characters are here representing
consumer education activities. The "Fight Bac!" campaign
promotes the four basic food safety rules - Clean, Separate,
Cook, and Chill - while the "Thermy" campaign promotes
thermometer use to indicate when products are cooked to a high
enough temperature to kill harmful bacteria. And it's no accident
that these campaigns were created in partnership with the private
- These are just two examples of what such
cooperation can accomplish.
Fourth, we must ensure that USDA's food safety policymaking process
continues to be transparent and that the public has the opportunity
to provide input and be fully involved. ...
Fifth, we need to encourage public-private partnerships to address
food safety problems.
California provides an excellent model for the kind of public-private
partnerships that can help ensure the safety of the food supply.
In 1996 and 1997, in the wake of two strawberry scares in California,
we at the California Department of Food and Agriculture brought
together government, industry, and university leaders to address
The result was the creation of the first of many Quality Assurance
Plans, voluntary agreements that developed guidelines for safe
food production and sound environmental practices. ...
Finally, USDA will strengthen cooperative working relationships
with other agencies of government involved in food safety.
For instance, we at USDA were very pleased when Administrator
Whitman announced that the EPA will re-establish a liaison to
USDA. That position helps ensure that our respective agencies
are working together toward our common goals, and not at cross
We know that it is possible to make good policy that incorporates
all of these elements - and the Pathogen and Hazard Analysis
and Critical Control Point system (HACCP) is an excellent example.
HACCP, as you know, has been fully implemented into the 6,700
federally inspected and 2,500 state-inspected meat and poultry
plants nationwide, and the meat and poultry we import from other
countries must be produced under a HACCP-based, equivalent system.
We know that HACCP is working. A new report from FSIS shows that
the prevalence of Salmonella on raw meat and poultry products
continues to decline - by as much as half on raw chicken, for
example. We are seeing sustained reductions in foodborne illness
as well, according to the newest data released from the Centers
for Disease Control and Prevention. We are seeing more and stronger
partnerships among industry, government, academia, and consumers.
Some today argue that to ensure the safety of the American food
supply, the wisest course would be to isolate U.S. agriculture
from the rest of the world. But food safety is a global issue,
that demands a global response. Diseases and pathogens respect
no national borders. That's why the wiser course is to work cooperatively
with other countries on food safety and animal monitoring. We
need to harmonize inspections and regulations at ports before
diseases break out. We need to be as global as the pathogens.
The work that has been ongoing for many years through the Codex
Alimentarius Commission and the International Office of Epizootics
is a good model for the future.
If one theme stands out in all this, it is cooperation.
Every sector of the food economy - every link in the food chain
- needs to work together toward common solutions. Examples as
varied as HACCP and California's Quality Assurance Plans show
that when government, industry, scientists and consumers come
together to solve problems, the results are policies that satisfy
the interests of the various groups while promoting the public
I look forward to working with all of you to develop new approaches
that further protect consumers and ensure that America's food
supply remains the safest in the world.
- Papers and Presentations
- Curtis Kastner,
Kansas State, presented a paper on "Product Shelf Life"
in July at the American Association of Meat Processors annual
convention in Nashville. In August, Kastner also delivered a
presentation on "Meat Technology and Processing - Current
Issues and Trends" at the 47th annual International Congress
of Meat Science and Technology in Krakow, Poland.
Erdogan Ceylan, Daniel Fung, Melvin Hunt, and Curtis
Kastner, all of Kansas State, presented a paper on "Synergistic
Effect of Garlic, Cold Storage and Heating in Controlling Escherichia
coli O157:H7 in Ground Beef Patties" in June at the
annual meeting of the Institute of Food Technologists in New
Donald Kropf, Kansas State, presented a paper on "An
Update on Meat and Food Irradiation" in April at the Clemson
University Food Safety Symposium.
Michael Johnson and James Denton, both of Arkansas,
were invited participants in June at Tyson Foods' groundbreaking
ceremonies for a $5.2 million 17,000-square-foot expansion of
its Corporate Laboratory and Research Services Building in Springdale,
Ark. Denton, director of the University of Arkansas Center of
Excellence for Poultry Science, delivered an address on the importance
of food safety and what the new facility will mean to students
seeking internships in research. Johnson spoke on the UA food
science department's history of involvement with Tyson's corporate
lab since 1986. Denton and Johnson joined John Tyson, Tyson foods
chief executive officer, and nine Tyson personnel in turning
shovels on the site where construction would follow. Articles
about Johnson's and Denton's participation were published in
The Morning News of Northwest Arkansas and the Arkansas
James Denton, Arkansas, was named Man of the Year by the
Poultry Federation at its meeting in June in Hot Springs, Ark.
Denton has also been named director of the Poultry Safety Center,
one of 12 virtual centers of the National Alliance for Food Safety.
In March he attended the HACCP Alliance Board of Directors meeting
in Atlanta. He delivered an invited presentation at the Poultry
Symposium in April in Springdale, Ark. In May he traveled to
Scotland with other faculty in the University of Arkansas International
Agriculture Program where he discussed food safety issues and
poultry research with faculty from the Avian Science Center in
Auchincruive. Also in May, Denton attended the National Chicken
Council's Animal Welfare Task Force meeting in Atlanta.
- Food Safety Digest
By Dave Edmark
- It's not uncommon to hear food safety
advocates call for more consumer education. Researchers at Utah
State University have come up with the proof to verify the need
to concentrate more on what's going on in the kitchens at home.
Considerable effort is made in food safety research to find ways
to avoid contamination during production and processing. But
once the food lands in the home, consumers have ample opportunity
to undo all the precautions that were taken up to the time of
According to a report in the newspaper Feedstuffs, the
Food Safety Institute at Utah State went into the homes of consumers
with video cameras and recorded what went on in the kitchens.
Ninety-nine homemakers prepared an entree of chicken, fish or
meat loaf and a salad before the cameras. The subjects were told
that the video would be used to promote recipes, so presumably
they would not feel self-conscious about their food safety habits.
They apparently didn't. The videos showed that the homemakers
frequently failed to wash hands, or did so for only a few seconds.
Of those who did wash their hands, only about one-third used
They used cloth kitchen towels to dry their hands about two-thirds
of the time, the same towel that was used to clean the utensils
and pat meat dry. Almost all of them attempted to check the meat's
doneness, but only 5 percent of them used a cooking thermometer,
the only reliable way of determining if meat is fully cooked.
About one-third of them kept their refrigerators warmer than
the recommended level of 40 degrees Fahrenheit.
"It's like a black hole," said Janet B. Anderson, director
of the Food Safety Institute. She suggested that food safety
education should include repeated demonstrations and recommendations
to prevent foodborne disease from occurring in the home.
* * *
So what to do? There is an abundance of resources for consumer
education. One is on the U.S. Department of Agriculture Food
Safety and Inspection Service web site. FSIS has divided the
page into resources for consumers and for education and health
professionals. Viewers will find copies of FSIS brochures and
publications in addition to links to web pages highlighting various
consumer education campaigns. The site has enough material for
anyone to print hard copies and form a do-it-yourself consumer
education program. All this is on line at http://www.fsis.usda.gov/oa/consedu.htm.
* * *
New brochures about irradiation are available in short question-and-answer
formats. They are oriented toward consumers looking for basic
introductory information about food irradiation.
The Minnesota Department of Health has published one of the brochures,
titled "Irradiated Food - What It Means for You and Your
Family." A PDF version of the brochure can be downloaded
Pennsylvania State University has issued the other brochure called
"Questions and Answers About Irradiation of Meats."
The PDF version of this brochure is available at http://pubs.cas.psu.edu/FreePubs/pdfs/uk069.pdf.
Printed copies may be ordered from addresses listed on each brochure.
* * *
- Tensions in Hong Kong between citizens
and the mainland government have spilled over into food safety
issues. In June, Reuters news service reported that the Hong
Kong government was criticized when local health authorities
waited five days before revealing that a beef sample from the
mainland was contaminated with E. coli O157:H7. Government
officials were quoted as saying they tried to recall the tainted
meat when test results showed the contamination, but were told
had already been sold. The government said there were no reports
of any E.coli-related illnesses since the tainted beef
went on sale so it was unlikely to have infected humans since
the bacteria only has a gestation period of between three and
nine days. Doctors, however, said E.coli-related health
problems could lead to more serious illnesses which may not surface
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