Wooster, Ohio
September 13, 2007
A year after a spinach-related
outbreak of E. coli O157:H7 that sickened 199 people and killed
three, Ohio State University scientists are learning more about
how such organisms contaminate leafy greens, and how to more
effectively communicate findings to growers, retailers and
consumers to reduce risk.
Jeff LeJeune, a microbiologist with the Ohio Agricultural
Research and Development Center,
Ohio State University Extension and the College of
Veterinary Medicine, is leading two projects dealing directly
with this type of food safety issue.
The latest is a $2.5 million project that began Sept. 1. The
four-year project will focus on working with small and
medium-sized vegetable farms and with vegetable farmers who may
be under-served, such as Amish or African-American farmers, in
Ohio, Kentucky and Indiana. The project expands upon LeJeune's
other study, a three-year $600,000 project that began in
September 2006 focused on reaching larger commercial growers in
Ohio. Both studies include a significant amount of
microbiological research to examine how contamination occurs and
what can be done to remove it. And both were developed with
direct input from Ohio produce growers, LeJeune said.
"These produce-related outbreaks have been occurring for some
time, but the spinach outbreak seemed to be a wake-up call,"
LeJeune said. "Everyone started thinking more about what they
could do better, about developing new standards and best
management practices. But we need data to support those kinds of
recommendations. People want to know what to do, and we need the
research to be able to tell them what to do."
Doug Doohan, an OSU Extension specialist in fruit and vegetable
weed control and associate professor of horticulture and crop
science with OARDC, is co-coordinator of the new project. "Much
of this grant involves communicating our findings," Doohan said.
"To do that effectively, we need to understand the perceptions
that different segments of the farming community have about food
safety."
The new project involves:
- Identifying specific farm
management practices to enhance the microbiological quality
of vegetables, particularly on smaller farms.
- Identifying sources and
the magnitude of vegetable microbial contamination during
the processing, packaging and storage of leafy vegetables.
- Determining the beliefs,
attitudes and perceptions that underlie behaviors and
practices associated with vegetable handling among
producers, consumers, retailers, and food safety and public
health educators.
- Developing food safety
messages and communication strategies to encourage increased
adoption of effective food safety behaviors among vegetable
producers and consumers.
Doohan said the project has a
strong focus on risk communication and perception.
"For example, we know that, from a food safety standpoint,
growing produce and raising livestock may not mix very well on
the same farm. But that's a very traditional way of doing
things, especially on smaller farms. How do we get the message
across in a way that will minimize risk? And who would be best
to spread that message -- who will smaller farmers trust?"
As part of the study that started in 2006, graduate student Dan
Aruscavage, who earned his doctorate in August and is now on the
faculty at the State University of New York at Potsdam, examined
the survival of E. coli O157 bacteria on lettuce and tomato
plant leaves. Before 1990, E. coli was associated almost
exclusively with red meat, but between 1991 and 2002, 21 percent
of E. coli O157 outbreaks in the United States were related to
produce.
"If you think about it, a farm field isn't a great environment
for E. coli," said Ken Lee, director of Ohio State's Center for
Food Safety and Security and one of Aruscavage's advisers. "It's
used to living in the gut, in the colon. Outdoors, it's exposed
to sunlight, heat, a lack of moisture, and has to contend with
other flora.
"Dan found that if a plant is damaged -- if a leaf is cracked or
if another microorganism attacks the plant -- the plant's
wound-response itself helps E. coli survive. The wound exudes
sugars, like sap from a tree, that provides E. coli with what it
needs to survive."
Aruscavage's study also determined that once established on a
leaf, E. coli doesn't spread much, said Sally Miller, a plant
pathologist with OARDC and OSU Extension, another adviser on the
study and co-principal investigator on the new project.
"We didn't find much movement to healthy tissue," she said.
"That shows us it's important to keep plants as healthy as
possible." As part of the study, another of Miller's students is
currently looking at how human pathogens such as E. coli are
influenced by the presence of plant pathogens.
As new discoveries occur in the lab, the projects' researchers
will always turn to how best to communicate them, LeJeune said.
"People have a reason for doing what they do -- why they consult
experts, why they adopt certain management strategies," LeJeune
said. "If we understand these 'mental models,' maybe we can
nudge them into doing new things to accomplish new outcomes."
For example, new agricultural best practices, based on lab
research, may recommend new washing protocols, using water
treated with chlorine, ozone or ions. "If farms aren't adopting
these new practices, we need to know what the barriers are so we
can help overcome them," LeJeune said.
As part of the 2006 study, LeJeune's team interviewed 12 Ohio
vegetable producers for an hour each to gain a greater
understanding of their needs and decision-making processes. That
information gathered is still being analyzed, but LeJeune
believes it will help bridge gaps between experts and growers.
"Producers may already know 'A-B-C," LeJeune said. "But 'D'
might not even be on their radar screen. So, let's not waste
time on A-B-C, and direct our energy to get growers the
information they need to know."
With the new grant, such inquiries will be focused on smaller
farmers. "With today's food system, we believe that any grower,
anywhere, can have a major impact on the food chain," LeJeune
said. "But the information that small and medium-size farms need
may be totally different than what Dole or Fresh Express is
getting."
Doohan said this work could prove to be invaluable to efforts
such as the National GAPs (Good Agricultural Practices) Program.
Led by Cornell University, GAPs has become the industry standard
in food safety guidelines for farmers. Doohan is Ohio's liaison
to the program.
"GAPs is considered the authoritative word on food safety
practices on the farm, but it does have a one-size-fits-all
approach, and it's very linear -- from expert to grower," Doohan
said. "But the research shows that this is not the way all
farmers learn. With the information we're gathering, we could
gear food safety messages to different segments of the farming
community, and make it a much more dynamic relationship."
Lee, who also has appointments with OARDC and OSU Extension,
said it's important not to focus just on the farm when examining
food safety. For example, current distribution practices often
provide conditions just right for E. coli survival, he said.
"If you asked an E. coli cell what we could do to help it
survive, it would tell us to rinse the produce with water that
contains just enough chlorine to keep the water clean, but not
enough to kill the cell. Then it would ask for the produce to be
put in a plastic bag to hold some moisture in, and then be
stored in a cool, dark environment. Then, don't process it any
further at the retail level, and when you get it home, don't
wash it. That's exactly what we're doing now."
The answer doesn't lie with one new practice at one point in the
system, Lee said.
"We're looking at multi-point interventions," Lee said. "We're
never going to get all of the pathogens off the farm. But we
could be doing a lot better." For example, instead of washing
and packaging produce at the farm, it could be shipped in bulk
and processed at the retail level. At home, refrigerators could
come equipped with an ultraviolet light that turns on when the
door is closed, killing pathogens. There are many possibilities
to reduce risk using technology currently available, he said.
Both studies are funded by the National Food Safety Initiative
of the U.S. Department of Agriculture's Cooperative State
Research, Education, and Extension Service.
The study that began in 2006, "Biophysical and Ecological
Processes Impacting the Growth and Survival of E. coli O157:H7
on and in Vegetables," also involves the College of Wooster and
Michigan State University.
The new study, "Integrating Social and Biological Sciences to
Enhance Adoption of Vegetable Safety Behaviors from Farm to
Table," also involves Purdue University and Kentucky State
University. Other Ohio State faculty members involved in the
project are Doohan; Miller; Richard Moore, associate professor
of human and community resource development; and Lydia Medeiros,
associate professor of human nutrition. They all have
appointments with both OARDC and OSU Extension. Melanie Lewis
Ivey, an OARDC research associate and graduate student, is
involved in both projects. Doctoral student Sanja Ilic is
working on the new project. Robyn Wilson, who will be joining
the faculty in the School of Environment and Natural Resources
in October, will also be involved.
These interdisciplinary studies complement Ohio State's new
Targeted Investment in Excellence program in Public Health
Preparedness for Infectious Diseases. The TIE program targets
some of society’s most pressing challenges with a major
investment of university resources in programs with a potential
for significant impact in their fields. The university has
committed more than $100 million over the next five years to
support 10 high-impact programs.
OARDC and OSU Extension are part of Ohio State's College of
Food, Agricultural, and Environmental Sciences. |
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