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Enteric Pathogens in the Vegetable Production Chain: Is the risk higher in the organic than in the c

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Six-fold increase in gastro-enteritis and food ... Survival of E. coli 99507 gfp introduced in manure. and then with manure to soil ... – PowerPoint PPT presentation

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Title: Enteric Pathogens in the Vegetable Production Chain: Is the risk higher in the organic than in the c


1
Enteric Pathogens in the Vegetable Production
Chain Is the risk higher in the organic than in
the conventional chain?
  • Prof. Ariena H.C. van Bruggen
  • Organic Farming Systems
  • Wageningen UR
  • Marijkeweg 22
  • 6709 PG Wageningen

2
Health problems with food-borne pathogens
1
  • Six-fold increase in gastro-enteritis and food
  • poisoning in the last 20 years (Nicholson et
    al., 2000)
  • Water and food contaminated with pathogens from
  • human and animal manure
  • Animal products and plant products, especially
    raw meat,
  • eggs, but also fresh vegetables and fruits
  • Pathogens various bacteria
  • a.o. Salmonella spp. in pig and poultry manure
  • Escherichia coli O157H7 in cow manure


Source Nicholson et al., 2000
3
Markets grow for organic produce
1
Fresh vegetables in Italy FAO/N.Scialabba
Packaged vegetables in Brazil
4
Food safety issues

- Residues of synthetic pesticides - Inherent
components (organic, mineral) - Toxic compounds
(mycotoxins, plant derived toxins) - Disease
germs
Concerns about pathogen spread in the media
  • Manure contains human pathogens
  • Spread from manure via soil to roots and plant
    products
  • - Organic food more risky than conventional food

5
Counter-arguments which deserve investigation
1
  • Microbial compositions and pathogen contents of
  • ORG and CONV manure differ
  • - Manure handling differs on ORG and CONV farms
  • Microbial compositions and resistance against
  • pathogen invasion of ORG and CONV soil differ
  • root environment differs (exudation and N
    content)
  • plant physiology and endophytes differ (N
    content)

6
Differences between conventional andOrganic
animal and vegetable production
1
  • Conventional
  • fertilizer (and liquid manure)
  • high N-concentrates in feed
  • low-fiber diet for cows
  • antibiotics in feed
  • Organic
  • composted and liquid manure
  • limited organic concentrates
  • high-fiber diet for cows
  • no antibiotics in feed

7
Cow dung varies in
consistency, decomposition rate,
microbial diversity, pathogen content
1

Low-fiber, high-N feed
High-fiber, low-N feed
8
Survival of E. coli 99507 gfp introduced in
manure and then with manure to soil
1
Cells, CFU/g. d.m.
Semenov, unpublished
9
Survival of Escherichia coli O157H7 gfp in manure
1
Franz et al., unpublished
10
Survival of Escherichia coli O157H7 gfp manure-
amended soil
1
Franz et al., unpublished
11
Risk analysis
1
Based on HACCP (Hazard Analysis and Critical
Control Point) system
I. Risk Assessment 1. Hazard identification 2.
Hazard characterisation (evaluation health
effects ? dose-response relation) 3. Exposure
assessment (evaluation likely intake) 4. Risk
characterization (final risk expressed as a
probability) II. Risk management III. Risk
communication
12
Possible human factors affecting risk analysis
1
  • Societal - perceived risk of consumers and
    their reaction
  • - food production and processing
    infrastructure
  • - knowledge of food producers, processors,
  • traders, and consumers
  • - scientific and healthcare
    infrastructure
  • Biological - ability to quantify data (bias
    and precision)
  • - abiotic versus biotic approach
  • - medical versus ecological approach
    (exposure
  • and dose-response assessment versus
    microbial
  • cycles in ecosystems)

13
Conclusions
  • The general public is concerned about food
    safety
  • use of manure is perceived as risk
  • Conditions in organic production systems are
    different from conventional systems (a.o. animal
    feed and microbial communities)
  • Real risks need to be determined scientifically
    and
  • need to be distinguished from perceived
    risks
  • 4. Complacency and conceit are dangerous and
    must be avoided!!

14
Acknowledgements
1
- Alexander V. Semenov (jr.), MSc
student Experiment with P. fluorescens 32 gfp -
Eelco Franz, PhD student Literature review and
survival of E. coli O157H7 in manure
and soil - Dr. Anne van Diepeningen Literature
review, microbial diversity in soils,
survival of E. coli O157H7 in manure and soil
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