Water, Contaminants and Flooding

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Water, Contaminants and Flooding
John Strang University of Kentucky
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• Water destined for agricultural production can
  easily get contaminated with human and/or animal
  feces by direct or indirect routes.

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Sources of Contamination1 Water

• Anytime water comes in contact with fresh
  produce, the waters quality determines the
  potential for pathogen contamination, since water
  may be a carrier of a number of types of
  microorganisms.

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Water Carries Pathogens

• E. coli 0157H7 viewed primarily as a water-borne
  pathogen.
• Many outbreaks associated with recreational
  water.
• Salmonella, Giardia and Cyclospora outbreaks on
  produce caused by contaminated water.

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Agricultural Water

• Usually, water for agricultural uses comes from
• Surface sources such as rivers, streams,
  irrigation ditches, ponds, and canals
• Reservoirs (open or capped)
• Municipal water systems

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If you use surface water

• Test water quarterly for fecal coliforms and keep
  records of all water test results.

• Take a close look at where your water lies in
  relation to potential sources of contaminants.

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Ground water may be contaminated by a variety of
biological and chemical hazards, which include

• Bacteria and viruses
• Domestic waste
• Nitrate nitrogen
• Synthetic organic chemicals
• Heavy metals
• Petroleum residues
• Combustion products from roadways

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Spray Water Quality

• Use potable (drinking) water for pesticide
  sprays.
• When potable water is not available, test water
  quality and keep records.
• Low water volumes reduce risk.

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Flooding

• Crops in close proximity to soil can easily be
  contaminated by direct contact with flood waters.
• FDA considers ready-to eat crops (such as leafy
  greens and melons) that have contacted flood
  water to be adulterated.

• These crops are to be excluded from the food
  supply.

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Flooding

• Consider potential contamination of crops from
  agricultural run-off (i.e. manure piles, etc.)
• Prevent cross-contamination by (equipment or
  humans) from flooded areas to non-flooded areas
• Allow flooded soils to dry sufficiently and be
  reworked prior to planting additional crops

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If you have any concerns about your water

• Microbiological testing is used in the
  verification steps of a safety assurance program.
  It is important to document the frequency and
  results of each water test for comparison
  purposes. These records would become very
  important in the event of a microbiological
  outbreak investigation.

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Recommended Draft Guidelines on Water Testing for
The Produce Industry

• Preharvest/harvest water that contacts EDIBLE
  portions of the produce (i.e., water used
  exclusively for irrigation and/or in pesticide
  sprays for products such as lettuce and other
  leafy greens.)
• Generic E. Coli lt235 cfu/100 ml sample of
  generic E. Coli for a single sample or lt126
  cfu/100 ml sample geometric mean.
• Where surface water is used for irrigation,
  monthly tests are recommended minimum frequency.

Colony forming units
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Recommended Draft Guidelines on Water Testing for
The Produce Industry

• Preharvest/harvest water that DOES NOT contact
  edible portions of the produce (such as
  irrigation water for melons, apples, etc.) such
  as that used in drip or furrow irrigation.
• Generic E. Coli lt576 cfu/100 ml sample of
  generic E. Coli for a single sample or lt126
  cfu/100 ml sample geometric mean.
• Where surface water is used for irrigation,
  monthly tests are recommended minimum frequency

Colony forming units
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Recommended Draft Guidelines on Water Testing for
The Produce Industry

• Post Harvest Water, such as that used by
  processors or on-site sampling and cutting
  /processing.
• Water must meet standards for potable (drinking)
  water.

Note The Ky. public beach microbial standard is
130 cfu generic E. Coli/100ml sample on a single
sample.
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If Tests of Preharvest/Harvest Water are Found
to Exceed Recommendations

• Consider an alternative water source.
• Investigate what is causing the elevated
  microbial counts.
• Have irrigated crops tested for common human
  pathogens (E. Coli, salmonella etc.).

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Water Source Will Determine the Possible
Frequency of Testing
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Chlorine required to dose 100 ft (30 meters) of
water-filled casing at 50 mg/L (ppm)
1 Commercial brands include HTH,
Perchloron, Pittchlor, etc. 2 Commercial
house hold bleaches such as Chlorox, Purex, etc.
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Chlorination

• Everything that is harvested does not need to be
  sanitized or chlorinated!
• The need depends on how the produce will be
  marketed.

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Postharvest Processing Water
Singular critical control point capable of
amplifying an error in sanitation or hygiene
management
Suslow, UC Davis
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The Problem with Water Handling Systems

• Produce from the field usually harbors many
  pathogens (including dirty and decaying produce).
• Postharvest handling of fruits vegetables often
  includes cooling using water and washing.
• Pathogens can quickly accumulate in these water
  sources and contaminate healthy fruit.

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Wash Water Quality

• Use potable water for all produce washing,
  cooling, dipping, icing, and processing.
• Avoid water temperatures in dump tanks that are
  more than 10F cooler than produce.

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Bacteria can enter the stem scar with improper
handling or wash water management
Fruit pulp must be lt 10oF warmer than water
temperature to prevent infiltration.
Warm fruit contracts in cold water pulling water
and microbes into the fruit.