January 1998

Prevention of foodborne illness begins on the farm

Editor's Note: The following information is from the Agricultural Engineering Information Series AEIS #649. It was adapted by Roger Brook and Dan Guyer, Michigan State University Agricultural Engineering Department from a Cornell University fact sheet by Anu Rangarajan, Stephen Reiners, Marvin Pitts, Laura Pedersen and Anthony Shelton.

Outbreaks of foodborne illness are making headlines on a regular basis.
Hepatitis in strawberries, E coli in apple juice and lettuce and
Cyclosporeae in raspberries have shaken consumer confidence in the safety
of the food supply. As many as 30 million people contract some type of
foodborne illness each year - most cases are not diagnosed or reported, and
are probably just thought to be "stomach flu." However, up to 9,000 people
die from foodborne illness each year.

Fruits and vegetables may be harvested on a farm, processed in one plant,
repackaged in another and served by an institution or in the home. They may
be hand-harvested, stored and displayed in a store prior to home
preparation. Each of these steps is an opportunity for a pathogen to enter
the food supply.

How much foodborne illness originates on the farm? No one knows.

Are there reasonable steps that a grower can take to reduce the risk that a
pathogen will contaminate the food produced on the farm? Absolutely.

Clean Soil
The improper use of manure is a large risk factor contributing to foodborne
illness. Pathogens such as E. coli, Salmonella and Campylobacter can be
present in slurry and soil for up to three months, depending on temperature
and soil conditions. Troubling for growers is the fact that Listeria may
survive on vegetables growing in the soil, even though it may not survive
in the soil itself. Yersinia may survive, but not grow, in soil for up to
330 days. Composting manure, incorporating it prior to planting, and
avoiding top-dressing are important steps that can reduce the risk of
contamination while making use of this important source of nutrients.

Clean Water
Make sure that water used in overhead irrigation, produce cooling, washing,
dipping and processing operations is clean. Where possible, use chlorinated
water or groundwater. Surface water close to untreated sewage or a
livestock operation should be tested. (Contact your county Extension office
for water testing services, or look in the yellow pages of your phone book.)

Clean Hands
The failure of food handlers to wash their hands after using the restroom
or when infected with the hepatitis virus has been the cause of outbreaks
of foodborne illness as well. Attention should be paid to worker hygiene,
not only in the packing house, but in the field as well. Provide soap and
clean water in the field, and insist that all workers wash their hands
before handling fruits and vegetables.

The following checklist summarizes preventative measures for growers.


Minimizing Pathogen Contamination during Production of Fresh Vegetables and
Fruits

Pre-Plant Manure Source and Type
- Slurry: store for 60 days in summer or 90 days in winter prior to field
application.
- Fresh: incorporate into soil.
- Compost: most pathogens killed within days by high temperatures during
aerobic composting.

Manure Application Time
- Fall: preferably onto cover crop to minimize erosion and nutrient losses
- Spring: preferably onto agronomic rotation crop. If applied to vegetable
or fruit ground, incorporate.
- Do not harvest within 60 days of manure application.

Manure Incorporation
- Poor survivability of most pathogens in soils.

Crop Choice
- Avoid root and leafy crops in year manure is applied.
- Preferable to apply manures to agronomic rotation crop.
- Perennial crops: minimal risk with manure incorporation and harvest delay.

Production Irrigation Water Contamination
- Drip: minimizes risk since no direct crop wetting.
- Overhead/well water: minimal risk if wellcasing is maintained and
livestock excluded from pump areas.
- Overhead/surface water: consider water testing if downstream from
livestock operations or raw sewage.

Manure sidedressing
- Absolutely not fresh or slurry manure.
- Compost sidedressing: OK

Animal Exclusion
- No grazing of livestock (including poultry) during season of harvest.
- Minimize wild animal traffic, where possible.

Worker Hygiene
- Provide restrooms in field.
- Supply antibacterial soap and fresh water for hand washing and enforce use.

Harvest
Storage Facilities
- Clean and sanitize prior to harvest.

Bins and Containers
- High pressure wash and sanitize prior to harvest.
- Store bins in full sun (ultraviolet rays destroy several pathogens).
- No standing in bins during harvest.

Worker Hygiene
- Provide restroom facilities in the field.
- Supply antibacterial soap and fresh water for hand washing and enforce use.

U-Pick Operations
- Promote cleanliness: encourage customer hand washing prior to entering fields.
- Provide antibacterial soap for hand washing in field and in restrooms.
- Provide clean and convenient restrooms for customer use.

Drops and Damaged Produce
- Do not use decayed, damaged or wormy produce.

Post Harvest Worker Hygiene
- Provide restroom facilities in the field.
- Supply antibacterial soap and fresh water for hand washing and enforce use.

Washing and Packing Lines
- Use chlorinated wash water
- Monitor chlorine levels to maintain 100 ppm solution.

Packing House Sanitation
- Clean and sanitize packing areas daily
- Exclude all animals, especially rodents. No smoking or eating in packing areas.

Produce Cooling and Storage
- Cool product quickly to minimize growth of any potential pathogens.
- Store at appropriate temperatures to maintain product quality and minimize pathogen growth.