If you use manure in your garden, take precautions

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Last Updated: 
February 19, 2003

Recent food poisoning outbreaks have been traced to fruits and vegetables eaten raw. Sprouts, lettuce, cabbage, tomatoes and melons have all been involved in isolated outbreaks, explained Carolyn Raab, food and nutrition specialist with the Oregon State University Extension Service.

"The sources of contamination included manure, irrigation water, ice, unsanitary human handling, harvesting equipment or transport vehicles," said Raab.

Home gardeners should be aware that if they grow their produce in soil amended with unsterilized animal manure, they may expose their families to pathogens, microorganisms which may cause disease.

Microorganisms which have been linked to manure applications include bacteria such as Listeria, Salmonella and E. coli 0157:H7. Parasites found in manure include roundworms and tapeworms. These hazards can be avoided by home gardeners with a little common sense and care, said Raab.

If you use unsterilized manure to amend your soil, you should be especially careful when washing garden produce that has had direct contact with soil or irrigation water. Carrots, onions, lettuce, radishes, and other crops eaten raw should be especially well washed. Peeling vegetables also helps insure your produce is safe.

"It is better to be safe than sorry," said Raab. "To reduce health risks, wash all fruits and vegetables thoroughly under running water before eating them. Use a vegetable brush to remove visible soil."

"Safe handling is particularly important when fruits and vegetables will be eaten by people who are more prone to get food poisoning," she said. "Young children, pregnant women, older adults and those with cancers, AIDS and other illnesses that affect the immune system are more susceptible than others."

If a family member is at higher risk, Raab recommends serving cooked or canned vegetables and fruits for an extra margin of safety. Heating kills bacteria and parasites. But don't go overboard with soap, as the residues can be harmful.

To lower your risk from soil-borne pathogens:

  • Apply manure at least 60 days before harvesting any garden vegetables to be eaten raw. Fall is the best time to amend soil with manure; it allows enough time for breakdown of pathogens before spring planting.
  • Never apply manure after root crops or to produce that comes in contact with the soil is planted.
  • Do not use dog, cat or pig manures in gardens or compost piles because pathogens or parasites may survive and remain infectious to people.
Author: Carol Savonen
Source: Carolyn Raab