Publicity about illnesses due to E.coli 0157:H7 has made people more aware of the potential risk of foodborne illness from manure contamination. As a result, many are now asking whether it is safe to use manure on their gardens.
In August 1993, The Lancet Medical Journal reported on a small E.coli 0157:H7 outbreak that appeared to be the result of manure applications to a garden. The gardener ate eggs and milk products, but no meat, and her diet relied heavily on vegetables from her garden. She fertilized the garden all summer with manure from her cow and calf. No E.coli 0157:H7 bacteria were isolated from fecal samples taken from the cow and calf; however, the animals did have antibody counts for the pathogen, suggesting they had been previously infected. E.coli 0157:H7 was isolated from the manured garden soil.
So, how risky is the use of manure in gardens and compost piles? If you use fresh manure in the garden, there is a small risk that pathogens which cause disease may contaminate garden vegetables. The risk is greatest for root crops, like radishes and carrots, and leafy vegetables, such as lettuce, where the edible part touches the soil. Careful washing and/or peeling will remove most of the pathogens responsible for the disease. Thorough cooking is even more effective.
To reduce the risk of disease, we suggest these precautions: