Over a quarter of household dishcloths contain e.coli and one in seven are carrying listeria, research by Safefood has found.
Safefood unveiled the statistics as part of a new campaign aimed at making consumers more aware of how everyday kitchen habits could cause food poisoning.
It based its research on a study of 200 dishcloths.
"The dishcloth is a familiar sight in almost every kitchen in Ireland, but if not cleaned properly can be a source of food poisoning — especially if used to wipe worktops where we prepare raw meat, poultry and vegetables," Dr Gary Kearney, director of food science at Safefood said.
"A damp dishcloth can serve as a breeding ground for bacteria, especially if we leave it folded overnight to dry. Using it again before properly cleaning means bacteria can spread to other surfaces in the kitchen."
The four main types of dishcloth identified in the research as being used by consumers were cloth (34%), sponge (19%), "J cloth" (16%), and micro-fibre cloth (15%).
They represent over 80% of the dishcloth types most commonly used.
The researchers found a third (32%) of consumers who re-use dishcloths clean them in bleach and almost one-in-four (23%) wash them by hand.
But it said neither method was effective at removing the germs that can cause food poisoning.
"Our research found that washing kitchen dishcloths in a washing machine or boiling them in water for 15 minutes was the most effective way to properly clean them," said Dr David McCleary, chief specialist in microbiology.
"Ideally, we should also wash dishcloths every two days. If you’ve used a dishcloth to wipe up after raw meat, poultry or vegetables, then you should replace it immediately with a clean one. And if there’s a noticeable smell from your dishcloth, then it’s definitely time to change it."
Of those surveyed, about 40% threw out dishcloths instead of washing them for re-use, but 20% kept dishcloths for at least two weeks before disposing of them.