The claim has appeared in TV commercials for Reckitt Benckiser's kitchen cleaning product, Dettol Surface Cleanser, in a campaign created by Euro RSCG London.
The latest campaign to carry the claim attracted three complaints, which challenged whether the claim could be substantiated.
In the ad, a voice-over makes the claim alongside a grim looking toilet seat, which has been dressed to resemble a chopping board, with pieces of fruit and a knife.
The claim was based on a 2004 study, in which five households in Hertfordshire were surveyed.
The results of the survey revealed that the chopping boards in the households contained a higher number of living micro-organisms on the surface than the toilet seats in the same households.
RB said that raw foods, and in particular raw meats, were a proven source of food borne pathogens such as Salmonella and Camplyobacter.
However, the Advertising Standards Authority considered five households in one area a very small sample, and as many of the households had children under three years of age the survey was not representative of the average household in the UK.
It then turned its attention to the bacteria found in the survey, which it concluded "did not pose a risk to health" and as such did not present robust evidence to support the claim in the ad.
The watchdog also noted that four out of the five chopping boards tested in the survey were either grubby or dirty and it was unclear whether they had been cleaned.
The ASA has imposed a ban on the ad, concluding that it "misleadingly exaggerated the dangers posed by the bacteria on the chopping board".