Kitchen sponges are dirtier than toilets teeming with bacteria, researchers found. A group of researchers from the Faculty of Medical and Life Sciences, Institute of Precision Medicine (IPM), Microbiology and Hygiene Group, Furtwangen University in Germany conducted DNA analysis of 14 different kitchen sponges. The researchers said their study revealed "an amazing bacterial colonization of kitchen sponges, and visualized its extent for this common microbial hot spot for the first time."
Since sponges are moist almost all of the time and are made for absorption, they tend to pick up bacteria such as E. coli, salmonella and Staphylococcus when they are used to clean dishes, swab counters, or merely from hands touching them. The study stated, “Kitchen sponges are likely to collect, incubate and spread bacteria from and back onto kitchen surfaces, from where they might eventually find their way into the human body, e.g. via the human hands or contaminated food.”
The analysis revealed 362 different kinds of bacteria in the sponges. They discovered 118 genera of bacteria, most of which were not harmful. However, there were pathogens that could cause infections among humans. Sponges are also capable of spreading bacteria in places where it was not previously present.
The recommended ways to clean sponges thoroughly include microwaving them for a minute, soaking them in a bleach solution using hydrogen peroxide, ammonia, vinegar or isopropyl alcohol. All of these are said to kill at least 99.9% of bacteria. However, the researchers found that microwaving sponges does not kill all of the potentially harmful bacteria, and any sterilizing method only reduces bacteria content by 60%.
The study said, despite common misconception, it was demonstrated that kitchen environments host more microbes than toilets. Sponges are “the biggest reservoirs of active bacteria in the whole house,” the study said.
While most of the bacteria present are not harmful, there were pathogens that could lead to certain infections in humans. Sponges are also able to spread bacteria to other clean places.
Some bacteria are actually able to resist sanitation and increase instead of dying out. The best thing to do is to change kitchen sponges weekly to avoid contamination, the study concluded.
