Tan was one of eight participants in a study at the Republic Polytechnic laboratory in Singapore. She washed her towel every three to four times a week. Some other towels in the study, washed only when they smelled, contained numerous bacteria, mold, and yeast.
A Republic Polytechnic survey of 1,200 people found that 11% changed their towels monthly or less, 14% every two weeks, and 50% weekly. Frequency, however, is only part of the issue. 43% admitted storing their towels in damp, poorly ventilated bathrooms.
"We have natural bacteria, and shampoo or soap doesn't eliminate all of it," explained James Ho, a professor of science and the environment at Nanyang Technological University. "Bacteria cling to towels and multiply."
Unwashed towels can harbor Pseudomonas, a bacterium that causes skin infections like folliculitis (inflammation of hair follicles) in hot tubs and green nail syndrome. This bacteria can enter the respiratory tract or bloodstream, leading to more severe infections.
People with compromised skin barriers, such as those with eczema or atopic dermatitis, young children, the elderly, and those with weakened immune systems are more susceptible to infection. Sharing towels between the face and body can spread Escherichia coli bacteria to the face.
Damp towels can also breed mold, which can cause allergies or skin irritation. Yeast can cause infections such as candidiasis (a fungal infection), common in infants and adults who wear diapers. In individuals with weakened immune systems, yeast can affect the mouth.
Ho noted that frequently used towels accumulate bacteria and fungi because they struggle to dry between uses. Washing frequency is crucial; towels washed every three to four days harbor fewer bacteria.
The American Cleaning Institute recommends washing bath towels after three to five uses. However, if a towel comes into contact with bodily fluids or if the user has sensitive skin or a weakened immune system, it should be washed after each use to reduce the risk of infection.
Fluctuating temperatures also promote microorganism growth. Mold thrives between 16 and 26 degrees Celsius, while yeast prefers higher temperatures. Cycling air conditioning creates a favorable environment for bacteria and fungi. Only 8% of survey respondents dried their towels outdoors, despite sunlight being an effective natural disinfectant.
Towel material also influences bacterial growth. Cotton towels are absorbent but slow to dry, promoting bacterial proliferation. Microfiber towels are better, while bamboo towels retain fewer bacteria and only some fungi. Antibacterial towels are effective but don't completely eliminate microorganisms.
Ngoc Ngan (via CNA)
