The Unexamined Life

Keep It Little ‘Germy’: Clean House Is Not Always Healthy, Study Finds

Cleaning your house may allow some unwanted organisms to join you in the kitchen, shower and other areas. That is according to a new study that found cleaning products could wipe out friendly microbes and allow potentially harmful fungi to spread around your place. 

Researchers analyzed the microorganisms present in rural and urban homes in Peru and Brazil, and the cleaning activities of owners. They said many antibacterial cleaning products only target bacteria, which should prevent other kinds of microbes from forming in certain areas of the house, NPR reported Wednesday

"We expected that all the microbes would actually become less diverse with urbanization, and that's not at all what we found for the fungi," Laura-Isobel McCall, a biochemist at the University of Oklahoma, said. "Maybe they're scrubbing away all the bacteria and now you have this big open surface for fungi to grow on; maybe [the fungi] are also becoming more resistant to the cleaning agents that we use."

The researchers took samples of microbes from four locations, including thatched huts and city apartments. Samples came from indoor surfaces, such as walls, floors and countertops, and skin swabs from pets and people.

After collecting microbes, the researchers then analyzed chemicals inside the homes. Results showed that urban lifestyles have been killing friendly bacteria and providing more space for fungi. 

The findings, published in the journal Nature Microbiology, suggest that one factor that allows fungus to grow in clean houses is the lack of natural light inside. Urban houses also have less space, which traps carbon dioxide (CO2). 

Blocking the sunlight and the high levels of CO2 inside the house create hospitable environments for fungi. Fungi are harder to kill with household cleaning products because of their thick cell walls.

A genus of fungi, called Malassezia, was found in some of the urban homes. They have been linked to infections in hospitals in other countries.

"My guess is that this gradient they've established for these fungal communities is largely representative of what's happening all over the world," Justin Sonnenburg, a microbiologist at Stanford University and not associated with the study, said. 

Cleaning house A new study found that a clean house may allow fungi to form and spread in certain areas. Pixabay