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What darkness lives inside household appliances?

Researchers discover in dishwashers a high prevalence of fungi, which present potential health risks and can survive extreme heat and salt concentrations.

We've all opened a household appliance--maybe a dishwasher, washing machine, or coffee maker--and winced at the ensuing smell.

This almost-new dishwasher may look clean... Elizabeth Armstrong Moore

The funk, according to new research published in the British Mycological Society journal Fungal Biology, comes in the form of various types of fungi that are frequently found to be an agent of human disease in compromised and healthy individuals alike.

"This is such a new thing that we have few tips," Nina Gunde-Cimerman, a professor at the University of Ljubljana in Slovenia, said in an e-mail. "A thorough heating at high temperatures would probably be beneficial, although it would not permanently remove or destroy them."

Out of a sample of a few hundred private homes in 101 cities on six continents, Gunde-Cimerman said, a whopping 62 percent of dishwashers alone contain fungi on the rubber band, 56 percent of which accommodate the polyextremotolerant black yeasts Exophiala dermatitidis and its cousin, E. phaeomuriformis.

What's new is that these fungi are able to survive heat, high salt concentrations, aggressive detergents, and both acid and alkaline water. The researchers say this range of durability has not been observed in fungi until now.

The researchers say the widespread presence of what they call "extremophilic" fungi in our homes (yet rare in nature) suggests that the organisms have "embarked on an extraordinary evolutionary process that could pose a significant risk to human health in the future."

Next up: determine the best ways to get rid of the fungi. In the meantime, those rubber strips in the doors of dishwashers and washing machines seem to be the most common host. Let's hope a replacement material exists that won't be so friendly to the invaders.