Wallpaper can be a breeding ground for toxic moulds, study shows

Is wallpaper toxic? In a new study, scientists have discovered that toxic fungi can grow on wallpaper and become airborne, impacting human health and potentially leading to problems such as sick building syndrome.

Researchers at the National Veterinary School of Toulouse in France applied spore suspensions from three fungal species to wallpapered surfaces and then tested to see how readily the spores became airborne when humidified air was blown across them. It turned out that the three types of spores were all able to lift off and become airborne and, importantly, spread harmful mycotoxins which can be inhaled and produce both chronic and acute conditions.

“The propensity to aerosolization differed according to the fungal species,” say the study’s authors, whose research is published in the journal Applied and Environmental Microbiology. “In this study, we demonstrated that three different toxinogenic species produce mycotoxins during their development on wallpaper. These toxins can subsequently be aerosolized, at least partly, from mouldy material.”

The findings are said to contribute to understanding what appears to be a growing phenomenon worldwide — mycotoxin exposure in mouldy homes. In the late 90s, a study conducted in the United States found that fungal toxic metabolites were causing pulmonary haemorrhages in infants, and mycotoxins have been implicated in the rise of what’s known as sick building syndrome, a collection of ailments running from headaches and dizziness to skin problems, swelling and fatigue which are thought to be brought about due to poor air quality in buildings (often office buildings where people spend a good portion of their time).

Ironically, sick building syndrome has been associated with energy efficient houses and buildings, where structures are built air-tight to keep out drafts and keep in the heat, the side-effect being a less-healthy circulation of air from inside to outside. The problem is thought to affect between 30 and 50 per cent of new or refurbished buildings.

As an example, renovation to the Alberta Court of Appeal building in Calgary turned out badly when judges and attorneys started to complain of fatigue, irritated lungs and watery eyes. “They couldn’t figure out what was wrong,” said Tang Lee, a professor of architecture in the Faculty of Environmental Design at the University of Calgary. Investigators found mould growing inside the air-tight walls which served as moisture traps and the building was shut down in 2001.

The new research has already led to some false reporting, however, as some news outlets have picked up on a quote from one of the study’s authors who suggested that kettles and coffee makers could produce the humidified air in much the same way as his team did in the experiment. “Coffee makers are just an example of a machine that may release steam indoors and increase the water and humidity that may help fungi to grow,” said study co-author Dr. Jean-Denis Bailly of the Université de Toulouse.

Unfortunately, news sources like the Mail Online and the Sun UK spun their stories to read as if kettles and coffee machines were themselves a potential threat (saying that “making a cup of coffee in the morning adds to household damp, creating fungus which grows often unseen on our walls”) whereas the research did not test the effects of these or other appliances.

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