We've know for a long time that wallpaper can be dangerous:
Scheele's Green was a colouring pigment that had been used in fabrics and wallpapers from around 1770. It was named after the Swedish chemist Scheele who invented it. The pigment was easy to make, and was a bright green colour. But Scheele's Green was copper arsenite. And under certain circumstances it could be deadly. Gosio discovered that if wallpaper containing Scheele's Green became damp, and then became mouldy (this was in the days of animal glues) the mould could carry out a neat chemical trick to get rid of the copper arsenite. It converted it to a vapour form of arsenic. Normally a mixture of arsine, dimethyl and trimethyl arsine. This vapour was very poisonous indeed. Breathe in enough of the vapour, and you would go down with a nasty case of arsenic poisoning.This, some say, was what killed Napoleon.
Anyway - and you'll note the role of mould in making this nasty wallpaper effect happen - to bring the story up to date:
In laboratory tests, "we demonstrated that mycotoxins could be transferred from a mouldy material to air, under conditions that may be encountered in buildings," said study corresponding author Dr Jean-Denis Bailly.'Sick building syndrome' has been blamed on lots of things but it does seem there's some mileage in blaming the wallpaper (or indeed any mouldy material knocking about). More worrying is the associated evidence that our enthusiasm for energy-efficiency and hermetically sealed environments makes matters worse;
"Thus, mycotoxins can be inhaled and should be investigated as parameters of indoor air quality, especially in homes with visible fungal contamination," added Bailly, a professor of food hygiene at the National Veterinary School of Toulouse, France.
The study was published in Applied and Environmental Microbiology, a journal of the American Society for Microbiology. Creating an increasingly energy-efficient home may aggravate the problem, Bailly and his colleagues said.
Such homes "are strongly isolated from the outside to save energy", but various water-using appliances such as coffee makers "could lead to favourable conditions for fungal growth", Bailly explained in a society news release.