Is spalted maple food safe?
I'm going to make a couple of cutting boards for family members. Is it safe to use spalted maple where food will be prepared?
—Scott Fleming, Barrie, Ont.
Great question, Scott. The dark lines prized in spalted wood are caused by white rot fungus. What the fungus adds in beauty, however, it takes away in hardness, leaving behind soft, punky areas. So right away we'd advise against using it for cutting boards.
What about for kitchen items, such as spoons, bowls, and platters? Because sawdust from spalted wood has been known to cause severe respiratory or skin reactions, many woodworkers know to take extra precautions, such as supplementing a dust-collection system with a properly fitted dust mask, when working with it.
But does the danger carry over into contact with food items where particles from the wood could be ingested? According to Tom Harrington, professor of plant pathology at Iowa State University, the white rot fungus, Hypoxylon deusta, that most commonly causes spalting is not toxic. The fungus lives on the outside of the tree and sends tendrils called hyphae into the wood to break down the plant and gather nourishment. To protect themselves and their rotting food source, these tendrils produce a protein coating that creates the black lines in the wood and likely causes the allergic reaction and irritation when it becomes airborne and lodges in your lungs.
Once your wood bowl is complete, however, the danger from airborne protein subsides. "If you ingest it, it's just going to get digested like all the other proteins that you eat," says Harrington.