Stachybotrys chartarum (also known as Stachybotrys atra) is a greenish-black mold that can grow on materials such as drywall or sheetrock, ceiling tiles and wood when they become moist or water-damaged. Not all greenish-black molds are Stachybotrys chartarum. Some strains of Stachybotrys chartarum may produce mycotoxins. Whether a mold produces mycotoxins depends on what the mold is growing on and conditions such as temperature, pH, humidity or other factors. When mycotoxins are present, they occur in both living and dead mold spores, and may be present in materials that have become contaminated with molds. While Stachybotrys is growing, a wet slime layer covers its spores, preventing them from becoming airborne. When the mold dies and dries up, air currents or physical handling can cause spores to become airborne.
Currently, there is no test to determine whether Stachybotrys growth found in buildings is producing toxins. There is also no blood or urine test that can tell if an individual has been exposed to Stachybotrys chartarum spores or its toxins.