In the mold remediation industry, the primary focus in regard to potentially harmful health effects, has historically been centered around mold colonies and the spores they release
into the building environment, and that may well be a valid concern.
Let us assume we have an environment that has visible mold growth (black or otherwise). Perhaps joined with some type of air quality testing that indicates an elevated level of mold spores. Now, let us further suppose under those conditions that we also have building occupants that are experiencing negative health effects, perhaps severely so. Imagine this happening repeatedly throughout the years, to more and more people. It would be understandable to conclude that the mold (cause) is the menace creating the health problem (effect).