Why the “toxic” label matters less than the cause
"Toxic mold" is a popular phrase, not a precise scientific term. It usually refers to molds that can produce substances called mycotoxins. The label sounds alarming, but the practical point is straightforward: significant indoor mold should be fixed, whatever it is called.
Some molds can release compounds that may affect health under certain conditions, which is where the "toxic" nickname comes from. In everyday terms, though, you do not need to identify a specific "toxic" species to have a real problem. What matters is that mold is growing indoors because of moisture that should not be there.
Chasing the exact type can actually distract from the real issue — the leak or dampness behind the growth. Fixing that source is what stops the mold from coming back. If mold in your home is serious and your landlord is focused on debating the type instead of repairing the cause, it may help to get guidance about your rights.
This is general information about California tenant rights, not legal advice. Every situation is different.