Is black mold bad for you if it is in your walls?

I rent a house and a plumber came to fix the toilet and there had been a leak from using a wrong piece meant for outside irrigation plumbing, so it has been leaking water there at least a year.
He and I found the insulation in the wall was black and there is black mold in the wall. I live in California
Update: I know black mold is bad for you. My question is does it have to be in direct contact with the air in the room for it to harm you or will it harm you if it is in the walls. My whole house has carpet flooring including the bathroom. The bathroom does not have a window that opens as well, so there is no way to bring... show more I know black mold is bad for you. My question is does it have to be in direct contact with the air in the room for it to harm you or will it harm you if it is in the walls. My whole house has carpet flooring including the bathroom. The bathroom does not have a window that opens as well, so there is no way to bring in fresh air
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