mother in law is a cardboard box horder has 40 year old boxs that have been wet

my name is Robert. There are over 500 hundred old boxs that have been wet, cat pissed on , dusty boxes. A lot of them full of junk and 100 of them, different sizes. Honeycomb boxes,straight cardboard and some glossy ink printed boxes. They are all stacked through out the house. Alot of them are empty.She is 80 years old and no changing her mind about getting rid of them. To her they all serve a purpose. It would emotionally destroy her to get rid of them. I tried to talk to her her about at least downsizing a lot of them to no avail.. despite the obvious fire hazards what kind of health issues are these boxes threatening us with ?? We have 3 adults and 3 children ages 15, 17 and 22 all living in the house.  What kind of health problems now and in the future can we expect ??