Every night, my cat heads out and comes home with 4-5 big chunks of insulation. It started about 7 months ago after she found a nest of mice living in insulation. Now I think she brings it to me as a gift. She shows up looking like she has a giant cotton candy in her mouth. I'm worried about the insulation she gets in her mouth and digestive tract. I'm not sure if there's any way to train her to change her behavior other than not letting her out. That drives her (and then me) crazy.
Thoughts: I would find the source of the insulation and clean it up. If it's on someone else's property, approach them and explain the issue. It needs to be covered securely or bagged and disposed of properly. Take it to a recycler in your area.
Her breathing the fiberglass particles, ingesting residue left on her fur when she grooms is very toxic and dangerous to her and your health.
When she comes inside, she is depositing these tiny particles everywhere she goes. Once they get in your lungs, they are there forever doing damage.
Hazards: It is important for InterNACHI inspectors to understand the health risks associated with exposure to fiberglass insulation. These risks are not, at present, fully understood or agreed upon, but it is generally accepted that, in certain situations, it has the potential to cause physical harm. Small particles that come into contact with skin can lodge in pores and cause itchiness, rashes and irritation. When inhaled, particles can cause coughing, nosebleeds, and other respiratory ailments. Very fine airborne particles are capable of becoming deeply lodged in the lungs and are believed by many to cause cancer and other serious afflictions. OSHA considers this threat to be serious enough that it requires fiberglass insulation to carry a cancer warning label.