Magic Erasers wear rapidly and would release nanofibres into the air. It does not appear that there are any published toxicity studies on these fine melamine fibres. Being fine, they would not be unpleasant to inhale. How toxic is the dust?
Fibres
What you see is not what you get. The paper: Stayner, L., E. Kuempel, et al. (2008). “An epidemiological study of the role of chrysotile asbestos fibre dimensions in determining respiratory disease risk in exposed workers.” Occup Environ Med 65(9): 613-619.
Asbestos fibre size
It appears that the Australian Government is about to offer free ceiling insulation to thousands of homes. That fine when you want to keep the cool in with air conditioning or the warmth in with heating. However,
Another insulation myth
The “natural” insulation industry has done lot to frighten people about mineral and glass insulation