Chewing any plastic item can be harmful.It can cause intestinal blockages,not to mention any other potential health risks
It definitely is a concern and must be taken seriously.
As far as the 9 inch Silent Runner openings being too large for a robo,that is very much opinion based but I'd consider it incorrect.Their diameter is approximately 2.75 inches,which is hardly too large for a robo!Plenty members use that wheel successfully for robos and Chinese
