I've been with my hamster for about 9 months and he tends to bite a lot so I'm afraid to let him on my hand. About 2 months ago, he started to bite the plastic wheel he has in his cage. I removed it and decided to let him exercise in a hamster ball so he doesn't bite plastic anymore. But now he's been biting the plastic litter box he has with sand in it. He has a wooden cube like thing already but stop biting it after he starts biting plastic. I need help and I'm afraid he might get sick from accidentally eating plastic. Thank you.