Risk of toxic poisoning
If you polish your nail with gel, then in that case it is best that you kick the nail-biting sooner rather than later. Regular nail polishes have plenty of toxins themselves, but gel polishes have chemicals that can be harmful when ingested.
Biting your nails increases the risk of infection and if the infection is bacterial, there may be plus-filled blisters at the site.
Nail biting is also bad for your pearly whites.