PFA chief executive Gordon Taylor is concerned for the career of Liverpool striker Luis Suarez.
Suarez, twice convicted of biting earlier in his career, on Tuesday night appeared to bite Italy defender Giorgio Chiellini during Uruguay's defeat of Italy and faces a lengthy ban.
"It was just so disappointing, really," Taylor told BBC Radio 5live.
"I've been disappointed about England, but doubly disappointing when our player of the year, the Footballer Writers' player of the year and last season I thought he'd got himself back on track.
"We felt these were issues he had and offered counselling with regard to anger management.
"We've seen the best of him and that other side in just two games over in Brazil.
"Issues with regard to biting is something not normally associated with senior players in the game.
"It can't be acceptable and from that point of view there are serious issues to be dealt with and they're health issues, counselling issues, mental health issues.
"It certainly needs that to try to eradicate this from his make-up, otherwise I fear for his career."
