Harassment on the job (NON SEXUAL)

Could you sue your employer for not taking action against a group of harassing co workers?

My husband works for a large hospital as a surgical tech, there is a group of nurses that harass him daily. This is not in a sexual manner. He has been reprimanded for missing work which the only reason he is missing work is because the women are intolerable, they question things like his septic technique in non sterile surgery, try to place blame on him for missing or incorrectly marked specimens when he was not even working on them, and now the latest is these women got together over the weekend to call his boss to alert her of my husbands threat to "go postal" and commit suicide. Which was taken entirely out of context. Now he has been placed on addministrative (paid) leave pending a psych evaluation and investigation. He has brought the harassment to the attention of his boss several times. He has talked to his therapist on the matter as well. His boss even gave him a book on "How to work with the hard to work with co worker" that to me indicates that she knows there is something going on. Other than leave his job what should we do?

This article may be of some interest to you: Hostile Work Environment Harassment Lawyers