My field placement was with the severe and persistently mentally ill. None of them were violent or dangerous, though some of them had histories of being violent and dangerous to themselves or others. If you enter a situation that you are uncomfortable with and feel like you are putting yourself in harm's way, say one of the persons made you extremely uncomfortable and you felt they were going to inflict harm on themselves or you, I would cancel with the person and bring this issue up with your field supervisor. I had to do plenty of home visits at my field placement and was always encouraged to cancel with a person if I felt the environment was not safe. We do important work, but don't feel like you have to do something that you feel is dangerous.