At my job they say to stay away from a man on erivedge (vismodegib) (that cancer medication) if u are pregnant or trying to become pregnant. how can it harm you?

Nonsense : As long as you don't steal his medicine from him and take it yourself it won't affect you. Also, at a cost of over $300/capsule he probably takes it at home and doesn't take it at work. I think it's great that your employer is letting him continue to work while he can. Don't shun him out of ignorance. Maybe you can be an example to your coworkers. Remember the hysteria at beginning of HIV.