My handshower has a little green between the rubber and the steel...is it green rust? can it harm me? i am really worried

Not rust: Most likely a little fungus that is probably not harmful. You should be taking apart and cleaning your shower head on a regular basis using a little Clorox solution in water and an old toothbrush to get into the crevasse. Routine cleaning of a shower stall is a good habit to get into and should be done every few weeks in order to avoid problems.