Copper Bracelets for arthritis?

Hi,
i asked a question before about copper bracelets which are claimed to be good for Arthritis and other things. You wear them and it seeps into the skin. Are they actually bad for you? I used to wear one for probably a good while, maybe a year, when i was about sixteen, six years ago. I actually stopped wearing it because i started getting spots on the green stuff,
Regards
Brian