That is not uncommon side effect. Too much silver in the bloodstream will turn you blue since the colloidal particals are too big to flush out of your system. Must be taken in very small doses but very effective!
The poor guy worked over-night (our whole building didn't have over-night shifts...but they made exception for him).
One night I was working REALLY late on a project, and he came up and asked me a question. I had never seen him before...luckily I didn't screech, or anything, but he must have seen the look in my eyes.