Can I use a vintage Canon Program Flash on a nikon?

I have a Canon Program with a flash attached, it fits on my Nikon D3000 and works, but someone mentioned that it could damage my nikon? Is this true?

Added (1). My dilemma is that I have an important assignment on the 19th, and because of an error through ebay I will not have the designated flash in time.

If the trigger voltage is too high or you use a borderline dangerous voltage for too long, it will eventually fry the electronics.

Get a camera flash made for your D3000.It's safer

Would you rather risk destroying your precious dSLR for something you could avoid by getting cheap but compatible alternative?