Interesting you say this, who apart from people selling creatine and those regurgitating the spiel on the back of the creatine label recommends 5-10 grams per day?? Who came up with that figure considering almost no person alive on this planet would eat enough meat/fish etc to even go close to this imaginary requirement?
So I can only come up with two possible scenarios:
1) Pretty much every person that has ever lived on this planet would have spend their whole life living in a creatine deficient state.
2) We don't really need 5-10 grams of creatine a day.
Applying common sense I would say the second one applies here, and that this figure of imaginary creatine requirement was created so that we can get money out of gullible people's pockets looking for the magic pill.
No you can't.
People have not been ingesting this stuff long enough to see if it's 1/100,000 or 1/10 that will develop issues down the road, only time will tell, it's still early days, people once though smoking was safe as well till the long term effects started to show through.