If you're talking about "rolled" copper tubing that you can buy at Lowe's or HD then that is what you are looking for as an IC. Either 3/8" or 1/2" will work. As far as being detrimental to brewing or your health? Such a small amount is leeched out when brewing. Not sure if this is detremental to the yeast or not. I've been using a copper IC for a couple of years now and have not had any problems with fermentation.
The other compound that you would be concerned about is using a lead based solder if you sweat copper fittings. DON"T use lead based alloys for sweating copper fittings.
BTW copper has been used as a bacterialcide and algaecide for years.
Here's a link: ATSDR - ToxFAQs™: Copper