Cast iron has been around for thousands of years where cast aluminum is an historically new invention, since aluminum cookware has only been available since 1899.
Cast iron is praised for it's even heat which makes it perfect for use over open fire, either wood or gas.
Both Cast iron and cast aluminum are now made with a coating to provide not only a non-stick surface that needs no seasoning, but also to prevent metal from leaching into the food.
I have been around the web and I found a lot of good information on cookware at www.listentoyourgut.com (click on blog and search cookware) and a vote for "dead set against any ceramic utensils and coatings" at www.greenprophet.com.
In the kitchen, it is a crap shoot to guess if this is the chemical leaching that will kill us or teflon, or aluminum or arsenic or ....... WE now have known for some time that teflon is dangerous to ingest and it is being phased out of the market. Frankly, it isn't worth the high cost of investment in new cookware to experiment on new chemical risks, in my opinion.
Above, left is a photo of cast iron with a credit to the web page that reviews cast iron. I vote stick with what works. Learn to season a pot whether it comes coated or not. I vote....IRON!
Get rid of your old scratched teflon coated pots and pans and if you feel nanotechnology is a safe science, enjoy the very expensive pretty colored pots and pans!