What material/metal is typically used under the layer of coating in 'ceramic' frying pans? I am looking at different ceramic frying pans, e.g. this lagostina one, but from reading the product description it is really hard to figure out what metal is the main body of the pan made of. For health reasons, I'm hoping to find one that uses steel rather than aluminum, but the manufacturers seem reluctant to explain it. Is there a general recommendation for how to find a ceramic pan that uses safe metals?
There is no material which is "typically" used. The ceramic coating works on different bases, and I have seen both aluminum pans and steel pans with it. There are probably other types too. 

If the manufacturer won't tell you what a given pan is made of, there is no way for anybody else to tell.