Cans are not made to be cooking containers

Factiva: "McCarty concedes that some cans are indeed heated during the packing process. 'But that isn't all cans or all foods, and it is a carefully controlled and monitored process done in an environment that is made to do it.'

As for what metals may be leaching into your canned food, it depends. In the United States, most food cans are made of steel while beverage cans are usually made out of aluminum. Chromium and nickel can find their way out of steel, but the amounts would be miniscule to nil."