The cans used for food packaging are made of tinplate or aluminium. Canning methods mean that some metal naturally dissolves into food, yet there's strong evidence to suggest that there's no significant level of toxicity for human consumption.
Tin has no known natural biological role in living organisms. It is not easily absorbed by animals and humans. The low toxicity is relevant to the widespread use of tin in dinnerware and canned food. Organotin compounds can be very toxic.