Cookware
When acidic foods are cooked in unlined copper cookware, or in lined cookware where the lining has worn through, toxic amounts of copper can leach into the foods being cooked. This effect is exacerbated if the copper has corroded, creating reactive salts. Actual cooking may not be required for copper to leach into acidic liquids if they are stored in copper for a period of time. Many countries and states prohibit or restrict the sale of unlined copper cookware.
Read more about this topic: Copper Toxicity