Calphalon anodized aluminum cookware is considered safe for food preparation. The anodization process hardens the aluminum and prevents it from reacting with acidic foods and becoming toxic.
Aluminum is not naturally harmful. It's used for food storage and is found in many ubiquitous items such as deodorant, toothpaste, antacids and infant formula. However, it can react to acids and discolor and transfer metallic flavors to the food.
Anodized aluminum is submerged in an acid bath and shocked with electrical current. This forces the surface of the aluminum to form aluminum oxide, which is stronger and more resilient than native aluminum. It will not chip or peel and is not damaged by high heat.