Hard anodized aluminum cookware is made of aluminum bathed in acid solution, then exposed to an electric current. A layer of aluminum oxide is deposited on the surface, thus anodization occurs. Cookware that is anodized has a very hard surface that is corrosion resistant and durable. Commonly referred to as hard anodized aluminum, Calphalon is a well-known brand of hard anodized cookware. Because anodized products contain aluminum, a few questions have been raised about health warnings of hard anodized aluminum cookware.
In 2007, Helen Suh MacIntosh, a professor in environmental health at Harvard, citing a study by Clemson University, states that while it is true that foods cooked at high temperature in aluminum can leach aluminum into acidic foods, "This leaching of aluminum with acidic foods does not happen with aluminum cookware that is anodized, or electro-chemically processed to seal the aluminum in the cookware."
The misunderstanding about anodized aluminum cookware stems from the fact that simple aluminum cookware can indeed cause aluminum to leach into foods. As MacIntosh states, "Most exposures to aluminum occur through ingestion or eating and drinking, with daily intakes generally low, averaging between 30 to 50 mg. For the typical person, drinking water, medicines and other pharmaceuticals (such as antacids and antiperspirants) are the biggest contributors to aluminum exposures; however, aluminum cookware is also a potential source."
Research by Clemson University, and analysis by Harvard professor Helen Suh MacIntosh, conclude that anodized cookware does not create a health warning. By its very nature, anodized cookware is meant to prevent aluminum infiltration.