Aluminum metal does not naturally occur; it has to be manufactured from ores containing aluminum (bauxite) using electrolysis, which consumes a lot of energy. This means that aluminum is a relatively “new” metal, and aluminum foil, in particular, was only invented in 1910. It takes a while for ANY new invention to reveal its bad effects, especially if the effects are benign or only manifest slowly.
The worst conjecture regarding aluminum toxicity is that it MIGHT be a contributing factor in Alzheimer’s disease. Fairly low concentrations (less than 5 ppm) is considered “potentially dangerous” to the human brain. Alzheimers disease was only discovered in 1906. Clearly, Alzheimer’s disease existed before we ever had
aluminum foil, so aluminum foil is not the direct cause of it. Alzheimer’s disease exhibits symptoms usually in old age, and progresses slowly most of the time, it became much more evident (diagnosed) only after human lifespan increased to a level where it becomes possible for such diseases to present its symptoms (~1970s). And, frankly, we had much bigger fires to fight (polio, bacterial infections, etc.) before Alzheimer’s disease even showed up on the healthcare radar. This is possibly why aluminum foil has “suddenly” become toxic.
[It could also be a negative marketing tactic against aluminum foil by the plastic wrap folks, but I have no proof of this.]
Using
aluminum foil in food contact applications (direct contact with food) may cause some of the aluminum to leach into ACIDIC foods - e.g. vinegar in sauces, tomato sauce, lemon juice. The amount of aluminum that leaches into the food is minuscule, compared to the total surface of
aluminum foil that is exposed to the food. It also depends on the duration of contact (longer contact might cause more leaching) and temperature of contact (hotter means faster leaching).
Use of
aluminum foil is considered generally to be safe. However, you want to be judicious in how you use aluminum foil. It is best to avoid wrapping acidic foods with aluminum foil, or using aluminum foil to hold food that is being baked or cooked. However, it may be perfectly OK to wrap food at room temperature, or to store wrapped food in the refrigerator.
The biggest toxic effect for aluminum foil is if you use it to wrap food that you would warm up in a microwave oven. When this happens, it is extremely toxic to your wallet.