Prompted by comments in the family, help me clear this up. A Google search for is aluminum foil safe yields articles that claim it's dangerous, as well as articles that claim it's safe. So which one is it?
The above search has among the top results this very tin-foil-hat-sounding (pardon the pun) article (emphasis mine):
A recent study has shown that heat causes aluminum from the foil to leach out into foods in significantly harmful amounts ... High aluminum levels in the body alter bone mineralization, matrix formation, as well as parathyroid and bone cell activity. ... Additionally, chronic aluminum toxicity greatly reduces osteoblast population and inhibits bone mineralization, resulting in osteoporosis.
Another contra article is here, but it seems sensationalist to me.
There is also this opposite article (emphasis mine):
Though results aren't entirely conclusive, the overwhelming consensus is that there's little cause for worry. One concern has been that foil use might contribute to the buildup of aluminum found in the brains of some Alzheimer's patients. "Aluminum has neurotoxic properties, but no direct link to human neurodegenerative disease has been established," says Jean Harry, Ph.D., a toxicologist at the National Institute of Environmental Health Sciences. Harry also says any leaching from utensils, pans, and foil accounts for only a fraction of the amount considered safe to ingest daily through food, drinking water, and pharmaceuticals (some antacids contain aluminum; so does most buffered aspirin).
Aluminium has had bad press for a long time, mostly beginning around the 1920s. Rudolph Valentino's death in 1926 at the tender age of 31 was blamed on aluminium poisoning from aluminium cookware - but he was actually killed by a perforating stomach ulcer. Howard J. Force, a self-proclaimed "chemist" added momentum to the anti-aluminium movement with pamphlets such as Poisons Formed by Aluminum Cooking Utensils. It was probably not a coincidence that he also sold cookware - stainless steel cookware.
The first scientific "evidence" about aluminium's toxicity appeared in the mid-1970s. People with Alzheimer's Disease have typical changes in the brain that can be seen only with a microscope. They're called "neuro-fibrillary tangles". Various studies found high concentrations of aluminium at autopsy in the brains of people suffering with Alzheimer's Disease - and almost always in the characteristic neuro-fibrillary tangles in the nerves. So, did the aluminium cause Alzheimer's Disease? No. It eventually turned out that the neuro-fibrillary tangles were very "sticky" - and absorbed the aluminium out of the water used to wash them.
... So, giving aluminium in massive concentrations directly into the blood of very sick people with failed kidneys did cause dementia. But there are lots of causes of dementia. Alzheimer's Disease is one of these. The dialysis patients, even though they had very high aluminium levels and dementia, never developed the neuro-fibrillary tangles, that are characteristic of Alzheimer's Disease.
On average, we each take in about 10 - 50 mg of aluminium per day. But even people who take antacids and buffered aspirin, which bumps up their aluminium intake to 1,000 mg of aluminium per day, have no increased incidence of Alzheimer's Disease.
Dr. Charles DeCarli, the director of the Alzheimer's Disease Center at the University of Kansas Medical Center says, "In my opinion, the supposed relation between aluminum and Alzheimer's Disease is a simple case of neuromythology".
In summary, I am getting the general impression that pro-aluminum sources indicate that actual bodily Al intake is negligible and therefore harmless, while contra-Al sources indicate a significant intake that also remains in the body. They can't both be right.