Since I am not a medical doctor but a chemist I can only answer what I found by doing some searching on the web. If you are concerned with your health it is always best to discuss these issues with your doctor.

In my opinion it is safe to cook in aluminum pans and it is definitely fine to let your pet eat out of an aluminum pan. The controversy about aluminum started with a report in 1970 that brains of people with Alzheimer's disease contained abnormally high levels of aluminum. At that time it was not clear whether the increase is part of the cause of the disease or a result.

Because it has long been known that aluminum from cookware can leach into food people started to get worried about cooking with aluminum pots and pans. But aluminum is also the third most abundant element on earth. It's everywhere -- in soil, water and air. Because it's so ubiquitous it is ultimately in the water we drink and the plants and animals that we eat. Aluminum may be ingested in over-the-counter medications, certain antacids, buffered aspirin. Normal daily ingestion of aluminum is 10 milligrams (but one antacid tablet can contain 50 milligrams of aluminum or more) mostly from food; cookware contributes only about one or two milligrams of the total.

The FDA however recommends that food, particularly acidic or salty foods, should not be stored in cookware (aluminum or other) for extended periods of time. I found a quote in a Scientific American Article which I will copy for your information:

Leonard Berg is a professor of neurology at the Washington University School of Medicine in St. Louis; until recently, he directed the Alzheimer's Disease Research Center there. He replies: "There is no proof, and the current consensus is that aluminum does not play a major role in the development of Alzheimer's disease. But because the causes of the disorder are not understood at this time, one cannot rule out the possibility that aluminum could play a minor role. In our Center, we do not recommend that people avoid aluminum cooking pans or aluminum-containing antiperspirants or antacids because there is little evidence that such lifestyle changes are helpful. Moreover, it is impossible to avoid ingesting a certain amount of aluminum, which is found naturally in food and water."