I know you stated that aluminum cookware should be avoided, but what if the aluminum is only in the base of the pan?

The health problems associated with aluminum in cookware do not occur unless foods (or fluids in which they are cooking) come into direct contact with the aluminum. Many stainless steel pots and pans feature cores and bases made from aluminum since this metal offers about 17 times greater heat conduction. (Copper would be an even better choice for conducting heat—it’s about 60% faster than aluminum.) Therefore, as long as the cooking surface is not made from aluminum, you do not need to worry about migration of this aluminum into your food. (From an environmental point-of-view there is still the issue of aluminum-containing cookware being ultimately disposed of in a landfill, where the metals making up the cookware, including aluminum, will eventually leach back into the groundwater.)