flowerbug
Sustainability Master
some pot & pan makers use a blended meatal,, you never know what you are cooking into your food
one reason for cooking on iron to begin with is to get some into the food. metal recycling does happen and will there be some trace other metals in there? sure, but i doubt enough to worry about. even iron ore taken from the ground is going to have some trace other metals in there. not likely enough to make any difference or they'd not use it to begin with (or the ore would be specifically mined for those other metals since they are of more value than iron). also any trace carbon sources are not likely to be an issue either.
if you want to worry about metal contaminations then there are much worse things than what you might get from an iron pan. mercury, radioactives, lead, some forms of chromium. those are the ones that seem the most common and those all have known sources which are either from burning coal, using leaded gas, various water system issues (lead pipes or lead in solder used to put together copper pipes) or old paints or improper disposal of car batteries or other batteries and any issues from old landfills before they put liners and drainage systems in.
other metal sources can come from all sorts of sources but to me the one i would discourage would be using municiple sewer sludge on farm fields or gardens. since many larger cities combine sewage from industrial and residential sources that can add more metals to the sludge. in the future this will be a bigger issue as we have to figure out how to be sustainable and you can't indefinitely keep adding certain metals to the gardens or farm fields and have that be a good thing.
medical procedures can also be a source of some trace contaminants. drugs in human or animal wastes can also be an issue, but those are not often a problem for recycled metals.