It could. In reality though most of the street venders I used to eat from in Mexico didn't use the galvanized wash tubs to cook food in, although some did. But even if they did, I've been told that the health department (in the US) found out this leaching of metals (zinc in particular from the galvanizing) does happen, but it takes a long time. Like the food has to be cooking in it all day. Some of the venders in the US that they were cracking down on indeed were letting the food cook or simmer all day, and then many times storing the leftovers overnight and reheating again the next day, all in the galvanized wash tubs. It seemed the venders I saw in Mexico never had enough food at any one time to simmer or store it very long. Lines of hungry neighbors were always eating it all too fast! :yes Maybe the risk was made negligible by the lack of time in the tubs?