Galvanizing is the process of electrolytically coating
iron metal with zinc, which protects the iron from rusting. Zinc is one of several heavy metals which can be toxic if consumed in large quantities. When acid foods (fruit juices, tomatoes, pickles) are placed in galvanized utensils of when meats or vegetables are cooked in galvanized containers, toxic amounts of zinc can brought into solution.
Numerous reports of zinc poisoning can be found in the
public health and medical literature, and essentially all of them relate the illness to the type of utensils used in food preservation. Symptoms of zinc toxicity are fever, nausea, vomiting, stomach cramps and diarrhea in three to twelve hours following ingestion.
Galvanized utensils (some types of old refrigerator
shelves for outdoor grilling, galvanized trash cans for
quantity cooking, etc.) should never be used for food
preparation or preservation. (Source: Michigan State University Extension)