Use of galvanized steel containers for food storage or container gardening can be dangerous because of the chance of zinc, possibly contaminated with cadmium, leaching from the steel and entering the food chain. In particular, the acid content of some foods can corrode the zinc coatings of galvanized steel containers. Zinc absorbed by the body can be responsible for minor illness, and cadmium irritates the stomach severely.
Galvanized steel containers should not be used for container gardening involving food plants, according to Urban Farm. If the zinc is contaminated with high doses of cadmium, it results in diarrhea and vomiting. Low doses of cadmium can contribute to kidney disease and lung damage.
Foods with acidic content should not be stored in galvanized steel containers. Acidic foods convert the zinc coating of galvanized steel to zinc salts, which cause minor illness when absorbed by the body.
Galvanized steel is widely used for transportation of water on a large-scale basis. If the water has a low pH factor and is acidic, it can corrode the zinc coating of the pipes. When this occurs, lead and cadmium can leach into the drinking water. If tap water tastes bitter, it may be the result of high lead or cadmium. If tests show cadmium content of greater than 0.015 milligrams per liter or lead content of greater than 0.005 milligrams per liter, the water is not safe to drink. An older plumbing system containing galvanized steel pipes has a greater likelihood of contaminated water, especially if the water sits a long time.