Using galvanized wire mesh for supporting tomatoes is suggested on your
website. I know that working with galvanized wire entails risks — one roll of
standard galvanized wire I bought recommended washing hands before eating and
avoiding repeated exposure — so why would this material be safe for growing
food, especially if the food comes in contact with the wire?
From the CRC Handbook of Chemistry and Physics: “Zinc poisoning is mostly
accidental from the intake of pesticides, inadvertent therapeutic use of heavy
doses of zinc salts (oral supplements), or drinking of acidic juices or brews
made in galvanized iron utensils.”
The only real risk with galvanized steel fencing is from breathing fumes
while cutting, burning or welding, or from breathing dust from grinding, etc.
The warning label on the wire is the brainchild of some litigation department.
Zinc toxicity is most generally caused by inhalation, not ingestion. And in the
case of the wire fencing, the only risk is in the small amount of zinc dust that
might be present. I would be much more worried about taking a zinc supplement
than handling wire on a weekly basis.
So, I cannot think of any reason to worry about handling galvanized wire
fencing and I most definitely wouldn't worry about galvanized wire for my tomato
cages.
