Does galvanized steel contain lead? Learn about the manufacturing process of galvanized steel to make a informed decision when selecting fencing for the garden.
I’ve read conflicting advice about whether using galvanized wire in gardens is safe; some sources indicate high lead and mercury content. What’s a safe solution for fencing an organic garden?
You’re right to be concerned. Lead and mercury are quite toxic. I’ve similarly encountered a writeup from an author who tested soil levels beneath galvanized steel and found that it contained higher levels of lead than soil on the same property but away from the steel.
Does Galvanized Steel Contain Lead?
Though steel is made of iron, lead and mercury become involved during the galvanizing process, whether through hot-dip or electro-galvanizing procedures. So, almost any galvanized metal will contain at least some lead, though the mercury evaporates above 375 degrees Celsius. (Galvanizing takes place at 450 degrees Celsius.)
Protection agencies have become aware of the lead persisting through this process. The 2006 Restriction of Hazardous Substances Directive indicates a maximum concentration of lead at 0.1% of material weight. However, steel galvanization puts the lead amount outside this scope, so a lead exemption (made in May 2010) allows lead up to 0.35% for galvanized steel. (If the product is sold in California, the label must state whether it contains lead.)
Though plants don’t transport every soil-persistent chemical and element, they do transport lead. But how much transfers into fruits and vegetables? That depends on the plant. Often, soil contamination manifests in plant damage before the vegetables become toxic to humans. That doesn’t apply to lead. Soil levels have to exceed 1,000 ppm before apples and grapes show any damage – but that doesn’t mean those fruits won’t harm humans, who are more sensitive to lead exposure than plants are.
So, you’re probably already considering forgoing galvanized steel within your gardens or livestock and pet areas. Thankfully, you do have some alternatives:
Vinyl-coated wire provides a polymer coating to the galvanized steel. These polymers are effective when sealing lead paint. However, water may eventually cause the polymer to separate from the steel.
Rabbits and squirrels can chew through plastic fencing, though it may deter them for a while. But plastic isn’t environmentally sustainable, and its manufacturing process involves other issues you may not wish to support, such as the use of fossil fuels.
Stainless-steel fencing, though the most expensive, is the safest metal that avoids leaching toxins into soil or water. It’s also durable; some people have reported finding stainless-steel hardware cloth intact after 30 years.
We hope this helps you make the best material choice to protect your hard-earned produce from opportunistic critters!
