Is Hardware Cloth Toxic Around Garden

Chicken Wire / Mesh / Hardware Cloth

Published: April 25, 2018
Updated: March 28, 2020

Can chicken wire test positive for Lead?

Years ago, in response to a friend's concerns about chicken wire (otherwise known as poultry cloth or hardware cloth)I tested several examples. Chicken wire is a popular example of a category of galvanized wire products – available in a variety of forms, styles, and gauges, sold in rolls or flat panels, traditionally used primarily in animal control and husbandry, and now sold in most hardware stores – and used for a wide variety of purposes. This product is also called wire cloth, wire mesh, woven wire, wire fence or wire fencing, etc., — or associated with the name of an animal (e.g. poultry cloth / chicken wire;deer fencing; non-climbing horse fencing, etc.) — depending on specifications, as well as common uses / markets.

When I first tested this type of product (back in 2014), I originally tested TWO examples — one each of 2 different types of galvanized wire cloth that my friend sent me. As with each item with the test results reported here on this blog, testing was done using a high-precision XRF instrument. You can read more about the testing I do on this link.

One of those two examples is pictured here on this post (image above). Photographs and readings for the second sample can be seen here: link . With both samples, I have the same considerations: the wire (even after trying to scrunch it into a lump as tightly as I could) did not fill up the full sampling window/screen of the XRF — as a result the actual content (in ppm) is likely much, much higher for the toxic heavy metals found to be present in each case .

Here are the XRF readings I got for the sample pictured on this post:

Lead (Pb): 2,201 ppm
Cadmium (Cd): 30 ppm

As mentioned above, this information was originally shared with my readers in June of 2014. Since that original posting, I have dozens of additional samples of this type of wire.I have never once tested a sample of galvanized chicken wire (or other galvanized hardware cloth / wire cloth) that was negative for Lead! As a result I stopped using any galvanized chicken wire (or any other galvanized products – including animal feed buckets and animal feed dispensers) for anyand all applications around my home and garden.

How much Lead is "too much" Lead?

The amount of Lead that is considered toxic (by current Federal regulatory standards) in an item intended for use by children is anything 90 ppm Lead or higher in the paint or coating, and anything 100 ppm Lead or higher in the substrate. If this chicken wire (pictured here in this post) were considered to be "an item intended for use by children" it would certainly be illegal today, but it is not – even though children often participate in gardening [and children eat food from gardens where people use these products]. As evidenced by the fact that it is so very common to see high levels of Lead (and trace levels of Cadmium and Mercury) in these products – the presence of toxic heavy metals in chicken wire is not – under current U.S. regulation, as it stands – illegal at all.

Can I test this myself at home?

When you test something like this (anything with a metal substrate actually, and specifically anything made of galvanized metal) it may or may not test positive with a reactive agent test (like a LeadCheck® swab). If metals (any metal objects) do test positive with a reactive agent test, the positive is often much more faint (faint pink or red), than when you might test paint that is positive for Lead at the same level. However, sometimes with galvanized metal the swab will turn bright pink. The variation in results when testing a metal substrate (even if it is already known to be high lead) is because the swab testing methodology (includingreactive agent tests for Lead) are specifically designed for testing paints and other surface coatings — not metal substrates. Metal substrates can only reliably and quantitatively tested using a high-precision XRF instrument .

But is this actually a problem?

In a word, yes. In my experience (based on testing of garden soil that I have done around the country over the years) this is a real problem – a real potential source of Lead exposure to humans. Where there is chicken wire installed, I have consistently found the soil in close proximity to that wire is more likely to test positive for a high level of Lead (usually measurably higher levels than the surrounding soil that one might otherwise find in a garden or chicken coop.) The only exception to this is if the soil is heavily contaminated already because it is next to a lead painted building or there are other lead painted components in the garden or chicken coop.

One story from my archives: I worked with a family (fairly recently) whose child [who has an autism diagnosis and also tested positive for Lead, in spite of living in a fully-remodeled home with no notable building-component based Lead hazards] had a favorite activity: growing tomatoes in his garden. After finding virtually no potential sources for his Lead exposure in the home, we went out to his garden — and determined that his galvanized metal tomato cages were all positive for a high level of Lead. We also discovered that the soil underneath the tomatoes (the soil he was planting in and touching each day that he gardened) was also positive for a relatively high level of Lead. Soil in the other areas of this child's garden –not under the galvanized metal – tested negative for Lead. It was then that I realized the potential for galvanized metal fencing to specifically and directly contaminate the soil underneath the items – as well as for it to be a potential source of exposure for the gardener. The simplest solution: use stainless steel alternatives or other readily available Lead-free options.

My primary concerns with using galvanized metal in gardening and farming:

Tomatoes: point noted above, potential contamination of soil under tomato cages.
With chickens: they like Lead because it tastes sweet — and they are more likely to peck at contaminated soil under Leaded fencing and even to peck directly at the fencing itself. This can result in Lead-poisoned chickens and Lead-contaminated eggs.
As a pest barrier: unfortunately I have seen this COUNTLESS times – folks create an organic gardening bed, and before laying down the top 6 or 12 inches of soil for their vegetables to grow in, they lay down a full layer of hardware cloth over the bottom of their garden bed to keep out burrowing rodents. This risks that (eventually, with rain, time and normal soil turnover expected in a garden) all of the soil in that bed may become contaminated with Lead.
As trellis: same concern as with the tomatoes – potential contamination of the soil below (and possibly of the items grown if the edible component of the plant touches the trellis during the growing period.)
In all applications: potential exposure to the person who handles or installs the metal or touches it in general daily use with gardening. Potential contamination of food plants that come in direct contact with the wire.

Solutions/alternatives/considerations:

For tomato cages and similar, use stainless steel chicken wire – or consider using untreated natural wood (organic if possible.)
For other vegetable applications, please consider using actual cloth (natural fiber/organic ground cloth), rather than metal or plastic.
IMPORTANT NOTE: the rubber or vinyl coatings on some of these types of items can also be high-Lead; and several of the solutions that have no metal, but are wholly some type of supple plastic – can also have high levels of Lead — so I also avoid those entirely.
When researching this back in 2014, we did find a Lead-free option for hardware cloth that could be imported from Japan [I believe this was a stainless steel product], however, it carried a very high price-tag (relatively) — even before the cost of shipping/importing. Here is a more-current example that I found on Amazon [although I have not tested this specific product] it says it is 304 stainless steel (not galvanized) — and therefore it should be Lead-free: https://amzn.to/2HXMwQY

Some more Stainless Steel options on Amazon
(updated March 28, 2020)

Stainless steel hardware cloth: https://amzn.to/3arq5kE
Stainless steel chicken wire (we bought this in 2020 for our veggie garden): https://amzn.to/2UthloJ
Stainless steel rodent mesh: https://amzn.to/2QTndVY

UPDATE : One of my readers recently informed me she found a product at Home Depot specifically marketed/labeled as "Lead-free" [although I have not yet confirmed this myself] that may be worth checking out!

As always, please let me know if you have any questions.

Thank you for reading and for sharing my posts!

Sincerely,

Tamara Rubin
#LeadSafeMama

*Links may be Amazon Affiliate links. If you make a purchase after clicking on one of these links I may receive a small percentage of what you spend (at no additional cost to you.)

Chicken Wire / Mesh / Hardware Cloth