I have searched, found similar questions but none answer my specific need.

I have built a raised garden bed to grow vegetables (ironically due to a high lead content in our garden soil - planning to put new, lead-free soil in the raised bed).

I used galvanised corrugated steel panels for the sides. I believe any zinc leaching would be beneficial, not a hazard.

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However, now I learn that the galvanising process often involves lead. When something is "hot-dipped", apparently adding lead to the process helps the zinc run off. My understanding is limited. A crude 3M home swab test indicates lead, possibly a high content (it went very dark red). https://en.wikipedia.org/wiki/Hot-dip_galvanization https://galvanizeit.org/knowledgebase/article/why-is-lead-added-to-the-galvanizing-bath

My chemistry isn't very good, which is why I came to the experts. Here are my concerns:

  1. How much lead would be likely to leach into the soil?
  2. Would this lead be in a form that could be absorbed by lead-absorbing plants (e.g. lettuce)?
  3. Would this lead be in a form that might endanger small children "helping" with the vegetables?
  4. Would this lead be in a form that might be absorbed by the body when eating these vegetables, if not carefully washed?

Thanks in advance!

  • $\begingroup$ Could you please provide a reference for how lead is associated with galvanization? The wikipedia article says nothing about lead contamination of the zinc, but it does say that acid rain may be a problem with outdoor galvanized steel. Hypothetically, if the zinc did contain lead at low or trace levels, then it will get into the soil as the zinc sacrifices itself to protect the steel it coats. Then the soil would be a problem. But you already have soil with elevated lead levels, if I read you right, so that is already an issue with kids because kids eat dirt. $\endgroup$
    – Ed V
    Jun 29 '20 at 1:42
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    $\begingroup$ @EdV - thank you, added some links to the "hot-dip" galvanising process. Planning to use new, lead-free soil in the raised bed, and mulch / cover the rest of the yard to lock in the lead. $\endgroup$
    – ttt
    Jun 29 '20 at 1:55
  • $\begingroup$ If it was me (and it wouldn’t be since I couldn’t grow lichens on a rock), I would paint the panels, as per Galvanization and lime the soil underneath your raised garden bed so calcium is in relative abundance relative to soil lead content. $\endgroup$
    – Ed V
    Jun 29 '20 at 1:58
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    $\begingroup$ Excellent, thanks for the link! I had no idea that lead was deliberately added, especially nowadays when people go nuts about lead. The mulch idea is excellent, but adding lime is also an inexpensive additional step. $\endgroup$
    – Ed V
    Jun 29 '20 at 2:04

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