I've heard about the problem of lead contamination in multiple kinds calcium supplements (dietary/human use) and I assume that the dolomite lime and/or calcium carbonate I use for gardening is not tested at all, considering it's a cheap, basic commodity that's sold in bulk - and so there's no way they could test the huge amounts produced(?). I'm wondering if anyone has anything to say about the issue?
Of course raising the PH with lime is supposed to make Lead less available to plants, so that's a positive thing at least....
You're never going to avoid lead entirely. Lead, arsenic, mercury, these are elements found in nature, concentrated in some spots more than others. Dolomite, being a common rock material, might contain lead, it might be relatively free of lead. Bonemeal, on the other hand, is only going to have significant amounts of lead if the bones came from an animal that was being poisoned by lead. In fact, bones are relatively free of lead and can actually sequester it as is shown in this study.
Unless you are growing vegetables on top of a mine tailings or coal ash dump, I wouldn't be too worried about your plants picking up a problematic amount of it.
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