'Literally nothing' is of course hyperbole, but I'd like to point out that there are remediations short of removing and landfilling the topsoil available.
As I understand it, strategies for lead involve binding it into a mineral form with very low water solubility, such that plants won't accumulate it in the first place, it's not hard to find permaculture folks who will talk your ear off all day about this stuff.
My experience, after being big into permaculture some years ago before we bought our farm and for a couple years after is..
Permaculture people will talk your ear off all day about this stuff, but almost none of them have any clue on the actual application of said concepts beyond backyard urban gardens.
Farm scale permaculture is mostly a fantasy, almost nobody is doing it, except maybe Mark Shepard but in his case the actual profitable business on his farm is an organic market gardening operation and the 'regenerative agriculture', keyline design, permaculture stuff is frankly a side show.
It's one thing to lay down piles of sheet mulch and make nice "food forests" in your urban reclaimed vacant lot or whatever. It's another to do anything similar to that across many many acres. Too much of what they talk about is hand labour focused and not automation friendly.
Also a lot just doesn't work. Like, doesn't produce a crop. Just sounds nice. A whole sub-culture full of opinionated dudes (almost always) regurgitating a lot of pop philosophy and "natural wisdom" without a lot of effective science to show.
That's fine since we're discussing backyard gardens.
I've had just enough experience with larger permaculture projects to recognize the issues you're describing, but they aren't relevant to remediating 10m^2 of topsoil.
Yikes, never heard of spraying lead as an insecticide! Even more eye opening is that according to Wikipedia it was a "less toxic alternative to then-used Paris Green, which is about 10x more toxic." [1] Makes you wonder what common practices today will frighten future generations.
Complete noob question, but if it never goes away how does it get into chickens? It sounds like your point and this article combined are implying that having chickens (whose eggs you don't eat but who do eat the bugs) would actually be a method of removing lead from the land?
Some companies are looking at this for nickel mining: grow trees that leech metals out of the soil and end up with metal concentrations that are competitive with ore!
Back of the envelope calculation using the data from article.
To take soil from the Australian residential guideline for soils of 300mg/kg to the article recommended 117mg/kg, you need to remove 183mg/kg from the soil.
The average lead content in the eggs was 301µg/kg, so 183mg/301µg = 608. Meaning, for every kg of soil in your backyard, you need the chickens to lay 608 kg of eggs.
It isn't literally true that it never goes away, or you would be right that the eggs couldn't have lead in them, but my understanding is the amount removed by chickens is pretty minimal as a fraction of what's there
Yes all of this is possible. But incredibly costly and pointless on a large (farm) scale. I was (as another poster pointed out) being hyberbolic. But realistically there's no way we'd do what you're saying for hundreds of acres.
You can actually grow edible things, though. Carefully. My understanding is that the metals accumulate in the tissues of the plant but not in its fruits. Depending on the kind of fruit. So actually orchard crops can ironically be safer in these old orchards, as the metals should not accumulate into the fruits. Instead they accumulate in the vascular tissues of the plant (stems, leaves, etc.)
So:
* Avoid bare soil, as the metals would be more exposed this way.
* Don't eat or be exposed much to the plant tissues growin there (which includes things like making hay or straw)
* Could maybe grow fruits, but carefully.
* Even mowing could be dangerous, maybe.
There's people who talk about cleanup using fungus, to accumulate then dispose. But I truly wonder about if this would ever be effective.
Spraying lead arsenate as a pesticide on apples was a fairly common practice up until the 60s.
It accumulates in the soil and never goes away.
The scale of the problem isn't spoken about much because there's literally nothing that can be done about it.