[sha256sum]

> We assessed trace metal contamination in backyard chickens and their eggs from garden soils across 55 Sydney homes. We also explored other possible sources of contamination such as animal drinking water and chicken feed.

I’m not surprised this would be the case with chickens foraging yards in cities. The title should probably reflect that as I doubt this would be the case in a less urban environment.

[mauvehaus]

If you have an old farmhouse on your rural property, it's highly likely that it was painted with lead-based paint at some point in its history. Likely many times, in fact. A lot of the soil contamination comes from lead paint flaking off as it weathers. Fortunately(ish), this is mostly confined to the adjacent areas.

Given that you likely have more space in which to free range your chickens, the problem is now reduced to free ranging them away from the house. Arranging this is left as an exercise to the reader :-)

[cmrdporcupine]

Even more concerning is that a large # of rural properties are on old apple orchards.

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.

[samatman]

'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.

Much as crops can be planted to enrich the soil with nitrogen, arsenic hyperaccumulators can pull arsenic out of the soil: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513893/

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.

[cmrdporcupine]

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.

[samatman]

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.

[patentatt]

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.

[1] https://en.wikipedia.org/wiki/Lead_hydrogen_arsenate

[selfhoster11]

My bet? The use of PFAS/"forever chemicals" will make future generations tear their hair out in frustration.

[faceplanted]

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?

[beckingz]

Bioaccumulation!

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!

[abdullahkhalids]

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.

This will clearly take many many many years.

[oneplane]

It doesn't go away by itself, but you can of course physically move it (including ingesting it).

[jefftk]

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

[selimthegrim]

Cotton too no? (and maybe rice if the field is reused) Or was that just elemental arsenic.

[jefftk]

> there's literally nothing that can be done about it

What about testing your soil, and if there are high levels of lead then either put in raised beds or don't grow edible things?

[cmrdporcupine]

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.

But, yeah. What a smart species we are.

[unlikelymordant]

If people have dumped engine oil as a weed suppressant or just poured it out on the ground, youll get a lot of heavy metals including lead.

Also leaded gasoline used to be popular, and would likely have been used for all sorts of things like an accelerant or a degreaser. It doesnt take many incidents like that over 50 years to spread lead all over the place.

[partomniscient]

And that's just the lead...

https://en.wikipedia.org/wiki/Botany_Bay_Groundwater_Plume

I don't know what's worse 'progress' with known costs and done anyway, or 'progress' done in ignorance (sometimes rather intentionally).

It's the future's problem - not ours. Welcome to said future.

[s1artibartfast]

yeah, my understanding is that a significant portion of the urban lead contamination is from automobile exhaust. This is a much better explanation than some paint chips.

I do wonder about the contribution from leaded piping. If you imagine many decades of garden irrigation, it seems that some accumulation would be expected.

Another consideration is if there were ever any coal plants in the area.

[cmroanirgo]

Looking at the maps, the worst levels are in the city centre, not in the suburbs, which is a weird result because it hints at pollution being a cause, but there would be less chickens being raised there than in the suburbs.

[duxup]

Also most chicken farms aren’t like some old stereotype with chickens in the yard up to the house.

They are usually far from the house and “old farmhouses” aren’t all that common.

[raverbashing]

I wonder how much of this is from lead paint around buildings