Backyard hens’ eggs contain 40 times more lead on average than shop eggs | Hacker News Reader

Backyard hens’ eggs contain 40 times more lead on average than shop eggs

theconversation.com

112 pointssohkamyung163 comments

So, while the impact on eggs is interesting and all, a more appropriate title for the article would be "urban Australia is so lead-polluted that gardening and raising chickens shows lead poisoning". In other words, if the place you're living has so much lead in the soil that it is unsafe to produce food there, it seems unlikely that it is safe to be living there at all.

> it seems unlikely that it is safe to be living there at all

Is it?

Just living there you’re not ingesting the soil.

In all likelihood it is reaching the soil through the air as particulates.

Leaded petrol was banned decades ago

There is still aviation fuel using lead.

True, but unless you live really close to a busy airport, I doubt it's an issue. I live fairly close to a rural grass strip that sees moderate use. I have about 40ppm which is 10x less than the allowed limit for crops.

It sounds like accumulation from lead based paint and leaded car gas is the issue in the article. Which makes sense since you generally can't fly low over cities anyways (disperses) and small planes are not huge emitters (low in numbers).

Melbourne's general aviation airport (i.e. light planes like Cessnas) is Moorabbin, in the south east. The map shows the City of Kingston which contains it with a dark green dot, meaning safe. Planes often do a circuit south and then turn and follow the coast (over my house...) and all those places are shown as safe.

The neighbouring City of Casey to the east is shown as unsafe, but this contains a "noxious industries area". Planes usually take off and land on a roughly north–south alignment because of the prevailing winds.

Only "avgas" which is basically the same stuff we used to put in cars and is running the same sort of engines, a piston engine, driving a propeller roughly the same way your car engine turns the wheels. Most little things, from smaller airports.

JetA, which is basically kerosene (still terrible, don't drink it - but at least it doesn't have lead in it) is used by all the jet engines. That includes lots of things a casual observer wouldn't think of that way. A King Air, or a C-130, they've got propellers, but that's a turboprop engine, the propeller is spinning because there's a turbine behind it, and instead of kicking hot fast air out the back (like an A320) it's using that energy for turning the propeller really fast.

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

It was banned worldwide by the UN only last year. (And not, I think, for all aviation and perhaps other industry fuels, as sibling commenter says.)

Also, 'leaded petrol still in London air 22 years after ban': https://www.bbc.co.uk/news/uk-england-london-57564953

> you’re not ingesting the soil.

You don't have kids, do you?

I suppose you're getting downvotes because of the snark, but you're right.

Young kids will put anything in their mouths. Eating dirt is not an uncommon behavior.

And part of the reason kids are particularly susceptible to eating lead paint chips, is that lead acetate is sweet enough to be used as a sweetener in the olden days and called "sugar of lead".

It's not snark, it's a logical deduction. It's not that my kid "eats" dirt but his dirt-covered hands are in his mouth if they're otherwise unoccupied.

I highly doubt they're eating sufficient quantities to make any impact. They'd have to eat about 1/4 pound in the highest contaminated area to even hit the action level, assuming they fully absorb all the lead which isn't how it works.

Over several years of playing in the muck every day before maturing past the tendency to eat dirt / cram dirty hands in mouth, 1/4 pound is just not that much. There is no "safe" level of lead exposure.

"There is no "safe" level of lead exposure."

And...? Do you think there's no exposure anywhere? This line, at least the way it's being used in arguments here, might as well be religion - used as a one line ideology that doesn't add anything to the discussion and ignores the realities.

How is 1/4 pound of dirt not that much? And remember, they would have to eat multiple times that much to actually absorb 100% of lead in that amount. If you're really that concerned, then you shouldn't be letting them eat any dirt due to other health concerns, like toxoplasmosis.

Spread over a childhood of say, 8 years, 1/4lb is only 28mg per day. That's a couple grains of rice. So, yeah, it's not much dirt.

I'm clearly not that concerned, as I don't keep my child in a bubble, but environmental lead is detrimental to society at large and something that we should make every reasonable effort to reduce.

8 years is a bit long, right? Newborns aren't playing in the dirt. By at least age 6 I would hope that most kids have basic hygiene to not be eating dirt. At such a low dose over such a long time, it's unlikely to accumulate. Plus, 28mg of dirt is still like eating a teaspoon of it.

"make every reasonable effort to reduce."

I agree. It's the reasonable part that comes up for debate. To me, it seems reasonable to live in an area that has elevated lead in the soil while not growing crops or raising chickens. It's more reasonable to replace the "lead free" plumbing components with truly lead free components, carefully select toys (eg no Chinese), and stay away from certain foods (carrots are a big one if I remember correctly).

Even 4 years at an average of 10 grams of dirt per day is a lot of lead, almost certainly enough to lead to developmental problems.

I have kids.

Why would it be unsafe to live there at all? The cutoff for crops is typically 400 ppm. That seems like it would be low enough to live there.

There is no level of exposure to lead that is known to be without harmful effects. [1]

Fortunately, plants don't seem to generally absorb lead.[2] It may be in the soil, though, which means you should carefully wash your plants before eating them.

It does seem to be a big deal, though, that chickens absorb lead and that the lead ends up in their eggs. There are many people who have backyard chickens who likely aren't aware of this.

[1] https://www.who.int/news-room/fact-sheets/detail/lead-poison...

[2] https://extension.oregonstate.edu/gardening/soil-compost/sho...

Plants can absorb lead. This is especially true in poor, acidic soils, and for root vegetables.

While there's no known safe level of lead, they do set action limits because effects under that level are not known or are negligible. It's also not practical to set a level of zero in many cases, such as soil levels for crops.

So again, why would it be unsafe to simply live there? Where else would they live? Is there anywhere that is lead free (since the argument is that any level is unacceptable)? What level do you consider safe to live around?

Does this mean that root vegetables as similar natural "lead absorbers" can be used to remove lead from the soil?

It can. But it would likely be too slow and deplete the other nutrients. At that point, you might as well just replace the soil.

I live in a town that used to be a lead mining community. I know some folks around here who have backyard chickens.. in fact, I get eggs from one of them (though they live in a ways away from where I think the lead mining was, so hopefully we are safe..)

This is a very interesting news to me. I wonder if there is a cheap and easy way to test the eggs to see if they are absorbing lead from the soil?

You might be able to send two samples to a soil testing facility - one with just soil, the other with 50% soil and 50% soil with 50% eggs. Maybe want to let it compost so it doesn't stink too much in the mail/lab. Or ask the lab if they can test an egg. Other labs should be able to, but probably more expensive.

its more fair to say that food cultivated by professional farms who are held to strict safety standards is safer than food cultivated by you in your backyard that was never zoned for mass agriculture. IIRC, Michelle Obama even had some sort of community-garden project where she was growing vegetables on the White House lawn and giving it to local poor people but she had to quit after it was found out that they had toxic chemicals in them.

> food cultivated by you in your backyard that was never zoned for mass agriculture.

The way you turned that around seems similar to "Free speech zones".

So now we need official "Health Zones" where children can play safely and ordinary people can grow food as they've done for 12,000 years?

Urban soil is poisoned in Australia. Let's not make excuses or try to hide behind fancy interpretations.

Wow, you apparently recall correctly:

https://www.theguardian.com/world/2009/jul/02/michelle-obama...

Dumb question: is replacing the soil not an option? Too expensive? But surely that's amortized quickly over the term you use the garden? Or maybe you can't fully replace it because the soil is permeable and the lead comes from somewhere else (lower in the ground, rain, etc.)?

I guess it is from leaded petrol and paint which are forbidden now so replacing the garden soil should work to some extent? Unless there is water coming downhill from some neighbour.

Replacing the top layer of soil is the most common method of soil remediation, but there are others. For most urban gardeners it's usually more cost-effective to put in raised beds.

Seems pretty notable that everything is so polluted that people can't have chickens nor grow some backyard tubers without heavy lead ingestion.

I think it is news to most people that they should have to care about "zones" just to safely grow a garden. Almost seems like you're saying it's their fault.

I'm sorry, but why exactly should the production of food be professionalised? A far better outcome it seems, would be to make sure that everywhere people live is non-toxic enough that food can be grown safely.

How do you propose to remove lead residue from backyard soil?

> a more appropriate title for the article would be "urban Australia is so lead-polluted that gardening and raising chickens shows lead poisoning".

As an Australian resident of one of the cities mentioned in the article who has three chooks we keep for eggs, my take would be a little different. I had trouble squaring these statements in the article:

> The average level of lead in eggs from the backyard chickens in our study was 301µg/kg. .... Some 51% of the eggs we analysed exceeded the 100µg/kg “food safety” threshold. To keep egg lead below 100μg/kg, our modelling of the relationship between lead in soil, chickens and eggs showed soil lead needs to be under 117mg/kg.

with the maps. How did they get an average of 301ug/kg when most of the area covered by the maps were below the safe level?

Naturally I looked very closely at the maps to see if my suburb was in a high lead area. It wasn't included by the maps at all, so I looked for a pattern I could extrapolate from. Only the inner suburbs were above the 117mg/kg level. My house is a long way away from an inner suburb.

Why the inner suburbs? The article hints at one reason - houses painted with lead paint. Another one sprang to mind - areas with high vehicle density when lead petrol was a thing, but the areas are so small the paint explanation seems a better fit. In Australia, most lead paint ceased to be sold in 1970.

In comparison, Wikipedia says the USA dropped lead paint in 1997, EU formally banned lead paint 2003 (but phase outs happened much earlier in most places, eg UK in 1980), India in 2016.

It's probably obvious to most Australian's, but those maps are misleading for another reason. Australian cities are huge and those maps only cover a small faction of where people live. If indeed it is only the very inner suburbs that are effected, it really is a small portion. Add to that backyards aren't a thing in the CBD, let alone backyard egg laying chooks, and I doubt too many people are effected. That said, I suspect the article has put all egg laying chooks in Mount Isa in mortal danger.

I'd be curious to have a lab test your eggs and see how poor this reporting is.

> How did they get an average of 301ug/kg when most of the area covered by the maps were below the safe level?

Presumably outliers with much higher concentration.

Also possible the maps are wrong. It wouldn't be the first time that unsafe conditions were officially stated as being safe.

> 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.

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 :-)

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.

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.

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.

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.

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

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?

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

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!

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

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.

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

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

> 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?

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.

'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.

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.

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.

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.

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

Mushrooms found growing anywhere near cities or suburbs should also never be consumed, as they specialize in concentrating heavy metals from soils. The most well-known example is the radioactive mushrooms of Chernobyl, which end up eaten by wild boars in the region (and boars don't stay in one place):

https://www.theverge.com/2017/2/24/14733094/radioactive-pigs...

In cities and suburbs the main problem is likely due to the use of tetraethyl lead additives in gasoline for many decades (~1930s to ~1990s). Downwind of coal plants the mercury and arsenic are more problematic. Add both and some more industry and you end up with heavy metal cocktails that just recirculate endlessly.

If you want to grow foods in cities, there is a solution - raised beds that are separate from the underlying dirt, filled with soil trucked in from rural farms that aren't adjacent to industrial pollution sources. Note also that some 'natural environments' have quite a bit of heavy metals and toxic elements, due to natural weathering from geological outcrops, and some plants in these environments accumulate such metals (nickel, arsenic, etc.).

If you're concerned, sending a sample of your local soil to a testing lab is relatively inexpensive.

Mushrooms (to be more specific, only certain species) can be used to clean up dirty sites, since they absorb heavy metals so well.

+1 for raised beds.

+1 for testing. Here in the US, almost every college has a Cooperative Extension, and does soil testing. At Rutgers [1], it's just an extra $18 for lead testing.

[1]: https://njaes.rutgers.edu/soil-testing-lab/services-fees.php

Had me a bit freaked out until I saw that this was due to tainted soil in urban settings. I’m sure there is still lead at lower concentrations pretty much everywhere considering it was in our gasoline for so long. But the title should probably be more like the eggs of free range hens in urban setting contain 40x lead than chickens confined to a tiny box.

Had me a bit freaked out until I saw that this was due to tainted soil in urban settings.

While that's true, what they determined to be dangerous levels are still low enough to be in the "zero to low" category for most other classifiers like universities. I wouldn't assume your soil is safe unless you have an actual measurement done.

To keep egg lead below 100μg/kg, our modelling of the relationship between lead in soil, chickens and eggs showed soil lead needs to be under 117mg/kg

A good number to remember if you or anyone you know is considering getting chickens.

I wondered how much the chickens may have been concentrating the lead and if it was significant compared with the extra lead the owners of those chickens are being exposed to from their city home environment.

But this article suggests that air lead pollution is not an issue:

https://www.abc.net.au/news/2017-04-09/lead-pollution-threat...

Its almost as if...there is a bias in the media in favor of the egg and gas industry. No...don't raise your own eggs. Buy OUR eggs! They are safer, and don't contain lead like yours! Oh, the lead in the air is more dangerous? No, you are being paranoid.

Since many HN'ers live in the greater Seattle area, it's important to be aware of the Tacoma Smelter Plume:

https://ecology.wa.gov/Spills-Cleanup/Contamination-cleanup/...

For almost 100 years, the Asarco Company operated a copper smelter in Tacoma. Air pollution from the smelter settled on the surface soil of more than 1,000 square miles of the Puget Sound basin. Arsenic, lead, and other heavy metals are still in the soil as a result of this pollution.

And for anyone in the East side of Toronto, there used to be a lead smelter that polluted the whole neighborhood - http://laurajones.ca/wp/?p=515

Insanely disingenuous to conflate "55 Sydney urban gardens" with "backyard" hens. This should be flagged.

Interesting, makes me question if the local farms here the EU are checked for lead amount in the blood.

I mean, even local farms are usually in rural areas, where the lead contamination is probably much less than in the inner cities studied by this article. Still, I wonder where the lead originally came from? Old deposits from leaded gasoline fumes? Or does it come from lead paint, lead roofing, lead pipes or similar?

Not sure why I was downvoted, but it doesn't look good in the EU either.

https://europepmc.org/article/MED/30204015

I think it's from paint the chickens pick on, fallen off older farm houses, it wasn't uncommon in the 60-70s.

https://www.familyhandyman.com/list/ways-to-minimize-lead-pa...

Looking at the actual numbers it seems like the suburbs are a safe enough place to raise the chickens compared to the older inner core of these Australian cities.

Of course this will vary radically from one place to another.

Perhaps most important may turn out to be how much lead paint has flaked off buildings in the area.

I wonder if this can be remediated by covering the chickens run in a deep layer of mulch and shredded leaves, letting that compost over time as the chickens poop and scratch in it. Over time the layer of contaminated soil could be buried deeper under fresh compost. I also wonder if you could innoculate the wood chips with a fungus whose mycelium could filter out the soil a bit.

Chickens scratch, seeking tiny rocks for their crop. If they don't find any in your overlayer, they go deeper.

Maybe mix the mulch with some fine gravel

Is forty times an extremely small number still negligible? (asking not out of skepticism but curiousness)

There isn’t an official safe exposure amount for lead [1].

[1] https://www.who.int/news-room/fact-sheets/detail/lead-poison...

In the US there is: https://www.cdc.gov/niosh/topics/lead/limits.html

This was an interesting bit from that link:

> Some studies suggest that the current OSHA PEL and NIOSH REL may be too high to protect against certain health effects.

The line from the CDC page reads almost like a call for help:

"Some studies suggest that the current OSHA PEL and NIOSH REL may be too high to protect against certain health effects"

The medical limit for lead is zero (you can find that statement in various forms on all the major - official, main stream, government, education - sites that have something to say about the subject).

The reason we have non-zero "official" threshold values is for practical reasons: In our times and on this earth right now it simply is not possible. The values are set so that medical people are kind of okay with it - any damages are too subtle and not too obvious (e.g. less IQ as well as most small issues nicely also correlate with age so it can always be attributed to aging, and proving for an individual (and not just statistically for a lot of people without being able to say anything about each individual) that some issue was caused by or was contributed to by e.g. lead is impossible (we can't tag all the atoms and follow them around and see what they do, and even if we could do the first part perfectly, the following those atoms, we still would not know what they actually do just from knowing where they've been, even less so how the local bio-chemistry deals with consequences longer term than we can observe). So we need to have a limit that is low enough to not cause medical alarm bells to go off, but high enough to not bankrupt government and industry if they were told they had to clean it all up. Which, quite frankly, they can't at this point.

Last time I heard about China they have an already huge and increasing problem with heavy metals on large parts of their agricultural lands... (Example, two links of many randomly chosen: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6239058/ or https://www.chinawaterrisk.org/resources/analysis-reviews/he...) and the West had a lot of time where nobody cared about pollution one bit, during and after industrial revolution. The "superfund sites" (https://en.wikipedia.org/wiki/List_of_Superfund_sites) are just the biggest concentrations. Oh and then there's coal - burning it also has been releasing heavy metals such as mercury for a long time, and it's still going on.

Oh and by the way, please nobody blame "capitalism". I grew up in East Germany, near ash mountains and a river clearly unsuitable to even be touched by a human, everything was dirty and gray. I did not even live in one of the known polluted places (e.g. Bitterfeld). After reunification everything was cleaned up with Western money and methods - ash mountains gone, the river is clear and has nice water plants showing it's really healthy, etc. East Germany under capitalism is A LOT cleaner than under socialism. I say this because in sooo many discussions about the environment always somebody blames capitalism, but it's deeper and orthogonal to whatever system is used I think. People do or don't care about their environment, if it was just about economic pressure, you have them in all systems, because all systems need to produce something.

Thank you for that last paragraph. It is so tiresome to read other people saying that "capitalism" is to blame for everything. You make an excellent point that it's neither socialism nor capitalism per se that's to blame.

The little gray snippet (“backyard hens’ eggs…”) at the top of the page is clickable.

That is always going to depend on the context. Sometimes a small number makes a difference, sometimes not.

40 times greater chance of a comet hitting you on the head? Still gonna be negligible and you probably shouldn't be too concerned.

40 times more lead in your eggs? Well, you should really be aiming for zero lead in your eggs and lead poisoning can happen over time (My cousins got lead poisoning from old plates and bowls). If you have chickens, you are probably being fed a consistent diet of eggs. So yeah, it might very well be a concern.

You didn't answer the question, you just reiterated that lead is bad.

Is this 40x the chance of getting hit by a comet, or 40 games of Russian roulette.

The study talks about increased blood lead levels ~1 to 1.4 μg/dL. Now how risky is that? The CDC has alert levels for children of 5 ug/dL, recently revised from 10 ug/uL.

What the measurable impact is from 5ug, let alone 1 ug is hotly debated because it is so difficult to asses.

Here is the study they cross reference:

>Our IEUBK model predictions suggested that consuming one egg per day with a lead concentration less than 100 μg/kg, in addition to the model’s default lead exposure from diet and all other sources, would result in estimated GM blood-lead concentration increases of less than 1 μg/dL in children. However, daily consumption of one egg with the highest lead concentration we found in eggs from NYC community gardens (167 μg/kg) would increase GM blood-lead concentrations by 1 to 1.4 μg/dL, and daily consumption of one egg with 300 μg/kg lead would increase GM blood-lead concentrations by as much as 2.4 μg/dL, well above the 1 μg/dL guideline.

The IEUBK model output was also used to estimate the number of eggs children could consume without excessively increasing blood-lead concentrations. Among children 1 – 6 years of age, the model output suggested that an increase in dietary lead intake of up to 5.6 μg/day for 1 to 2 year olds (and slightly larger increases – as much as 7.6 μg/day – for older children), would raise GM blood-lead concentrations by less than 1 μg/dL. This intake translates into the consumption of about 6 medium eggs/day at 20 μg/kg lead, 2.5 eggs/day at 50 μg/kg, or 1.2 eggs/day at 100 μg/kg.

These evaluations implied that, overall, the lead concentrations we found in eggs from NYC community gardens were not likely to significantly increase lead exposure or to pose a significant health risk. However, frequent consumption of eggs with the highest lead concentration we found could significantly increase lead exposure, and chickens exposed to higher concentrations of lead in soil are likely to produce eggs with higher concentrations of lead. This exposure pathway could potentially be significant in some gardens, and it should not be ignored

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4037389/

The CDC has lowered its threshold to 3.5 micrograms/dL https://www.cdc.gov/nceh/lead/news/cdc-updates-blood-lead-re...

All, large cities are filthy, contaminated places. You shouldn't be growing food in random soil you find lying around in them and you shouldn't be raising animals in that soil unless you are carefully managing the sources and exposure of everything.

In old neighborhoods in the US (anything over a century is old in the US) you find the craziest things in the soil. The sheer amount of glass and plastic and metal is staggering. Just digging the holes for ornamental plants was enough to make me realize all food gardening would need to be in raised beds with liners and known soil.

In parts of the world with longer periods of habitation (all of them) what do you find in the soil?

Does anybody know whether fruit & vegetables can contain lead if all external matter is 100% removed or peeled off? i.e do plants suck this stuff up? my parents grow fruit and vegges at home and we live next to a road in a fairly old neighborhood..

Plants don't typically pull lead out of the soil through their roots. Your main concern should be surface contamination from soil getting splashed onto the plant when it's watered / rains

This is why one always rinses plants off before consumption.

Sunflowers are known bioaccumulators.

Here's the standard advice: https://extension.oregonstate.edu/gardening/soil-compost/sho...

If soil lead is sufficiently high, leafy greens and root vegetables are not recommended.

Get a lead test for your backyards then, and raise your chickens with peace of mind

Title could add "in urban Australia" to dissuade the idea that sustainable backyard chickens as a whole are a threat to public health.

Are there any known examples where evolution has produced a solution to a problem like this? I've heard of humans adapting to Malaria and lactose consumption in adulthood.

Also, are there any organisms that don't experience lead as a toxic substance, at least in the way that humans do? That might point to adaptation plausibility.

That makes me wonder - does human sperm or eggs show signs of lead poison as well? Has there been any studies on that?

1. Lead is known to cause certain illnesses, for example cancer / kidney... ? 2. Now wow does the statistic looks like on a massive dataset for group of people eating more eggs than a median, have they got these diseases ???

yes: study has a valid point no: ignore the study, nobody keeps hens in the suburbs & small yard

The study isn't saying that this is a reason to avoid eggs in general, they're saying this is a reason to consider stopping eating eggs from urban backyard chickens.

Or at least get your soil tested.

> noooo you can't just be self sufficient and have your own food, IT'S POISON > buy ours instead

Nah, fuck you. I'll eat my lead eggs, thanks.

>117mg/kg

God forbid the authors spend 60sec to transform the unit into something that is easily visualize-able to the general public. That should be SOP when writing and editing these kinds of press releases.

Density of typical soil is around 1250kg/m^3 so 117mg/kg is ~146g/m^3. Density of lead is 1.34g/cm&^3 so ~146g/m^3 is 110cm^3 or roughly the size of a small container of cough syrup or 3-4 decent sized fishing weights per cubic meter of soil. That's a lot of lead but probably readily attainable under certain circumstances.

  roughly the size of a small container of cough syrup or 3-4 decent sized fishing weights per cubic meter of soil

This does not mean anything to general public either thou. Is it high? Low? How high?

The article says it should be 117mg/kg while guideline is 300mg/kg. Which is pretty clear to me.

[in Australian cities]

amazing how much damage cars have done in 100 years

Translating this from agendese to plain English:

We don't want backyard producers to compete with any of our product lines.

We want to feed the population with what we deem healthy for them, and prevent them from deviating from our approved diet.

Reply on news.ycombinator.com