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> 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

> 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 4y ago
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 :-)
- unlikelymordant 4y ago
  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 4y ago
    And that's just the lead... https://en.wikipedia.org/wiki/Botany_Bay_Groundwater_Plume 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 4y ago
    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.
- cmrdporcupine 4y ago
  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.
  - selimthegrim 4y ago
    Cotton too no? (and maybe rice if the field is reused) Or was that just elemental arsenic.
  - faceplanted 4y ago
    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?
    - oneplane 4y ago
      It doesn't go away by itself, but you can of course physically move it (including ingesting it).
    - beckingz 4y ago
      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!
    - jefftk 4y ago
      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
    - abdullahkhalids 4y ago
      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.
- duxup 4y ago
  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.
- cmroanirgo 4y ago
  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.
raverbashing 4y ago
I wonder how much of this is from lead paint around buildings

mauvehaus 4y ago

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 :-)

unlikelymordant 4y ago
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 4y ago
  And that's just the lead... https://en.wikipedia.org/wiki/Botany_Bay_Groundwater_Plume 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 4y ago
  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.
cmrdporcupine 4y ago
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.
- selimthegrim 4y ago
  Cotton too no? (and maybe rice if the field is reused) Or was that just elemental arsenic.
- faceplanted 4y ago
  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?
  - oneplane 4y ago
    It doesn't go away by itself, but you can of course physically move it (including ingesting it).
  - beckingz 4y ago
    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!
  - jefftk 4y ago
    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
  - abdullahkhalids 4y ago
    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.
duxup 4y ago
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.
cmroanirgo 4y ago
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.

raverbashing 4y ago

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