5 ms·

... so we're just going to slowly build up base-level contamination in the soil, water, and ecosystem? Let's not?

throwaway0a5e 5y ago
I'm not endorsing lead emissions, just pointing out that emitting them not into people is a lot better than emitting them fairly directly into people. While obviously it would not be ideal to evenly distribute lead evenly throughout the surface of the earth lead is a fairly common element and exists in ground deposits more or less worldwide without poisoning people. It's not as common as iron but it was used for all sorts of thing historically specifically because of how common (and therefore cheap) it is/was.
- henearkr 5y ago
  Well, NO, lead tetraethyl is not naturally present. It's a human-made metallo-organic molecule.
lazide 5y ago
Elemental lead is nearly completely insoluble and very difficult to absorb. If entrained in dirt, even more so. Breathing vapors or aerosolized fine powders isn’t great, but uptake even then isn’t high compared to many other toxic substances - that is usually the dominant form however. It usually requires some kind direct ingestion + acid exposure of a significant amount of lead, or breathing in a large quantity of lead vapor or fine dust to get notable exposure. Which is exactly what you get when every car in a city was burning tetra ethyl lead in large quantities, and/or kids were eating sweet tasting lead paint chips. Leaded AVgas is a concern, but dilution of the resulting lead from combustion gets diluted very widely very quickly resulting in actual low concentrations. And since it’s not ‘every car in the LA basin’, it just isn’t at the scope or scale of a problem you’re making it out to be. We’re probably having bigger issues from all the random new stuff companies put into tires (including carbon nanotubes now), which then gets ground up and dispersed as fine power at the million ton scale every day. Lead is not mobile in typical soil or water environments, and as long as the water isn’t strongly acidic, it settles out and stays where it lands. There is naturally occurring trace lead in most soils - it’s a somewhat common element.
- henearkr 5y ago
  Lead tetraethyl is not elemental lead. I think you are mixed up. Lead tetraethyl (the component found in lewded gas) is easily absorbed, it even diffuses through skin to the blood!
  - sokoloff 5y ago
    Once combusted, the exhaust contains primarily lead oxide (PbO), not TEL (C8H20Pb)
    - henearkr 5y ago
      Alright, but it's still not elemental lead. I'll look up PbO, but I'm expecting to be horrified at its harmfulness, rather than be reassured. And neither PbO is "naturally occuring", it's anthropogenous. Naturally occuring Pb species are lead sulfide, sulfate, and carbonate.
      - lazide 5y ago
        Did you find anything? I can't find any evidence it is significantly more toxic (hard to quantify, and most sources didn't seem to try - it all seemed within an order of magnitude or so). At least what I ran across seems to be that the organic lead compounds (aka tetra ethyl lead, among others) are super nasty. Similar to how mercury is not great (and has similar exposure routes), and the common compounds of mercury in soil, etc. are the same - but the organic mercury compounds that occur when mercury is in wetlands environments are super nasty (like 100000x) The EPA mentions on their lead site (albeit backhanded) that runoff, water contamination, etc. is usually not an issue even at heavily contaminated sites. Where you see lead poisoning around drinking water, it is always due to very acidic water conditions which leach/dissolve the lead. This can be from lead pipes pulling water from acidic sources (big no no), or heavily acidic mine runoff going through heavily contaminated sites. The only major concern ground contamination wise seemed to be at smelting sites, which is truly a unique situation - and well know and easy to test for. I did find some evidence that it is also a concern with fly ash, though apparently the other really nasty stuff (including radon, uranium, nasty active chemical species, etc.) overwhelms the lead concern. Places still have to do a ton of paperwork on it though. If you die from fly ash exposure, it isn't going to be due to lead poisoning.

I'm not endorsing lead emissions, just pointing out that emitting them not into people is a lot better than emitting them fairly directly into people. While obviously it would not be ideal to evenly distribute lead evenly throughout the surface of the earth lead is a fairly common element and exists in ground deposits more or less worldwide without poisoning people. It's not as common as iron but it was used for all sorts of thing historically specifically because of how common (and therefore cheap) it is/was.

henearkr 5y ago
Well, NO, lead tetraethyl is not naturally present. It's a human-made metallo-organic molecule.

lazide 5y ago

Elemental lead is nearly completely insoluble and very difficult to absorb. If entrained in dirt, even more so. Breathing vapors or aerosolized fine powders isn’t great, but uptake even then isn’t high compared to many other toxic substances - that is usually the dominant form however. It usually requires some kind direct ingestion + acid exposure of a significant amount of lead, or breathing in a large quantity of lead vapor or fine dust to get notable exposure. Which is exactly what you get when every car in a city was burning tetra ethyl lead in large quantities, and/or kids were eating sweet tasting lead paint chips. Leaded AVgas is a concern, but dilution of the resulting lead from combustion gets diluted very widely very quickly resulting in actual low concentrations. And since it’s not ‘every car in the LA basin’, it just isn’t at the scope or scale of a problem you’re making it out to be. We’re probably having bigger issues from all the random new stuff companies put into tires (including carbon nanotubes now), which then gets ground up and dispersed as fine power at the million ton scale every day. Lead is not mobile in typical soil or water environments, and as long as the water isn’t strongly acidic, it settles out and stays where it lands. There is naturally occurring trace lead in most soils - it’s a somewhat common element.

henearkr 5y ago
Lead tetraethyl is not elemental lead. I think you are mixed up. Lead tetraethyl (the component found in lewded gas) is easily absorbed, it even diffuses through skin to the blood!
- sokoloff 5y ago
  Once combusted, the exhaust contains primarily lead oxide (PbO), not TEL (C8H20Pb)
  - henearkr 5y ago
    Alright, but it's still not elemental lead. I'll look up PbO, but I'm expecting to be horrified at its harmfulness, rather than be reassured. And neither PbO is "naturally occuring", it's anthropogenous. Naturally occuring Pb species are lead sulfide, sulfate, and carbonate.
    - lazide 5y ago
      Did you find anything? I can't find any evidence it is significantly more toxic (hard to quantify, and most sources didn't seem to try - it all seemed within an order of magnitude or so). At least what I ran across seems to be that the organic lead compounds (aka tetra ethyl lead, among others) are super nasty. Similar to how mercury is not great (and has similar exposure routes), and the common compounds of mercury in soil, etc. are the same - but the organic mercury compounds that occur when mercury is in wetlands environments are super nasty (like 100000x) The EPA mentions on their lead site (albeit backhanded) that runoff, water contamination, etc. is usually not an issue even at heavily contaminated sites. Where you see lead poisoning around drinking water, it is always due to very acidic water conditions which leach/dissolve the lead. This can be from lead pipes pulling water from acidic sources (big no no), or heavily acidic mine runoff going through heavily contaminated sites. The only major concern ground contamination wise seemed to be at smelting sites, which is truly a unique situation - and well know and easy to test for. I did find some evidence that it is also a concern with fly ash, though apparently the other really nasty stuff (including radon, uranium, nasty active chemical species, etc.) overwhelms the lead concern. Places still have to do a ton of paperwork on it though. If you die from fly ash exposure, it isn't going to be due to lead poisoning.