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.
Contaminated soils don't contain elemental lead. The dominant form is lead oxide, one of the two common additives in lead paint (along with the carbonate) and also the end point of the combustion of TEL in fuel. Lead from lead oxide is easily absorbed orally from soil, paint chips, and household dust, and it's also a serious inhalation hazard.
> sweet tasting lead paint chips
What makes you think lead paint tastes sweet?
> Lead is not mobile in typical soil or water environments
Which is exactly the reason lead-contaminated soils are such a long-lasting hazard. It's the reason little kids playing in the dirt around old houses can be poisoned decades after contamination was laid down. For example, here in Denver entire urban neighborhoods were built on the site of a smelter that was demolished a hundred years ago, and the contamination is still largely unchanged. Remediation requires completely replacing the top several feet of soil.
> There is naturally occurring trace lead in most soils - it’s a somewhat common element.
Significant deposits of lead in surface soil are rare, and are limited to sites with unique geology. The vast majority of distributed lead in surface soils is of human origin.
That sentence in the wikipedia article doesn't cite any sources to support the claim that lead acetate was used in paint. It only links to the article for lead acetate. It's unfortunate but common on wikipedia, and in this case serves only to perpetuate the myth of "sweet paint chips".
See my earlier response to @sokoloff, who helpfully posted an article debunking the myth of sweet paint chips.
Lead acetate is sweet, no doubt, and it is possible that it was used in small quantities as a drier in old oil-based finishes, however I've seen no actual evidence of this, and even if it was, the quantities are unlikely to be sufficient to be detectable at all, especially years later.
When we talk about lead paint, the lead is in the form of pigments such as lead oxides, carbonate, or chromate. These pigments constituted a large propertion of the paint, and it's these pigments that present the lead poisoning hazard.
Lead acetate is not a pigment-- it was only ever used as a drier-- and it would make absolutely no sense to add it in any significant quantity to pigmented paint, because the pigments are themselves very effective driers. And indeed, I've never seen evidence that lead acetate was ever used in any significant quantities in paint.
The legend about the Romans using it to sweeten drinks and sauces is historically verifiable.
I asked a simple and genuine question in the midst of my longer comments. If you think that qualifies as sealioning, then I imagine no discussion forum is a safe place for you.
If you have anything to contribute, I'd actually like to hear it.
Did you not actually read that article? The title is "Lead Paint, Sweet It Ain't", and its entire purpose is to debunk the myth of sweet tasting paint.
Even there, the claims that lead paint sometimes contained small amounts of lead acetate are unsupported. It's true that heavy metal salts have a long history of use as siccatives in oil-based finishes, but the vast majority of lead-based driers were the oxides, because they could serve double duty as pigments. And even if lead acetate were to be used in paint, it wouldn't taste sweet, because it would be bound in the polymer matrix (as your article points out), and there wouldn't be enough of it anyway. Look at the SDS for any oil based finish, and you'll see that metallic diers are added in just tiny amounts.
Regardless, I have never seen historical or scientific evidence that suggests lead acetate was used in any significant amount in paint. If you know of such evidence, I would genuinely love to see it.
> Remediation requires completely replacing the top several feet of soil.
I think the normal recommendation for backyards is several inches, not feet, of soil.
But there's also an alternative: fish bones. They bind the lead so it can't be absorbed well even if ingested. You can buy them by the ton from PIMS NW, Inc: http://www.pimsnw.com/ But you need to spread quite alot of fish bones. As cheap as they are, it's still not very cost effective, especially considering that, excepting extreme industrial contamination, lead-contaminated soil usually goes to a non-hazardous dump site or used for backfill, and rarely to a much more expensive hazardous dump. It's cheaper to haul the dirt away than to haul in tons of fish bones.
The more common chemical abatement technique is amendment with lime. Maybe fish bones are cheaper in some coastal locations, I don't know, but it's interesting.
There's also some evidence that calcium supplements given concurrently with lead exposure could reduce the absorption into sensitive tissues (particularly brain and bones), but I don't know how strong the evidence is.
EDIT:
The depth of excavation is determined based on the expected use of the land, and how deep the contamination extends based on soil sampling. Anecdotally, I know that excavation of residential areas at the smelter superfund site in Pueblo (south of me) extended to two feet around the houses.
Correct - and lead oxide is not tetra ethyl lead, or the nasty lead salts. It isn’t great, but it is also not that much worse than elemental lead from a mobility or toxicity perspective.
And I noted the exact hazard for breathing dusts and vapors, so thanks for repeating it?
It’s also a bit disingenuous to use someone LITERALLY BURNING AND VAPORIZING MASSIVE AMOUNTS OF LEAD, at a huge and industrial scale for a very long time time, as a safety comparison. Of course that is going to make a giant mess. Whoever let them build houses there without it being remediated should be in jail.
It doesn’t change the fact that you essentially have to play every day in a literal superfund site with probably 1000x or more the worrisome levels before it really becomes a serious problem?
Lead isn’t a thing you want to eat or play in. It will mess you up. But let’s not pretend that a little piston plane is going to poison LA in any measurable way because it is flying over it while burning leaded gas.
And thanks for the lead paint chips not being sweet! I personally never tried, so good to know it’s not true
> Correct - and lead oxide is not tetra ethyl lead, or the nasty lead salts. It isn’t great, but it is also not that much worse than elemental lead from a mobility or toxicity perspective.
No, the dominant lead compounds found in soils are much more hazardous than elemental lead. They are much more easily absorbed orally, and elemental lead isn't a realistic inhalation hazard unless you work in an actual smelter.
> It’s also a bit disingenuous to use someone LITERALLY BURNING AND VAPORIZING MASSIVE AMOUNTS OF LEAD, at a huge and industrial scale for a very long time time, as a safety comparison. Of course that is going to make a giant mess. Whoever let them build houses there without it being remediated should be in jail.
The neighborhood is around a hundred years old. The smelter operated in the late 1800's. Who do you propose should be jailed?
> you essentially have to play every day in a literal superfund site with probably 1000x or more the worrisome levels before it really becomes a serious problem?
No, the vast majority of lead poisoning in kids happens in ordinary households. The most common sources of lead in thee poisoning cases are paint dust and chips, dust from vinyl miniblinds, leaded glazes in dishes, stuff like that.
So we agree that leaded gasoline in common use for aviation is not a significant contributor to lead poisoning in the population?
And perhaps that whoever hasn’t red tagged the houses sitting on a well know multi hundred year old superfund site should do so, or is being negligent? And that said site is not representative of literally any other type of situation?
And that eating paint chips is indeed bad for kids - even if they aren’t sweet?
Nope. My original response addressed your bizarre and irrelevant comparison with "elemental lead". You wrote a whole paragraph downplaying the risks of elemental lead. When it was pointed out to you that environment contamination doesn't involve elemental lead, but rather compounds that are much more dangerous, you pretended to know that, but then kept on saying that they're "not that much worse than elemental lead from a mobility or toxicity perspective." If you would just do a bit of reading about this stuff, it would be clear to you that you've been talking a lot of nonsense.
> So we agree that leaded gasoline in common use for aviation is not a significant contributor to lead poisoning in the population?
I have no idea. I never mentioned avgas in this discussion, and I'm not informed enough about it to have an opinion.
> And perhaps that whoever hasn’t red tagged the houses sitting on a well know multi hundred year old superfund site should do so, or is being negligent?
Um, yes... these are superfund sites. By definition, dwellings at risk have been identified and remediation has been ongoing since the 80's. That's like, the whole point. So again, who exactly do you think should be going to prison for this?
> And that said site is not representative of literally any other type of situation?
No, a lot of non-industrial contamination is even more hazardous. As I said before, the vast majority of lead poisoning is due to lead paint and PVC miniblinds. Again, you could easily educate yourself about this if you wanted to.
> And that eating paint chips is indeed bad for kids - even if they aren’t sweet?
Someone else just made a good point though. These planes run full rich a lot which means some of the fuel is not burnt but simply evaporated, cooling the engine.
I still think the amount is so minor as to not cause concern but it's a point.
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.
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.