4 ms·

One in four US households likely exceed new soil lead guidance levels

44 points by geox 2y ago

nayuki 2y ago
I found this point interesting: > With the Clean Air and Clean Water Acts, US policy began severely limiting the production and use of lead in infrastructure and consumer products, including water pipes, paint, and gasoline that have been historical sources of lead entry into the environment.
- ttyprintk 2y ago
  Water providers right now are digitizing records so all lead service lines can be tracked and removed. Curious about deteriorating gas stations and underground oil tanks.
ttyprintk 2y ago
I have a feeling mercury and arsenic will prompt a lot of people to follow the cover and mulch recommendations in this. Many lush suburbs were downwind of a coal plant which contaminated the surface beyond the safe levels for vegetable gardening.
elromulous 2y ago
"...far cheaper strategy: capping current soils with clean soils and/or mulch" Oh yes, cover the thing up and let someone else deal with it. The same strategy employed for years with lead paint. We can either spend billions covering it up over and over again, or we can deal with it once and be done.
- JumpCrisscross 2y ago
  > or we can deal with it once and be done What does this mean? Dismantling the community and replacing everything above the bedrock?
  - maxbond 2y ago
    You could probably decontaminate the soil in place by cultivating plants that bioaccumulate the lead, harvesting them, burning them, and then disposing of a relatively small volume of ash into which the lead had been concentrated. There's sure to be complications, I can think of a few and I'm not an expert, but you wouldn't necessarily have to rip out everything.
    - JumpCrisscross 2y ago
      > could probably decontaminate the soil in place by cultivating plants that bioaccumulate the lead, harvesting them, burning them, and then disposing of a relatively small volume of ash into which the lead had been concentrated Is this a random guess or based on anything? What rate does it remove at? You’ll need to depopulate a quarter of American housing during that period. Are we sure none of the lead will emerge in the volatiles from burning?
      - maxbond 2y ago
        Based on coursework I did years ago. I could've given you more information back then but it's been a while. You would definitely need to look into the lead coming out the chimney; if it does, you just dry the material and accept less concentration. (Or use a more complex technology like a molten salt reactor to keep it from escaping the chimney, but if it's eg concentrating in the leaves, drying it out is probably almost as effective as burning it.) You only need to kick people out of their homes if the soil is so dangerous they can't live there anyway. You're not disturbing the soil more than gardening would. There would definitely be huge challenges, my main point is that it's a naive assumption that you necessarily have to relocate people to remediate the soil. It doesn't necessarily have to work quickly as much as steadily. If you can do it in 10 years by relocating people and 100 years without, it probably makes sense to go the slow route and the soil will get less and less dangerous all the time. If you're curious, you might look up bioremediation and biomining.
        JumpCrisscross 2y ago
- zdragnar 2y ago
  Poorly remediating lead paint is more dangerous than just painting over it. Same thing is true with asbestos. Capping leaded soil isn't great, in that you can't look at dirt and guess that it's old enough to probably be bad the way you can with paint or tile, and many plants tend to have deep roots that'll suck the lead right back up to the surface. That said, so long as it is disclosed properly to future occupants, it's better than doing a bad job (accidentally or otherwise) and telling everyone it's been taken care of.
- _heimdall 2y ago
  This is likely an over simplification. Adding healthy soil, compost, and/or wood chips promotes bacterial and fungal activity. I'd rather people didn't bury garbage, and bacteria won't eat glass anytime soon, but it isn't as simple as assuming that covering waste in wood chipsakes it someone else's problem.
- marklubi 2y ago
  > Oh yes, cover the thing up and let someone else deal with it. The same strategy employed for years with lead paint. If lead paint is sequestered, it poses no threat. When you start trying to scrape all of it off and replace it is the point at which you've now exposed yourself and everyone that might inhale some of that dust. Same thing with asbestos. As long as it's somewhere that you won't inhale/ingest it, there isn't a problem. Asbestos brake pads, problem. Asbestos siding on a house, only a problem if you're doing construction that disrupts it. Similarly, if you have a location with high levels of lead in the dirt or are concerned about it, perhaps you should import soil and do some raised bed planting.
ImaCake 2y ago
I think this says more about the guidance level than the soil quality. In fact I think it makes things worse rather than better. Continually ratcheting up the safety level to spur continuous improvement is great in principle. But what I think this does in practice is mean that people are no longer able to evaluate soil lead levels appropiately. What does 400ppm mean versus say 1600ppm? They are both "bad" according to the US EPA now but one is clearly worse. If 10% of soil area is above your limit it is easier to allocate your limited resources to fix it than if 25% is. At 25%, with the same resources maybe you just throw up your hands and walk away from the problem. There's similar problems with air quality limits. When the WHO says there is "no safe limit" they simulatenously misunderstand odds ratios and give a lot of people a great excuse to stop worrying about a problem they now think is unfixable.
- refurb 2y ago
  This is a very insightful comment. Analytical techniques have rapidly improved over the past few decades. Our limit of detection has gone from tens of parts per million (ppm) to fractions of parts per trillion (ppt) for many analytes. That's a million fold better detection level. So in the past you might test drinking water and say there is no lead present. You test using techniques today and you'll find lead is present. But the level hasn't changed. At the sensitivity of parts per trillion you'll find the presence of toxins in damn near everything. People forget that toxins like lead, arsenic are naturally occurring. And pushing "acceptable levels" down as detection improves needs to be done based on proven biological effect, not "no level is safe".
  - ImaCake 2y ago
    I think these guidelines are also a political problem. They need to balance risk, communication, and what is feasible given the resources available and threat level. That’s not an easy thing to do. Still I am deeply skeptical that the people publishing these guidelines are considering these aspects effectively when their lead guideline puts 25% of residential areas in the US “at risk”.
    - 2y ago
mtgentry 2y ago
My backyard was full of broken glass, metal, and plastic, buried about a foot deep. The previous owners had buried lots of trash in random holes they dug all over the yard. I spent the past few months sifting it all out and putting back the “good” soil. Now, I wonder if I should have just thrown it all away.
- londons_explore 2y ago
  If you plan to grow edible vegetables, lay a new layer of fresh soil over the top.
deleted 2y ago
[deleted]

44 points by geox 2y ago

I found this point interesting: > With the Clean Air and Clean Water Acts, US policy began severely limiting the production and use of lead in infrastructure and consumer products, including water pipes, paint, and gasoline that have been historical sources of lead entry into the environment.

ttyprintk 2y ago
Water providers right now are digitizing records so all lead service lines can be tracked and removed. Curious about deteriorating gas stations and underground oil tanks.

ttyprintk 2y ago

I have a feeling mercury and arsenic will prompt a lot of people to follow the cover and mulch recommendations in this. Many lush suburbs were downwind of a coal plant which contaminated the surface beyond the safe levels for vegetable gardening.

elromulous 2y ago

"...far cheaper strategy: capping current soils with clean soils and/or mulch" Oh yes, cover the thing up and let someone else deal with it. The same strategy employed for years with lead paint. We can either spend billions covering it up over and over again, or we can deal with it once and be done.

JumpCrisscross 2y ago
> or we can deal with it once and be done What does this mean? Dismantling the community and replacing everything above the bedrock?
- maxbond 2y ago
  You could probably decontaminate the soil in place by cultivating plants that bioaccumulate the lead, harvesting them, burning them, and then disposing of a relatively small volume of ash into which the lead had been concentrated. There's sure to be complications, I can think of a few and I'm not an expert, but you wouldn't necessarily have to rip out everything.
  - JumpCrisscross 2y ago
    > could probably decontaminate the soil in place by cultivating plants that bioaccumulate the lead, harvesting them, burning them, and then disposing of a relatively small volume of ash into which the lead had been concentrated Is this a random guess or based on anything? What rate does it remove at? You’ll need to depopulate a quarter of American housing during that period. Are we sure none of the lead will emerge in the volatiles from burning?
    - maxbond 2y ago
      Based on coursework I did years ago. I could've given you more information back then but it's been a while. You would definitely need to look into the lead coming out the chimney; if it does, you just dry the material and accept less concentration. (Or use a more complex technology like a molten salt reactor to keep it from escaping the chimney, but if it's eg concentrating in the leaves, drying it out is probably almost as effective as burning it.) You only need to kick people out of their homes if the soil is so dangerous they can't live there anyway. You're not disturbing the soil more than gardening would. There would definitely be huge challenges, my main point is that it's a naive assumption that you necessarily have to relocate people to remediate the soil. It doesn't necessarily have to work quickly as much as steadily. If you can do it in 10 years by relocating people and 100 years without, it probably makes sense to go the slow route and the soil will get less and less dangerous all the time. If you're curious, you might look up bioremediation and biomining.
      - JumpCrisscross 2y ago
zdragnar 2y ago
Poorly remediating lead paint is more dangerous than just painting over it. Same thing is true with asbestos. Capping leaded soil isn't great, in that you can't look at dirt and guess that it's old enough to probably be bad the way you can with paint or tile, and many plants tend to have deep roots that'll suck the lead right back up to the surface. That said, so long as it is disclosed properly to future occupants, it's better than doing a bad job (accidentally or otherwise) and telling everyone it's been taken care of.
_heimdall 2y ago
This is likely an over simplification. Adding healthy soil, compost, and/or wood chips promotes bacterial and fungal activity. I'd rather people didn't bury garbage, and bacteria won't eat glass anytime soon, but it isn't as simple as assuming that covering waste in wood chipsakes it someone else's problem.
marklubi 2y ago
> Oh yes, cover the thing up and let someone else deal with it. The same strategy employed for years with lead paint. If lead paint is sequestered, it poses no threat. When you start trying to scrape all of it off and replace it is the point at which you've now exposed yourself and everyone that might inhale some of that dust. Same thing with asbestos. As long as it's somewhere that you won't inhale/ingest it, there isn't a problem. Asbestos brake pads, problem. Asbestos siding on a house, only a problem if you're doing construction that disrupts it. Similarly, if you have a location with high levels of lead in the dirt or are concerned about it, perhaps you should import soil and do some raised bed planting.

ImaCake 2y ago

I think this says more about the guidance level than the soil quality. In fact I think it makes things worse rather than better. Continually ratcheting up the safety level to spur continuous improvement is great in principle. But what I think this does in practice is mean that people are no longer able to evaluate soil lead levels appropiately. What does 400ppm mean versus say 1600ppm? They are both "bad" according to the US EPA now but one is clearly worse. If 10% of soil area is above your limit it is easier to allocate your limited resources to fix it than if 25% is. At 25%, with the same resources maybe you just throw up your hands and walk away from the problem. There's similar problems with air quality limits. When the WHO says there is "no safe limit" they simulatenously misunderstand odds ratios and give a lot of people a great excuse to stop worrying about a problem they now think is unfixable.

refurb 2y ago
This is a very insightful comment. Analytical techniques have rapidly improved over the past few decades. Our limit of detection has gone from tens of parts per million (ppm) to fractions of parts per trillion (ppt) for many analytes. That's a million fold better detection level. So in the past you might test drinking water and say there is no lead present. You test using techniques today and you'll find lead is present. But the level hasn't changed. At the sensitivity of parts per trillion you'll find the presence of toxins in damn near everything. People forget that toxins like lead, arsenic are naturally occurring. And pushing "acceptable levels" down as detection improves needs to be done based on proven biological effect, not "no level is safe".
- ImaCake 2y ago
  I think these guidelines are also a political problem. They need to balance risk, communication, and what is feasible given the resources available and threat level. That’s not an easy thing to do. Still I am deeply skeptical that the people publishing these guidelines are considering these aspects effectively when their lead guideline puts 25% of residential areas in the US “at risk”.
  - 2y ago

mtgentry 2y ago

My backyard was full of broken glass, metal, and plastic, buried about a foot deep. The previous owners had buried lots of trash in random holes they dug all over the yard. I spent the past few months sifting it all out and putting back the “good” soil. Now, I wonder if I should have just thrown it all away.

londons_explore 2y ago
If you plan to grow edible vegetables, lay a new layer of fresh soil over the top.

deleted 2y ago

[deleted]