Wouldn’t this type of concentration happen directly as a result of any irrigation system? If you keep transferring water to the same land, anything that doesn’t get absorbed by plant matter and picked or evaporate would stay in the soil. So without some other process to leech the metals, it’d keep building up. Main determinant would be the baseline rate of the source water.
Nopoint2 2 hours ago [-]
Why wouldn't they accumulate by natural processes exactly the same?
When you look at the ice cores, the "emissions" were higher just before the last glacial maximum.
The only reason why the metals weren't there 5000 years ago was that the soils had gotten recently stripped. The whole concept was invented by insane people.
giraffe_lady 2 hours ago [-]
When there's a natural process that consistently brings groundwater into a place where it evaporates you do see exactly this. Flood plains, salt flats, vernal pools, dry lake beds etc.
AnimalMuppet 36 minutes ago [-]
Irrigation water (especially if pumped from aquifers) may have more metals in it than rainwater.
Robotbeat 4 hours ago [-]
It should be pointed out that some of the natural levels of heavy metals are somewhat toxic as well.
ziddoap 3 hours ago [-]
This is pointed out in the article:
"“The widespread distribution of cadmium contamination comes from both natural and anthropogenic sources,”"
"“Geochemically, certain parent rock materials [substrate below the ground], such as black shales, contain high levels of cadmium, leading to elevated concentrations in the soil due to weathering.”"
"However, the study does not assign blame to either natural or human causes."
Robotbeat 2 hours ago [-]
Yeah, natural or human caused, it’s toxic. Sometimes in modernity, we forget that Nature Herself is massively dangerous.
hilbert42 2 hours ago [-]
Right, both Nature and life itself are dangerous, they conspire together and eventually kill us. :-)
hilbert42 3 hours ago [-]
Right, for example naturally occurring arsenic, which is commonly found in soils across large areas of the planet, can be dangerous if concentrated.
To put that into perspective, I recall seeing one estimate that put the typical levels of arsenic in a cubic meter of soil that if concentrated would kill the average human.
Now, a cubic meter of soil is a very large amount, so the effective concentration is what actually counts. How relevant to human health is this 'typical' amount/quantity? Well, I don't know as it's not my field. I'd suggest however it cannot have a big effect on human health as we've lived and evolved for hundreds of millennia with that level of arsenic in soils—that's long before anthropogenic sources would have had time to kick in.
That said, we know that in some locations natural arsenic levels are high enough to cause significant health problems, in fact sometimes concentrations are so high as to be life-threatening. Such high levels are especially dangerous when leached out of rocks and soils and they end up in water supplies (contaminated bore water being the main culprit, it's a well-known problem).
dyauspitr 3 hours ago [-]
That’s why I only buy basmati rice from India because it has by far some of the lowest levels of arsenic in the world.
sevensor 1 hours ago [-]
I’d heard US rice was heavily contaminated with arsenic due to having been planted in regions that formerly grew cotton. And cotton was once treated with arsenates to control boll weevil (https://a-c-s.confex.com/a-c-s/2005am/techprogram/P4552.HTM)
I was surprised not to see this reflected in the map
dyauspitr 1 hours ago [-]
US, Chinese and Bangladeshi rice have the highest levels. Especially in brown rice.
Strangely California white basmati has relatively low levels.
toast0 1 hours ago [-]
California rice having low levels fits with sevensor's theory about boll weevil control with arsenates on fields used for cotton and later for rice. This report [1] says that boll weevils weren't an issue in California cotton fields, and that likely means arsenates wouldn't have been used, so if those fields switch to rice, they won't have high levels of arsenic from previous insecticide application.
In researching nutrition and organic agriculture, I formed an interesting hypothesis. Various fruits and vegetables are often touted as being "rich in X" or "high in Y" and therefore lists are drawn up for people seeking a particular vitamin or nutrient or mineral.
Now plants can synthesize certain vitamins and there's no doubt that citrus is high in Vitamin C, for example. But many minerals must be drawn out of the soil where something is grown. So are all <X> high in selenium? What about historically selenium-impoverished areas? What about cropland that's been depleted after decades of use? Still the same selenium in there?
I've decided that without constant analysis and assay of each and every plant, you can't really tell the composition of what we're finding in our groceries. It's the winegrower's concept of terroir, that is, the soil, the environment, the climate, all contributing to the makeup of the final product.
This line of reasoning was enough to send me to a regime of supplementation. Unfortunately it is also impossible for my HCPs to track or validate any intake, baseline, or improvements to attribute to the supplements, so I terminated them just as abruptly. But it was a good thought. I think anyone who needs a particular nutrient should supplement with it, rather than try and derive it from diet alone, in light of this.
And also we cannot get too uptight about toxins in food, because that's just a neverending bugaboo that could simply kill us from anxiety more than anything else!
hilbert42 2 hours ago [-]
"And also we cannot get too uptight about toxins in food, because…"
Nevertheless, I continue to be concerned about whether I'm exposed to too higher levels of mercury. Trouble is I love eating those small cans of tuna and by my estimate I eat too many of them.
Are my levels of methyl mercury too high? All I can say is that I don't know. That I'm still compos mentis enough to write this could perhaps be a rough indicator. :-)
njarboe 1 hours ago [-]
Do you spend extra for albacore? That usually has higher levels of mercury than regular canned tuna (skipjack).
goda90 3 hours ago [-]
For selenium specifically, Wikipedia[0] talks about how regions with low soil selenium can cause issues for animals and a need for supplementing them.
Per best available science about, when presented with otherwise equal choices, I'll avoid grains from fields previously used for cotton. So California over Texas, Missouri. (Obviously, my preferences will change as (my understanding of) the best available science matures.)
To your point, I do think my mental health would improve were I blissfully ignorant.
tough 1 hours ago [-]
ignorance is bliss
specialist 3 hours ago [-]
Soil science continues to march forward. Noob me trusts we'll invent ways to mitigate metals and metalloids (and toxins in general).
It could prove to be as easy as novel fertilizers and soil amendments.
Much like how Zeke Hausfather is researching how to leverage agriculture to accelerate carbon capture.
"What's the deal with enhanced rock weathering to store CO2?" [2025-02-07]
Surely there's (economical) ways to neutralize toxins in place. Storing them in compounds which are no longer bio-available.
IIRC the term of art is bio-remediation.
andy99 4 hours ago [-]
I don't like this headline that implies something but doesn't say any thing. So? What if anything are the implications on people? I skimmed the article and didn't see anything about that. It sounds bad, any "toxic levels" sound bad, but is it?
ecocentrik 4 hours ago [-]
Let me direct you to a short story by Jorge Luis Borges titled "Del rigor en la ciencia" or "On Exactitude in Science".
If every article contained every bit of prior knowledge required to understand the article, the average article length would be 3000 pages and all articles would be prefaced with a guide to language.
redczar 4 hours ago [-]
Shouldn’t it be assumed that toxic is bad? We’ve polluted the whole planet. Our trajectory has obvious long term negative consequences. Are we going to say to each piece of evidence, “Is it really that bad?”.
Edd314159 3 hours ago [-]
Sure, "toxic" is word that means bad things. But I don't think you read the article.
It only talks about the levels in the soil. It says nothing about what impact this has on the food we eat from that soil (in fact it explicitly states that the level in food was not measured).
It also doesn't quite agree with your use of the word "we". The article does not conclude whether the elevated levels of metals were down to natural processes or humans (e.g. it suggests that weathering could be at least a contributing factor).
I get what you're saying, if someone says something is "toxic", it means something somewhere is at a level which is dangerous in some context. But the original comment on what the article itself is saying is not wrong. There is no information on real-world implications.
hilbert42 23 minutes ago [-]
"It also doesn't quite agree with your use of the word "we". The article does not conclude whether the elevated levels of metals were down to natural processes or humans…"
That point is key from the perspective that natural levels of dangerous metals act as a reference for comparison.
That said, science tells us that some elements are both toxic and carcinogenic and that humans have contributed to their increased levels in the environment is not in any doubt.
The dangers heavy metals from anthropogenic sources pose to human health depends on many, factors, location, concentration, dispersabity, etc.
The point the article makes about "chromium (in its highly toxic hexavalent form, often released by leather tanning and pigment industries)…" is particularly poignant for me. I recall seeing a documentary on WWI military archeology—a new factory was being built in Belgium over a WWI battlefield. When builders discovered soldiers' graves during construction work had to stop until all archeological evidence had been collected and documented.
The grave of one soldier was particularly revealing, except for his skeleton, his boots and a small purse containg a few coins nothing much else remained. What's particularly interesting and relevant to this discussion is that his leather boots were in almost perfect condition, so too was his tiny leather purse.
That these articles were still so intact after nearly 100 years underground was directly because of the high levels chromium used in the tanning of the leather. The chromium was so toxic that after all that time microorganisms were still unable to attack the leather without being killed. (I found this distressing to watch because of the almost pristine condition of those leather items, especially so the purse with its tiny cache of small coins, they vividly brought home the tragedy that had befallen this poor unfortunate soldier.)
Moreover, it also brought home the fact that one didn't have to know an iota of chemistry to know hexavalent chromium is highly toxic. It was so damn obvious.
That said, it's clear from the nature and location of the chromium that it's been largely contained at its source, if it had been dispersed widely then the concentration would have fallen by a significant amount, by now the residual level would such that microorganisms would have been able to attack the leather.
We have to use forensic evidence such as this on a wide scale to ascertain the actual danger these heavy metals pose to human health.
redczar 1 hours ago [-]
I did read the article. It’s always the same response: “Can you show this is bad?”, where this is microplastics, metals in the soil, forever chemicals, etc. At some point we will we get to the stage where the standard response is, “Yes it’s bad but there’s nothing we can do about it.”
ekianjo 3 hours ago [-]
Toxicity is not a binary property.
redczar 1 hours ago [-]
Would you drink a glass of toxic water?
ziddoap 4 hours ago [-]
>It sounds bad, any "toxic levels" sound bad, but is it?
If it wasn't bad, it wouldn't be stated as "toxic levels".
Robotbeat 4 hours ago [-]
Are we talking regulatory limits or LD50 limits? Usually regulatory limits are much stricter than any tangibly toxic effect. (Which isn’t necessarily irrational, because it gives a safety margin to account for measurements being sparse.)
xhkkffbf 4 hours ago [-]
Toxicity depends upon the amount. CO2 is toxic and regularly kills humans when space heaters fail. But it's everywhere in the atmosphere in small amounts.
barbazoo 3 hours ago [-]
You probably mean CO and not CO2. CO2 can be toxic but isn’t related to space heaters.
AlexandrB 3 hours ago [-]
When I think "space heater" I imagine one of those electric things you put in a cold room. So I'm not sure where CO or CO2 would be coming from.
zdragnar 3 hours ago [-]
Plenty of space heaters that burn propane are available. They're especially handy for hunting shacks and ice fishing houses.
Alas, some people will occasionally use them indoors with poor ventilation, which is a Bad Idea.
barbazoo 2 hours ago [-]
I gave them the benefit of the doubt and assumed they meant some sort of gas heater.
ekianjo 3 hours ago [-]
Gas heaters exist as well. This is presumably what the above poster referred to
cess11 4 hours ago [-]
[flagged]
dcminter 3 hours ago [-]
Well, it depends. Is the alternative the same people starving to death?
When you look at the ice cores, the "emissions" were higher just before the last glacial maximum.
The only reason why the metals weren't there 5000 years ago was that the soils had gotten recently stripped. The whole concept was invented by insane people.
"“The widespread distribution of cadmium contamination comes from both natural and anthropogenic sources,”"
"“Geochemically, certain parent rock materials [substrate below the ground], such as black shales, contain high levels of cadmium, leading to elevated concentrations in the soil due to weathering.”"
"However, the study does not assign blame to either natural or human causes."
To put that into perspective, I recall seeing one estimate that put the typical levels of arsenic in a cubic meter of soil that if concentrated would kill the average human.
Now, a cubic meter of soil is a very large amount, so the effective concentration is what actually counts. How relevant to human health is this 'typical' amount/quantity? Well, I don't know as it's not my field. I'd suggest however it cannot have a big effect on human health as we've lived and evolved for hundreds of millennia with that level of arsenic in soils—that's long before anthropogenic sources would have had time to kick in.
That said, we know that in some locations natural arsenic levels are high enough to cause significant health problems, in fact sometimes concentrations are so high as to be life-threatening. Such high levels are especially dangerous when leached out of rocks and soils and they end up in water supplies (contaminated bore water being the main culprit, it's a well-known problem).
I was surprised not to see this reflected in the map
Strangely California white basmati has relatively low levels.
https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Cotton_Pro...
Now plants can synthesize certain vitamins and there's no doubt that citrus is high in Vitamin C, for example. But many minerals must be drawn out of the soil where something is grown. So are all <X> high in selenium? What about historically selenium-impoverished areas? What about cropland that's been depleted after decades of use? Still the same selenium in there?
I've decided that without constant analysis and assay of each and every plant, you can't really tell the composition of what we're finding in our groceries. It's the winegrower's concept of terroir, that is, the soil, the environment, the climate, all contributing to the makeup of the final product.
This line of reasoning was enough to send me to a regime of supplementation. Unfortunately it is also impossible for my HCPs to track or validate any intake, baseline, or improvements to attribute to the supplements, so I terminated them just as abruptly. But it was a good thought. I think anyone who needs a particular nutrient should supplement with it, rather than try and derive it from diet alone, in light of this.
And also we cannot get too uptight about toxins in food, because that's just a neverending bugaboo that could simply kill us from anxiety more than anything else!
Nevertheless, I continue to be concerned about whether I'm exposed to too higher levels of mercury. Trouble is I love eating those small cans of tuna and by my estimate I eat too many of them.
Are my levels of methyl mercury too high? All I can say is that I don't know. That I'm still compos mentis enough to write this could perhaps be a rough indicator. :-)
[0]https://en.wikipedia.org/wiki/Selenium#Deficiency
Well said.
I'm anxious, rightly or wrongly, about arsenic.
Per best available science about, when presented with otherwise equal choices, I'll avoid grains from fields previously used for cotton. So California over Texas, Missouri. (Obviously, my preferences will change as (my understanding of) the best available science matures.)
To your point, I do think my mental health would improve were I blissfully ignorant.
It could prove to be as easy as novel fertilizers and soil amendments.
Much like how Zeke Hausfather is researching how to leverage agriculture to accelerate carbon capture.
"What's the deal with enhanced rock weathering to store CO2?" [2025-02-07]
https://www.volts.wtf/p/whats-the-deal-with-enhanced-rock
https://thebreakthrough.org/people/zeke-hausfather
Surely there's (economical) ways to neutralize toxins in place. Storing them in compounds which are no longer bio-available.
IIRC the term of art is bio-remediation.
If every article contained every bit of prior knowledge required to understand the article, the average article length would be 3000 pages and all articles would be prefaced with a guide to language.
It only talks about the levels in the soil. It says nothing about what impact this has on the food we eat from that soil (in fact it explicitly states that the level in food was not measured).
It also doesn't quite agree with your use of the word "we". The article does not conclude whether the elevated levels of metals were down to natural processes or humans (e.g. it suggests that weathering could be at least a contributing factor).
I get what you're saying, if someone says something is "toxic", it means something somewhere is at a level which is dangerous in some context. But the original comment on what the article itself is saying is not wrong. There is no information on real-world implications.
That point is key from the perspective that natural levels of dangerous metals act as a reference for comparison.
That said, science tells us that some elements are both toxic and carcinogenic and that humans have contributed to their increased levels in the environment is not in any doubt.
The dangers heavy metals from anthropogenic sources pose to human health depends on many, factors, location, concentration, dispersabity, etc.
The point the article makes about "chromium (in its highly toxic hexavalent form, often released by leather tanning and pigment industries)…" is particularly poignant for me. I recall seeing a documentary on WWI military archeology—a new factory was being built in Belgium over a WWI battlefield. When builders discovered soldiers' graves during construction work had to stop until all archeological evidence had been collected and documented.
The grave of one soldier was particularly revealing, except for his skeleton, his boots and a small purse containg a few coins nothing much else remained. What's particularly interesting and relevant to this discussion is that his leather boots were in almost perfect condition, so too was his tiny leather purse.
That these articles were still so intact after nearly 100 years underground was directly because of the high levels chromium used in the tanning of the leather. The chromium was so toxic that after all that time microorganisms were still unable to attack the leather without being killed. (I found this distressing to watch because of the almost pristine condition of those leather items, especially so the purse with its tiny cache of small coins, they vividly brought home the tragedy that had befallen this poor unfortunate soldier.)
Moreover, it also brought home the fact that one didn't have to know an iota of chemistry to know hexavalent chromium is highly toxic. It was so damn obvious.
That said, it's clear from the nature and location of the chromium that it's been largely contained at its source, if it had been dispersed widely then the concentration would have fallen by a significant amount, by now the residual level would such that microorganisms would have been able to attack the leather.
We have to use forensic evidence such as this on a wide scale to ascertain the actual danger these heavy metals pose to human health.
If it wasn't bad, it wouldn't be stated as "toxic levels".
Alas, some people will occasionally use them indoors with poor ventilation, which is a Bad Idea.