But I wonder how much salt is mined. Only one sample was plastic-free. But maybe it's mostly commingled. If one were really interested, one could look at plastic content vs Cl-36 (nuclear fallout) level.
I don't know about their selection, but most table salt here is pumped out of the ground in Windsor. When I want coarse salt I just mix some table salt with water and dry it like seawater.
> The size of the smallest particle was 160 μm and the largest sized 980 μm.
This was shocking to me, that they could miss a millimetre-scale particle of plastic in salt seems bonkers. I mean, you can more or less just filter things that size!
They really ought to have put that in the title. They could have easily said "the presence of microplastics in saltwater salts from different countries".
Possibly so, but this is filed as environmental monitoring, so I think most people in the field this article is written for wouldn't have your same uncertainty.
Salt derived from underground sources wouldn't be at risk of microplastics contamination.
Well, but there might be other sources for plastic contamination, as they discuss. And there "is" nothing in the article with evidence for origin. Or even a statement like "We tested samples of lake and sea salt." Only those two lake salts are mentioned specifically. Maybe it's just an oversight, but it could also be just their assumptions. Maybe it's really "We tested samples of salt that were presumably produced from lake water and seawater."
OK, so I just went back and read carefully about that point. I don't think that they actually say clearly that they looked only at sea and lake salt. They talk about contamination pathways for sea and lake salt. And they mention lake salt from Malaysia and Iran. But Methods has:
> A total of 17 brands of salt from Australia, France, Iran, Japan, Malaysia, New Zealand, Portugal, and South Africa were purchased from a Malaysian market.
That confirms that they assume all their table salt is from water. I have only skimmed the article, so I may be missing something, but the only origin information I saw was country of origin and that they "were purchased from a Malaysian market". If the researchers actually confirmed that each brand came from water and not a mine, they don't mention that that I can see. If I've missed something, please let me know.
To be honest, I wonder if "purchased from a Malaysian market" might not be a factor here, and if the products are truly from Australia, France, Japan, New Zealand, Portugal, etc.
Sorry for double comment, just wanted to mention a thought about the filtration:
You can filter them - and they certainly do - but with sea and lake salts the filtration is mainly to screen out sediments such as sand grains and bits of shell. Naturally, the filtering is a costly process and the filters need to be discarded after a certain level - I imagine there is a cost-control factor here, where screening at a 1mm threshold catches 99.9% of sediments to make the product reach a certain purity level and more thresholds are not worth the money.
Further screening is probably not cost effective - and seeing from the results of the study, plastic microparticles are not a source of concern.
I thought of that too, but the expense of operation is very likely not worth it to the producers. The low level of plastic contamination would not seem likely to produce health hazards.
Not at industrial scale for fine plastic particulates. It's OK for continuous removal of denser coarse particles > 1mm but wouldn't be good for separating plastics with approximately neutral density since it wouldn't separate efficiently. Big industrial centrifuges are static (no moving parts) and operate purely by high speed liquid flow in a spiral path (like spinning a bucket of sand and water where the heavy particles collect in the centre).
In the brewing industry we use Kieselguhr (perlite) filtration with filters like this: https://www.ryebeckltd.com/current-equipment/schenk-kieselgu.... These can sterile filter particles as small as 1 micron and are density-independent. These work by having a steel plate with fine slots upon which you deposit a coarse bed of filter material, and then you dose kieselguhr into the liquid flow passing through, and this gradually builds up on top of the coarse bed to create an ultrafine filter. The ultrafine filter increases in depth over time, and this prevents blinding (blocking) of the filter as filtered particulates accumulate. While used to remove yeast and other particulates in brewing to create "bright" beer, it can be applied to most liquid filtration problems, and at high flow rates (30000 litres/hr); and you can run multiple filters in parallel to further increase the flow rates. We also used kieselguhr in research labs for fine filtration--just add the powder to regular filter paper.
Interesting! How do you ensure enough kieselguhr is flowing into the mix to regenerate new layers of filter? Is it just based on periodic measurement of the end product, or is there some calculation or continuous feedback used?
It's added at a constant rate to the liquid entering the filter, so it builds up at a constant rate. However, this can be varied depending upon the filter backpressure. If the particulate load is high, you need to dose at a higher rate or else the filter will start to blind.
In practice this is based upon manual calculation and adjustment. In the place I worked, the filter room had two of these, each about 1.5 storeys high. It had a dedicated control room to operate, and the two operators would be continuously monitoring and adjusting the flow rates, dosing and other parameters to ensure efficient operation. When you have an unexpectedly dirty product or you muck up the calculations, the flow rates can become very low and that starts to cost serious amounts of money when it's a rate-limiting step in an industrial process.
When the filter becomes too inefficient, the backpressure excessively high, or the filter depth approaches the tank capacity, the metal filter plate is spun and this destroys the filter bed which is spun off. The coarse filter base is then reapplied to "regenerate" the filter.
Well, they could dissolve, filter and evaporate. But that would be energy expensive. I'm guessing that they crush and fractionate by size. Air flow separation could do it, but nobody cares enough.
I sometimes buy "himalayan salt" which are coarse salt in almost pebble sizes (presumably from the himalaya) and I actually found a pebble in a package once. Well above 2 square millimetres.
A lot of the salt (~80%) produced in the US goes to road salt and chemical industries. For roads it's better if it's in rock form, so a lot (if not most) is mined. For chemical industry they can often re-use brining wells to hold other things later, so the great majority of chemical salt is brined.
Of all the salt production methods, non-brine mined salts have the least toxic or harmful byproducts - at the source. But they still go through processing plants to sift, grind and package the salt, and not every processing plant has the same quality standards. If you wanted to get really picky about it you should choose a mined, non-brine, non-processed, non-refined salt produced at a facility that follows modern standards. The easiest to identify would be "himalayan" salt, but many countries have ancient lake/sea beds and mine and produce salt in the same way.
In general, you can't tell how salt was produced unless the company very explicitly tells you. Even kosher and sea salt sometimes is processed or refined with additives or in a way that could introduce MPs. (In case it helps, only some places like Australia and the mediterranean have the right environment to solar-evaporate sea salt at a commercial scale)
> The abundance of MPs per salt sample ranged from 0 per kg in the salt sample # France-F (i.e. Country of origin: France, brand F) to 10 in the salt sample # Portugal-N
I guess I'll keep buying the French Gros Sel de Guérande from world market, plus the fact that it tastes really good when sprinkled on meat :)
It tastes good indeed, but in figure 3, France had 5 other brands containing some plastic polymers and/or pigment particles ... I now wonder from which brand is that F sample (clue : apparently packaged in a Glass container)
Anyway the conclusion rather place the problem, not on the consumption of those salts, but in the gradual accumulation in products from the aquatic environments.
I happen to be trading in a fair bit of Fleur de Sel from Guérande, and can assure you that any difference between Portugal and our product can only be either chance, or almost deliberate efforts to sabotage the Portuguese product.
They both start with the same "raw material": water of the Northern Atlantic, which I would think is mixed enough not be significantly different in these two locations. Guérande is probably one of the largest locations for sea salt, but the processes are far away from industrial scale. They manually remove contamination that they see, but I've found a few fish in the salt. Contamination at the millimetre-scale is tested for, but there are no filtration processes in place to reduce them.
Does it seem really low that they only extracted 72 particles? In their methods section they mention using 1kg of salt from each of the 17 brands.
Skimming FDA guidelines for defects in food, I see "action levels" like "average of 2 or more rodent hairs per 50g" for ground pepper, or "average of 1 or more whole insects per 50 grams" for cornmeal. 72 particles in 17 kg of salt sounds really shockingly clean given all the stuff in the oceans.
Not really, because of high internal industry standards. The FDA guideline is a federal minimum baseline for quality to establish fitness against varying state standards during interstate commerce.
It's partly to deter and punish dealing in adulterated bulk or raw domestic products, partly for consumer protection, and partly a way to protect everyone along the supply chain where state laws might fail.
Flour often contains eggs from insects like flour weevils, and if you let flour sit in the cupboard too long they'll hatch. But I would be disgusted to find 50 whole adult weevils per 5 lb. bag, on average. Maybe they're counting eggs?
From the introduction "Microplastics might be of health concern since they have been shown to carry hazardous chemicals and microorganisms.". So it is still a might whether it is a concern. We all eat, drink and breathe "chemicals" everyday. Everything from dihydrogen monoxide (http;//dhmo.org ) to Julius Caesar's urine (http://redneckmath.blogspot.com.au/2011/09/drinking-caesars-... ) to things like particulate carbon, lead, virii, bacteria and more things that actually are known to be bad. Our bodies are amazingly good at filtering or otherwise ignoring such attacks. Any idea whether we will know whether microplastics actually are bad, or just a visible distraction?
Our bodies are good at filtering because those of our ancestors that couldn't, didn't reproduce. We could become equally good at handling lead if we just removed those pesky regulations.
His two most prominent example are DHMO and Ceasers' Urine, both commonly known as "water".
Yes, we are very good at "filtering" water, and have even managed to evolve to use this potentially harmful chemical as a biological cooling mechanism (sweat).
Who knows what we'd be able to do with lead in our systems? I'm betting on protection against pesky UV radiation, or maybe kryptonite.
My totally naive understanding of evolutionary biology makes me think we'd have to be much simpler and/or much lower energy consuming organisms to evolve considerably higher radiation tolerance.
"The results of this study did not show a significant load of MPs larger than 149 μm in salts originating from 8 different countries and, therefore, negligible health risks associated with the consumption of salts. The increasing trend of plastic use and disposal50, however, might lead to the gradual accumulation of MPs in the oceans and lakes and, therefore, in products from the aquatic environments. This should necessitate the regular quantification and characterization of MPs in various sea products."
Is interesting to me, because I feel like this is where environments politics properly starts. Should the US federal government (insert your home gov't, or the EU, or whatever) fund regular monitoring for micro plastic levels? Maybe! it's a hard cost/benefit question that involves weighing priorities and careful thinking. But that's the kind of question we should be asking when it comes to environmental politics, not "should the EPA exist," or "is climate change real?"
"Politics" in practice is a way to give the people something to argue about that is related to, but fundamentally separate from, the real decisions being made.
It's best if we're arguing about useless memes while real decisions are made or else we might question those decisions.
Obviously every state should build their own parallel monitoring program with its own duplicated bureaucracy and time spent developing regulations. Because obviously people in New York and people in Alabama have different levels of plastic tolerance. Heck, I hear people in Alaska like plastic in their fish! Why are we taking away their rights?
Foreign products arrive in a country at specific locations---most likely large seaports. Impounding and stamping these products as having X standard or Y standard isn't very different if the standards body is the singular federal government, or applying 5-10 different standards levied by states.
Also, even if there is a federal standard, the states themselves are always free to set greater limitations---for example federal emissions controls on cars, versus California emission controls.
Well, in fact each state would and does need a parallel monitoring program, which inevitably would come with some duplicated bureaucracy. You can mostly skip the duplicated regulation process however.
How are you planning to interface with people in each state, in regards to community and business, as it pertains to policy changes and dozens of other scenarios (some of which may be limited to just a few states based on industry and environment)? There's no scenario under which you don't need to have parallel monitoring for every state.
Furthermore, what happens when the wind blows pollution from one state across state lines into another? Does Louisiana get a say in what Iowa dumps into the Mississippi? And gee, it's not like anything dumped into the ocean in one place ever comes out in another, does it?
This is only one source of microplastics, but in 2015 Obama signed signed the Microbead-Free Waters Act, banning plastic microbeads in cosmetics and personal care products. Seems smart to target the source instead of monitor and clean up afterwards.
I agree but the monitoring and cleaning is still something you have to do if you want to follow the situation.
You cannot just say 'we will ban X, problem solved'
I agree, it's not a solution. But maybe not doing that anymore is enough. Maybe not, and we need to investigate more. It reminds me of DDT. Oh gosh, that's useful but problematic, let's be super careful using this in the future.
Yeah, all salt is sea salt. If it's up in the mountains it just means it was laid down a long time ago.
That salt should be free of microplastics, but hell, you never know what's what these days. Some of the most polluted areas in the world are off of Antarctica.
Let me understand: this substance in the salt came from the sea, where it came from drains that contained flushed facial scrubs. So this stuff that is made to rub on your face by the hundreds of thousands or millions is present in salt by ones and twos per pound? Did I read that right?
You read it wrong or you didn't even read it. The article is talking about particles far tinier than the kind in those facial scrubs.
The origin of these microplastics is likely "biodegradable" plastic material which rather than reverting to some harmless form, simply breaks up in to trillions of microscopic pieces.
149um or larger is right in the ballpark for 'micro beads' which are anything smaller than 2mm. Of course I read it (thanks for the slam though!)
As for 'reverting to some harmless form' that's exactly what is taking place. Particles the same size (or exactly the same particles) as micro-beads in face wash (which have been tested and proven safe) are present in microscopic quantities. So what?
56 comments
[ 2.7 ms ] story [ 68.9 ms ] threadBut I wonder how much salt is mined. Only one sample was plastic-free. But maybe it's mostly commingled. If one were really interested, one could look at plastic content vs Cl-36 (nuclear fallout) level.
> The size of the smallest particle was 160 μm and the largest sized 980 μm.
This was shocking to me, that they could miss a millimetre-scale particle of plastic in salt seems bonkers. I mean, you can more or less just filter things that size!
Salt derived from underground sources wouldn't be at risk of microplastics contamination.
> A total of 17 brands of salt from Australia, France, Iran, Japan, Malaysia, New Zealand, Portugal, and South Africa were purchased from a Malaysian market.
> Accordingly, it is expected that products originating from the contaminated water bodies are also loaded with MPs.
This sentence is the entire premise of the study. Testing non-waterbody-derived salts would not provide any valid data in pursuit of that hypothesis.
Furthermore the entire body of the abstract, introduction, and discussion discusses marine microparticles, impacts on aquatic health, and whatnot.
You can filter them - and they certainly do - but with sea and lake salts the filtration is mainly to screen out sediments such as sand grains and bits of shell. Naturally, the filtering is a costly process and the filters need to be discarded after a certain level - I imagine there is a cost-control factor here, where screening at a 1mm threshold catches 99.9% of sediments to make the product reach a certain purity level and more thresholds are not worth the money.
Further screening is probably not cost effective - and seeing from the results of the study, plastic microparticles are not a source of concern.
In the brewing industry we use Kieselguhr (perlite) filtration with filters like this: https://www.ryebeckltd.com/current-equipment/schenk-kieselgu.... These can sterile filter particles as small as 1 micron and are density-independent. These work by having a steel plate with fine slots upon which you deposit a coarse bed of filter material, and then you dose kieselguhr into the liquid flow passing through, and this gradually builds up on top of the coarse bed to create an ultrafine filter. The ultrafine filter increases in depth over time, and this prevents blinding (blocking) of the filter as filtered particulates accumulate. While used to remove yeast and other particulates in brewing to create "bright" beer, it can be applied to most liquid filtration problems, and at high flow rates (30000 litres/hr); and you can run multiple filters in parallel to further increase the flow rates. We also used kieselguhr in research labs for fine filtration--just add the powder to regular filter paper.
In practice this is based upon manual calculation and adjustment. In the place I worked, the filter room had two of these, each about 1.5 storeys high. It had a dedicated control room to operate, and the two operators would be continuously monitoring and adjusting the flow rates, dosing and other parameters to ensure efficient operation. When you have an unexpectedly dirty product or you muck up the calculations, the flow rates can become very low and that starts to cost serious amounts of money when it's a rate-limiting step in an industrial process.
When the filter becomes too inefficient, the backpressure excessively high, or the filter depth approaches the tank capacity, the metal filter plate is spun and this destroys the filter bed which is spun off. The coarse filter base is then reapplied to "regenerate" the filter.
Himalayan salt (found frequently in warehouse clubs) is a product of Pakistan and is produced >100 mi from the nearest portion of the Himalayas.
I still use and enjoy some on occasion.
A lot of the salt (~80%) produced in the US goes to road salt and chemical industries. For roads it's better if it's in rock form, so a lot (if not most) is mined. For chemical industry they can often re-use brining wells to hold other things later, so the great majority of chemical salt is brined.
Salt mines: https://en.wikipedia.org/wiki/Salt_mining
Of all the salt production methods, non-brine mined salts have the least toxic or harmful byproducts - at the source. But they still go through processing plants to sift, grind and package the salt, and not every processing plant has the same quality standards. If you wanted to get really picky about it you should choose a mined, non-brine, non-processed, non-refined salt produced at a facility that follows modern standards. The easiest to identify would be "himalayan" salt, but many countries have ancient lake/sea beds and mine and produce salt in the same way.
In general, you can't tell how salt was produced unless the company very explicitly tells you. Even kosher and sea salt sometimes is processed or refined with additives or in a way that could introduce MPs. (In case it helps, only some places like Australia and the mediterranean have the right environment to solar-evaporate sea salt at a commercial scale)
I guess I'll keep buying the French Gros Sel de Guérande from world market, plus the fact that it tastes really good when sprinkled on meat :)
Anyway the conclusion rather place the problem, not on the consumption of those salts, but in the gradual accumulation in products from the aquatic environments.
They both start with the same "raw material": water of the Northern Atlantic, which I would think is mixed enough not be significantly different in these two locations. Guérande is probably one of the largest locations for sea salt, but the processes are far away from industrial scale. They manually remove contamination that they see, but I've found a few fish in the salt. Contamination at the millimetre-scale is tested for, but there are no filtration processes in place to reduce them.
Skimming FDA guidelines for defects in food, I see "action levels" like "average of 2 or more rodent hairs per 50g" for ground pepper, or "average of 1 or more whole insects per 50 grams" for cornmeal. 72 particles in 17 kg of salt sounds really shockingly clean given all the stuff in the oceans.
so you can have 9 whole insects in a pound of cornmeal and still be in the clear?
It's partly to deter and punish dealing in adulterated bulk or raw domestic products, partly for consumer protection, and partly a way to protect everyone along the supply chain where state laws might fail.
Yes, we are very good at "filtering" water, and have even managed to evolve to use this potentially harmful chemical as a biological cooling mechanism (sweat).
Who knows what we'd be able to do with lead in our systems? I'm betting on protection against pesky UV radiation, or maybe kryptonite.
"The results of this study did not show a significant load of MPs larger than 149 μm in salts originating from 8 different countries and, therefore, negligible health risks associated with the consumption of salts. The increasing trend of plastic use and disposal50, however, might lead to the gradual accumulation of MPs in the oceans and lakes and, therefore, in products from the aquatic environments. This should necessitate the regular quantification and characterization of MPs in various sea products."
Is interesting to me, because I feel like this is where environments politics properly starts. Should the US federal government (insert your home gov't, or the EU, or whatever) fund regular monitoring for micro plastic levels? Maybe! it's a hard cost/benefit question that involves weighing priorities and careful thinking. But that's the kind of question we should be asking when it comes to environmental politics, not "should the EPA exist," or "is climate change real?"
It's best if we're arguing about useless memes while real decisions are made or else we might question those decisions.
Also, even if there is a federal standard, the states themselves are always free to set greater limitations---for example federal emissions controls on cars, versus California emission controls.
How are you planning to interface with people in each state, in regards to community and business, as it pertains to policy changes and dozens of other scenarios (some of which may be limited to just a few states based on industry and environment)? There's no scenario under which you don't need to have parallel monitoring for every state.
I agree, it's not a solution. But maybe not doing that anymore is enough. Maybe not, and we need to investigate more. It reminds me of DDT. Oh gosh, that's useful but problematic, let's be super careful using this in the future.
That salt should be free of microplastics, but hell, you never know what's what these days. Some of the most polluted areas in the world are off of Antarctica.
This is significant how?
The origin of these microplastics is likely "biodegradable" plastic material which rather than reverting to some harmless form, simply breaks up in to trillions of microscopic pieces.
As for 'reverting to some harmless form' that's exactly what is taking place. Particles the same size (or exactly the same particles) as micro-beads in face wash (which have been tested and proven safe) are present in microscopic quantities. So what?
Again I ask, how is this significant?