3 ms·

Microplastics have always fascinated me, because I keep seeing article after article about how much microplastic exists around us, but far less strong evidence

Microplastics have always fascinated me, because I keep seeing article after article about how much microplastic exists around us, but far less strong evidence about its actual effects. That is not to say there are no effects, of course. Maybe we just have not found them yet. A friend of mine worked on her bachelor’s thesis about the effects of microplastics on the immune system, specifically T cells. Her result was that the microplastic particles she studied were too large to interact with T cells. She probably will not publish this result because she thinks it is not interesting enough. Classic file-drawer problem in academic science. While I encourage her to do it anyways as a negative results is also interesting but she wanted results that are worthing of headlines in magazines.

app13 3mo ago
I participated in research from 2017-2022 that found similar results regarding bio-interactions, generally. Learned a lot about making microfludic flow cells at least
codybontecou 3mo ago
Can microplastics never get small enough to interact with T cells?
- Retric 3mo ago
  There’s a transition point where things stop being micro plastics, then nano plastics, and become specific chemicals. Those molecules may be toxic but the interactions are distinct from microplastics or nano plastics.
- tristor 3mo ago
  Unknown to me, but something useful to know is that there is something smaller than microplastics called nanoplastics. The distinguishing factor is that nanoplastics are particles smaller than 1 micron, while microplastics are particles between 1 micron and around 5 millimeters. As your other respondent notes, at some point you're talking about single molecules. As plastics is an entire category and not a single thing, there's no one size where that happens, but some polymers have chains that are as little as 0.01 (1/100th of a) micron in size. As far as I am aware, we have yet to have effective, replicable research on what if any biointeractions exist with nanoplastic particles, including single polymer chains.
  - cwillu 3mo ago
    > 5 millimeters TIL thermoplastic pellets are “microplastics” :)
    - tristor 3mo ago
      I don't make the definition
- Borg3 3mo ago
  Once microplastics fall apart futher, to nano-plastic, it will start to get absorbed by T cells because they want to destroy any invaders. Once absorbed, T-Cell start to produce H2O2 to destroy anything they absorbed. Unfortunately, plastics are mostly chemically neutral and so, it cannot be destroyed like that. T-Cells produce more H2O2, eventually it leaks outside and start inflamation of surrunding tissue. There is research about it.
  - Shog9 3mo ago
    Link to that research, please. It would add meaningfully to this discussion.
    - Schmerika 3mo ago
      [dead]
  - dzhiurgis 3mo ago
    AKA nanoplastic-induced oxidative stress, but it's actually macrophages (and neutrophils), not T-cells. The reason this is problem is because cells can never destroy nano-plastic so they keep self destroying forever (chronic inflammation). I still have my doubts about actual scale of this, especially how we still haven't solved pm2.5 pollution or even asbestos and heavy metals. And then there's PFAS, VOCs, Phthalates and Bisphenols. There's insane amounts of benzene in gas stations and traffic jam, yet no one really gives a fuck (until there's like a ppm in a sunscreen lol). You are most likely to inhale it due to plastic abundance in environment, just like thousands of other things. It doesn't even have ICD yet. Ingested microplastic unlikely to breakdown while it travels thru your body. p.s. my partner de-plastified a lot of my life (thru a lot of opposition of me) to the point where a lot of plastic objects feel gross now.
    - Terr_ 3mo ago
      > macrophages Right, and when it comes to "what happens when the macrophage can't destroy what it engulfed", we can probably learn a lot from parallel work studying tattoos, where the ink-particles are similarly "attacked". Plus it's a lot easier to create studies or even just observe the cells in question.
jagged-chisel 3mo ago
> ... too large to interact with T cells. Also, unfortunately, a result that industry and the anti-regulation crowd will use to say microplastics are harmless.
- w10-1 3mo ago
  also, asbestos is too small to interact with T-cells, so it must be safe.
  - nostrademons 3mo ago
    It's not really analogous. One of the hypothesized ways that microplastics are harmful is that they disrupt the immune system; there has been evidence found of this in bivalves. Another is that they cause inflammation, which is also mediated by T-cells. A null result on the impact of microplastics on human T-cells is directly relevant to these hypotheses. The mechanism of harm for asbestos is known to be that the fibers enter the lungs and can't be expelled, eventually leading to cancer. Its interaction with T-cells is quite irrelevant there.
    - Supermancho 3mo ago
      >>>> ... too large to interact with T cells. >>> Also, unfortunately, a result that industry and the anti-regulation crowd will use to say microplastics are harmless. >> also, asbestos is too small to interact with T-cells, so it must be safe. > It's not really analogous. Ironically, this is missing the point. They were commenting on flawed reasoning. This shouldn't need to be spelled out, as it's part of the conversation context. Sometimes "dunking" comments are a variation on https://www.instagram.com/p/DY2DRKDhqaa https://www.instagram.com/p/DY2DRKDhqaa - where everyone is arguing about who is wrong, because they aren't treating it like a conversation.
    - pfdietz 3mo ago
      I understand asbestos fibers literally get tangled with DNA, and that this can be demonstrated in vitro.
legitster 3mo ago
> She probably will not publish this result because she thinks it is not interesting enough. Classic file-drawer problem in academic science. It's truly insane that everyone in the academic class understands the fundamental problems of herding and sampling bias and yet every incentive is in place to do this.
- etrautmann 3mo ago
  Having lived this reality, people respond to incentives. Your have to very fundamentally re-architect the incentives and career progression in academia to make publication of null results more common. The other side of this is reducing the time and hassle of publication. Right now I’m unlikely to battle for 1.5-3 years to get something through peer review for a result that nobody will find interesting.
  - anonym29 3mo ago
    >people respond to incentives Careful, you're starting to sound dangerously close to an Austrian economist! [ ;) ]
    - pfdietz 3mo ago
      "Show me the incentive and I'll show you the outcome." -- Charlie Munger
  - cortesoft 3mo ago
    I think this is exactly what the person you are replying to is saying; everyone knows it, but the people in charge of setting up the incentives still don’t seem interested in changing the incentives.
    - a_bonobo 3mo ago
      Yes, this has been my experience in the Australian academic system as well: everything is broken and nobody with the power to change it, cares. China seems to make some strides for their own academics, thinking loudly about moving away from glam publications as career incentives: https://www.ft.com/content/64a811f1-b132-4211-8a8c-2252cf964039?syn-25a6b1a6=1 https://www.ft.com/content/64a811f1-b132-4211-8a8c-2252cf964... It's supposedly about the worry of leaking state secrets, but it will have positive outcomes apart from that.
schiffern 3mo ago
I expect many researchers are using fresh lab-made microplastics, which are indeed mostly harmless. However part of the problem is that real-world plastics are chemical sponges that absorb toxins (heavy metals, PCBs, etc) from the environment and deliver them in a concentrated dose into the body. https://www.eurekalert.org/news-releases/923529 https://www.eurekalert.org/news-releases/923529
- gruez 3mo ago
  >However part of the problem is that real-world plastics are chemical sponges that absorb toxins (heavy metals, PCBs, etc) from the environment and deliver them in a concentrated dose into the body. >https://www.eurekalert.org/news-releases/923529 https://www.eurekalert.org/news-releases/923529 But your linked study only talks about biofilms and E.coli?
magicalist 3mo ago
> Her result was that the microplastic particles she studied were too large to interact with T cells. Her "result" of what? Was there an actual experiment and what was its scope or was this by surveying literature? Microplastics are of a pretty large range of size, and then there are nanoplastics below that. I'm also not an expert, but a quick search shows a number of results of microplastics affecting T cells, some directly and some in terms of immune signaling, so this negative result doesn't seem that definitive. (as usual, the difficulty is in teasing out in vivo effects)
- vitally3643 3mo ago
  I'm not an expert but I'm going to condescend about an expert's "results" anyway. Very informative, thank you for your comment. You have truly contributed to the conversation. Good job.
  - magicalist 3mo ago
    > I'm not an expert but I'm going to condescend about an expert's "results" anyway. I mean it's a detail free second hand anecdote about someone's informal discussion of their bachelor's thesis. Which part of that is the basis of a good scientific conversation?
zug_zug 3mo ago
> but far less strong evidence about its actual effects. Yeah, but we shouldn't take absence of evidence as evidence of absence. The fact is that it's just really really hard to establish a causal relationship, even if it's there, because of all the cofounders. Heck even if you constructed a study with a known poison, like lead, and you might not see the results in a single study. You could give 50 participants water with flint levels of lead in it for a month, and you might not get scientifically significant result just due to the wide variance in a population. Or another example is just thinking how hard it would be construct a study with a control, when every single construction material has plastics in it and they are floating in the air around us all the time (as mentioned in the article). Could it affect mental or reproductive wellbeing? Certainly. Can we construct a study to establish either way? Not easily. And one of the plasticizers they talk about, pthalates, are known to be endocrine disruptors (i.e. mess with hormones).
- marcosdumay 3mo ago
  > Yeah, but we shouldn't take absence of evidence as evidence of absence. That's wrong. Yes, we should. Each and every study that doesn't find evidence for what they are looking for is evidence for its absence.
  - unparagoned 3mo ago
    That’s wrong. Only if the studies are powerful enough and are looking at the right stuff can you make any reasonable conclusions. If the studies are powerful enough then that absolutely isn’t evidence of absence at all.
    - Xirdus 3mo ago
      Evidence can be strong or weak. Every positive study result is evidence of presence, usually strong evidence. Every negative study result is evidence of absence, usually very weak evidence.
      - rTX5CMRXIfFG 3mo ago
NoImmatureAdHom 3mo ago
She should at least put it on https://www.biorxiv.org/ https://www.biorxiv.org/ !
guelo 3mo ago
One thing I learned from this article is that even though the plastic particles themselves are poorly studied the chemical additives, such as phthalates and bisphenols, are very well studied and are known toxins. So even if the tiniest plastic particles (smaller than the ones your friend studied, that can cross from your gut into your bloodstream), don't affect your health at all, you still don't want to ingest these things because of the other chemicals in them.

app13 3mo ago

I participated in research from 2017-2022 that found similar results regarding bio-interactions, generally. Learned a lot about making microfludic flow cells at least

codybontecou 3mo ago

Can microplastics never get small enough to interact with T cells?

Retric 3mo ago
There’s a transition point where things stop being micro plastics, then nano plastics, and become specific chemicals. Those molecules may be toxic but the interactions are distinct from microplastics or nano plastics.
tristor 3mo ago
Unknown to me, but something useful to know is that there is something smaller than microplastics called nanoplastics. The distinguishing factor is that nanoplastics are particles smaller than 1 micron, while microplastics are particles between 1 micron and around 5 millimeters. As your other respondent notes, at some point you're talking about single molecules. As plastics is an entire category and not a single thing, there's no one size where that happens, but some polymers have chains that are as little as 0.01 (1/100th of a) micron in size. As far as I am aware, we have yet to have effective, replicable research on what if any biointeractions exist with nanoplastic particles, including single polymer chains.
- cwillu 3mo ago
  > 5 millimeters TIL thermoplastic pellets are “microplastics” :)
  - tristor 3mo ago
    I don't make the definition
Borg3 3mo ago
Once microplastics fall apart futher, to nano-plastic, it will start to get absorbed by T cells because they want to destroy any invaders. Once absorbed, T-Cell start to produce H2O2 to destroy anything they absorbed. Unfortunately, plastics are mostly chemically neutral and so, it cannot be destroyed like that. T-Cells produce more H2O2, eventually it leaks outside and start inflamation of surrunding tissue. There is research about it.
- Shog9 3mo ago
  Link to that research, please. It would add meaningfully to this discussion.
  - Schmerika 3mo ago
    [dead]
- dzhiurgis 3mo ago
  AKA nanoplastic-induced oxidative stress, but it's actually macrophages (and neutrophils), not T-cells. The reason this is problem is because cells can never destroy nano-plastic so they keep self destroying forever (chronic inflammation). I still have my doubts about actual scale of this, especially how we still haven't solved pm2.5 pollution or even asbestos and heavy metals. And then there's PFAS, VOCs, Phthalates and Bisphenols. There's insane amounts of benzene in gas stations and traffic jam, yet no one really gives a fuck (until there's like a ppm in a sunscreen lol). You are most likely to inhale it due to plastic abundance in environment, just like thousands of other things. It doesn't even have ICD yet. Ingested microplastic unlikely to breakdown while it travels thru your body. p.s. my partner de-plastified a lot of my life (thru a lot of opposition of me) to the point where a lot of plastic objects feel gross now.
  - Terr_ 3mo ago
    > macrophages Right, and when it comes to "what happens when the macrophage can't destroy what it engulfed", we can probably learn a lot from parallel work studying tattoos, where the ink-particles are similarly "attacked". Plus it's a lot easier to create studies or even just observe the cells in question.

jagged-chisel 3mo ago

> ... too large to interact with T cells. Also, unfortunately, a result that industry and the anti-regulation crowd will use to say microplastics are harmless.

w10-1 3mo ago
also, asbestos is too small to interact with T-cells, so it must be safe.
- nostrademons 3mo ago
  It's not really analogous. One of the hypothesized ways that microplastics are harmful is that they disrupt the immune system; there has been evidence found of this in bivalves. Another is that they cause inflammation, which is also mediated by T-cells. A null result on the impact of microplastics on human T-cells is directly relevant to these hypotheses. The mechanism of harm for asbestos is known to be that the fibers enter the lungs and can't be expelled, eventually leading to cancer. Its interaction with T-cells is quite irrelevant there.
  - Supermancho 3mo ago
    >>>> ... too large to interact with T cells. >>> Also, unfortunately, a result that industry and the anti-regulation crowd will use to say microplastics are harmless. >> also, asbestos is too small to interact with T-cells, so it must be safe. > It's not really analogous. Ironically, this is missing the point. They were commenting on flawed reasoning. This shouldn't need to be spelled out, as it's part of the conversation context. Sometimes "dunking" comments are a variation on https://www.instagram.com/p/DY2DRKDhqaa https://www.instagram.com/p/DY2DRKDhqaa - where everyone is arguing about who is wrong, because they aren't treating it like a conversation.
  - pfdietz 3mo ago
    I understand asbestos fibers literally get tangled with DNA, and that this can be demonstrated in vitro.

legitster 3mo ago

> She probably will not publish this result because she thinks it is not interesting enough. Classic file-drawer problem in academic science. It's truly insane that everyone in the academic class understands the fundamental problems of herding and sampling bias and yet every incentive is in place to do this.

etrautmann 3mo ago
Having lived this reality, people respond to incentives. Your have to very fundamentally re-architect the incentives and career progression in academia to make publication of null results more common. The other side of this is reducing the time and hassle of publication. Right now I’m unlikely to battle for 1.5-3 years to get something through peer review for a result that nobody will find interesting.
- anonym29 3mo ago
  >people respond to incentives Careful, you're starting to sound dangerously close to an Austrian economist! [ ;) ]
  - pfdietz 3mo ago
    "Show me the incentive and I'll show you the outcome." -- Charlie Munger
- cortesoft 3mo ago
  I think this is exactly what the person you are replying to is saying; everyone knows it, but the people in charge of setting up the incentives still don’t seem interested in changing the incentives.
  - a_bonobo 3mo ago
    Yes, this has been my experience in the Australian academic system as well: everything is broken and nobody with the power to change it, cares. China seems to make some strides for their own academics, thinking loudly about moving away from glam publications as career incentives: https://www.ft.com/content/64a811f1-b132-4211-8a8c-2252cf964039?syn-25a6b1a6=1 https://www.ft.com/content/64a811f1-b132-4211-8a8c-2252cf964... It's supposedly about the worry of leaking state secrets, but it will have positive outcomes apart from that.

schiffern 3mo ago

I expect many researchers are using fresh lab-made microplastics, which are indeed mostly harmless. However part of the problem is that real-world plastics are chemical sponges that absorb toxins (heavy metals, PCBs, etc) from the environment and deliver them in a concentrated dose into the body. https://www.eurekalert.org/news-releases/923529 https://www.eurekalert.org/news-releases/923529

gruez 3mo ago
>However part of the problem is that real-world plastics are chemical sponges that absorb toxins (heavy metals, PCBs, etc) from the environment and deliver them in a concentrated dose into the body. >https://www.eurekalert.org/news-releases/923529 https://www.eurekalert.org/news-releases/923529 But your linked study only talks about biofilms and E.coli?

magicalist 3mo ago

> Her result was that the microplastic particles she studied were too large to interact with T cells. Her "result" of what? Was there an actual experiment and what was its scope or was this by surveying literature? Microplastics are of a pretty large range of size, and then there are nanoplastics below that. I'm also not an expert, but a quick search shows a number of results of microplastics affecting T cells, some directly and some in terms of immune signaling, so this negative result doesn't seem that definitive. (as usual, the difficulty is in teasing out in vivo effects)

vitally3643 3mo ago
I'm not an expert but I'm going to condescend about an expert's "results" anyway. Very informative, thank you for your comment. You have truly contributed to the conversation. Good job.
- magicalist 3mo ago
  > I'm not an expert but I'm going to condescend about an expert's "results" anyway. I mean it's a detail free second hand anecdote about someone's informal discussion of their bachelor's thesis. Which part of that is the basis of a good scientific conversation?

zug_zug 3mo ago

> but far less strong evidence about its actual effects. Yeah, but we shouldn't take absence of evidence as evidence of absence. The fact is that it's just really really hard to establish a causal relationship, even if it's there, because of all the cofounders. Heck even if you constructed a study with a known poison, like lead, and you might not see the results in a single study. You could give 50 participants water with flint levels of lead in it for a month, and you might not get scientifically significant result just due to the wide variance in a population. Or another example is just thinking how hard it would be construct a study with a control, when every single construction material has plastics in it and they are floating in the air around us all the time (as mentioned in the article). Could it affect mental or reproductive wellbeing? Certainly. Can we construct a study to establish either way? Not easily. And one of the plasticizers they talk about, pthalates, are known to be endocrine disruptors (i.e. mess with hormones).

marcosdumay 3mo ago
> Yeah, but we shouldn't take absence of evidence as evidence of absence. That's wrong. Yes, we should. Each and every study that doesn't find evidence for what they are looking for is evidence for its absence.
- unparagoned 3mo ago
  That’s wrong. Only if the studies are powerful enough and are looking at the right stuff can you make any reasonable conclusions. If the studies are powerful enough then that absolutely isn’t evidence of absence at all.
  - Xirdus 3mo ago
    Evidence can be strong or weak. Every positive study result is evidence of presence, usually strong evidence. Every negative study result is evidence of absence, usually very weak evidence.
    - rTX5CMRXIfFG 3mo ago

NoImmatureAdHom 3mo ago

She should at least put it on https://www.biorxiv.org/ https://www.biorxiv.org/ !

guelo 3mo ago

One thing I learned from this article is that even though the plastic particles themselves are poorly studied the chemical additives, such as phthalates and bisphenols, are very well studied and are known toxins. So even if the tiniest plastic particles (smaller than the ones your friend studied, that can cross from your gut into your bloodstream), don't affect your health at all, you still don't want to ingest these things because of the other chemicals in them.