6 ms·

Does someone have good papers on the negative effects of microplastics (ideally on humans)? A while back I tried to look for those, and it was nontrivial to fi

Does someone have good papers on the negative effects of microplastics (ideally on humans)? A while back I tried to look for those, and it was nontrivial to find papers that would conclusively show that they are harmful, and the mechanisms of this harmfulness. There's a ton of press about where they are (everywhere) but (as a layman) you could argue it's because they're not very reactive, and this lack of reactivity could mean they're not actually that harmful, and are just there. Take TFA as an example. Based on the abstract it shows that microplastics are there, but concludes with "highlighting the need for further research on their neurotoxic effects and implications for human health". Now of course doing good studies about this is extremely hard, as it's hard to find subjects untouched by microplastics for control groups, but I hope someone here can provide me with some good sources on this. To be clear, I'm not trying to deny the harmfulness here, I'm just looking for good related content.

ch4s3 2y ago
Based on a similar search, my take away was that it’s too early to tell. Animal models suggest some risks, but it’s not very clear if that translates to humans. Feeding plastic to mice isn’t an exact analogue.
hollerith 2y ago
> they're not very reactive, and this lack of reactivity could mean they're not actually that harmful. Per- and polyfluoroalkyl substances (PFAS) are so stable they are called "forever chemicals", but according the NRDC, "PFAS are also toxic at extremely low levels (i.e. parts per quadrillion), posing significant risks to our health": https://www.nrdc.org/stories/forever-chemicals-called-pfas-show-your-food-clothes-and-home https://www.nrdc.org/stories/forever-chemicals-called-pfas-s...
maltyr 2y ago
A quick search led me to this review, which has a number of studies linked in references, including a few that studied humans. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ Quote from the abstract: The direct consequences of MPs and NPs on the thyroid, testis, and ovaries are documented. Still, studies need to be carried out to identify the direct effects of MPs and NPs on the hypothalamus, pituitary, and adrenal glands.
- simonh 2y ago
  Disappointingly nothing in that study relates these health impacts to known levels of microplastics in humans. That means there’s no way to tell, from that study, if the levels of microplastics to be found in you and me are likely to have material impact. I definitely feel we should be more serious about reducing use of plastics, especially for uses likely to contribute to microplastic levels, but it’s going to be hard to convincingly make that case without quantifying these risks in relation to actual human microplastics levels.
  - londons_explore 2y ago
    One doesn't reduce the use of plastics without using something else as a replacement. If we replace all plastic cups with glass cups, might we get micro-glass inside ourselves instead? Glass, mostly silicon dioxide, might sound harmless, but glass can chip off in microscopic sharp fragments (think fiberglass dust - which some suggest might be as bad as asbestos). Glass also slightly dissolves in water (this is how glasses start to look frosty after enough dishwashing - they're dissolving), and slightly evaporates (everything has a vapour pressure!). And obviously the glass isn't pure - there can be all kinds of deliberate and accidental additives. Am I worried about glass? No. But it seems naive to wholesale replace plastic with something else until there is a decent understanding of the replacement.
    - PlattypusRex 2y ago
      This is completely inaccurate and disingenuous. Glass suffers from no such thing as "microglass", unlike plastic. Plastic actively sheds micro/nanoplastics into bottled water, with hundreds of thousands of particles (and probably more depending on its handling) floating in the water, along with any chemicals used to make plastic moldable, fire-retardant, etc. Glass bottles have no additives that leach out in anything but the most minute quantities, even in an alkaline solution. The same can't be said for plastic containers. Also, while glass does dissolve in water, it is an extremely slow process that does not affect containers at room temperature in any significant way. As for the claim about glass evaporating due to vapor pressure, while technically true, the vapor pressure of glass at room temperature is so infinitesimally small that it's completely irrelevant for practical purposes. This process occurs at such a slow rate that it would take far longer than the age of the universe to have any measurable effect on a glass container.
netbioserror 2y ago
"Being there" can be harmful in and of itself. Blocking receptors, clogging up conduits, etc. As I understand it, this is why certain elemental metals are so toxic: They're big atoms that deposit in harmful places and can't be effectively filtered out.
- jenadine 2y ago
  True, but it could also be totally innert and not have any measurable negative effect. Who knows?
  - eurekin 2y ago
    Bisphenol A have a carbon ring structure that resembles hormones like the estrogen. It can bind to the estrogen receptors and potentially increase risk of hormone related cancers.
    - wlesieutre 2y ago
      Don't worry, we got rid of BPAs and replaced them with substitutes that probably do the same thing! https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387873/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387873/
- stevenwoo 2y ago
  Also interfering with immune response https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9552327/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9552327/ and directly or indirectly via immune response triggering inflammation https://www.sciencedirect.com/science/article/pii/S016041202200099X https://www.sciencedirect.com/science/article/pii/S016041202....
- hammock 2y ago
  Small amounts of mercury and aluminum have been shown to be safe in the bloodstream. The dose is the poison
  - 2y ago
clumsysmurf 2y ago
Here is one on human GI track "Micro- and nanoplastics in the body are passed on during cell division" https://www.sciencedaily.com/releases/2024/03/240306150719.htm https://www.sciencedaily.com/releases/2024/03/240306150719.h...
nextos 2y ago
This is probably one of the most prominent studies till date: https://pubmed.ncbi.nlm.nih.gov/38446676 https://pubmed.ncbi.nlm.nih.gov/38446676 Microplastics and nanoplastics in atheromas and cardiovascular events. N Engl J Med. 390(10):900-910, 2024. Summary: People with artherial plaque that contains micro- and nano-plastics have a higher risk of death during the followup period. It's an observational study, sample size is not too big, but some findings look quite mechanistic suggesting causality, e.g. "electron microscopy revealed visible, jagged-edged foreign particles among plaque macrophages and scattered in the external debris". The effect size induced by microplastics on death risk also looks substantial. Personally, I think microplastics are a very important pollutant, and evidence of this will unfold during the next years. Sadly, it is extraordinarily hard to remove them from our environment. They are everywhere. For example, car tires shed lots of microplastics that end up in eggs or inside vegetables and plants, which absorb them from soil. Most liquids are packaged inside plastic, which is continuously leaking into the content. We should at least be measuring their levels and setting up maximum concentration thresholds in our food chain. We should go back to glass bottles, whenever possible. Suspended microplastics in the air are also a major concern. Plastics are great for certain applications, but we use them in places where they don't belong.
- Dalewyn 2y ago
  >We should go back to glass bottles, whenever possible. There are very good, very practical reasons we moved from glass (and metal and other materials) containers to plastic. Unless those factors are sufficiently addressed, plastic is here to stay. For those who haven't been keeping track or are just too damn young to know history, those factors include: * Weight. Glass and metal, and also other materials like ceramic and wooden containers, are heavy compared to plastic. This additional weight means it takes more energy to transport, meaning more costs in fuel and labor. * Fragility. This namely applies to glass; glass containers are fragile and they are very dangerous to handle if and when they break. Plastic containers are much more durable, and even if they break they are seldom as dangerous as broken glass. More broken containers also mean more goods lost to spillage, which in turn means additional cost to re-manufacture and re-ship. * Durability. Going along with the above, plastics are equal to metal containers in keeping contents and the outside world separated. This is incredibly important for ensuring food safety. * Contaminants. This applies primarily to metal containers, but also paper and sometimes ceramic. Metals leach into foods, this is mostly prevented with special coatings but it's not perfect and the coatings themselves are also contaminants that will eventually leach. Likewise paper containers which have coatings applied so liquids don't seep through, and sometimes ceramic containers to prevent leaching. We know these contaminants are bad, unlike microplastics where we still aren't conclusively sure. * Cost. Plastic is cheap compared to basically every other material we can make containers out of. This is a great boon to the consumer who ultimately ends up paying the most markup.
colechristensen 2y ago
You can back that question up one level to "what are the biological effects of plastics?" And the answer is, broadly, they mimic hormones. Compounds in plastics can activate endocrine receptors because they are similar enough to hormones which are more or less everywhere across the animal kingdom. Sometimes it can be hard to pin down the specific negative effects in isolation, but there are some pretty clear metrics. "A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/
- hammock 2y ago
  The most common plastic, PET, is inert and does not mimic hormones
  - colechristensen 2y ago
    This is not correct. "When comparing water of the same spring that is packed in glass or plastic bottles made of polyethylene terephthalate (PET), estrogenic activity is three times higher in water from plastic bottles." https://www.sciencedirect.com/science/article/pii/S0960076010003572 https://www.sciencedirect.com/science/article/pii/S096007601...
    - hammock 2y ago
      PET in consumer products has a lot of contaminating non-PET plastics, precursors and other chemicals co-present, which can lead to the effects you cite. If you were to get a block of lab grade PET you’d find it was inert
deleted 2y ago
[deleted]

ch4s3 2y ago

Based on a similar search, my take away was that it’s too early to tell. Animal models suggest some risks, but it’s not very clear if that translates to humans. Feeding plastic to mice isn’t an exact analogue.

hollerith 2y ago

> they're not very reactive, and this lack of reactivity could mean they're not actually that harmful. Per- and polyfluoroalkyl substances (PFAS) are so stable they are called "forever chemicals", but according the NRDC, "PFAS are also toxic at extremely low levels (i.e. parts per quadrillion), posing significant risks to our health": https://www.nrdc.org/stories/forever-chemicals-called-pfas-show-your-food-clothes-and-home https://www.nrdc.org/stories/forever-chemicals-called-pfas-s...

maltyr 2y ago

A quick search led me to this review, which has a number of studies linked in references, including a few that studied humans. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ Quote from the abstract: The direct consequences of MPs and NPs on the thyroid, testis, and ovaries are documented. Still, studies need to be carried out to identify the direct effects of MPs and NPs on the hypothalamus, pituitary, and adrenal glands.

simonh 2y ago
Disappointingly nothing in that study relates these health impacts to known levels of microplastics in humans. That means there’s no way to tell, from that study, if the levels of microplastics to be found in you and me are likely to have material impact. I definitely feel we should be more serious about reducing use of plastics, especially for uses likely to contribute to microplastic levels, but it’s going to be hard to convincingly make that case without quantifying these risks in relation to actual human microplastics levels.
- londons_explore 2y ago
  One doesn't reduce the use of plastics without using something else as a replacement. If we replace all plastic cups with glass cups, might we get micro-glass inside ourselves instead? Glass, mostly silicon dioxide, might sound harmless, but glass can chip off in microscopic sharp fragments (think fiberglass dust - which some suggest might be as bad as asbestos). Glass also slightly dissolves in water (this is how glasses start to look frosty after enough dishwashing - they're dissolving), and slightly evaporates (everything has a vapour pressure!). And obviously the glass isn't pure - there can be all kinds of deliberate and accidental additives. Am I worried about glass? No. But it seems naive to wholesale replace plastic with something else until there is a decent understanding of the replacement.
  - PlattypusRex 2y ago
    This is completely inaccurate and disingenuous. Glass suffers from no such thing as "microglass", unlike plastic. Plastic actively sheds micro/nanoplastics into bottled water, with hundreds of thousands of particles (and probably more depending on its handling) floating in the water, along with any chemicals used to make plastic moldable, fire-retardant, etc. Glass bottles have no additives that leach out in anything but the most minute quantities, even in an alkaline solution. The same can't be said for plastic containers. Also, while glass does dissolve in water, it is an extremely slow process that does not affect containers at room temperature in any significant way. As for the claim about glass evaporating due to vapor pressure, while technically true, the vapor pressure of glass at room temperature is so infinitesimally small that it's completely irrelevant for practical purposes. This process occurs at such a slow rate that it would take far longer than the age of the universe to have any measurable effect on a glass container.

netbioserror 2y ago

"Being there" can be harmful in and of itself. Blocking receptors, clogging up conduits, etc. As I understand it, this is why certain elemental metals are so toxic: They're big atoms that deposit in harmful places and can't be effectively filtered out.

jenadine 2y ago
True, but it could also be totally innert and not have any measurable negative effect. Who knows?
- eurekin 2y ago
  Bisphenol A have a carbon ring structure that resembles hormones like the estrogen. It can bind to the estrogen receptors and potentially increase risk of hormone related cancers.
  - wlesieutre 2y ago
    Don't worry, we got rid of BPAs and replaced them with substitutes that probably do the same thing! https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387873/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387873/
stevenwoo 2y ago
Also interfering with immune response https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9552327/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9552327/ and directly or indirectly via immune response triggering inflammation https://www.sciencedirect.com/science/article/pii/S016041202200099X https://www.sciencedirect.com/science/article/pii/S016041202....
hammock 2y ago
Small amounts of mercury and aluminum have been shown to be safe in the bloodstream. The dose is the poison
- 2y ago

clumsysmurf 2y ago

Here is one on human GI track "Micro- and nanoplastics in the body are passed on during cell division" https://www.sciencedaily.com/releases/2024/03/240306150719.htm https://www.sciencedaily.com/releases/2024/03/240306150719.h...

nextos 2y ago

This is probably one of the most prominent studies till date: https://pubmed.ncbi.nlm.nih.gov/38446676 https://pubmed.ncbi.nlm.nih.gov/38446676 Microplastics and nanoplastics in atheromas and cardiovascular events. N Engl J Med. 390(10):900-910, 2024. Summary: People with artherial plaque that contains micro- and nano-plastics have a higher risk of death during the followup period. It's an observational study, sample size is not too big, but some findings look quite mechanistic suggesting causality, e.g. "electron microscopy revealed visible, jagged-edged foreign particles among plaque macrophages and scattered in the external debris". The effect size induced by microplastics on death risk also looks substantial. Personally, I think microplastics are a very important pollutant, and evidence of this will unfold during the next years. Sadly, it is extraordinarily hard to remove them from our environment. They are everywhere. For example, car tires shed lots of microplastics that end up in eggs or inside vegetables and plants, which absorb them from soil. Most liquids are packaged inside plastic, which is continuously leaking into the content. We should at least be measuring their levels and setting up maximum concentration thresholds in our food chain. We should go back to glass bottles, whenever possible. Suspended microplastics in the air are also a major concern. Plastics are great for certain applications, but we use them in places where they don't belong.

Dalewyn 2y ago
>We should go back to glass bottles, whenever possible. There are very good, very practical reasons we moved from glass (and metal and other materials) containers to plastic. Unless those factors are sufficiently addressed, plastic is here to stay. For those who haven't been keeping track or are just too damn young to know history, those factors include: * Weight. Glass and metal, and also other materials like ceramic and wooden containers, are heavy compared to plastic. This additional weight means it takes more energy to transport, meaning more costs in fuel and labor. * Fragility. This namely applies to glass; glass containers are fragile and they are very dangerous to handle if and when they break. Plastic containers are much more durable, and even if they break they are seldom as dangerous as broken glass. More broken containers also mean more goods lost to spillage, which in turn means additional cost to re-manufacture and re-ship. * Durability. Going along with the above, plastics are equal to metal containers in keeping contents and the outside world separated. This is incredibly important for ensuring food safety. * Contaminants. This applies primarily to metal containers, but also paper and sometimes ceramic. Metals leach into foods, this is mostly prevented with special coatings but it's not perfect and the coatings themselves are also contaminants that will eventually leach. Likewise paper containers which have coatings applied so liquids don't seep through, and sometimes ceramic containers to prevent leaching. We know these contaminants are bad, unlike microplastics where we still aren't conclusively sure. * Cost. Plastic is cheap compared to basically every other material we can make containers out of. This is a great boon to the consumer who ultimately ends up paying the most markup.

colechristensen 2y ago

You can back that question up one level to "what are the biological effects of plastics?" And the answer is, broadly, they mimic hormones. Compounds in plastics can activate endocrine receptors because they are similar enough to hormones which are more or less everywhere across the animal kingdom. Sometimes it can be hard to pin down the specific negative effects in isolation, but there are some pretty clear metrics. "A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885170/

hammock 2y ago
The most common plastic, PET, is inert and does not mimic hormones
- colechristensen 2y ago
  This is not correct. "When comparing water of the same spring that is packed in glass or plastic bottles made of polyethylene terephthalate (PET), estrogenic activity is three times higher in water from plastic bottles." https://www.sciencedirect.com/science/article/pii/S0960076010003572 https://www.sciencedirect.com/science/article/pii/S096007601...
  - hammock 2y ago
    PET in consumer products has a lot of contaminating non-PET plastics, precursors and other chemicals co-present, which can lead to the effects you cite. If you were to get a block of lab grade PET you’d find it was inert

deleted 2y ago

[deleted]