Summary
A new study from Spain’s Autonomous University of Barcelona reveals that tea bags made from nylon, polypropylene, and cellulose release billions of micro- and nanoplastic particles when steeped in boiling water.
These particles, which can enter human intestinal cells, may pose health risks, potentially affecting the digestive, respiratory, endocrine, and immune systems.
Researchers urge regulatory action to mitigate plastic contamination in food packaging.
Consumers are advised to use loose-leaf tea with stainless steel infusers or biodegradable tea bags to minimize exposure.
I mean nothing about the methodology is even close to representing normal tea brewing behavior.
For starters, a typical cup of tea is around 300-350ml, not 2ml and certainly not 1, so the low end is already down to 23,371 particles even before accounting for the brewing technique.
Secondly, nobody holds their tea at an active boil while stirring it at 750 rpm. That’s virtually blending it. There isn’t a meaningful way to compare that to typical tea brewing behavior but I wouldn’t be surprised to learn that it produced 10,000x more particles.
“I WANT A GOD DAMN LITER OF
COLATEA!”-British Super Troopers movie maybe?
Right. You still drink 300-350 ml per cup. It doesn’t matter if you did 1 teabag per 300 ml or 300 teabags per 300 ml. In the first instance, you would have to measure 300 ml to get the X particles per cup. In the second instance, you can get the X particles per ml which is effectively per cup, or more accordingly, per teabag. It’s the same. Please correct me if I’m wrong, but I think your math of 23k particles per teabag is not mathing.
Also, usually you don’t measure 1 teabag because of individual variability, so what they are doing is getting the average amount of particles from those 300 teabags. Much more accurate.
They likely are using a magnetic stir bar. 750 RPM will not virtually blend it. This video shows it going at 3000 RPM max for reference. (https://youtu.be/fzzV75aMM1c?feature=shared) In a large container, the water at the bottom will be swirling faster than the water at the top. And also, 95 C will not be at an active boil - that’s at 100 C. It suggests to me that they boiled water, then poured it into the teabag beaker.
I think that maybe you haven’t worked in a lab before, so it seems like the methodology isn’t right, but as a scientist, this passes the sniff test for me. Honestly, this part isn’t even the novel part of their study - the interesting part is that they found that intestinal cells took up the particles, but I digress.
They report their findings as particles/ml, not particles/teabag. It should be obvious to you, as a scientist, that the particles/ml evolved given 1 teabag in 350ml of water will be massively different from the particles evolved with 1 teabag per 2ml of water.
Effectively, they are reporting effectively particles per half a teabag, right? So the numbers really should be double, is that what you’re saying?
As for the massively different concern, agreed, but maybe in a different way that doesn’t change my conclusions. Let me illustrate. My question to you is, if you dissolve (insert anything here) in a smaller volume of water, would you expect to get out more or less of the dissolved particles than if you were to dissolve the same thing in a larger volume?
My answer is less. The reason is because there are fewer water molecules to pull away particles when there’s a smaller volume of water. I suspect that their methodology underestimates the amount of plastic particles than if they were to use a very large chamber to brew 1 teabag to 350 ml water.
A saw another comment you made - Maybe you think that teabags are colliding with one another, but they are all spinning in the same direction in a beaker with a magnetic stirrer, so there’s not really all that much agitation.
I’m not totally sure what you mean by “get out more or less of the dissolved particles”, but I think I understand where your confusion lies. You keep referring to quantities, i.e. mass or particle counts. Their data is reporting these things as concentrations.
It should be obvious to you that 7.14g of salt dissolved in 2ml of water will produce a highly concentrated solution (saturated, in fact), whereas the same 7.14g dissolved in 350ml of water will produce a dilute solution. The concentration of the first one is 3.57g/ml, but the concentration of the second is 0.0204g/ml.
If somebody then turns around and says that 7.14g of salt dissolved in a mug of water will produce a concentration of 3.57g/ml, it should be readily apparent that they are incorrect. That is in effect what the authors are saying by reporting their results as particles/ml and then saying that those numbers are representative of what you might expect when brewing tea under normal conditions.
Does that all make sense?
Hmm, interesting. Maybe I’m being dense here. Let’s say that the teabag is that 7.14g of salt you mentioned - a chunk of salt, let’s say. They either A) try to dissolve 300 of those (each 7.14g) in 600 ml of water or B) they dissolve 1 chunk in 350 ml water. Like you said, they either report A) 3.57 g/ml or B) 0.204 g/ml.
I’m really just saying that either way, it’s still 7.14 g/chunk. Quite a lot of salt/particles per chunk/teabag.
I think maybe I don’t have an issue with them reporting the concentration because I didn’t interpret them as saying that they were saying there’s a billion particles per ml of a regular cup of brewed tea - it was always apparent to me that it was about the number of particles in a teabag (in this case, half a teabag with just a ml volume). I think we’re ultimately just arguing clarity of their language.
In a sense, but clarity of language can be the difference between accurate conclusions and misrepresentation. Just on data presentation alone, formal issuance of a correction is absolutely necessary.
Following on from that is where the issues with study design and methodology come in, and in my opinion they are both so flawed as to lead to spurious conclusions.
The other major problems I see so far:
as mentioned previously, their brewing methodology is so different from what would be done under normal conditions/at home that comparison between the two is meaningless. A good paper should discuss these differences and explain why some conclusions can still be drawn, but this one just makes a direct comparison.
the authors used empty mesh sleeves from an unnamed aliexpress vendor for their samples. We have no idea whether these sleeves are in use by any tea manufacturer, we don’t know anything about how they were made, and we don’t even know whether they were intended for food usage.
one of the three samples produced only cellulose particles, which a) isn’t a plastic and b) is a component of plant cell walls. I don’t know the cellulose particle concentration in a kale smoothie, but I’m certain that it’s higher. And yet the authors still just report this figure alongside the others.
Ultimately, the only thing this paper demonstrates is that certain types of thin-fibre plastic will, when handled roughly, shed nanoparticles. This isn’t a new conclusion, and doesn’t provide us with anything actionable with respect to our tea drinking habits.
I think you might have skimmed over the methods, but think what the OP was trying to say is:
Concentration: 300 tea bags / 600mL = 1 teabag per 2mL (175 tea bags in one 350mL cup of tea, doesnt appear typical?)
Mixing: 750rpm × [1m/60s] = 12.5 rotations a sec (Awfully fast to be stirring tea, constantly)
Incubation time: Not specified. (They could have left boiling overnight?)
There seems to be many points about the methodology that raise eyebrows. Maybe it’s ok if you want to use this method to purify particles for structural analysis or test toxicity on cells, but it doesn’t seem fair to present this as “release of micro/nanoplastics (MNPLs) from polymer-based teabags into the aqueous phase during typical usage”, as the amounts seem exaggerated.
Thanks for the clarification of the concerns.
For concentration, it’s not typical for 2 reasons. 1) their instrument may have a detection limit, so if they brewed 1 teabag per 300 ml, they’d have to concentrate it in another way. 2) they’re pooling a batch of teabags, which gives an average, reducing variability teabag to teabag.
Besides mimicking the exact real world scenarios, I think I don’t get what the issue is with concentration. If you boil something that’s dissolvable in a larger volume of water, you’ll typically get out more “pieces” than if you were to do it in a smaller volume. In the experiment, if anything, they may be underestimating the particle release.
For mixing, this method is super standard in the lab. I think that when the methods say 750 RPM, they’re talking about the speed of the stir bar - most definitely with the mass of the 300 wet teabags in that volume, the whole mixture isn’t actually going to get to 750 RPM. If it did, everything would spill out the side, over the top lol
Fair point about incubation time. Do we have a standard for how long people keep their teabags in hot water? I usually don’t take it out of the container when drinking it to go, and if it sits over a few hours and there’s stuff left over, I will usually finish the drink.
In any case, what’s the lowest amount of plastic microparticles we’re okay with? Above, the other commenter said 20k after every generous interpretation moving the number lower. Isn’t that still an insane amount for one drink?
I think my issue with the commenter’s first comment is that they call for the paper’s retraction over what is completely standard in lab science.
'bout four minutes should be enough. Otherwise it just turns bitter. A few hours? 🤢
Yeah, if you increase concentration until it’s visible you will get high concentration solution. By the same principle water is a deadly poison because scientists forse fed a bunch of rats liters of water until they died.