[DangerousPie]

I don't have access to the paper, but just reading the abstract it gives these numbers:

> Exposure modeling results suggested that the highest estimated daily intake was 20.3 ng/kg·day for infants drinking microwaved water and 22.1 ng/kg·day for toddlers consuming microwaved dairy products from polypropylene containers.

> Furthermore, an in vitro study conducted to assess the cell viability showed that the extracted microplastics and nanoplastics released from the plastic container can cause the death of 76.70 and 77.18% of human embryonic kidney cells (HEK293T) at 1000 μg/mL concentration after exposure of 48 and 72 h, respectively.

If I'm reading this right, they exposed these HEK293T kidney cells to far higher concentrations (1000 μg is 1000000 ng, and that's per mL) than toddlers would be exposed to from these containers. So the fact that the cells die doesn't really mean much, since exposure to too much of anything will cause cells to die.

The real question is whether the exposure you'd receive from occasional microwaving would be enough to ever cause any meaningful health problems. Unfortunately papers like these always like to talk about dramatic metrics like 'billions of nanoplastics' without putting that into any meaningful context.

[WithinReason]

So it seems that a concentration of microplastics that's 50 million times higher than a toddler would get still leaves 20% of cells alive? To me this implies that normal exposure levels to microplastics are likely completely harmless.

[peteradio]

Sleeping next to abandoned nuclear batteries will give you radiation burns and kill you in a few weeks to months, exposure to high radon will give you cancer in decades. Unrealistically high dosages can hint at problems that might occur at low levels.

[rflrob]

While the Linear, No Threshold model is relatively widely used by regulatory and safety bodies, evidence for it (or any other competing mode of low dose exposure) is quite weak.

https://en.m.wikipedia.org/wiki/Linear_no-threshold_model

[WithinReason]

An interesting addition is that a small amount of radioactivity might even be good for you:

https://en.m.wikipedia.org/wiki/Radiation_hormesis

[evilduck]

And yet living near the Rocky Mountains with a background radiation dose 3 times higher than gulf coast states still correlates with longer than average lifespans. Extrapolation of high dose outcomes might hint at what research needs to be performed but it doesn't mean the results will follow the same path.

[peteradio]

Curious on that. Is this based on a study intending to understand background raditation and lifespan? Or are you just asserting gulf states have lower lifespans than rocky mountain states and also they have lower background radiation. Without controls for cough cough obesity its meaningless.

[evilduck]

The very justified and panic-worthy deadly dose of radiation is around 1.4 million times greater than the background radiation that you can double or triple and not even notice.

And yet here we are with a comment thread of heated debate over a plastics exposure study that's 50 million times greater than realistic exposure levels. When or if a realistic exposure study is done we may find that a plastic cup is more like a transcontinental flight than living near a reactor meltdown. Let's find out before we jump to conclusions either way.

[sfn42]

Drinking a shitload of water can kill you, not drinking water will certainly kill you. In fact having a shitload of just about anything is likely to harm or kill you.

Unrealistically high doses imply absolutely nothing about lower doses.

[john-radio]

This comment is unhelpful; the person you're replying to clearly is not claiming that "absolutely everything that's harmful in large doses is harmful in small doses."

> Unrealistically high doses imply absolutely nothing about lower doses.

The example they give of nuclear radiation is a clear illustration of how a useful hint can be drawn from the high-level example of harm, a pattern which microplastics might very well follow.

[cowl]

But it's not actually a clear illustration. Quite the opposite of it. We are all (no exception) at all times exposed to radiation (And this is not something recent or man-made, we are exposed to natural radiation all the time). So his Assertion that High-level -> harm means low level -> harm is clearly False without specifying a threshold where this happens.

[sfn42]

If it doesn't apply to everything then we don't know whether it applies to this which is exactly my point.

Ionizing radiation is also a great example of something everything on the planet is exposed to all the time and we're fine. So clearly the fact that you'll die standing next to the molten core in Chernobyl does not imply that you'll die from background radiation.

Similarly, showing that an extreme dose of microplastics is harmful does not imply that a normal dose of microplastics is. It might be, but we don't know because we've only tested extreme dosages, apparently.

We also don't know that it works the same way in the body as it does in a test tube.

[s1artibartfast]

Models can breakdown at huge scales because they introduce other non-representative factors or nonlinear responses.

Sending an astronaut to the center of the Sun and concluding their death is from radiation would be a pretty bad model.

Hitting a person with a car would be a pretty bad model for a fly landing on them.

The first model is bad because the sun is doing more than just exposing them to radiation.

The second model is bad because there's a nonlinear response to force applied to a human body.

[peteradio]

There needs to be an understanding of the mechanism of cell death in the OP. And then the question is, under what circumstances will it occur in the human body? Is it basically impossible because the body is filtering it out? Or is there some long-term accumulation where eventually we will see some parts of the population suffering these ill effects? Unknown, but without studies like OP we aren't on the first rung of the ladder.

[pseudosaid]

Read better please

[Dalewyn]

I wouldn't frame it as "harmless", but it is probably accurate to say any harm is insignificant at worst.

[nucleardog]

If it's a single, acute exposure sure.

I'm no doctor or microbiologist or anything, but there definitely seems to be a strong connection between "things that cause cellular damage" and "increased risk of cancer with long term exposure".

[sfn42]

Yeah but cellular damage in the body is not the same as cellular damage in a petri dish.

I bet water kills cells in a petri dish. It's just a really useless test to do, that at absolute best gives a vague hint at something that may be true.

It's not useful to talk about in any capacity other than "let's explore this further with better experiments".

[cowl]

We don't know if it can be a long term exposure. We don't know at what rate they are expelled from a live person. And One thing is for sure. Cell Death that this experiment showed off at the unreasonbly hight concentration is still quite the opposite of Cancer. Cancer is Uncontrolled cell multiplication not death. So according to this we could use nanaplastics to kill cancer. See How easy it is to draw any conclussion that you want if you forget to factor the real conditions?

[amluto]

The concentration they used was 1000ppm or about 0.1%. Many things are toxic at that concentration. (This doesn’t cross the threshold of absurdity of “sodium chloride is toxic at that concentration,” but it would be preferable not to drink 0.1% salt water.)

[parentheses]

I agree with your question:

> whether the exposure you'd receive from occasional microwaving would be enough to ever cause any meaningful health problems

Another question worth asking:

How much of the ~20 ng/kg/day makes its way to the kidney cells? Said another way, if one were to consume a liquid concoction with a certain concentration of nano/micro-plastics, what would the total negative effect be? How much would simply be excreted? That answer for babies vs adults may also vary.

[polishdude20]

These studies also don't take into account the fact that humans have an immune system that helps protect and repair against cell damage.