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Microplastics in the human brain

smithsonianmag.com

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Re: Microplastics in the human brain

#171

Post by timr »

myrmidon wrote: post #168
timr wrote: post #141

Earlier quoted context omitted.

You're talking about reduction in statistical variance due to replication of measurement (and then averaging). I'm talking about what happens when they extrapolate from that value by a huge factor (which is what they've done, and the silly article does egregiously). The paper isn't clear what they mean when they said "~25% within-sample coefficient of variation", so I can't directly address what you're asking, but it…

I think there is some kind of mixup, you can not scale up the variance percentages quadratically: If you do a small-scale measurement, say you get result of 5g, with a standard deviation of 0.2g. That means the variance is 0.04 g^2. If you then scale the setup up by 1000 (=> getting 5kg as expected value), then the variance scales to 1000^2 * 0.04 = 40000 g^2. BUT the standard deviation is still 200g. The relative un…

> If you then scale the setup up by 1000 (=> getting 5kg as expected value), then the variance scales to 1000^2 * 0.04 = 40000 g^2.

They didn't "scale the setup". They made a small-scale measurement, then extrapolated from that result by many orders of magnitude. They didn't grind up whole brains and measure the plastic content.

Imagine the experiment as a draw from a normal distribution (the distribution is irrelevant; it's just easier to visualize). You then multiply that sample by 10,000. What is the variance of the resulting sample distribution?

Re: Microplastics in the human brain

#172

Post by myrmidon »

timr wrote: post #171
myrmidon wrote: post #168

Earlier quoted context omitted.

I think there is some kind of mixup, you can not scale up the variance percentages quadratically: If you do a small-scale measurement, say you get result of 5g, with a standard deviation of 0.2g. That means the variance is 0.04 g^2. If you then scale the setup up by 1000 (=> getting 5kg as expected value), then the variance scales to 1000^2 * 0.04 = 40000 g^2. BUT the standard deviation is still 200g. The relative un…

> If you then scale the setup up by 1000 (=> getting 5kg as expected value), then the variance scales to 1000^2 * 0.04 = 40000 g^2. They didn't "scale the setup". They made a small-scale measurement, then extrapolated from that result by many orders of magnitude. They didn't grind up whole brains and measure the plastic content. Imagine the experiment as a draw from a normal distribution (the distribution is irreleva…

> What is the variance of the resulting sample distribution?

Relatively? The same. Yes it scales quadratically, but that is just because variance has such a weird unit.

Just consider standard deviation (which has the same physical unit as what you are measuring, and can be substituted for variance conceptually): This increases linearly when you scale up the sample.

An example: Say you take 20 blood samples (5 ml), and find that they contain 4.5 ml water, with a standard deviation of 0.1 ml over your samples.

From that, your best guess for the whole human (5 liters, i.e. x1000) has to be 4.5 liters water, with standard deviation scaled up to 0.1 liters (or what would you argue for, and why?)

Re: Microplastics in the human brain

#173

Post by bluefirebrand »

globular-toast wrote: post #167
bluefirebrand wrote: post #147

Earlier quoted context omitted.

> you don't need to haul a weeks worth of groceries but can get fresh food every single day I lived that life in my 20s Turns out I don't actually want to go to the grocery store every day. I want to go once a week and stock up, which I can do thanks to inventions like the refrigerator and the automobile

I don't believe it. If you lived right next door to the grocery shop would you still only go once a week and stock up? Nobody wants less flexibility, rigid plans and higher maintenance costs. I think what you really want is a big house with lots of space away from other people and since you can't have your cake and eat it too you've sacrificed everything else.

You got me

I actually did live in an apartment a block away from a grocery store and yes, you're right. I would not trade my current house for having a grocery store that close

Because living in apartments sucks

But even if I did live in my current house with a grocery store right next door, I still would prefer to go as few times a week as possible. Planning ahead and limiting how often I am at stores helps me tremendously with sticking to a budget, which is also something I place a lot of value on

When I lived close to a grocery store not only did I spend more because the prices were higher, I also made more frequent trips for things on a whim, like snacks and treats. It was a much more expensive lifestyle

Maybe other people don't have that same struggle with convenience, but I do. By making the barrier higher, my life is more affordable and I eat less junk food for sure

This is all just my experience though

Re: Microplastics in the human brain

#174

Post by bluefirebrand »

lurking_swe wrote: post #154
bluefirebrand wrote: post #147

Earlier quoted context omitted.

> you don't need to haul a weeks worth of groceries but can get fresh food every single day I lived that life in my 20s Turns out I don't actually want to go to the grocery store every day. I want to go once a week and stock up, which I can do thanks to inventions like the refrigerator and the automobile

no judgment on you in particular, but i’m not a fan of this thought process. I believe it’s a major cause for why americans (statistically) are so obese. and i say this as an american that lives in a city but has family in the suburbs. running errands with your own two feet every day by walking, cycling, etc keeps people healthy and lean. this country has a major car problem. it’s sad. of course one can go to the gym…

> running errands with your own two feet every day by walking, cycling, etc keeps people healthy and lean. this country has a major car problem

I did live this exact lifestyle in my 20s. I was definitely more active but my diet was way worse. I was closer to a lot of restaurants, and I was closer to a lot of bakeries and convenience stores and such as well.

A healthy lifestyle also requires a healthy diet and city living gave me far too much easy access to snacks and junk food. A lot of "it's only 5 minutes to go buy a snack". Daily stops for coffee that often included a pasty

Yeah, the walkable city does mean people are more active

It doesn't necessarily mean they are much more healthy. It still requires other forms of self control (which I admit, I struggled with)

Re: Microplastics in the human brain

#176

Post by repiret »

kirubakaran wrote: post #146
repiret wrote: post #91

Earlier quoted context omitted.

Do you have a citation for the vehicle weight to the fourth figure? There is about a 2X variation in the weight of the vehicles I’ve owned, but even accounting for differences in tire size, I can’t come up with a 16x difference in how often I change the tires. Thinking about it a different way, there isn’t much difference in recommended tire pressure among the autos I’ve owned. That means that the pressure between th…

https://en.wikipedia.org/wiki/Fourth_power_law

That says nothing about tire wear.

Re: Microplastics in the human brain

#177

Post by robertlagrant »

tstrimple wrote: post #142
lenerdenator wrote: post #92

Earlier quoted context omitted.

I should specify: it's more expensive for the developers and their home-buying customers to build up instead of out. All of that stuff you listed comes from tax dollars, and people ultimately care less about that than what's coming out of their pockets for a home purchase. Well, until it's unsustainable, anyways.

Yes exactly. Building is cheap in the US relatively speaking. There are tons of grants and government money to help move things along. Those avenues don't really exist for maintaining things that were built with grants and outside funds. So we see TONS of expansion followed up with almost no maintenance and suburbs and less populated places literally cannot afford to maintain the services that they utilize. The burde…

> Never will this rugged individualist acknowledge that providing him with internet access on the state's dollar costs orders of magnitude more than someone living in a sustainable location

Thankfully we have Starlink to replace pork consumption with actual services.

Re: Microplastics in the human brain

#178

Post by robertlagrant »

twelvechairs wrote: post #113
hammock wrote: post #24

Earlier quoted context omitted.

And we need more lightweight cars , not heavier, since tire wear is proportional to vehicle weight to the fourth power. Ironically, CAFE regulations and EV incentives both did the opposite

Roads and road standards are a tragedy of the commons. People keep buying bigger cars and demanding more, wider lanes and parking spaces because they don't take any of the burden individually - it's the taxpayers as a whole that foot the bill. Paradoxically most of the 'small government' types are often the biggest road users.

> Paradoxically most of the 'small government' types are often the biggest road users.

I think it's "limited government". I'm pretty sure they would prefer roads get more spending.

Re: Microplastics in the human brain

#179

Post by epistasis »

bluefirebrand wrote: post #147
epistasis wrote: post #103

Earlier quoted context omitted.

Imagine a grocery store that is within a short walking distance, such that you don't need to haul a weeks worth of groceries but can get fresh food every single day. US supermarkets are massive, take forever to buy small amounts of groceries, and even the walk to and from the car is long. A better world is possible! (If better grocery stores constitute a "better world")

> you don't need to haul a weeks worth of groceries but can get fresh food every single day I lived that life in my 20s Turns out I don't actually want to go to the grocery store every day. I want to go once a week and stock up, which I can do thanks to inventions like the refrigerator and the automobile

Well good news, nothing is stoping you from bringing home a full cartful of groceries that walking distance either. You just have more options.

Now, if you are really attached to your car and are only open to using your car for groceries, stay in suburbia, it's oversupplied through centralized planning and not at risk of going anywhere!

Re: Microplastics in the human brain

#180

Post by synergy20 »

stevenwoo wrote: post #153
synergy20 wrote: post #139

why did not they got flushed by our digestive system,yes micro plastics are tiny,still they are too large to get into arteries and veins thus no way to reach the brain?

Nanoplastics can be so small that they can get inside most cells even blood cell so could pass through gut lining and blood brain barrier and sometimes are shaped like the key/lock our body already uses for certain intracellular chemical interactions and interferes with the correct molecules doing work, so they can be both inert for the most part and harmful because our cells just don’t just eject them automatically…

Great to know the insights! It seems inevitable though as plastics are everywhere.
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