Scrutable

I've recently seen a few articles pop up in the Guardian and Wired on my news feed on the 'menace' of PFAS (per- and polyfluoroalkyl substances). These chemicals are highly stable, pervasive and added to a lot of consumer products. Using the language of the articles, they are 'linked' to various ailments, mostly in the 'its complicated' areas of inflammation and immunity. There seem to be a few environmental action groups and researchers interested in them. My initial feeling is that this seems to be a gift for chemophobes and sellers of detox nonsense and blood tests for the worried well, but could there be more to it?

RELEASE THE TUMBLEWEEDS!

[https://amp.theguardian.com/commentisfr ... ones-water]

https://toxicfreefuture.org/key-issues/ ... nightmare/

Stupidosaurus wrote: ↑

Wed Feb 24, 2021 6:03 pm

I've recently seen a few articles pop up in the Guardian and Wired on my news feed on the 'menace' of PFAS (per- and polyfluoroalkyl substances). These chemicals are highly stable, pervasive and added to a lot of consumer products. Using the language of the articles, they are 'linked' to various ailments, mostly in the 'its complicated' areas of inflammation and immunity. There seem to be a few environmental action groups and researchers interested in them. My initial feeling is that this seems to be a gift for chemophobes and sellers of detox nonsense and blood tests for the worried well, but could there be more to it?

RELEASE THE TUMBLEWEEDS!

[https://amp.theguardian.com/commentisfr ... ones-water]

https://toxicfreefuture.org/key-issues/ ... nightmare/

I saw that and it had my possible b.llsh.t detectors activated. They were somewhat vague in their evidence.

Watch Dark Waters. It's a good movie. It's got Mark Gruffalo in it. He plays a lawyer suing over these PFASs.

I think it's on Amazon Prime as a freebie.

Journalists are normally pretty vague with their evidence

The US EPA - not normally known for scaremongering - says this:

Studies indicate that PFOA and PFOS can cause reproductive and developmental, liver and kidney, and immunological effects in laboratory animals. Both chemicals have caused tumors in animal studies. The most consistent findings from human epidemiology studies are increased cholesterol levels among exposed populations, with more limited findings related to:

infant birth weights,
effects on the immune system,
cancer (for PFOA), and
thyroid hormone disruption (for PFOS).

This is the same EPA that tried to suppress a report on the health effects of PFAS a couple of years back.

It seems to be one of those things that's plausible, but more evidence would be useful to draw a firm scientific conclusion. It sounds like they're very stable with the ability to bioaccumulate, so long-term low-level exposure could still build up. Of course, policy rarely has the luxury of waiting for firm scientific conclusions.

But so far the people who seem to have been exposed to high doses for long enough were living next to known contaminated sites on military bases in the US. That may well be many many orders of magnitude more exposure than a lifetime of normal use of normal consumer products. Or it might not. At the very least, industrial workers could potentially be at risk too, and developing some sort of regulation sounds sensible given the known risks, even if the regulation just says "don't let families live on contaminated sites for a long time".

Just on general principle I wonder to what extent a molecule can be simultaneously highly dangerous and highly stable ("forever"). Helium is chemically forever, but it's pretty harmless (unless you replace all the oxygen in the room with it, and even then it's not the helium killing you), precisely because it doesn't react with anything.

The wiki page suggests that for most of the proposed problems the mechanism is unknown, but in at least one case teh boffinz haz determined that it agonises some receptor involved in gene expression for lipid metabolism. There's quite a lot of ways to alter biological processes without chemically reacting per se.

https://en.wikipedia.org/wiki/Per-_and_ ... substances

Some interesting stuff there, thanks. Some of the Guardian links went through to an old court case where some epidemiologists ran through a long list of diseases and gave a 'linked to/not linked to' conclusion in a way that was highly reminiscent of the XKCD Green Jellybean comic both in terms of the number of conditions considered and the 'hit rate'. Legal and scientific proof has different standards and assumptions and the two often seem to get conflated. I also wonder how many confounding factors apply to any health study of people living in 'contaminated areas'. Not to say these things are harmless, but definitively pinning a complex health outcome on low levels of one of a (probable) cocktail of environmental chemicals is a hard problem.

There's also a documentary "Poisoning America: The Devil we Know" which is available on iplayer as part of the Storyville strand.

Stupidosaurus wrote: ↑

Thu Feb 25, 2021 7:31 am

Some interesting stuff there, thanks. Some of the Guardian links went through to an old court case where some epidemiologists ran through a long list of diseases and gave a 'linked to/not linked to' conclusion in a way that was highly reminiscent of the XKCD Green Jellybean comic both in terms of the number of conditions considered and the 'hit rate'. Legal and scientific proof has different standards and assumptions and the two often seem to get conflated. I also wonder how many confounding factors apply to any health study of people living in 'contaminated areas'. Not to say these things are harmless, but definitively pinning a complex health outcome on low levels of one of a (probable) cocktail of environmental chemicals is a hard problem.

To be clear, the studies finding harm were based on serum concentrations in human subjects, not posited population-level environmental exposure, which makes addressing confounding factors a bit easier.

I've just been sent a link to a special issue of the journal Environmental Toxicology and Chemistry entitled "Understanding Environmental Risk from Exposure to Per‐ and Polyfluoroalkyl Substances (PFASs)".

There's quite a lot of papers, including several focussing on human health, many of them open/free access. https://setac.onlinelibrary.wiley.com/t ... /2021/40/3

There will also be a live discussion with one of the authors in a month https://www.setac.org/events/EventDetai ... 950&group=

This U.S. congressional report on Federal Role in Responding to Potential Risks of Per- and Polyfluoroalkyl Substances (PFAS) may be of interest, particularly the section on "Health Effects Studies".

sTeamTraen wrote: ↑

Thu Feb 25, 2021 12:24 am

Just on general principle I wonder to what extent a molecule can be simultaneously highly dangerous and highly stable ("forever"). Helium is chemically forever, but it's pretty harmless (unless you replace all the oxygen in the room with it, and even then it's not the helium killing you), precisely because it doesn't react with anything.

Biology is a bastard. Phosphodiesters are very stable to hydrolysis but DNAses have no problem hydrolysing them.

You also don't need a reaction to occur as there are plenty of non-covalent interactions in biology (e.g. the mechanism of most of pharmaceuticals).

sTeamTraen wrote: ↑

Thu Feb 25, 2021 12:24 am

Just on general principle I wonder to what extent a molecule can be simultaneously highly dangerous and highly stable ("forever"). Helium is chemically forever, but it's pretty harmless (unless you replace all the oxygen in the room with it, and even then it's not the helium killing you), precisely because it doesn't react with anything.

Similarly, Xenon shouldn't chemically react much, but is an effective (though expensive) anaesthetic.

Turdly wrote: ↑

Fri Feb 26, 2021 10:36 am

sTeamTraen wrote: ↑

Thu Feb 25, 2021 12:24 am

Just on general principle I wonder to what extent a molecule can be simultaneously highly dangerous and highly stable ("forever"). Helium is chemically forever, but it's pretty harmless (unless you replace all the oxygen in the room with it, and even then it's not the helium killing you), precisely because it doesn't react with anything.

Biology is a bastard. Phosphodiesters are very stable to hydrolysis but DNAses have no problem hydrolysing them.

You also don't need a reaction to occur as there are plenty of non-covalent interactions in biology (e.g. the mechanism of most of pharmaceuticals).

Yes, it's tricky to try and give oneself heuristics while not descending to Toby Young-like levels of reasoning.

aiui dioxins are stable and lethal

Lead is famously quite unreactive and not very good for you.

Hunters and fishers still shoot millions of tonnes of it into the environment every year, though at least they've recently been banned from doing it in wetlands in the EU https://www.unep-aewa.org/en/news/eu-ta ... g-wetlands

Good to see people poring over the links posted to assuage their scepticism.

Bird on a Fire wrote: ↑

Sun Feb 28, 2021 1:11 pm

Good to see people poring over the links posted to assuage their scepticism.

Sorry, busy week in Dinoland. I do appreciate the various efforts and will have a poke through the links when I can muster the mental energy. Also the fireball meteorite panicked me a bit.