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Comment by bhouston | Hacker News Reader

How safe are these? It is cool science, but so far PFAS seem to be poisoning us. Are some PFAS considered safe? Or as a class are they all harmful?

Details: https://www.epa.gov/pfas/our-current-understanding-human-hea...

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The substantive claim against PFAS is that they're very persistent in the environment, can bioaccumulate, and end up in places we didn't anticipate (e.g., in the rain). This is a good argument for scaling back.

Separately from this, there's some science to suggest that PFAS are harmful to humans, but at doses very much higher than experienced by the general population. Many of the headlines about PFAS being detected in weird places involve parts per trillion, and at that level, no health impacts have been demonstrated. Even for lead and ethylmercury in water, the norms are in parts per billion.

Then, there's a cottage industry of anti-progress doomsayers who want to equate it to a handful of big environmental missteps of the past, so the lines get blurred. Same as with microplastics, where you're bombarded with headlines about them being found in random places and being vaguely bad for you.

> and at that level, no health impacts have been demonstrated.

Right, but since it bio-accumulates even if your exposure is low over the decades you may accumulate enough of it for it to affect your health. If your body can't get rid of it then it's not the dosage that counts anymore, it's the total exposure over your lifetime that matters.

If they were measuring dangerous levels of bioaccumulation then you can be sure we'd hear about it. You'd need to live 1000 years though given the levels we're talking about.

This is not self-evident. Biology is extremely complex and we have a lot left to learn before we can make definitive statements about safety. This idea of 'you can be sure we'd hear about it' places too much of the burden on journalists, random medical researchers, and eventually regulators to suss out what is going on.

As it stands in our system today any awareness we may have about dangers will come far after the danger to us, and then we'll all say a collective 'oops' as we've had to do the last hundred times. Look no further than all the 'I [live near the plant/play on the field/drink the water] and have [cancer/autoimmune/rare disease/etc]' stories that keep coming out year after year.

There's lots of evidence that long-chain PFAS can bioaccumulate across generations. You don't need to live a millennium personally. (Also the effects are disproportionately bad on infants, so you don't need 1000 years of generations either.)

Also we didn't really stop putting them in the water yet...

> you can be sure we’d hear from it

If it’s widely used and profitable to many, you can be sure you won’t hear from it.

https://en.m.wikipedia.org/wiki/Choice-supportive_bias

Or you just need to be a fetus.

Yes, did you know, fetuses start as single cells?

We are in the stone ages of medicinal and biological understanding. We have no idea what levels or forms of exposure are "safe", not only for humans but the ecosystem as a whole.

Your argument about "total exposure over a lifetime" can be applied to literally every single thing people ingest or do.

Can be, but the ones that we know are harmful, like lead, have or are being removed from the cycle. I'm sure you're doing a logical fallacy of sorts here, appeal to tradition or something - just because it happens with something else, doesn't make it right.

No, we shit, piss, and/or otherwise emit most things back out. Chemicals which genuinely bioaccumulate are naturally rare and we should be careful with them.

the point of PFAS and the related fear is that 1) they are NOT rare and are everywhere, and 2) we don't piss them out

Hi! I'm Clippy. It looks like you are trying to make a point. Maybe I can help?

Because you definitely need it if you thought your comment did anything.

Parts per trillion are small, but can still be bad for you. And this is an area of active study, the old threshold of 70 ppt was dropped a thousandfold recently:

https://www.hsph.harvard.edu/news/features/stricter-federal-...

The Wolverine shoe leather tannery up the road dumped their ScotchGuard contaminated scraps/waste in the swamps behind a farm owned by a family friend back in the 70s and 80s. Now my well water is contaminated with a few parts per trillion of PFAS, and the PFAS levels in my blood are significantly higher than the threshold of proven harm.

How were you able to get a blood test?

Everyone in the township was invited/asked to participate in this study:

https://www.michigan.gov/mdhhs/safety-injury-prev/environmen...

>Same as with microplastics, where you're bombarded with headlines about them being found in random places and being vaguely bad for you.

Compounds in plastics mimic hormones putting everyone (and the whole biosphere) on low grade hormone replacement. There's not a question about "if", but "how much". They are biologically active, they are present inside you.

I think many people would rather get upset about some miniscule detection in a random place than take a hard look at their own home where their highest exposure is.

As someone who lived in a place that's still dealing with pfoa contamination, your characterization of "anti-progress doomsayers" feels insensitive. If you tell people that they and their kids have toxic chemicals in their blood at 100x the normal concentration they're going to be concerned. Writing them off as outliers is dismissive and misses the point; it doesn't matter if things are safe in small doses if companies can't be trusted to avoid exposing people to unsafe doses.

From a 2016 study in Vermont:

> More than 400 wells tested positive for PFOA. More than 300 wells had concentrations at levels greater than the state’s PFOA/PFOS drinking water standard of 20 parts per trillion (ppt). The maximum level of PFOA detected in a private drinking water well was 4,600 ppt.

https://dec.vermont.gov/sites/dec/files/documents/PFAS%20Sam...

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

Thanks for posting the (ppt) 20 ppt. It looks like all the animals have higher levels.

One example, with a Science(TM) paywall, cited on the wiki - Great tit near 3M, Port of Antwerp, Belgium 2007 liver 553–11,359[39]

Had a 553-11,359ppb from liver tests published in 2006.

Really happy we moved away from ppb to ppt.

I mean, we’ve understood negative impacts of climate change for like a hundred years now, and minimizer propaganda is still winning the information war for a majority of the planet, and some 40% of Americans.

I don’t think there’s any issue at all with getting ahead of forever chemicals and regulating them before it gets to climate change levels of disaster (in some deregulation parts of the country, it will soon be legal to contaminate the soil and groundwater with pfas and radioactive materials because some politicians friend wants to sell their companies waste to road work).

I am sorry, but I simply disagree that the issue is minimal here. We should be treating this as if it’s already out of control and stamping it out before propaganda pieces settle and let it become out of control.

great summary! I wrote a blog post focusing on DWR clothing, but ended up covering PFAS human and animal studies and concentration sampling. Overall with very similar conclusions: https://open.substack.com/pub/molecularspec/p/water-repellen...

However, if we are able to better detect them, we can build better remediation which we need.

The problem with PFAS isn't the amount found in the general environment, it's the amount found in the immediate area around factories that produce them or apply them to products.

>> and at that level, no health impacts have been demonstrated

But again, absence of evidence is not evidence of absence.

The fact is, our ability to detect harmful health effects, particularly over the long term, is still in its absolute infancy. There is absolutely no reason to declare things safe until proven unsafe, particularly, particularly when you look with a historical lens.

The damage of a chemical will always be greater than what we can measure, because science (measuring blood levels of tens of thousands of people with mass spectometry and correlating against long-term health events like cancer) is incredibly hard, expensive, and slow.

As a thought experiment, suppose a chemical released in the water increased emotional irritability by 1%, or ADD by 2%, or reduced sperm count by 3%? What are the odds that we'd be able to conduct a study sensitive enough to prove the link? And what are the odds that anybody would happen to guess that correlation existed and choose to look in the first place?

> There is absolutely no reason to declare things safe until proven unsafe

I wish i could upvote this more

>> and at that level, no health impacts have been demonstrated

There’s a really important distinction between these two mindsets. The presumption that small amounts of chemicals should have to be demonstrated harmful to be considered toxic, is a mindset that is common in the self-identified scientifically skeptical, yet is anything but. It’s somewhere between careless - something like “humans have always consumed whatever is in the environment, therefore that’s the baseline” - and simply parroting corporate propaganda and lobbyist talking points.

Checknthrowup238's response elsewhere for a great response. You seem to recognize the properties of PFAS but wave away the risk over time.

Like asbestos, we should shelve this substance, even if it's good at what it does.

> Are some PFAS considered safe? Or as a class are they all harmful?

I don't think many chemists want to admit that there's very little reason to believe any PFAS formulation could ever really be safe. Perhaps one could be designed to break down faster and be less bioaccumulating in animals but realistically their mechanism of action as surfactants - the reason they're so industrially useful - is the very reason they're toxic to living organisms.

Surfactants fundamentally change the surface tension of water and other fluids which has an effect on everything from how biological surfaces adhere to each other (including to the internal extracellular matrix that most multicellular life depends on to organize its cells) to how proteins fold together. Normally surfactants like soap, lecithin in egg yolks, and glycolipids are not a problem because they're immediately biodegradable but not PFAS.

The carbon-flourine bonds that make them so resistant to breakdown and so bioaccumulating are the reason why they work in such a wide range of industrial environments, surviving high temperature and strong redox reagents that would normally rip apart any other molecule. It's the worst kind of catch 22. The whole class should be banned and the industry forced to live with the consequences like all the anti-fouling agents that are banned in the maritime industry.

This applies only to small molecule PFAS, not PFAS polymers, which are about as inert as you can get. You need the small molecules to make the polymers, but there's no reason you need to release them into the environment. Strong regulation (e.g. Chinese style, with lengthy prison sentences or death penalty for CEOs of companies violating them) could enforce strict containment of the reactions and safe disposal of the waste with techniques such as supercritical water oxidation.

This would increase the cost, but there's no good substitute for PFAS polymers, so people who really needed them would be willing to pay.

If the case is that clear, then perhaps so could regulatory enforcement?

This was a great simple, explanation of the reason for the harm and why small amounts matter. Thank you

Unless I misunderstood the article, the UNC researchers developed a way to detect more PFAS in the water. They didn’t develop new PFAS.

Good video on the topic here https://www.youtube.com/watch?v=t8qGtEVh7oQ

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