US EPA sets health advisory limits for PFAS from 70 ppt to .02 ppt (2022) | Hacker News Reader

US EPA sets health advisory limits for PFAS from 70 ppt to .02 ppt (2022)

cen.acs.org

87 pointsJimmc41443 comments

As a doctor, I find it hard to understand why or how a substance that is generally unreactive could cause health problems in the human body. Generally, the less reactive a substance, the less it causes health problems e.g. helium (sure, if you breathe a “hypoxic mixture” of 100% helium, you die, but thats from lack of oxygen, not the helium itself).

Any biochemists out there who can tell me if I’m missing some important context?

I'm not a biochemist, but that unreactive property likely contributes to persistence and bioaccumulation, and like with microplastics, silica, and asbestos, trigger an immune response, cause release of inflammatory cytokines or fibrosis. PFAS can in fact bind to specific proteins in the blood, like albumin as well and other proteins in the liver and kidneys. PFAS molecules have structural similarities to natural hormones, particularly thyroid and allows it to bind to hormone receptors creating agonistic or antagonistic effects.

Isn't the mechanism by which a bunch of carcinogens work by also non-reactive? Like asbestos is carcinogenic due to size and shape, not chemical composition, right?

But it is possible to use e.g. Argon as an anesthetic.

See e.g.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3996095/

In the EPA review they go over some of the chemistry involved through the research that has been done. For example with serum albumin binding, the predominant mechanism is van der waals forces and hydrogen bonding.

https://www.epa.gov/system/files/documents/2024-05/appendix-...

In related news, 33% of dental floss tested in 2022 was found to have contained levels ranging from 11 parts per million to 248,900 ppm.

https://news.ycombinator.com/item?id=40471525

Interestingly our dentist says waterpik devices work better. Not sure what data exists supporting either.

I've heard differently from the two dentists I've seen. The first suggested using a water pick and the second told me it was fine as a first pass but I still needed to floss. Might be because my teeth are very close to each other though.

If there's evidence stronger than a dentist's opinion, I'd like to hear it, because I preferred the water pick...

Can confirm that water pick and flossing work differently. Flossing is not primarily to dislodge food particles but distupt bacteria between teeth. So just water pick alone would be like trying to wash your car by just hosing it down with mild pressure. You want to firsh disrupt bacteria with mechanical action them flush them away with water.

My dentist recommends interdental brushes over flossing.

Interdental brushes are more effective in removing plaque than floss. [0,1]

Water picks are good for reducing gingival inflammation. [1]

[0] https://pubmed.ncbi.nlm.nih.gov/19820738/

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6630384/

That’s a good point that i never thought to ask about, how tight teeth fit might have influenced the advice i heard.

Was also sold one by my dentist. Turns out you still have to floss so it was just another thing I paid for at the dentist that I didn't really need. Cool.

try alternately flossing, then using the waterpik, or vice versa. You’ll find that either way, the second modality dislodges food particles left behind by the first. I take that as evidence that both > one > neither in terms of dental health and this of course assumes you then also brush your teeth.

Flossing doesn't replace water picking, and vice versa.

Both have independent benefits. Most importantly, using a waterpik is never a replacement for flossing.

My waterpik has solved pretty much all of my gum problems. I have one attached to my shower which is very convenient. Highly recommended.

Where did you get the attachment? Or which brand model?

It’s called Showerbreeze

Has those tests been repeated by any other researchers? The company refutes the results and I've never heard of this group previously. Not refuting the risk but would like corroboration

Should be easy for Proctor & Gamble or Johnson & Johnson to have grounds for a lawsuit if that's the case. I'd love it if they sued ehn.org so we could clear it all up.

Good thing I only aspire to floss regularly, since we primarily use Glide.

No, they tested for organic fluorine, and then acted surprised when they predictably realized that many floss products contain PTFE, widely known as Teflon, which we've already known for decades. It's not a secret, and it is in fact the only floss that I can use on my tightly arranged teeth.

PTFE is not a PFAS in the sense used in health research. Teflon is a hard, waxy plastic which is among the most inert, biologically inactive substances known. It is used everywhere from medical implants, Gore-Tex, and other clothing, teflon tape used to seal plumbing joints in your house, and many other other common uses. There is no evidence (that is, evidence from scientifically solid studies-- there are a couple poor ones), that any dental floss raises physiologic levels of PFAS.

The reason you know this reporting is bullshit is that nobody is proposing that we outlaw teflon tape in drinking water plumbing, even though it's made from the same plastic as the best floss products.

That’s… 1/4 PFAS. At that point it’s essentially made of PFAS.

I’m not 100% convinced this is that problematic though. You floss and then rinse/spit. And of course this would only need to get rid of the quantity actually shed from the strand. It would be interesting to see the load actually consumed on average, but my gut says it’s probably irrelevant.

The real issue is the unchecked spread into our environment, causing us (and everything else) to unavoidably ingest it regularly and without limit.

Edit: To be clear, my general position on PFAS is “broadly enact bans on its use out of sheer caution” due how rapidly it’s turning up in the environment. This would be no exception. I’m just saying I’d be surprised if its presence in dental floss actually contributed meaningfully to your daily load given the amount you consume incidentally due to widespread environmental contamination.

It's the mouth - a whole lot of kids aren't spitting properly and swallowing a bunch of the organoflorines. Also your dentist is probably using Glide stuff which is the biggest offender.

As a side note, definitely switch to silk floss - completely natural stuff + wax. I prefer the Radius brand since they were the first.

Nice to know. I’m not a regular flosser but I do have Glide floss. I never considered that it contains PFAS, it was just the first thing I grabbed. I’ll toss it and switch just to be safe.

Some people get bleeding gums when they floss, which would introduce the PFAS directly to the bloodstream..

It also accumulates in the environment after you spit it down the drain.

Note the article is from June 2022

> The agency’s new advisory levels aren’t requirements that drinking water suppliers must meet. The EPA only recommends that utilities notify customers when concentrations exceed the limit.

> But they set the stage for further EPA action. The agency plans to propose mandatory drinking water limits for PFOA and PFOS later this year.

So here we are, in April 2024 with some actual rules and timelines: https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas

Please add 2022 to the title.

What's the current precision for measuring devices?

How much money do you have?

What does it cost me to p .95 reliably differentiate 0.04 ppt from 0.02 ppt?

In water? Doesn't seem like an issue.

In pure water it's not an issue. In drinking water which has all sorts of "stuff", getting very to that level of precision isn't easy.

I was browsing test kits where you send a sample back to a lab. They're $79 - $300 and advertise 1 or 2 parts per trillion. Looks like getting to 0.02 ppt requires some very specialized equipment, and would probably be optimized for continuous monitoring of a water supply.

It's more meaningful to get a blood test which Quest Health offers without a prescription in the US, although it's not cheap. Obviously the blood test is very precise, but it tests only for a few types of PFAS, whereas thousands of types exist in the environment.

Thinking about PFAS makes me feel so unhealthy, how screwed are we?

We are so screwed we can't even quantify how screwed we are, because the entire planet and population are contaminated and have been contaminated for a long time now, so there is no longer a control group to compare to.

that's not entirely true (reddit snark way) -- there's blood samples from the Korean war, that are un-tainted. I think that's like the only place though, on earth... not affected. The chemical companies who did this can't pay enough to make amends, and Criminal charges should be on the table for everyone who had any knowledge.

Sometimes I’ll read something like this and feel too depressed to even get out of bed in the morning :(

"The agency’s new advisory levels aren’t requirements that drinking water suppliers must meet."

So it's entirely meaningless.

See my comment upthread, but in the meanwhile some more concrete rules and timelines have passed:

https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas

Aren't most environmental targets? Setting extremely high targets, often on unreasonable timetables, makes for great PR regardless of whether or not the targets will ever be enforced.

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