Water repellent clothing and PFAS – are they a danger? | Hacker News Reader

Water repellent clothing and PFAS – are they a danger?

molecularspec.substack.com

62 pointsadomasm370 comments

Disappointing that the TL;DR doesn't address the title question.

As a backpacker and a sailor, I strongly feel that DWR/Gore-Tex stuff is garbage anyways- it's (only slightly) breathable when new, but when the coating wears after a few weeks or months, or gets dirty it becomes no longer hydrophobic, and the water sheets on completely blocking the pores. This leads to zero breathability like a sheet of plastic, yet they usually also manage to leak water in constant all day heavy rains or ocean spray. The gore-tex membrane inside is very fragile and becomes ripped and unglued pretty rapidly, in places you cannot see- you don't know until you are counting on it, and it fails.

Two vastly superior alternatives that are PFAS free, much cheaper, more durable, more waterproof, and already on the shelf at most major outdoor stores:

* Polyurethane coated polyester raincoats, e.g. by Helley-Hansen cost about $100 USD new, and are more durable and waterproof than DWR/Nylon/Gore-Tex. Zero breathability (just like Gore-Tex in practice!) but because designers know this, they have excellent vents added, with waterproof zippers to close in extreme weather. Although they look similar, these are much better than your standard cheap PVC raincoat. I use these for sailing and stay bone dry with waves crashing over my body all day long.

* Membrane only jackets (membrane on the outside) such as Columbia OutDry. Because the surface material is fundamentally hydrophobic, they need no PFAS DWR coating, and stay waterproof and breathable even when dirty or aged. Only about $150 new.

// Edit: a third great option is PFAS free Nikwax brand waterproofing you can apply yourself to almost any garment. I've personally only used this on tents and car convertible tops, but it worked great.

The maker of Nikwax also offers membrane-free waterproof clothing under the name Paramo. Environmentally friendly and very effective - used by a lot of UK mountain rescue teams. It's basically carefully chosen and designed fabrics with Nikwax already applied.

Came here to say the same thing. Paramo is great, robust, and sustainable.

Another nice option, especially for streetwear, is Ventile cotton: https://en.wikipedia.org/wiki/Ventile

Ventile clothes without nasty water repellents applied on top are generally marketed as EtaProof.

Ventile is an exception to the "rule" that "cotton kills" (in the cold).

Especially great is for staying dry is double layered ventile, which is now free of flourine chemistry for extra waterproofing (older iterations used PFAS as an extra waterproofing coating.)

The cotton breathes, it's more durable than gore-tex or off-brand knockoffs (stressed PTFE), and it doesn't make annoying "swish swish" noises either, which is helpful for bird watchers and other folks that want to move quietly in nature.

There are two major disadvantages: cost and weight. A ventile garment is many times the price of a similar ptfe garment, especially now that the original gore-tex patents have expired. And it's also many times the weight.

However, let's be honest, if you can afford ventile, you probably can drop 3 pounds of fat through the additional time you will spend outside, lengthen your healthspan and lifetime, and use the garment long enough to pay for the several "waterproof" ptfe garments you would have gone through in the same time.

Cotton kills, don’t wear that outdoors in anything serious.

Jeans used to be standard hiking attire in the Sierra Nevada in the '80s. Most of them survived the experience. It's fine in the summer if you find them comfortable. They chafe and if you dip in a stream get wet and heavy, but for casual hiking it's fine. I wear nylon running shorts and cotton socks. For winter, I have a closet of 3L, 2L, soft shells but in all honesty 99% of hikers will not find themselves in those conditions.

Ive been in plenty situations where summer + sweat-wet + evening or colds gets cold real quick. Add in situations like too tired to quickly get off the 40F peak + windchill, it can get dicey real quick. Same with a wet cotton shirt sailing. On and on.

In the 80’s wool hiking gear used to be around for this reason too. I’d never feel appropriate recommending cotton for anything serious, any season.

Cotton kills in cold weather, but in hot weather it is a lifesaver... it breathes much better than synthetics so your natural evaporative cooling still works, and it keeps your skin drier so you don't get jungle rot or fungal infections.

This is just bad advice. Hot weather days have cool evenings, nights and mornings, and it’s not like you magically stop sweating and dry off at 6pm when the sun is setting. There are plenty synthetics or wool that dry out fine and insulate fine. Those same situations in cotton I’ve seen turn very dangerous.

You gotta use common sense in the right environment, and definitely don't get stuck in the cold in a wet cotton shirt, but a good cotton shirt can save you from heatstroke in situations where synthetics or wool would not, even thin stuff designed for hot weather. I honestly think the "cotton kills" stuff is overblown, it's a lot more complex than that. I would also say "plastic kills" because synthetic clothes make the sweat drip off under the clothes without evaporating- so you lose much of your "cooling capacity", and are also susceptible to jungle rot, fungal infections, etc.

If you look at people that do hard labor or outdoor guide work in extreme hot climates around the world- they all use cotton or similar plant fibers. All of the concerns about cotton come from it cooling "too well" and that often simply isn't an issue. Synthetic and wool stuff is also just not very durable, and incredibly expensive.

I say this as someone with decades of outdoor experience, an ex-boy scout, etc. who used to be a hardline proponent of "cotton kills" in all outdoor conditions. I learned the hard way that I was wrong after being proven wrong time and again in real world conditions, by people with more experience than me that were able to keep functioning in extreme heat better than I was.

I’ll leave it with I’ve been in situations where people actually got trench foot, and pushed into hypothermia/cold casualties bc of starting in the afternoon warm and dry and finishing in the late night and wet/cold in the 40s/50s.I’ve been with people getting heat causality/heat stroke and neared it myself.

The trench foot etc has nothing to do with cotton or synthetics, it’s being wet for days and days. I’ve seen people get it. I’d trust synthetic or wool socks to dry faster and hold their shape (blisters are just as bad) than cotton any day. Also nobody is overheating (or breaking the bank) in Darntough socks.

Your assumptions on moisture and temp management are based on an assumption of environmental control that doesn’t exist in the outdoors. The margin of error is very small for slipping into chilly and then cold as hell, and it happens quickly. Lack of durable synthetics (which I’ve never had give out on me, inspect your equipment prior to leaving lol) vs durable but risky cotton is a silly trade off, in this light.

Heat stroke, the actual type that’s bad, gets prevented from pounding salted water and ice sheets. For it to get this far such that it happens, no amount of sweaty cool cotton will help it.

I say this as someone who learned the hard way as well or watched others did. I am an Eagle Scout, was in a combat branch in the army for a while, been in very hot places for very long, seen trench foot, heat cats, cold cats galore.

100% agree. Cotton is great in hot temps. Yes you can die if you wear it in a snow storm but seriously, how many novices are hiking in these conditions today? I think it might be a holdover from decades ago when forecasts were less reliable and people really did get caught in "random" storms up in the mountains, and were generally less familiar with planning. I can't even remember the last time I saw someone on a real trail hiking in jeans though where hypothermia would be a risk... Most casual guys, if it was really cold, would probably just be like "f this let's stay at home" since hiking for 90% of people is a summer activity.

How many novices hike peaks, start at 80F and end at 40F, tired and sweaty as hell, and have another 2 hours to get down off the mountain before temps go back to non-chilly. Hypothermia starts easier than conditions like this.

In what way, and by what mechanism, does cotton kill?

Cotton does not wick away moisture as effectively as technical fabrics or wool, leaving the wearer wet during physical activity thus increasing the risk of hypothermia when exposed to the elements.

Hypothermia

https://www.trailhiking.com.au/gear/cotton-kills/

Sure, but Ventile was designed for exactly the opposite, to prevent hypothermia on WWII pilots while they were awaiting rescue in the North Sea.

It was also worn in the summit of Mt Everest by Edmund Hillary as it is a great windstopper.

It has nothing to do with regular cotton.

Ventile requires re-proofing though, no? It’s not like a magical variant of cotton, it’s just cotton with treatment.

With the margin of error in the outdoord being as small as it is, I’d trust synthetics or wool that will always work vs the risk my cotton isn’t treated recently and reaches failure.

On the contrary, Ventile should never be proofed. PFAS and such were used earlier as a lubricant in the textile mills, but is now replaced with something more eco-friendly. The water-repellant properties of this was something akin to a happy accident. Original WW2-era Ventile did not use this, as you might guess.

Ventile works it's magic by the combination of long fibered cotton, thigtly spun thread and a close weave. The result is a fabric that after some time swells in rain by absorbing water, and then becoming saturated and impermeable(ish) to further ingress of the wet stuff. The inside will feel damp, but not wet. Wool as a base layer is of course an excellent counter to this. And, all the while excess body heat is shed quite effectively. When at rest, put on a wool or fleece 2nd layer, just like with a synthetic shell.

A compromise, yes. But the greatest advantage over 3L membrane etc. in my opinion is the ruggedness and durability, "experienced wetness" beeing alike. And in the high mountains, boreal or a mid-winter climate with months of stable sub-freezing tempratures, this is a supreme choice for your outer shell. Sweat converted to frost forms on the outside of the garment, instead of the inside as it is want to do in a 2L or 3L. Brush it right of, and carry on.

Most of the fear of cotton is from its use as a base layer, not as an outer layer. Militaries around the world still use cotton heavily, but layered over wool (in WW2) or polypropylene (modern) for colder weather.

Ya and also those militaries have cold weather gear, scheduled conditions to switch into them, and aggressive measures for moisture control (to include no movements in goretex). Joe the hiker in cotton rarely does.

I assume they mean that it takes a long time to dry and holds water too well, and doesn't provide warmth when wet, so cotton is often avoided for hiking.

It absorbs a lot of moisture, it kills by hypothermia.

Awesome, thanks for sharing this- I had no idea! This is great because I feel Nikwax is hard to apply. I once trued unsuccessfully using their "wash in" stuff- I think I somehow applied the coating incorrectly... but the spray on product I have works great.

What are some Paramo jackets available in the US? This brand is unheard of here but I've seen it mentioned in Scottish winter climbing.

“and the water sheets on completely blocking the pores“

Yeah, that's apparently the key problem: the shakedry product line (exposed membrane) was incredibly good at breathability, but I guess the usage restrictions (no backpacks that would rub off the membrane) should be taken seriously, considering the footprint.

> Zero breathability (just like Gore-Tex in practice!) but because designers know this, they have excellent vents added, with waterproof zippers to close in extreme weather.

That's not a distinction. Most Gore-tex or similar proprietary brands also have vents and waterproof zippers.

In fact, for the vast majority of readers here on HN, pit zips and a storm flap on a seam-sealed jacket will keep them dry and keep the garment from wetting out in the vast majority of conditions.

Heck, they could probably even get away with one of those super-lightweight packable windbreakers with a DWR from Mountain Hardware, Patagonia, etc. You could be out for maybe 25-30 minutes of driving rain before water finally gets in through the seams. That's more than enough time for most indoor cats here. :)

I have an ongoing joke with my wife that GoreTex is a myth. We both spend a lot of time on trail and once I splurged for GoreTex trail runners. The first time I wore them on snow I was amazed. My socks stayed dry. Three outings later they were no different than non-GoreTex trail runners. Anecdotal evidence but there seems to be a huge spectrum of GoreTex effectiveness across garments. I'm not sure how these items are manufactured. Is it possible some items have "more" Goretex or have it applied in a specific way to make them last longer than others?

I think this is due to the membrane getting worn or punctured.

Hiking boots now almost all have a goretex membrane, and they seem to last maybe one or two seasons of regular use before they leak. The leather can last many years with care, and the sole can be replaced, but once the goretex is shot you only have whatever water proofing you can apply to the leather itself.

AFAIK Gore Tex are pretty rigid about how it's used with significant QC done within the factory using it to ensure a consistent experience. Then of course, I'm unsure how good that QC really is.

(I work in the industry, but not directly with these sort of things).

How is GoreTex applied? Is it a chemical that you spray on fabric or a fabric itself?

I had a fantastic Gore-Tex jacket (Browning) that was simply magical for hiking in the rain or wet snow.

For two seasons.

Now I have a Arc'Teryx with real water proofing and huge side vents. Still working 100% after 6 years. I just checked and Arc'Teryx looks to have gone full Gore-Tex now, my jacket isn't on the product list :-(

>As a backpacker and a sailor, I strongly feel that DWR/Gore-Tex stuff is garbage anyways- it's (only slightly) breathable when new, but when the coating wears after a few weeks or months, or gets dirty it becomes no longer hydrophobic, and the water sheets on completely blocking the pores.

Most jackets that use a durable water repellant require the coating be regularly maintained (cleaning, re-heating) and re-applied after some time. Manufacturers usually say "years", but one year seems more realistic, even in a not-that-wet climate.

That being said, I agree that Gore-Tex stuff is not waterproof enough for sailing. It's a compromise between waterproof/light-weight/packability/breathability.

Some of the sweat molecules are larger than the holes in some membranes!

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7277079/#:~:tex....

Well, I'm really old and also (for probably unrelated reasons) really dumb, but for me Gore-Tex has been an absolute revelation. Whereas previously, rain gear was heavy and had a very limited lifetime, anything with the magic GORE-TEX (sorry for the all-caps, but that is the trademark...) label actually worked and lasted pretty much forever (like PFAS, I get it now, but still...).

I'm sure that PE-coated and membrane-only gear are also really great, and I'll definitely check them out the next time I need a new softshell, but for the next decade or so, I'm also sure my current jacket will be just fine.

But, Nikwax? Nope... good for the outside layer of shoes (with the inside layer taking care of heat/moisture), but that's really about it. Tents, maybe, car-tops, no idea, but for garments that's just a no-go, since it will all but eliminate outgoing heat transfer.

For backpacking I would highly recommend a hiking umbrella (attached to backpack) https://www.youtube.com/watch?v=rv-2-vAzTRw

How effective is oilskin? I see from a web searh that some people still use this, and it is potentially biodegradable with the right fabric and coating.

as a former sailor, lycra & noeprene were the way to go

Really depends on the area. If you’re sailing late in the season on Lake Superior or the North Sea, you might need a bit more than that when it’s below freezing and raining.

This raises a question i see a lot of confusion about, but doesnt quite answer it:

Are finished PTFE products contaminated with the base PFAS monomers?

Its like how vinyl chloride is dangerous, but when its the polymer PVC its basically safe. People are confused about this in general. I am too.

The monomer is tetrafluoroethylene, which is a gas:

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

As I understand it, the three concerns are:

1. The manufacturing and processing of PTFE is usually done in water with a fluorosurfactant mixed in. The fluorosurfactant varies from nasty to extremely nasty.

2. PTFE could potentially degrade into something less benign than PTFE.

3. PTFE has mediocre thermal stability — it starts to decompose a bit at temperatures that you can easily reach with careless cooking and, notably, it starts to decompose while it’s still a solid. This makes any kind of theromoplastic processing (extruding, molding, etc) a bit nasty. I think the decomposition products are gasses. They are noted for killing birds and concentrations at which their presence is not obvious to mammals.

For another, older, weatherproofing material that was hazardous, consider tent canvas covered in paraffin thinned with gasoline: https://todayincthistory.com/2023/07/06/july-6-the-saddest-d...

The Ringling Bros. and Barnum & Bailey Circus set up in Hartford, CT and a fire broke out with a big crowd inside the big tent. 160+ people died.

And when I attended scout camp (in Connecticut) our tents were all painted with block letter warnings not to bring a flame anywhere close to them because they were similarly weatherproofed. Always gave me the heebie jeebies in a campsite full of teenagers!

The HN title is a bit misleading; the article is mostly about washing the clothing rather than wearing it.

Thanks - I've reverted the title now (minus the "to us" as I don't know who else they'd be a danger to).

Submitted title was "Does wearing waterproof clothing increase PFAS in our bodies?".

Submitters: "Please use the original title, unless it is misleading or linkbait; don't editorialize." - https://news.ycombinator.com/newsguidelines.html

thanks for the note. It used to say "to us" meaning us humans. PFAS is potentially also a danger to the other nature ecosystems.

Actual title: "Water repellent clothing and PFAS - are they a danger to us?"

The article briefly mentions exposure from touching (wearing) DWR clothing - appears to be 700x lower than washing.

TL;DR: No, at least not by skin contact, although you may ingest PFAS in your drinking water later on, caused by the washing of said clothing. Whether PFAS is (/are?) truly bad for you is still TBD, although the chances of this being an 'asbestos' situation are uncomfortably high.

PFAS are so common that it’s unlikely that they’re as bad as asbestos. They probably aren’t more dangerous than leaded gasoline.

I would not feel comfortable, making such a statement. There is plenty of evidence out there, that they mess with our endocrine system, and are perhaps responsible for the obesity crisis in some part.

https://www.hsph.harvard.edu/news/press-releases/pfass-chemi...

I'd also add that even though asbestos is awful and dangerous, it is a) still everywhere and b) still being made and imported into the US [1].

I guess my point being that even if PFAS are as terrible as asbestos that's not enough to keep us from continuing to produce it.

[1] https://www.asbestos.com/asbestos/statistics-facts/

Wouldn't another explanation of the result be that eating more calories is correlated with ingesting more PFAS?

There is also plenty of evidence that lead is very bad but one can be exposed for decades with effects that only show up in epidemiological studies. Asbestos on the other hand is dangerous enough that one unsafe remodeling job has a good chance of giving you cancer.

That's a pretty low bar, both of those are massive health crises, that we may not fully understand the extent of yet. Moreover, it took us a really really long time to realize how dangerous they were- so they are a good example that extremely dangerous things can still take a long time to isolate... especially when the exposure is fairly widespread and we can't isolate/control to study it.

> They probably aren’t more dangerous than leaded gasoline.

You've heard of the Lead-Crime Hypothesis right?

This title needs to be changed. Don't clickbait us with a question, just tell us what is going to be proven

We just can't have nice things, god damn!!

> Finally aspartame is proven to cause cancer

mmm... no

"IARC classifies aspartame as “possibly carcinogenic to humans” (Group 2B), based on limited evidence it might cause cancer (specifically liver cancer) in people. IARC also notes there is limited evidence for cancer in lab animals and limited evidence related to possible mechanisms for it causing cancer."

https://www.cancer.org/cancer/risk-prevention/chemicals/aspa...

With all the attention it's gotten, and some really great explanations of how it's metabolized, I suspect we could safely say aspartame is safer than sugar.

That's not a very good conclusion to draw

Why not? Sugar seems to be, at least partially, causing a LOT of health issues right now.

Sounds like we're just trading a known evil for an unknown one

We literally just established that sugar is a known evil and aspartame is probably not.

I'm actually pretty happy with the amount of push back this "aspartame is proven to cause cancer" narrative is getting in social media circles. People I would not have expected to be aware of the subtleties, including ones prone to conspiracy theories, are chiming into conversations explaining exactly this difference.

I guess people got burned-up way too many times by the media sensationalizing cancer related studies (on both directions).

I wonder if this is a reliable phenomenon that will eventually happen to other kinds of fake news.

We can dream!

I think there a lot of fitness/diet professionals that are posting videos with the message of "WTF!! I'm trying to get my obese, prediabetic clients off of sugar water!!"

Growing up in lake tahoe, we would spray "Scotch Guard" on tons of things, to make them 'waterproof' in winter, like all our ski gear, and even some furniture.

Scotch Guard is basically 'spray teflon' and is super toxic for you, but in the 80s we were encourdaged to spray it all over the place.

https://www.ewg.org/news-insights/news/ask-ewg-why-there-tef...

That reminds me of an occasion as a kid in the 80s, when I sprayed some kind of impermeabilizer on a jacked. I fell ill for a whole day, face glowing red, from the exposure.

Might be a good idea to check if I have been exposed to some of this rubbish

You have.

Watch this disturbing documentary on teflon

"the devil we know"

https://www.youtube.com/watch?v=NJFbsWX4MJM

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