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Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

theguardian.com

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Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#51

Post by nate_meurer »

GordonS wrote: post #28
nate_meurer wrote: post #13

Earlier quoted context omitted.

There are no mobile PFAS chemicals in nonstick cookware. Nonstick coatings are made from PTFE, which is a completely inert polymer that cannot be broken down into mobile components unless it's overheated. The fluorinated chemicals used in the manufacture of the coatings (largely surfactants) are completely removed when the coating is baked on, and they have to be or else the coating would fail. PTFE is used in medica…

With every non-stick pan I've ever owned, the coating eventually starts flaking off. Usually after less than 1 year of use. I'm pretty sure I must have ingested plenty of these coatings over the years...

I have many pieces of well-used nonstick cookware well over a decade old, which are in pretty much the same condition as when I bought them. This includes cheap IKEA pans that my kids used. Some of them get used literally every day. We don't overheat them, and don't use metal utensils in them, and there's no reason they can't last forever.

Regardless, you can eat the entire coating off of your pan, and there will be no detectable fluorinated compounds in your blood. PTFE is completely inert and indigestible. It is widely used in medical implants inside people's bodies, with no detectable leaching of any chemicals.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#52

Post by tzs »

DoingIsLearning wrote: post #31
pdabbadabba wrote: post #8

Earlier quoted context omitted.

For those uninterested in digesting these details, the upshot of this seems to be: Yes. HEPA filters should capture these. Edit: Though perhaps inefficiently. See the replies below.

Hold on, that is very much the opposite of my interpretation. HEPA filters are typically designed with 0.3μm pores this is mostly a legacy of medical applications (i.e. to guarantee they catch bacteria). Submicron performance ( The PFAS is a group of substances, the article is specifically talking about 6:2 FTOH (one of many PFAS substances) that is found in carpets etc. 6:2 FTOH specifically is a sub-micron compound…

> You need the submicron particle to travel on a larger liquid particule for it to adhere to the filter lattice

That's what intuition would suggest, but intuition turns out to be wrong when dealing with filters for microscopic things. There are at least four mechanisms by which a filter can trap particles, three of which work on particles smaller than the pores [1].

Briefly:

1. Big particles don't fit between the fibers of the filter. Think fish in a fish net. This is called sieving.

2. Particles too small for sieving but heavier than the surrounding flow don't make the turns as well as the surrounding flow when the flow goes around the fibers. The particles can get embedded in the fibers. This mechanism is called inertial impaction.

3. The smallest might be too small to actually be affected much by the flow of the surrounding fluid through the filter. The move by diffusion, and many will randomly hit the fibers and get stuck.

4. Particles too big for diffusion but too light for inertial impaction still can run into fibers and get stuck. This is called interception.

The effectiveness of sieving, inertial impaction, and interception all follow S shaped curves that start out low for small particles, then at some point start rising, and then level out. The sieving curve's rise is almost vertical. The rise for inertial impaction is steep but not nearly as steep as it is for sieving. The curve for interception's rise is much more relaxed.

The effectiveness for diffusion goes the other way. Much more effective for very small particles, then above some size drops down and is low from then on.

When you put all these together, you get a curve that is effective at the small end, and at some point as size goes up effectiveness drops, reaching a minimum, and then rises again to reach high effectiveness for particles above some certain size.

There is also a fifth mechanism in some filters where electrostatic attraction between the fibers and the particles catches some particles.

[1] https://donaldsonaerospace-defense.com/library/files/documen...

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#53

Post by pdabbadabba »

DoingIsLearning wrote: post #31
pdabbadabba wrote: post #8

Earlier quoted context omitted.

For those uninterested in digesting these details, the upshot of this seems to be: Yes. HEPA filters should capture these. Edit: Though perhaps inefficiently. See the replies below.

Hold on, that is very much the opposite of my interpretation. HEPA filters are typically designed with 0.3μm pores this is mostly a legacy of medical applications (i.e. to guarantee they catch bacteria). Submicron performance ( The PFAS is a group of substances, the article is specifically talking about 6:2 FTOH (one of many PFAS substances) that is found in carpets etc. 6:2 FTOH specifically is a sub-micron compound…

I don't claim to know one way or the other. I was basing my interpretation on GGP's quotation from Wikipedia, which seems to indicate that HEPA filters can capture down to 0.02 μm. I note now, however, that it then goes on to suggests that HEPA filters don't reliably capture some other categories of larger particles, which is consistent with your comment. Edited accordingly.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#54

Post by smallerfish »

GuB-42 wrote: post #35
q_andrew wrote: post #4

This contributes to the theory that PFAS is affecting ambient obesity rates in the modern world: https://slimemoldtimemold.com/2021/07/26/a-chemical-hunger-p...

It may be a contributor but there are so many "obvious" things that cause obesity in the modern world that a paper needs really strong arguments with a rigorous statistical analysis with confounding factors in order to draw conclusions. The obvious include: high availability of energy-rich, cheap food, lower amount of physical activity, food designed to be addictive (usually with lots of sugar),... There is also a st…

The slimemold series addresses those. It's worth a read.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#55

Post by ironmagma »

ashildr wrote: post #42
doitLP wrote: post #40

The problem is not PFAS. It is extreme regulatory capture that got us to the this point. Even if we ban PFAS tomorrow, there are other alternatives that will be used and another 2 decades of lies and cover ups before we find out what harm those chemicals have. Example: look at what happened when BPAs harms became known. Manufacturers switched to using any of the other 40 chemicals in the same bisphenol family (BPS, e…

> from "safe until proven otherwise" to "unsafe until (independently) proven safe" That’s about how the EU does it.

How can you prove anything safe without data on its use? Isn't that sort of a chicken and egg problem?

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#56

Post by barbazoo »

intrasight wrote: post #48
l30n4da5 wrote: post #20

Earlier quoted context omitted.

> HEPA filters This is probably the most important. If you work from home, it might be prudent to at least have a one-room HEPA filter in your home office.

I have in furnance airflow and also one in bedroom.

I'm having trouble figuring out what kind of filter I can use for my furnace. I've read a little bit about it and it seems that a residential furnace might not be able to handle the HEPA filter due to the higher airflow resistance. Even MERV 13 might already be too high.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#57

Post by hdjjhhvvhga »

doitLP wrote: post #40

The problem is not PFAS. It is extreme regulatory capture that got us to the this point. Even if we ban PFAS tomorrow, there are other alternatives that will be used and another 2 decades of lies and cover ups before we find out what harm those chemicals have. Example: look at what happened when BPAs harms became known. Manufacturers switched to using any of the other 40 chemicals in the same bisphenol family (BPS, e…

> Example: look at what happened when BPAs harms became known. Manufacturers switched to using any of the other 40 chemicals in the same bisphenol family (BPS, etc) many of which had even worse safety profiles, while proudly proclaiming their products were "BPA free".

It's worse than that. I remember when some 10 years ago Johnson&Johnson baby bottles were banned in one market, they were still available in others, and the FAQ on their website said they do this because they don't believe BPA is harmful. It is only after the total ban in 2012 that they stopped doing this.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#58

Post by BoxOfRain »

ashildr wrote: post #42
doitLP wrote: post #40

The problem is not PFAS. It is extreme regulatory capture that got us to the this point. Even if we ban PFAS tomorrow, there are other alternatives that will be used and another 2 decades of lies and cover ups before we find out what harm those chemicals have. Example: look at what happened when BPAs harms became known. Manufacturers switched to using any of the other 40 chemicals in the same bisphenol family (BPS, e…

> from "safe until proven otherwise" to "unsafe until (independently) proven safe" That’s about how the EU does it.

Which isn't without issues of its own of course, for example the EU is notoriously backwards on the issue of genetically modified crops which may turn out to be a vital lifeline if climate change causes agricultural collapse. Another example I can think of off the top of my head is the atrociously bad legislation to what was then the new technology of vaping, it came in pre-Brexit just when I was considering quitting smoking (which I eventually managed and never could have done without a vape) and it was so poorly thought out I'm convinced the tobacco industry had a hand in drafting it!

The precautionary principle has its merits, but I think it's often cargo-culted and its limitations not well articulated. In cases such as GM crops where the stakes may within a human lifetime be "devestating famine" versus "less famine", or cases like vaping where although the harm is unknown it's certainly less than what it's replacing (vaping is uncontroversially less harmful than smoking) the precautionary principle actually has a harmful effect in itself.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#59

Post by thatfrenchguy »

q_andrew wrote: post #4

This contributes to the theory that PFAS is affecting ambient obesity rates in the modern world: https://slimemoldtimemold.com/2021/07/26/a-chemical-hunger-p...

As someone who immigrated from France to the US, it’s pretty obvious why people in the US are obese: people don’t know / don’t have the time to know how to eat properly and eat junk food, all the time, at any hour, and don’t move around. It’s pretty obvious when you realize that there is a lot less overweight people in upper middle class areas.

Re: Toxic ‘forever chemicals’ contaminate indoor air at worrying levels

#60

Post by nate_meurer »

slumdev wrote: post #23
nate_meurer wrote: post #13

Earlier quoted context omitted.

There are no mobile PFAS chemicals in nonstick cookware. Nonstick coatings are made from PTFE, which is a completely inert polymer that cannot be broken down into mobile components unless it's overheated. The fluorinated chemicals used in the manufacture of the coatings (largely surfactants) are completely removed when the coating is baked on, and they have to be or else the coating would fail. PTFE is used in medica…

The idea that PTFE doesn't break down except at very high temperatures is not true. Breakdown begins to occur at either 200 or 260 degrees Celsius (depending on what data you're looking at). These temperatures are well within the realm of temperatures that even a home chef might encounter.

> Breakdown begins to occur at either 200 or 260 degrees Celsius (depending on what data you're looking at).

This isn't good data. The stories of PTFE coatings breaking down at less than 260 deg C are anecdotal. The most well known one comes from someone who swears their chickens were killed by coated light bulbs in a coop.

The lowest temperature that has lead to bird deaths in a controlled laboratory setting is 280 deg C, which is about 580 deg F. [1] This is way freaking hot, and likely only to be reached by accident.

Even in the case of accidental overheating of non-stick cookware, there have been only a few verifiable cases of injury, and certainly no fatalities. Most cases of polymer fume fever have been gleened from among workers in factories, which is remarkable considering that billions of pieces of nonstick cookware have been in use every day around the world for the past seventy years.

Also note that cooking fumes from food are themselves toxic, and kill birds and lead to long term respiratory issues in humans much more easily than PTFE coatings.

1 - https://sci-hub.st/10.1289/ehp.7511197 - An Industrial Approach to Evaluation of Pyrolysis and Combustion Hazards

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