everything in moderation, except when nah fuck that

Over fifty years of data show a peak in PFAS (also known as "forever chemicals") content in seabird eggs in the 90s, followed by a decrease as regulations went into effect. The most recent findings show a 70% decrease of most common PFAS.

We are making genuine progress! Producers are dramatically altering how much they use PFAS and how much gets released in effluent, but also there's a lot better understanding of how to remove PFAS from the environment!

you can think of this sort of like how water wicks into a paper towel. the water gets stuck to the paper because it's attracted to it via capillary forces, even though there's no chemical reaction going on.

the two main methods used are granular activated carbon (GAC) adsorption and ion exchange (IX).

activated carbon is already pretty familiar to a lot of us; it's the stuff in a lot of replaceable water filters. the activated carbon has a huge internal surface area, and that allows for the fairly weak intermolecular forces to add up and allow contaminants to get "stuck" onto the surface of the activated carbon. over time, the activated carbon gets filled with junk, and you have to replace it.

GAC is essentially this, except that the activated carbon is granularized and produced in specific ways to maximize how much it attracts certain chemicals. this can be tuned because activated carbon gets its massive surface area from internal "pores", and various processes will change how large and frequent those pores are.

It's essentially a Russian nesting doll of pores, and controlling the size of the larger pores influences the permeability of the activated carbon and controlling the size of the smaller pores (micropores) influences what exactly is most attracted to the activated carbon.

However, GAC has a few major downsides:

It is not specific to PFAS. This is more of a mixed blessing because it was already frequently used and well understood, and the infrastructure for producing and distributing it already existed. However,

It loses effectiveness over time and must be replaced. This is a continued cost, albeit a low one, but this has one final major issue

As time goes on, the PFAS previously adsorbed to the activated carbon is desorbed and replaced by other things that have a higher affinity for the activated carbon.

As such, ion exchange (IX) was always very compelling. The whole point of it relies on the fact that PFAS molecules are predominantly made of two parts: An acid head group (either a carboxylic or sulfonic acid group) and a perfluorinated tail.

The head groups on the right are what become ionized—or specifically, deprotonated. A hydrogen leaves and is replaced with a metal cation (usually sodium), forming a PFAS salt (chemical meaning of salt!). These are much more soluble in water because of polarity reasons, and so the mobile PFAS molecules are almost always in that salt form.

By passing through these PFAS salts through a permeable polymer matrix that has (1) numerous positively charged groups like quaternary amines and (2) highly mobile negative ions loosely attached to those stationary positive groups (most often chlorides), you can actually get the PFAS to be "stuck" inside the polymer matrix and what comes out is just good ol' sodium chloride, or salt (culinary meaning of salt!).

This shows a version with hydroxide (OH-) ions as the mobile anion, but it's the same idea. The +NR3 in yellow are stuck to the polymer matrix, but the OH- can freely move around. However, without another anion to replace the OH-, the ionic attraction prevents the hydroxides from leaving.

In comes the PFAS. Despite being slightly soluble in water, the anionic PFAS aren't really that mobile, and when they pass through, it's much easier for the hydroxide ions to leave. Another very important effect is that the long perfluorinated tail of the PFAS is attracted to the polymer matrix, whilst the counterions are ONLY attracted via the ionic force. Thus, PFAS would much rather hang out in the polymer matrix.

Of course, IX has its own downsides

These resins are much more expensive, both to manufacture and to transport.

While they can be "regenerated", it's a tricky process that currently requires the use of nearly anhydrous methanol, which is both poisonous and extremely flammable, increasing the operating costs.

As the hydrophobic tail is a key part of allowing the PFAS to stick to the matrix, short-chain PFAS are very poorly dealt with by this system. This is exacerbated by competition between different PFAS molecules, as long-chain ones will cause short-chain ones to desorb.

Overall, the best method appears to be using a series of ion exchange resins followed by an activated carbon filter. The ion exchange will capture the bulk of the PFAS molecules, and the activated carbon will grab any stragglers. Effective filtering of other contaminants prior to the PFAS removal system will also ensure minimal competition in the activated carbon.

Also a welcome reminder that just because a Big Problem doesn't seem practically solvable right now doesn't mean it won't become solvable in the future!

There are real labor problems here. Base pay is often insulting. Customer tips carry too much of the burden. Workers need better protections, more transparent algorithms, protection from arbitrary deactivation, and actual recourse when the app or a customer screws them over. Car-dependent delivery is also an environmental and infrastructural problem, though in a denser city I’d still be doing this work; I’d just be doing it by bike.

But when people talk about delivery work, I rarely see them talk to actual delivery workers. I see a lot of abstract arguments about convenience, consumer decadence, “hustle culture,” and internalized neoliberalism. Meanwhile, when I’m out working and waiting in restaurants for orders, the other Dashers I meet are usually people who only speak Spanish, people who read as neurodivergent, visibly physically disabled people, or some combination of the above.

I have not met this mythical Disco Elysium poor ultraliberal hustlegrinder-wannabe people seem to be arguing with. Maybe that archetype exists somewhere. If it exists among any kind of gig worker, it would probably be rideshare drivers. But most of what I see looks less like “rise and grind” and more like “this is one of the few forms of work available to people who need flexibility, low barriers to entry, limited managerial surveillance, or a way to work around language barriers, disability, burnout, chronic illnesses and injuries with symptoms that come and go unpredictably, caregiving, résumé gaps, or discrimination.”

That does not make the current system good. It means the current system is filling a real gap that a lot of supposedly better systems do not even acknowledge.

As a disabled person who is burnout-prone and demand-sensitive, contracting as a delivery driver has given me an unprecedented level of financial flexibility. I can work when I have capacity. I can stop when I’m deteriorating. I can build my day around my actual body instead of being trapped under a manager who thinks “reliable” means “able to perform the same way every day no matter what.” That matters. It does not cancel out the exploitation, but it is also not fake just because it is politically inconvenient.

And delivery itself is not some inherently decadent evil. Sometimes people live alone. Sometimes they are sick. Sometimes they are disabled, exhausted, overwhelmed, grieving, overloaded, or recovering from something else - perhaps the stress and fatigue induced by their own job. Sometimes they need medicine, groceries, or a meal that will actually unplug their sinuses instead of whatever generic community-care slop someone thinks they should be grateful for. Humans are allowed to need specificity. “Food” is not the same as “the food I can actually eat right now.”

A serious labor critique would ask how to make delivery work safer, better-paid, less tip-dependent, less car-dependent, less algorithmically punitive, and less precarious. It would ask what kinds of flexible, accessible work should exist for people who cannot thrive in conventional employment. It would ask how cities could support bike delivery, worker cooperatives, public infrastructure, and real protections without simply replacing one bad system with a moral sermon about how nobody should ever want takeout.

But a lot of the discourse does not do that. It treats convenience itself as suspicious. It treats wanting flexible work as false consciousness. It treats the needs of disabled people, immigrants, and other people who can't fit into traditional employment structures as details to be swept aside in favor of a cleaner political image.