joghurtbrot

Haruka Kawakami

There's a lot of confusion about different "poxes" in this post (which wasn't my intention, and now I feel bad), so here's a general overview (also, obligatory apology for messiness, this was written at like 1 AM):

Smallpox:

Smallpox, caused by variola virus, was a massive problem historically. It existed in the Western hemisphere for thousands of years (genetic evidence of smallpox has been found in Egyptian mummies from ≈1500 BCE, but it was probably around long before then), and it was introduced to the New World during the Columbian exchange, which had devastating consequences for indigenous populations (which were already suffering from colonialist violence, which made epidemics much worse than they already would've been). Historically, smallpox had a case fatality rate between 30-50%, and survivors were often left disfigured or permanently disabled (you've probably seen pictures of smallpox scars, but smallpox can also cause blindness and other complications). Importantly, smallpox only affects humans—it has no animal hosts—which is why it's one of the few infectious diseases to have been completely eradicated. As of May 8, 1980, it officially no longer exists outside of certain designated American and Russian laboratories. (There are, however, concerns that it could be used as a bioweapon, which is why the government still stockpiles smallpox vaccines and antivirals. I wrote my bioethics term paper on this exact issue, and incidentally, it's one of the major reasons why I believe that STEM majors should take ethics courses!)

There were two strains of variola virus: variola major and variola minor. Variola major was much more dangerous, with a much higher mortality rate; variola minor typically didn't cause severe disease. Fortunately, infection with one strain conferred immunity against the other. Both strains are now eradicated. (People sometimes confuse variola minor with other viruses like cowpox and horsepox, but they're different things.)

There were four clinical forms of smallpox: ordinary (classic smallpox, associated with the rash you usually see in pictures), modified (less severe, often occurred in vaccinated people who got infected anyway), malignant (caused a flat rash instead of the usual pustules, associated with immune dysfunction, almost always fatal), and hemorrhagic (caused severe bleeding, and also near-universally fatal.) All of the non-ordinary forms could be difficult to diagnose because they looked so different from typical smallpox. The less serious "modified" form was often confused with chickenpox, and the hemorrhagic form was sometimes assumed to be a completely different disease. Occasionally, historical sources will refer to hemorrhagic smallpox as "black pox," with or without an understanding that it's caused by the same virus as ordinary smallpox.

Other relevant viruses:

Cowpox, caused by cowpox virus (an orthopoxvirus similar to smallpox) causes mild disease in cows, humans, and several other animals. Infection with cowpox virus confers immunity to variola—Edward Jenner noticed this relationship and used material from cowpox lesions to inoculate people against smallpox.

Vaccinia virus, another orthopoxvirus, is the source of the modern smallpox vaccine. It's closely related to both cowpox and horsepox (weirdly, it's actually closer to horsepox), but it's distinct enough to be its own species. Infection usually causes mild symptoms, and, of course, confers immunity to smallpox.

Chickenpox is an entirely different thing. It's caused by the varicella-zoster virus, which is a herpesvirus, not a poxvirus at all! Infection with varicella-zoster does not confer immunity to smallpox or any other poxvirus—chickenpox is from a totally different family.

So why are the names so weird and confusing? Why is everything about all of this so weird and confusing?

There are multiple reasons for this, so bear with me.

Historically, a "pox" was any disease that caused a bumpy rash of pustles/blisters. Chickenpox, smallpox, and the other "poxes" all cause superficially similar rashes—thus the similar names. (Even though we know now that chickenpox comes from a completely different family, this wouldn't have been apparent before the dawn of modern medicine.)

Smallpox was given that name to differentiate it from syphilis, which was known as the "great pox" when it first appeared in Europe. (Fun[?] microbiology fact: There are debates about the origins of syphilis, but the most common theory holds that it originated in the New World, and Christopher Columbus brought it back to Spain. In that way, it's kind of the inverse of smallpox.) Historically, smallpox was also known by a variety of other names in different European, Asian, and African cultures. Again, this gets murky, because historical physicians sometimes struggled to distinguish between similar-looking-but-different diseases.

Other poxviruses are often named after the animals in which they were first identified. This is not a hard-and-fast rule, though, and it can sometimes be misleading (for example, monkeypox virus was first discovered in laboratory monkeys, but it more often affects rodents and other small mammals. The disease formerly known as "monkeypox" was recently renamed "mpox" because the name wasn't accurate.) Also, some poxviruses aren't named after animals at all! It's a weird and inconsistent system (but a lot of virus names are kinda weird and inconsistent).

Related to the above: We don't even know where the name "chickenpox" comes from. I mean, we know it was called a "pox" because it causes a pox-y rash, but we don't know where the "chicken" part originated. There are multiple theories about this, none of which are definitive. The disease itself has nothing to do with chickens.

Basically, a lot of the weirdness is a result of historical naming practices—people identified and named these diseases before modern virology existed, and those names stuck, so now we have similar names for superficially-similar-but-ultimately-different viruses, and names whose origins have been completely lost to time. Later, virologists muddied the waters further by naming newly-discovered poxviruses after the animals in which they were first seen, even when these animals aren't natural hosts or reservoirs of those viruses. It's a mess! And, again, all of this is complicated by the fact that some of these diseases were very hard to diagnose (or distinguish from one another) before modern medicine existed. Now, we can sequence viral DNA and figure out what's actually going on—which viruses caused which symptoms, whether those viruses were closely related, and whether being infected with one disease conferred immunity to another—but historical doctors and scientists didn't have those tools, so they were doing they best they could with very limited information, and that led to a lot of weirdness in terms of how these viruses were named and classified. Our current system inherited some of that weirdness, so here we are.

TL;DR: Poxvirus names are messy. Smallpox is caused by variola virus, which has two strains: variola major (the more severe one) and variola minor (less severe). Cowpox and vaccinia are different viruses in the same family, and being infected with one of them confers immunity to smallpox. Chickenpox isn't a poxvirus at all, but a herpesvirus—it just happens to cause a pockmark-y rash that looks superficially similar to smallpox pustules (and mild forms of smallpox were historically confused with chickenpox).

(P.S. none of this is super relevant to the average person, so don't feel bad if you didn't know any of it. Unless you are a history major inventing new conspiracies about smallpox, in which case you definitely should feel bad.)

Sources & further reading under the cut!

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!

1. The court holds Google responsible for statements made by its AI, considering them Google's statements (search engines have limited liability for results in their engine as they're the words of other sites/companies/people), meaning when their AI lies/hallucinates they're liable for the defamation/harm resulting from those statements.

2. Google's defense that customers are generally aware of the lack of reliability and are responsible for fact checking was dismissed. As the court pointed out, that would "significantly diminish" AI Search's stated purpose and it can't be distinguished from Google's business practices/statements as a search tool.

3. Studies have found about 91% of Google's everyday AI responses are accurate, leaving millions of searches per HOUR with potential liability for falsehoods. 56% of correct responses weren't supported by the sources the AI listed. Both of which mean Google is now liable for a LOT more AI "errors."

4. Google was held liable for 80% of court costs in this case and this precedent is expected to reverberate around the world. This is a massive shift from the 3rd-party search provider role Google has previously played and it comes right as they've tied ALL searches to their AI search.