It's a pretty popular hashtag on Twitter and I'm not exempt from joining in the joke, so Chris' criticism includes me. In brief, his point is that this joke unfairly mocks the uneducated:
The dihydrogen monoxide joke punches down, in other words. It mocks people for not having had access to a good education. And the fact that many of its practitioners use it in order to belittle utterly valid environmental concerns, in the style of (for instance) Penn Jillette, makes it all the worse — even if those concerns aren’t always expressed in phraseology a chemist would find beyond reproach, or with math that necessarily works out on close examination.(Emphasis in original)
I largely agree with Chris. As I've noted before, when responding to chemophobia we have to avoid the temptation to mock others' ignorance or to be condescending. It's unpleasant and counter-productive, and risks alienating people we ought to be communicating our work to and helping to educate. It gives us a bad name, makes us look arrogant and out of touch with the public, and is dismissive of legitimate or at least understandable concerns. None of what follows is intended to defend making jokes at the expense of the uneducated, or knee-jerk tribalism that 'belittles utterly valid concerns'.
Despite these important criticisms, I do think the DHMO trope has some merit. Conveniently, there's even a recent example to illustrate this for me. Buzzfeed recently ran a list of 8 food additives that are supposedly banned everywhere but the US. It's a classic of the chemophobia genre: scare-mongering, entirely (and probably deliberately) ignorant, and widely-read (over 5.2 million views and over 500,000 likes/tweets/shares at the time of writing). It's also a great example of churnalism and seems to have been lifted directly from a health food book.
The fears the article tries to whip up are pretty much baseless: Derek Lowe has pulled apart this article at length and he illustrates that the average high school student has a better grasp of chemistry than the author of this rubbish. Mark Lorch responded differently, with a satirical piece in the Guardian listing six chemicals that ought to be banned... including DHMO.
Mark's response illustrates the correct (in my view) application of the DHMO trope. He takes the same approach to everyday chemicals as the BuzzFeed writer: cherry-pick alarming-sounding properties, overextrapolate from extreme conditions to everyday conditions, and generally try to whip up as much unfounded fear as possible whilst ignoring logic at every turn. In doing so, he exposes these flaws in the original piece and hopefully provokes some thought amongst those who might otherwise have bought it.
It's not an approach that's to everyone's taste, but I think it's in the tradition of great satire: it punches up and is instructive rather than cruel. The authors of the BuzzFeed article and the book it's based on are not uneducated and have a huge platform: hardly the same demographic Chris rightly defends. Chris' comments are a welcome reminder that satire has to be deployed deliberately and at the right targets.
A final thought: how widespread do you think the ignorance Chris describes (and the BuzzFeed article preys upon) is?
Less than 10% of those who read the BuzzFeed article 'liked' it on Facebook, assuming everyone who 'liked' it read the damn thing first. Only 2-3% shared it on Twitter or Facebook. This isn't an unusually high attrition rate for articles like this, but I have to wonder how many people who didn't share it either knew outright that it was crap, or quickly googled it and found out.
Edit: I spelled Chris' surname incorrectly and have now rectified it. Sorry about that.
At SciAm Blogs, Janet Stemwedel has responded to Chris' post. Her response is considerably more interesting than mine and worth your time.