Showing posts with label anatoxin. Show all posts
Showing posts with label anatoxin. Show all posts

Sunday, April 7, 2013

WWWTP? Operatic Chemistry in the Boston Globe

Has anyone seen the fantastic writeup by Carolyn Johnson in the Boston Globe today?

Johnson covers the J. Chem. Ed. recently penned by Prof. João Paulo André, of the Universidade de Minho to celebrate the storied use of poisons in opera. I hadn't realized, honestly, that this rich history involved poisons from such a wide variety of plants, minerals, and animals, or that specific references to each substance can be found in the libretti. Fascinating!

Unfortunately, the graphic that accompanies the story takes a few chemical liberties, which I've circled:



(Update 4/7/13 - I should point out that more structures are right than wrong here, which a commenter points out is more than you usually see in mainstream media. Kudos to the BG for covering the article the way they have)

I've written a short note to the author, reprinted below, and I will post any response I receive.
Dear Carolyn:

Good afternoon! My name is See Arr Oh (a pseudonym), and I blog at Just Like Cooking, a chemistry blog aimed at general-interest audiences.


I noticed your article in today's Globe, and I want to applaud you for your outreach. The article is well-written, and the science seems solid.


However, the image that accompanies your article includes several inaccurate structures for the discussed poisons. For example, the structures of mannitol don't show explicit stereochemistry (3D structure); these might well be glucose drawn this way. 

Scheele's Green is actually a copper complex; trimethylarsine is the poisonous gas that evolves from the dye. Arsenic trioxide and mercuric sulfide aren't actually monomeric, as drawn, but adopt several different crystal forms involving multiple As and Hg atoms, respectively.

Finally, the neurotoxin shown in the "snake venom" box is not actually venom, rather, it's anatoxin-a, from blue-green algae. 

Please consider changes to the illustration. If you need anything further, don't hesitate to contact me at seearroh_AT_gmail.com

Sincerely,
See Arr Oh

Tuesday, April 2, 2013

Lake Erie Chemophobia: A Tale of Two Anatoxins

At first, I thought it might be an April Fools' prank in poor taste, but then I read the latest PNAS -

Looks like Lake Erie wants to hurt you.

OK, not the lake itself, but the potentially toxic concentrations of cyanobacteria formed in recent record algal blooms. Yesterday, a multi-institution group of ecologists and environmental engineers reported a 'perfect storm' of runoff fertilizer, warm weather, and quiet waters in the lake that led to a marked increase in 2011 cyanobacteria populations. In fact, there appear to have been two blooms - the first Microcystia, and the second Anabena, two bacterial baddies* associated with liver and neurotoxicity. Scary stuff!

Well, the press coverage stemming from the study hasn't calmed fears. Here's a sampling from NSF, Huffington Post, and Discover. The HuffPo title really runs the chemophobia angle:
"Lake Erie Blooms Expected to Continue, Threatening Ecosystem, People." (!!!)
They dress the presser up for the occasion, with words like noxious, toxic, ugly, hazard, and problem. Discover writes 'toxic' three times, without pointing out what the toxins are! Even the normally staid NSF jumps on the bandwagon, referring to a mysterious 'liver toxin.'

What types of toxins are we talking about? Actually, that's a bone of contention here: the researchers only mention two, microcystin and anatoxin. Those turn out to be confusing terms, since the generic names cover >80 types of different microcystins, and at least two anatoxins [A(s) and A, right]. One assumes that the scariest anatoxin (Anatoxin-A, or 'Very Fast Death Factor'), operates here, which certainly warrants concern.

But, sans information, there's a panicked sense to the releases not grounded in the published text. Both Discover and HuffPo indicate "~200x concentration" of "toxic stuff" in the cyanobacteria-enriched water. Do the researchers actually say this? Let's go to the PNAS (emphasis mine):
"Surface toxin concentrations could have reached over 4,500 μg/L in early August assuming all Microcystis and microcystin formed a surface scum 10 cm in thickness. The World Health Organization guideline for microcystin in recreational waters is 20 μg/L..."
This statement relies on multiple qualifiers and conditionals. Where's your skepticism, science writers? Yes, things were bad in Lake Erie in 2011, but to spit this couched statement back as fact does a real disservice.

Worst part? Of the three media, only Discover actually links back to the actual study. Sigh.

*Boy, I love science: the Purdue blue-green algae fact sheet I linked to for Anabena indicates that ecologists nickname the major detected species (Anabena, Aphanizomenon, Microcystia) Annie, Fannie, and Mike!