Field of Science

Formaldehyde: not just for dead things

Next spring I'm teaching a course on the physical chemistry of food while a colleague is teaching a course on the analytical chemistry of foodstuffs.  Among other science texts we'll be using John Coupland's Introduction to the Physical Chemistry of Food, but I'm also collecting short pieces to put some of the work into a historical and social context.

These aren't actual biological specimens preserved
in formaldehyde, but Halloween decorations.  
Though these days we tend to think of chemists as the untrustworthy creators of toxic, artificial everything, the systematic training of chemists was driven in part by the desire for the public to know what was in their food and water.  In 19th century Britain, hundreds of chemists made their living testing the purity of everything from butter to well water.  So when the Food Babe tells you there is something "yucky" in your food, the reason we know it is there is some chemist developed a careful protocol for its analysis, and other chemists tested the material.
Molecular structure
of formaldehyde


I've been thinking about formaldehyde, one of the simplest organic molecules (to a chemist, organic means made up mostly of carbon and hydrogen atoms, and has nothing to do with whether the molecule is synthetic or natural or...). Last year, formaldehyde, which is a preservative, was in the news because Johnson & Johnson had agreed to remove it from baby shampoo, though as Matt Hartings and Tara Haelle clearly pointed out in a piece at Slate, it was in such low concentrations that it posed no risk to babies (who, they point out, themselves contain substantial amounts of formaldehyde.)

Pepsi is reformulating Diet Pepsi to take out the artificial sweetener aspartame. The Food Babe is crowing that she and her army have forced Kraft to remove the so-called coal tar dyes (e.g. tartrazine/FD&C Yellow 5), to be replaced by natural colorings from spices.  What does all this have do do with formaldehyde?

From the Food Babe's 'campaign' literature.

To start with those natural colorings - at least one of them used in the UK version of mac and cheese, beta-carotene, isn't extracted from natural sources but synthesized from petroleum feedstocks (just like those coal-tar dyes).  One of the starting materials:  formaldehyde. The other natural colorings on the table — annatto, turmeric and paprika — are not quite what you might think either.  While you might imagine shaking in some spices from a quaint bottle, the spices themselves are not used as colorants, the colorants are extracted using organic (not that kind of organic, the chemist's kind of organic) solvents, such as ethyl acetate.  It's unclear to me why these colorants, particularly beta-carotene pass muster with the Food Babe.


Aspartame is sometimes vilified because it is metabolized into methanol and formaldehyde in the body.  Which it is.  You already contain a lot of formaldehyde, about 12 milligrams per liter of fluid in your cells.  One source is metabolism of the amino acids, particularly, serine and glycine (in naturally occurring proteins), from which your body scavenges methyl groups (CH3) to pop on to various structures.  Aspartame is a very tiny protein, so the same pathways that produce methanol and formaldehyde from natural sources, dismantle aspartame to yield methanol and formaldehyde, though the amounts produced are tens of times lower than what comes from eating apples and fish.

Because formaldehyde occurs naturally in foods (about 5 mg per serving in some fruits, fish is also high, pectin containing fruits such as apples add significantly to the amount of formaldehyde ingested), our bodies have a mechanism for dealing with it, we process about 60 to 100 grams of formaldehyde a day and do so quickly.  Formaldehyde has a half-life of about 1 to 2 minutes in the body.



Why are those spices colored?  What does it have to do with quantum mechanics, flamingos and canaries?  Read this post, the very first one written for the blog,  to find out.

References
EFSA report on endogenous versus exogenous sources of formaldehyde.
EFSA review of curcurmin, a component of turmeric, which had been suspected of being genotoxic.

Feeding the pseudoscience rumor mill

Source.
LA Times columnist Michael Hiltzik has a piece this week considering how (or whether) journalists should address pseudoscience and its purveyors.  He, along with others — Keith Kloor/Discover and Julia Belluz/Vox most recently —  have worried whether reporting on pseudoscience gives it more credibility and visibility than it deserves, particularly when the people involved are not otherwise newsworthy. And since most of the information about new science reaches people through the mass media, journalists play an enormous role in the ecosystem by which the public, that is to say all of us, scientists included, learn about and then use, information about science.

There is a growing body of social science research suggesting that effective science communication needs to be more than just filling in facts.  The notion that simply pushing out correct facts is unhelfpful isn't new.  Andrew Noymer modeled the spread of misinformation using epidemiological methods, and in 2001 showed that the persistence of information in the public sphere is improved if you have people trying to debunk the myths.  (Op-ed here, full paper here.)

Emotion potentially plays a bigger role than fact.  Katherine Milkman and Jonah Berger have explored what makes online content go viral (full paper here ($), summary here), suggesting that information that tugs at our emotions, particularly ones that run deep — anger or anxiety or awe — is more likely to spread.  Vani Hari, known as The Food Babe, plays off both the anger (can you believe that they put yoga mat in your bread?) and the anxiety (you don't know what you are eating?).

The who, where and how of the presentation matter as much or more (see the Yale Cultural Cognition Project for some well designed work on this), not just about what people conclude about the science, but about what they think scientists believe to be true.  It matters not just what an expert says, but who we think the expert is - in the sense of what are their core values.

What should journalists do?  What should scientists do?  Should both groups ignore pseudoscience entirely?

It has me thinking about how and when I might tackle pseudoscience, either on the blog, or perhaps even more importantly, in my classroom.   Given the knowledge that it may in fact reinforce the circulate myth, doing so is not necessarily benign.  So what are my personal guidelines?

1.  What is the risk of a lack of understanding?  Can it kill you not to know?  (Don't mix bleach with pesticides - it will not only kill more bugs, but more people.)
2.  Is there reliable and understandable information readily available online?
3.  Do I have the expertise to address the issue?
4.  Can I back up any assertion I make from the peer-reviewed literature?  (It's not personal opinion, but careful reading.)
5.  Can I help people develop a stronger conceptual framework, so that they can be usefully skeptical on their own?  In other words, I should not only assert, but communicate basic principles of science.  

Additional questions I might ask myself before approach something about pseudoscience in the classroom:

1.  Does it illustrate a concept this course addresses?
2.  Do my students have the knowledge base and conceptual framework to debunk something themselves, if prompted?  


Food Babe versus the Science Babe: Of Beaver Butts and Bullshit

A few weeks ago I wrote a piece for Slate about the Food Babe's tactics, prompted by the flurry of publicity for her new book, The Food Babe Way.  I pointed out the Food Babe's strategy of "malicious metonymy" whereby she deliberately confuses the source or use of something with the molecules.  So instead of reason you get "because beaver butts," her favorite example being that vanilla ice cream might contain castoreum, a  purportedly vanilla scented natural flavoring extracted from sacs found in beavers (yes, near their butts): "Readers of my blog know that the next time you lick vanilla ice cream from a cone, there’s a good chance you’ll be swirling secretions from a beaver’s anal glands around in your mouth." There is not, and here is why.

"While in low concentrations castoreum reputedly tastes of vanilla with a hint of raspberry, I’ll admit I’ve never tasted it. Not because I’m particularly disgusted by the source—I eat animal products and am inordinately fond of the fermented genitalia of Theobroma cacao—but because of its scarcity and cost. Enough castoreum extract to replace the vanilla in a half-gallon of ice cream would cost $120. Worldwide, less than 500 pounds of castoreum is harvested annually from beaver pelts, compared with the more than 20 million pounds of vanilla extracted from the ovaries of Vanilla planifolia orchids each year. Perfumers, not ice cream manufacturers, are the real market for castoreum. So while beaver secretions just might be in the expensive perfume you dabbed on your pulse points or in the aftershave you splashed on your face—did you just touch that with your hands, yuck—rest easy, there is no chance that the pint of ice cream you picked up at the store contains it. Not at the price you paid for it." -- read the rest at Slate.

The Science Babe took on the Food Babe yesterday in Gawker - neatly taking apart each of her standard tropes, with references to others who have done the same. The Food Babe wasn't happy and shot back.  Her response to the Science Babe, who has a long history of debunking her claims, begins with a nasty ad hominem attack.  But none of Food Babe's rant changes the science, or the history.

No Food Babe, nitrogen is not an additive to air in airplanes mixed in by evil airlines (up to 50% oh dear!), we breathe 80% nitrogen all the time.

No Food Babe, the microwave was not used by the German army in WW II, even Wikipedia knows it was invented after WW II.

Yes, Food Babe, that "MSG free tomato soup" you tout on your blog contains 400 mg of glutamate per serving and a lot of sodium, which makes?  Monosodium glutamate.  MSG.  It exceeds the limits for added MSG in the UK.

And did you know that Food Babe recommends high daily doses of oxidane, laced with 2-methyl-5-(6-methylhept-5-en-2-yl)cyclohexa-1,3-diene?  Write her now and demand that she confess to drinking chemicals with gross and hard to pronounce names.

Eat naturally, but eat knowledgeably.




One ring to bind them all: things you might not know about benzene

Space filling model.  c. Michelle Francl
UPDATE:  The Sceptical Chemist has a quiz up on benzene structural formulae based on the article in Nature Chemistry.  

Next year is the 150th anniversary of Kekulé's paper proposing the cyclic nature of the benzene 'nucleus.' and the 190th anniversary of Michael Faraday's paper on bi-carburet of hydrogen, more familiarly known as benzene.  In Berlin in 1890, on the 25th anniversary, German chemists threw the Benzolfest in honor of Kekulé.

I wrote a short 'fest' for Nature Chemistry, which appears in the January issue($).  I learned much about organic chemistry's iconic molecule, and herewith are 10 pieces of trivia that did not make it into the final piece.

1. There are 217 skeletal isomers of benzene, including the iconic hexagon, more than 300 if you count stereoisomers. [Patrick W. Fowler, MATCH Commun. Math. Comput. Chem. 63 (2010) 333-346].

 2. Benzene tastes sweet, with a hint of almond, and can be tasted in water starting at about 0.5 ppm, or roughly 1 drop in 40 gallons.

 3. An alternate synthesis (circa 1850) claims to passes benzoic acid through a “red hot gun” barrel packed with pumice. There's no evidence that it actually works.

 4. There is a tie knot that is hexagonal, perfect for tie-wearing chemistry conference attendees.  It was discovered by mathematicians, but you can still wear it.

 5. Dewar never suggested benzene's preferred structure was bicyclic. He used the structure, along with the more conventional structure, to demonstrate the potential of his brass molecular models. ["On the oxidation of phenyl alcohol, and a mechanical arrangement adapted to illustrate structure in the non-saturated hydrocarbons," Proceedings of the Royal Society of Edinburgh 6: 82–86 (1867), you can find it on Google Books]

6. The extraction of flowers of benzoin - benzoic acid - was first reported by Michel de Nostredame, otherwise known as Nostradamus, in the 16th century.

7  Kekulé actually didn't didn't present his revolutionary theory in January of 1865, his colleague Adolphe Wurtz read the paper in his absence.

8.  As late as the 1920s, major figures in organic chemistry did not think benzene or its derivatives were planar.  Sixty four years after Kekulé's paper was submitted (almost to the day), crystallographer Kathleen Lonsdale submitted her paper showing unequivocally that hexamethyl benzene, and presumably therefore benzene, was planar. "Thus the 'diamond' [puckered] type of benzene ring is shown to be wholly inadmissible." (Emphasis is Lonsdale's.) [K. Lonsdale, Proc. Roy. Soc. A, 494-515, 1929.]


9. In the days before ChemDraw, there were stamps.

10.  Hexagons were not the only proposed structural formula for benzene.  Loschmidt suggested the representation at the right.



If you would like a reprint of the essay, send me an email.

Tea transitions

Tea bag is paper. Vapor is from phase
transition of water
Introductory chemistry at my college has a broad audience.  My students are not just potential chemistry major and pre-meds, but I teach geologists, art historians, psychologists and even students who simply want to know more about how the hidden world of atoms and molecules works.

I tell them my job is to help them transition from being science students to scientists -- or rather into people who can critically assess and use the science information they encounter.  Can they filter the junk from the reality?

Enter the Food Babe, whose stirs up real science with fake science and then peppers it with a healthy dose of panic to produce posts that are at a perfect level for my students to read and try to tease out fact from fiction.1  I couldn't do a better job if I made them up.

This example is about my favorite beverage:  tea.  Are plastic tea bag safe, wonders the Food Babe?

To quote:
"Another temperature consumers need to worry about in tea is the “glass transition” temperature. Here’s the science behind the glass transition temperature or, Tg, and why it becomes dangerous according to The Atlantic: 
“That is the temperature at which the molecule in certain materials such as polymers begin to break down. As a rule, the Tg of a material is always lower than the melting point. In the case of PET and food grade nylon (either nylon 6 or nylon 6-6), all have a Tg lower than the temperature of boiling water. For example, while the melting point of PET is 482 degrees Fahrenheit, the Tg is about 169 degrees. Both nylons have a lower glass transition temperature than PET. (Remember that water boils at 212 degrees.) This means the molecules that make up these plastic tea bags begin to break down in hot water.” (Emphasis is the Food Babe's.)

Since we just finished looking at ways to display information about the phases of materials, this is a great piece to dissect.

Phase diagrams are a compact way to show not only the state a material might be in under a given set of pressure and temperature conditions, but the astute reader can pull some information out about the energies required to get a material to change state, and even something about the forces that hold a material together.

The iconic phase diagram in general chemistry is the one at the right for carbon dioxide.  The diagrams are not difficult to read.  The solid lines indicate conditions where two phases are present, in equilibrium.  So at normal atmospheric pressure (1 atm) and -78.5oC, solid CO2 ("dry ice") and gaseous CO2 are in equilibrium with each other.  At normal pressure, if you heat solid CO2 above  -78.5oC, it will change from a solid directly into a gas without melting, it's icy cold, but doesn't produce a liquid when it warms.  It's a "dry" ice.

When a material changes phase, it's important to understand that the core identity of the molecule doesn't change. That is, the structure of the individual molecules does not change, molecules do not 'break down' during a phase change. The CO2 molecules in the solid are just like the CO2 molecules in the gas.  What changes in a phase transition is the arrangement of the molecules, their relationships to each other.  In the gas phase, the molecules are widely separated and moving randomly, while in the solid they are arranged in a crystalline symmetrical array, and don't move much.

There are more possible phases for a material than the familiar solid, gas or liquid.  Many materials have several different ways for the molecules to pack themselves into a solid.  (Water has more than a dozen different types of ice, with different densities and other macroscopic properties.)  Some solid forms are crystalline, with all the molecules neatly arrayed.  Others show less order on the molecular level. These forms we call amorphous solids.  Some amorphous solids are called glasses.  At the glass transition temperature, a nice crystalline solid can change into a less ordered glass form.  For a polymer like the PET, the glass transition temperature is when (on the molecular level) the molecules become less rigidly ordered.  On the level we can observe, it means the polymer becomes less brittle, more malleable.  Softer.

It does not mean that the (presumably dangerous) molecules break down and leach into your tea water.  If there is a danger lurking in your fancy PET tea bag (and there might be) - this isn't it.


1.  The classic example is about airplane travel and gases, where she tries to get people incensed about the 'fact' that the cabin air contains nitrogen because the airlines are too cheap to use pure oxygen, and about pressurized cabins.  It's not only wacky fake science, but a bit scary because she suggests medication doses and timing will have to be adjusted due to the nitrogen content.  (Do not take medical advice from the Food Babe.  She doesn't even know what is in the air she breathes.)

You can't find the airplane air post on her blog anymore, like her infamous microwave post ("For the experiment pictured above, microwaved water produced a similar physical structure to when the words “satan” and “hitler” were repeatedly exposed to the water.") it's been taken down. She's blocked caching, but you can read it here.

Weird words of science: prilled iodine

"Sample of iodine" by LHcheM.
Licensed under Creative Commons
Attribution-Share Alike 3.0 via Wikimedia Commons
I was browsing the paper version C&E News on the train yesterday afternoon, and noticed two back to back advertisements for halogens, one for bromine reclamation, the other for iodine.  Prilled iodine to be precise.  Prilled?  I had a vision of lacy violets frills.

Prills are tiny balls of a substance, formed by letting droplets of the liquid fall from a height (in a prilling tower.) Surface tension has its way and the droplets become spheres, which then solidify.  Many bulk industrial chemicals, particularly fertilizers and detergents, are prilled for easier handling.

Prilling has its roots in 18th century copper mining, referring to beads of high purity copper.

While I rarely buy chemicals, I have purchased iodine flakes for a teaching lab.  The catalog does offer me the choice of "iodine, beads" — prills by another name.





Fire Burn and Caldron Bubble: A chemistry set for the iPad

From BlueCadet's design for the app
Round about the cauldron go;
In the poison'd entrails throw.
Toad, that under cold stone
Days and nights has thirty-one
Swelter'd venom sleeping got,
Boil thou first i' the charmed pot.

Double, double toil and trouble;
Fire burn, and cauldron bubble.
                            Macbeth, IV.i

Perhaps not surprisingly for the daughter of two chemists, this scene from Macbeth was my introduction to Shakespeare. I loved to hear my father recite the charm the three witches crafted 'round the cauldron.  It was so evocative of visits to my Dad's lab, where vapor from bubbling pots rose to collapse back into liquid form, dripping steadily into flasks.  The sweet-sharp scent of acetone swirled around like mist.   Worrying whether the tomato soup heating in a beaker on a Bunsen burner was safe to eat — poison'd I grasped (entrails were frankly a mystery when I was six, despite my kindergarten teacher's attempt to broaden her small town Midwest children's palates beyond chicken and mashed potatoes).

Though a confirmed theorist (the only things extracted in my lab are coffee and tea), I still love the idea that you can pull a chemical reaction off the paper and, by boiling and bubbling (along with much swelter'ng and perhaps even a dash of dragon's scale), transform the known into the new and very different.  The Chemical Heritage Foundation, where I was a fellow in 2012, has one of the world's largest collection of vintage chemistry sets.

The CHF teamed up with developer BlueCadet to develop an app, ChemCrafter, for the iPad that recreates some of the fun of these classic sets, right down to the bubbling beakers, explosions and fires.  I played a small part in the development, researching some of the more obscure reactions to be sure of the details of what happened.  Among the more fascinating things I learned was that when sodium metal reacts with liquid bromine, there is no reaction until the beaker is tapped (the source I consulted actually gave a minimum required force), then the reaction is explosive.  I'm trying to imagine (1) how someone discovered this and (2) what the experiments to determine the force must have looked like!

We worked hard to be sure the chemistry was as accurate as it could be (bubbles? fire? color?), down to the thermochemistry (yes, you can have fun with Hess' law and yes, the enthalpies of reaction and the points you earn thereby are extensive properties).

ChemCrafter (after the classic Chemcraft chemistry sets) is free and you can download it for the iPad at the iTunes store.


Watch Rosie Cook talk about the Chemical Heritage Foundation's chemistry sets and learn more about the collection here.


Nitrogen in the snow

We are expecting another round of wintry weather tomorrow, and an article in the local paper noted that the snow and bitingly cold weather we have had recently are good for farmers.  The cold reduces the population of some pests, particularly the species making their way north.  The article also noted that snow contains nitrogen from the atmosphere, providing a little extra boost for lawns come spring.

The atmosphere is roughly 80% nitrogen, in the form of N2.  The form matters.  Nitrogen gas is very unreactive, so much so that it many "air sensitive" materials are packed under pure nitrogen.  (The part of the air that is reactive is molecular oxygen, O2.)  Snow certainly contains dissolved nitrogen gas.  Henry's law predicts the solubility of a gas in a solvent, water in this case, as a function of temperature.  It might seem at first glance counter intuitive, but gases are more soluble in cold solvents than in water (the opposite is true of most solids, as anyone who has tried to dissolve sugar in cold ice tea knows).  An inch of snow contains about 7 milligrams of nitrogen gas per square foot, or about 1/3 of a kilogram in an acre of snow.  Given that fertilizers are spread onto fields at a field of roughly 300 kilograms per acre, it's not much.

The trouble is actually that this nitrogen isn't in a form that easily accessible to plants.  Nitrogen in the atmosphere must first be "fixed" or changed into a more reactive form, typically tetravalent nitrogen (ammonium) which is then converted to the nitrate ions that plants can use.  So where does the useful sort of nitrogen come from?

Industrially, nitrogen is fixed in the Haber process.  Since nitrogen is so unreactive, this requires pressures hundreds of times those of earth's atmosphere and temperatures more likely to be found on the surface of Venus (over 700oF).  Nitrogen is fixed in the biosphere by microbes, which undertake an elaborate enzymatic dance to do this at low temperatures and pressures (and yes, scientists are on the job of trying to figure out how to get the enzymatic processes to work at industrial scales.)

Lightening strikes also convert minuscule amounts of N2 in the atmosphere to nitrogen oxides, and industrial pollution has also injected nitrogen oxides into the atmosphere. Industrial pollutants are by far the biggest contributors. The nitrogen oxides become nitrate ions. These are the nitrogen sources that turn a blanket of snow into a gentle fertilizer.

To put it into perspective, snow and rain probably deposit about 5 kilograms total per acre over a year. It's not much, it's not quite all natural (the rates were much lower in pre-industrial days), but it's something.

Isotope and the hidden women of science

It was a century ago today that the word isotope first appeared in print, in a letter to Nature from Frederick Soddy, who would go on to win the Nobel prize in 1921.  Nature Chemistry has a Thesis column by Brett F. Thornton and Shawn C. Burdette ($) to commemorate the occasion, as well as a post up at the Sceptical Chymist.  The post is illustrated with a photo of a plaque which reads "At a dinner party held in this house in 1913 Frederick Soddy (1877-1956) introduced the concept of 'ISOTOPES'..."  Thornton and Burdette also point to the dinner party as the moment when the term isotope was coined.

But Soddy did not coin the word.  The woman who did coin the term, Dr. Margaret Todd, has been gently set aside and one is left to assume that the word came to Soddy out of thin air. Margaret Todd was a physician and novelist, one of the first women to enroll in medical school in Edinburgh after the exams set by the Scottish Royal Society of Physicians and Surgeons were opened to women.  She was gay.  She wrote a popular novel under a male psuedonym, but it's the single word she handed Soddy that is her most enduring authorial legacy.  You need a good Greek term, she told him.  Try this one.

Sweet Hearts and Frogs



Last week I was at a workshop on teaching in British Columbia where I learned to make a string from a stick (if you're talking about teaching, it's really useful to be put in a situation where you have to learn something entirely new). We used obsidian points to scrape the outer layer of bark from dried stalks of dogs bane (Apocynum cannabinum), then pulled free the fibrous layer at the surface.  The instructor warned us about handling the plant before it was dried, noting that the sap could disrupt your cardiac rhythm. The ethnobotanist and two chemists in the group immediately murmured, "digoxin?" As you might imagine, an activity that features obsidian points, bone knives and an open fire doesn't lend itself to a quick search of the literature, so we were left to wonder for the evening.

cymarine
The sap of apocynum plants, such as dogs bane, contains cymarine, which is a potent cardiac glycoside, like digoxin.  The term glycoside indicates these are structures that contain a sugar chemically bound to the rest of the molecule.  The sugary parts of each molecule are the hexagons with the O's in them on the left side.  Cymarine has one such hexose; digoxin has three.  At first glance the molecules might seem very different, but clip the sugars off and the remaining parts of the structures are very similar.

Cardiac glycosides are produced mostly by plants (foxglove, dogs bane, oleander), but toads also secrete them (check out this paper in Heart about someone who took a purported aphrodisiac that contained dried toad venom and died a few hours later from what looked like digoxin poisoning).  So don't kiss any toads, it's not sweet for your heart.
digoxin

Update: Read the Naked Scientists on why people might lick toads: Tripping over psychogenic toads.