Monthly Archives: Oct 2013

A scary Halloween tale…

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Food additives, E-numbers – they’re scary aren’t they? Everyone knows they’re horrible, toxic things that make kids jump around, refuse to go to bed, go purple in the face and generally drive their parents around the bend (do kids really need chemical help with any of those things?)

pumpkin eating

Be careful what you eat…

It’s Halloween, a day when children traditionally stuff their faces fully of sugary, brightly-coloured sweeties. But never mind those, let’s give some thought to the humble pumpkin. Yes the orange things that grow in the ground. Did you know they’re stuffed full of additives too? Even ‘organic’ ones? They are, really! Here’s an ingredients list…

Water, carbohydrate, protein, E300, E375, E101, pyridoxine, thiamine, E470a, pteroyl-L-glutamic acid, E306, E160a, palmitic acid, linoleic acid, oleic acid, palmitic acid, stearic acid, purines, E621, potassium, calcium, phosphorous, magnesium, sodium, iron, zinc.

Scared yet?

Ok ok, don’t panic. Put down the baseball bat. It’s all right really, allow me to translate…

E300 is ascorbic acid, otherwise known as vitamin C. E375 is niacin (vitamin B3). E101 is riboflavin (vitamin B2). Pyridoxine is vitamin B6. Thiamine is vitamin B1 (seeing a pattern here? Pumpkin is good for B vitamins). E470a represents potassium salts of fatty acids. Pteroyl-L-glutamic acid is another name for folic acid. E306 is tocopherol, or vitamin E. E160a is beta-carotene (vitamin A).

Palmitic acid is the most common fatty acid found in animals and plants, and linoleic, oleic, palmitic and stearic acids are essential fatty acids particularly found in pumpkin seeds (very tasty roasted). Purines are some of the building blocks of DNA (the word purine comes from ‘pure urine’ because they were first synthesised from uric acid, isolated from kidney stones – ewwww). E621 is the dreaded monosodium glutamate. A lot of people fear this one, but actually it’s just a sodium salt of glutamic acid, which is another key amino acid. Totally natural. In fact, it’s one of the most abundant naturally occurring non-essential amino acids. (I will confess I’m improvising a wee bit here, but there’s no doubt that there’s glutamic acid in pumpkin – very abundant amino acid see – and there’s also sodium, so chances are there’s some monosodium glutamate knocking around in there.)

Potassium, calcium, phosphorous, magnesium, sodium, iron and zinc are all elements, and also important nutrients – you’ll find them all listed on the back of any good multivitamin and mineral supplement.

Food for thought? There’s a lot of nonsense spouted about additives and E numbers. For starters, that E? It means they’re regulated food additives that have been tested and approved for use with the European Union. They are, by definition, safe. Not only that, but quite a few of them are in your food to keep you safe by preventing harmful bacteria growing in it, for example. Lots and lots of them come from natural sources. Chemists like to extract and identify things, which is why lots of entirely natural substances have ended up with chemical names. An unfamiliar and complicated-sounding name doesn’t make something inherently dangerous.

On the other hand, there is something that’s been proven time and time again to cause numerous health issues from crashing energy levels to obesity, type two diabetes and dental problems. Yup. Sugar. E numbers have nothing on it.

I’m not suggesting anyone gives up sugar (where would be the fun in that, especially on Halloween?) but it’s always worth thinking about relative risk. If you’re going to accept a bit of sugar isn’t the end of the world, then give additives a break as well.

Right, I’m off to eat some Halloween biscuits – trick or treat!

Realgar: don’t drink the AsS wine

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I was planning a lesson on empirical formulas recently and, bored with the usual well-worn examples (hydrogen peroxide, ethene, ethanoic acid, yawn), went hunting for some unusual chemicals. So it was that I came across a substance with the molecular formula As4S4, which appealed to my immature side since – fellow chemists will be ahead of me here – it has the empirical formula of AsS. Heh.

Realgar crystals

Realgar crystals

Anyway, turns out this stuff is interesting for more than just spelling a word that means bottom in American English. This particular form of arsenic sulfide is more commonly known as realgar, and for starters it’s very pretty: check out those lovely red crystals. In fact its other names are ‘ruby sulfur’ and ‘ruby of arsenic’.

It often turns up in the vicinity of other mineral deposits, such as lead, silver and gold ores, and has a long list of uses. It’s a source of arsenic, which is used to make gallium arsenide (formula GaAs – not quite as good, but credit for trying), an important semiconductor used in the production of integrated circuits, solar cells, and other electronics-y stuff.

Perhaps more interestingly, realgar used to be used by firework manufacturers to produce, somewhat counterintuitively, the colour white. It’s still used to make a contact explosive (who doesn’t love substances that spontaneously explode when touched?) At least, so says Wikipedia and numerous other pages that appear to have copied Wikipedia. I actually can’t find any more information on the chemistry of this particular substance – named as ‘red explosive’ – and if anyone knows I’d love to hear more.

What else? The Romans considered realgar valuable and used to trade it for use as a red paint pigment and in medicines. Which is ironic since, as a source of arsenic, it’s toxic and carcinogenic. Medieval Spaniards used it to kill rats, as did 16th century Brits. The Chinese call it xionghuang 雄黃, which translates to ‘masculine yellow’ (the related mineral orpiment, As2S3, is called cihuang 雌黃, or ‘feminine yellow’*) and used to use it as a handy insect- and snake-repellent. It turns up in traditional Chinese medicine, which isn’t particularly reassuring. Specifically, realgar is often added to treatments to reduce fever, inflammation, treat ulcers and calm skin conditions. Beware.

Realgar wine

It’s also mixed with rice wine to make something called ‘realgar wine’ which is, rather alarmingly, still consumed during Duanwu Festival, also known as the Dragon Boat Festival, to ward off evil. And it’s not just adults: children’s foreheads and limbs are also traditionally painted with the stuff. Yikes. Apparently this practice started because Duanwu falls just before midsummer, and the hot weather used to precipitate the rampant spread of various diseases. Realgar was believed to be a universal antidote to poisons, and was great at warding off insects and other bothersome creatures: why not disease as well? It would appear that the use of realgar has declined somewhat, now that people have a better idea of the potential dangers. I hunted around and couldn’t find realgar wine explicitly available for sale anywhere, although it’s not difficult to find realgar itself. Be careful: even a one-off exposure can cause kidney failure.

So there we go: that stuff with the empirical formula AsS that’s traditionally used to ward off disease turns out to do the exact opposite, and cause illness. Still, the red crystals are very pretty. And if you do know anything about ‘red explosive’, please comment!

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* Err, I hope. I’ve copy-pasted those symbols. Apologies if they actually say purple tadpole penis or something.