Marvellous Mushroom Science

Glistening ink caps produce a dark, inky substance.

Yesterday I had the fantastic experience of a “fungi forage” with Dave Winnard from Discover the Wild, organised by Incredible Edible Oxford. There are few nicer things than wandering around beautiful Oxfordshire park- and woodland on a sunny October day, but Dave is also an incredibly knowledgeable guide. I’ve always thought mushrooms and fungi were interesting – living organisms that are neither plants nor animals and which we rely on for everything from antibiotics to soy sauce – but I had lots to learn.

Did you know, for example, that fungi form some of the largest living organisms on our planet? And that without them most of our green plants wouldn’t have evolved and probably wouldn’t be here today?

And from a practical point of view, what about the fact that people once used certain fungi to light fires? I’ve always imagined fungi as being quite wet things with a high water content (unless they’re deliberately dried, of course), but some are naturally very dry. Ötzi, the mummified man thought to have lived between 3400and 3100 BCE, was found with two types of fungus on him: birch fungus, which has antiparasitic properties, and a type of tinder fungus which can be ignited with a single spark and will smolder for days.

Coprine causes unpleasant symptoms, including nausea and vomiting, when consumed with alcohol.

Then, of course, there’s all the interesting chemistry. Early on in the day, we came across some glistening ink caps.The gills of these disintegrate to produce a black, inky liquid which contains a form of melanin and can be used as ink. And there’s more to this story: as I’ve already mentioned, fungi are not plants and they can’t photosynthesise, but it seems that some fungi do use melanin to harness gamma rays as energy for growth. Extra mushrooms for the Hulk’s breakfast, then?

Moving away from pigments for a moment, a related species to the glistening ink cap, the common ink cap, contains a chemical called coprine. This causes lots of unpleasant symptoms if it’s consumed with alcohol, similar to Disulfiram, the drug used to treat alcoholism. For this reason one of this mushroom’s other names is tippler’s bane. The coprine in the mushrooms effectively causes an instant hangover by accelerating the formation of acetaldehyde (also known as ethanal) from alcohol. Definitely don’t pair that mushroom omelette with a nice bottle of red and, worse, you’ll need to stay off the booze for a while: apparently the effects can linger for a full three days.

Yellow stainer mushrooms look like field mushrooms, but are poisonous.

We also came across some yellow stainer mushrooms. These look a lot like field mushrooms, but be careful – they aren’t edible. They cause nasty gastric sympoms and are reportedly responsible for most cases of mushroom poisoning in this country, although some people seem to be able to eat them without ill effect. They had a slightly chemically scent that reminded me “new trainer” smell – sort of rubbery and plasticky. It’s often described as phenolic, but I have to say I didn’t detect that myself – although yellow stainers have been shown to contain phenol and this could account for their poisonous nature. Anyway, it was an aroma that wouldn’t be entirely unpleasant if I were opening a new shoebox, but it wasn’t something I’d really want to eat. Apparently the smell gets stronger as you cook them, so don’t ignore what your nose is telling you if you think you have a nice pan of field mushrooms.

4,4′-Dimethoxyazobenzene is an azo dye.

The real giveaway with yellow stainers, though, is their tendency to turn yellow when bruised or scratched, hence the name. This, it seems, is due to 4,4′-dimethoxyazobenzene. The name might not be familiar, but A-level Chemistry students will recognise the structure: it’s an azo-dye. Quite apart from being a very useful word in Scrabble, azo compounds are well-known for their characteristic orange/yellow colours. It’s not really clear whether it forms in the mushroom due to some sort of oxidation reaction, or whether it’s in the cells anyway but only becomes visible when the cells are damaged. Either way, it’s something to look out for if you spot a patch of what look like field mushrooms.

The blushing wood mushroom.

We also came across several species which are safe to eat. One I might look out for in future is the blushing wood mushroom. As is often the way with fungi, the name is literal rather than merely poetic. These mushrooms have a light brown cap, beige gills, and a pale stem, but they turn bright red when cut or scratched due to the formation of an ortho-quinone. It’s quite a dramatic colour-change, and makes them pretty easy to identify. Apparently they’re normally uncommon here, but we found quite a lot of them, which might be something to do with this year’s unusally hot and dry summer.

Red ortho-quinone causes blushing wood mushrooms to literally blush.

I tried to find out the reasons for these colour-changes. In the plant and animal kingdoms pigments are usually there for good reason: camouflage, signalling and communication or, as with chlorophyll, as a way of making other substances. Fruits, for example, often turn bright red as they ripen because it makes them stand out from the green foilage and encourages animals to eat them so that the seeds can be spread. Likewise, they’re green when they’re unripe because it makes them less obvious and less appealing. But what’s the advantage for the mushroom to change colour once it’s already damaged? Perhaps there isn’t one, and it’s just an accident of their biology, but if so it seems strange that it’s a feature of several species. I couldn’t find the answer; if any mycologists are reading this and know, get in touch!

Velvet shank mushrooms.

Other edible species we met were fairy ring champignons, field blewits and jelly ear fungus – which literally looks like a sort of transparent ear. I’ll definitely be looking out for all of these in the future, but it’s important to watch out for dangerous lookalikes. Funeral bell mushrooms, for example, look like the velvet shank mushrooms we found but, once again, the name is quite literal – funeral bells contain amatoxins and eating them can cause kidney and liver failure. As Dave was keen to remind us: never eat anything you can’t confidently name!


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Glow sticks or sparklers: which is riskier?

by Unknown artist,print,(circa 1605)

Remember, remember the 5th of November… (Image by Unknown artist, circa 1605)

It’s fireworks night in the UK – the day when we celebrate a small group of terrorists nearly managing to blow up the Houses of Parliament in 1605 by, er, setting fire to stuff. No, it makes perfect sense, honestly, because…. look, it’s fun, all right?

Anyway, logical or not, Brits light fireworks on this day to mark the occasion. Fireworks, of course, are dangerous things, and there’s been more than one petition to ban their sale to members of the general public because of safety concerns. It hasn’t happened yet, but public firework displays, rather than private ones at home, are more and more popular.

Which brings me to this snippet from a letter a friend of mine recently received.

screen-shot-2016-11-04-at-21-51-33

In case you can’t read it, it says:

“NO SPARKLERS PLEASE – with so many children runni[ng] around, we believe it is too dangerous fro children to be [words missing] lighted sparklers around.
Last year we had a few incidents of children drinking the [words missing] glowsticks – please advise against this.”

Now there are some words missing here, but it’s fairly clear that sparklers are prohibited at this event, and it seems to be suggesting that children have managed to get into, and swallow, the contents of glowsticks. But they, by contrast, haven’t been banned. Indeed, parents are merely being asked to “advise” against it.

Hmmm.

Does this seem like an appropriate response? Well, let’s see…

1024px-sparklers_moving_slow_shutter_speedWhat are these things? Let’s begin with sparklers. They’re hand-held fireworks, usually made of a stiff metal wire, about 20 cm long, the end of which is dipped in a thick mixture of metallic particles, fuel and an oxidising agent. The metal particles are most commonly magnesium and/or iron. The fuel usually involves charcoal, and the oxidiser is likely to be potassium nitrate. Sometimes metal salts are also added to produce pretty colours.

Sparklers are designed to burn hot and fast. The chemical-dipped end can reach temperatures between 1000-1600 oC, but the bit you hold doesn’t have time to heat up before the firework goes out (although gloves are still recommended). The sparks, likewise, are extremely hot but burn out in seconds. This makes sparklers relatively safe, if they’re held well way from the face and body, and if the hot end isn’t touched.

If. Every year there are injuries. Sparkler injuries aren’t recorded separately from other firework injuries in the UK, but the data we do have suggest we might be looking at a few thousand A&E admissions each year, and probably a lot more minor injuries which are treated at home.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous after they’ve gone out.

The biggest danger comes from people, usually children, picking up ‘spent’ sparklers. The burny end takes a long time to cool down, but once the sparkles are finished and it’s stopped glowing it’s impossible to judge how hot it is just by looking.

The burns caused by picking up hot sparklers are undoubtedly very, very nasty, but they’re also relatively easy to avoid. Supply buckets of cold water, and drill everyone to put their spent sparklers into the buckets as soon as they go out. Hazard minimised. Well, assuming everyone follows instructions of course, which isn’t always a given. Other risks are people getting poked with hot sparkers – which can be avoided by insisting sparkler-users stand in a line, facing the same way, with plenty of space in front of them – and people lighting several sparklers at once and getting a flare. Again, fairly easily avoided in a public setting, where you can threaten and nag everyone about safety and keep an eye on what they’re doing.

Although I do understand the instinct to simply ban the potentially-dangerous thing, and thus remove the risk, the idea does worry me a little bit. I was born in the 70s and I grew up with fire. I remember the coal truck delivering coal to us and our neighbours. I was taught how to light a match at an early age, and cautioned not to play with them (and then I did, obviously, because in those days it was usual for kids to spend hours and hours entirely unsupervised – but fortunately I emerged unscathed). Pretty much everyone kept a supply of candles in a drawer, in case the lights went out. And bonfires were a semi-regular event – this being long before garden waste collections.

These days things are very different. It’s not unusual to meet a child who, by age 11, has never lit a match. If their home oven and hob are electric, they may never have seen a flame outside of yearly birthday cake candles. But so what? You may be thinking. Aren’t fewer burns and house fires a good thing?

Of course they are, but people who’ve never dealt with fire tend to panic when faced with it. If the only flame you’ve ever met is a birthday cake candle, your instinct might well be to blow when faced with something bigger. This can be disastrous – it can make the fire worse, and it can spread hot embers to other nearby flammable items.

I’m personally of the opinion that children ought to be taught to handle fire safely, how to safely extinguish a small fire, when to call in the experts, and not to disintegrate into hysterics the presence of anything warmer than a cup of tea. Sparklers, I think, can be part of that. Particularly if they’re used in a well-supervised setting, with plenty of safety measures and guidance on-hand. (As opposed to, say, picking them up for the first time at university with some drunk mates, setting fire to half a dozen at once and immediately dropping them.)

Now. Onto glowsticks. They’re pretty neat, aren’t they? We’ve already established that I’m quite old, and I remember these appearing in shops for the first time, sometime in the very early 90s, and being utterly mesmerised by that eerie, cold light.

phenyl_oxalate_ester

Diphenyl oxalate (trademark name Cyalume)

They work thanks to two chemicals. Usually, these are hydrogen peroxide (H2O2 – also used to bleach hair, as a general disinfectant, and as the subject of a well-known punny joke involving two scientists in a bar) and another solution containing a phenyl oxalate ester and a fluorescent dye.

These two solutions are separated, with the hydrogen peroxide in a thin-walled, sealed glass vial which is floating in the mixture of ester and dye solution. The whole thing is then sealed in a tough, plastic coating. When you bend the glowstick the glass breaks, the chemicals mix, and a series of chemical reactions happen which ultimately produce light.

How Light Sticks work (from HowStuffWorks.com - click image for more)

How Light Sticks work (from HowStuffWorks.com – click image for more)

Which is all very well. Certainly nice and safe, you’d think. Glowsticks don’t get hot. The chemicals are all sealed in a tube. What could go wrong?

I thought that too, once. Until I gave some glowsticks to some teenagers and they, being teenagers, immediately ripped them apart. You see, it’s actually not that difficult to break the outer plastic coating, particularly on those thin glow sticks that are often used to make bracelets and necklaces. Scissors will do it easily, and teeth will also work, with a bit of determination.

How dangerous is that? Well… it’s almost impossible to get into a glowstick without activating it (the glass vial will break), so it’s less the reactants we need to worry about, more the products.

And those are? Firstly, carbon dioxide, which is no big deal. We breathe that in and out all the time. Then there’s some activated fluorescent dye. Now, these vary by colour and by manufacturer, but as a general rule they’re not something anyone should be drinking. Some fluorescent dyes are known to cause adverse reactions such as nausea and vomiting, and if someone turns out to be allergic to the dye the consequences could be serious. This is fairly unlikely, but still.

Another product of the chemical reactions is phenol, which is potentially very nasty stuff, and definitely not something anyone should be getting on their skin if they can avoid it, let alone drinking.

Inside every activated glowstick are fragments of broken glass.

Inside every activated glowstick are fragments of broken glass.

And then, of course, let’s not forget the broken glass. Inside every activated glowstick are fragments of broken glass – it’s how they’re designed to work. If you break the plastic coating, that glass is exposed. If someone drinks the solution inside a glow stick they could, potentially, swallow that glass. Do I need to spell out the fact that this would be a Bad Thing™?

The thing with hazards is that, sometimes, something that’s obviously risky actually ends up being pretty safe. Because people take care over it. They put safety precautions in place. They write risk assessments. They think.

Whereas something that everyone assumes is safe can actually be more dangerous, precisely because no one thinks about it. How many people know that glowsticks contain broken glass, for instance? Probably not the writer of that letter back there, else they might have used stronger language than “please advise against this.”

So glowsticks or sparklers? Personally, I’d have both. Light on a dark night, after all, is endlessly fascinating. But I’d make sure the sparkler users had buckets of water, cordons and someone to supervise. And glowstick users also ought to be supervised (at least by their parents), warned in the strongest terms not to attempt to break the plastic, and all efforts should be made to ensure that the pretty glowy things don’t fall into the hands of a child still young enough to immediately stuff everything into his or her mouth.

The most important thing about managing risks is not to eliminate every potentially hazardous thing, but rather to understand and plan for the dangers.


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Phabulous phenol

I was thinking about phenol the other day. “Very interesting,” I hear you say, “now if you don’t mind I’ve got a fascinating patch of drying paint I need to keep an eye on.” But wait! Bear with me. Phenol is a very interesting molecule. It’s history has a little something for everyone, from lawyers to doctors to advertising copywriters. There are gruesome tales from history, legal wrangles, and even a warning about the dangers of believing everything you read on the internet. So drag yourself away from the eggshell white, find yourself a comfy seat and I’ll begin.

Phenol

Phenol: a simple molecule with a complicated history.

Phenol is a simple molecule, consisting of a single -OH group attached to what chemists call a benzene ring (the structure of which was, so legend has it, finally determined after the German chemist August Kekulé dreamt of a snake eating its own tail).

You may think you’ve never heard of phenol, less still used it, but chances are you’ve come across the term ‘carbolic soap‘ somewhere. Phenol’s other name is carbolic acid, and it’s the main ingredient in carbolic soap, a mildly disinfectant cleaning agent that used to be a common household product in both Britain and America (in the form of Lifebuoy), was widely used in English state schools up until at least the 1970s, and is distributed to disaster victims for routine hygiene by the Red Cross to this day.

Carbolic soap isn’t so common these days since it has a tendency to irritate the skin and far gentler alternatives are available, although you can still find it in specialist outlets and apparently it’s quite popular in the Caribbean.

Friedlieb Ferdinand Runge

Friedlieb Ferdinand Runge

But back to phenol itself. It was discovered in 1834 when it was extracted from coal tar – a by-product of the coal industry – by the chemist Friedlieb Ferdinand Runge, also famous for identifying caffeine.

434px-Joseph_Lister2

Joseph Lister

Despite his rather glorious name, Runge is not the best-remembered scientist associated with phenol. That honour almost certainly goes to Joseph Lister who, in the late 19th century, pioneered the technique of antiseptic surgery. It may seem difficult to believe today, but back then surgeons weren’t required to wash their hands before treating patients, and even took pride in the accumulated stains on their surgical gowns. Until Lister’s use of phenol (or carbolic acid), people were more likely to die from infection following the treatment than from the original injury itself. Lister started using phenol to sterilise surgical instruments and wounds and after seeing his results others soon followed, completely changing surgery as we know it today.

In case you’re wondering, Lister had nothing directly to do with the invention of the (phenol-free) mouthwash product that bears his name. It was, however, named after him in honour of his work. Interestingly, Listerine was first marketed as a surgical antiseptic, then a floor cleaner and a cure for gonorrhoea, before it eventually found success as a solution for bad breath.

carbolic smoke ballI mentioned lawyers earlier, and that’s because phenol was instrumental in one of the first examples of contract law: Carlill v Carbolic Smoke Ball Company [1892]. It was the main ingredient of the Carbolic Smoke Ball, an ineffective piece of medical quackery marketed in London in the 19th century as protecting the user against influenza and other ailments. The manufacturer advertised that buyers who found it did not work would be awarded £100.

The Carbolic Smoke Ball Company thought this was nothing more than an inspired piece of advertising, and tried to argue that it was “mere puff” that no reasonable person would take literally. The judge rejected their claims, ruled that the advert made an clear promise, and ordered the company to pay £100 to the unfortunate flu-suffering customer Louisa Carlill. To this day, this case is often cited as an example of the basic principles of contract and how they relate to every day life.

Picture1

St. Maximilian Kolbe

Phenol also has a darker past, injections of it having been used as a means of execution. In particular, in World War II the Nazis used it in the euthanasia program, Action T4. Phenol was inexpensive, easy to make and fast-acting, and so quickly became the injectable toxin of choice. Famously, the Polish Catholic priest St. Maximilian Kolbe volunteered to undergo three weeks of starvation and dehydration in the place of another inmate and was ultimately executed by phenol injection. Kolbe was canonized on 10 October 1982 by Pope John Paul II; he is the patron saint of drug addicts.

Anyone who’s ever used phenol has probably experienced a phenol burn at some point. It doesn’t always hurt immediately but it slowly starts to burn after a little while, leaving white marks that ultimately turn red and slough off leaving brown-stained skin behind. It is, I should stress, not to be messed with – absorption of phenol through skin can result in phenol toxicity, and if left on the skin it can lead to cell death and gangrene. Even a tiny not-even-remotely-lethal spot is really quite painful. I can’t begin to imagine what death from phenol injection must have been like.

5012616170409Let’s end on a slightly lighter note. Have you got a bottle of TCP in your medicine cabinet? Many have fallen into the trap of believing that its initials relate directly to its ingredients, and specifically 2,4,6-trichlorophenol. In fact, a number of chemistry textbooks have stated this as hard, cold fact, as did a number of other online sources.

Not so, TCP originally contained trichlorophenylmethyliodosalicyl (not the same thing, and actually some have even wondered if this is truly a compound), but even that was replaced by other active ingredients in the 1950s. These days TCP contains a dilute solution of phenol (about 0.175% w/v) and halogenated phenols (0.68 w/v). So after all that, it does have phenol in it, but it’s not clear whether ‘halogenated phenols’ includes 2,4,6-trichlorophenol.

For a long time many, many websites stated that TCP contained trichlorophenylmethyliodosalicyl, probably traceable back to an earlier Wikipedia article (Wikipedia’s information has since been updated). As Jim Clark points out on his excellent Chemguide website, “The internet is a potentially dangerous tool. One single bit of misinformation can get multiplied over huge numbers of web sites”.

It’s true. Trust no one. (Except The Chronicle Flask of course*.)

(* If you spot an inaccuracy do let me know…)