Is acrylamide in your toast really going to give you cancer?

Acrylamide has been in the news today, and this might be the understatement of the year. Front page newspaper headlines have been yelling everything from “Brits officially warned off chips” to “Over-cooked potatoes and burnt toast could cause cancer” to the marginally more restrained “What is the real cancer risk from eating roast potatoes or toast?” All this has been accompanied by radio interviews with everyone from actual scientists to professional chefs to people keen to share their roast potato recipes. I expect there have been television interviews too – I haven’t had a chance to watch.

Hey, what could be more traditional, or more fun, than a food-health scare in January?

Acrylamide

Acrylamide

Never fear, the Chronicle Flask is here to sort out the science. Let’s get to the facts: what is acrylamide?

It’s actually a rather small molecule, and it falls into a group of substances which chemists call amides. Other well-known amides include paracetamol and penicillin, and nylon is a polyamide – that is, lots of amide molecules joined together. Amide linkages (the CO-NH bit) are a key feature of proteins, which means they appear in all kinds of naturally-occurring substances.

And this is where the food-acrylamide link comes in. Because acrylamide, or prop-2-enamide to give it its official name (the one only ever used by A-level chemistry students), forms when certain foods are cooked.

Acrylamide occurs naturally in fried, baked, and roasted starchy foods.

Acrylamide occurs naturally in fried, baked, and roasted starchy foods.

It begins with an amino acid called asparagine. If you’re wondering whether, with that name, it has anything to do with asparagus, you’d be on the right track. It was first isolated in the early 1800s from asparagus juice. It turns out to be very common: it’s found in dairy, meat, fish and shellfish, as well as potatoes, nuts, seeds and grains, amongst other things.

This is where the trouble begins. When asparagine is combined with sugars, particularly glucose, and heated, acrylamide is produced. The longer the food is heated for, the more acrylamide forms. This is a particular issue with anything wheat or potato-based thanks to the naturally-occurring sugars those foods also contain – hence all the histrionics over chips, roast potatoes and toast.

How dangerous is acrylamide? The International Agency for Research on Cancer have classified it as a Group 2A carcinogen, or a “probable” carcinogen. This means there’s “limited evidence” of carcinogenicity in humans, but “sufficient evidence” of carcinogenicity in experimental animals. In other words (usually) scientists know the thing in question causes cancer in rats – who’ve generally been fed huge amounts under strictly controlled conditions – but there isn’t any clear evidence that the same link exists in humans. It’s generally considered unethical to lock humans in cages and force feed them acrylamide by the kilo, so it’s tricky to prove.

screen-shot-2017-01-23-at-22-10-46At this point I will point out that alcoholic beverages are classified as Group 1 carcinogens, which means there is “sufficient evidence” of carcinogenicity in humans. Alcohol definitely causes cancer. If you’re genuinely concerned about your cancer risk, worry less about the roast potatoes in your Sunday roast and more about the glass of wine you’re drinking with them.

But back to acrylamide. In animals, it has been shown to cause tumours. It’s one of those substances which can be absorbed through the skin, and after exposure it spreads around the body, turning up in the blood, unexposed skin, the kidneys, the liver and so on. It’s also been shown to have neurotoxic effects in humans. BUT, the evidence that it causes cancer in humans under normal conditions isn’t conclusive. A meta-analysis published in 2014 concluded that “dietary acrylamide is not related to the risk of most common cancers. A modest association for kidney cancer, and for endometrial and ovarian cancers in never smokers only, cannot be excluded.” 

The dose makes the poison is an important principle in toxicology (image credit: Lindsay Labahn)

The dose makes the poison (image credit: Lindsay Labahn)

As I so often find myself saying in pieces like this: the dose makes the poison. The people who have suffered neurotoxic effects from acrylamide have been factory workers. In one case in the 1960s a patient was handling 10% solutions of the stuff, and “acknowledged that the acrylamide solution frequently had splashed on his unprotected hands, forearms and face.” The earliest symptom was contact dermatitis, followed by fatigue, weight loss and nerve damage.

Because of these very real risks, the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health have set occupational exposure limits at 0.03 mg/m3 over an eight-hour workday, or 0.00003 g/m3.

Let’s contrast that to the amount of acrylamide found in cooked food. The reason all this fuss erupted today is that the Food Standards Agency (FSA) published some work which estimated the amounts of acrylamide people are likely to be exposed to in their everyday diet.

The highest concentrations of acrylamide were found in snacks (potato crisps etc), and they were 360 μg/kg, or 0.00036 g/kg or, since even the most ardent crisp addict doesn’t usually consume their favoured snacks by the kilo, 0.000036 g/100g. (Remember that those occupational limits are based on continuous exposure over an eight-hour period.)

In other words, the amounts in even the most acrylamide-y of foodstuffs are really quite tiny, and the evidence that acrylamide causes cancer in humans is very limited anyway. There is some evidence that acrylamide accumulates in the body, though, so consuming these sorts of foods day in and day out over a lifetime could be a concern. It might be wise to think twice about eating burnt toast every day for breakfast.

Oh yes, and there’s quite a lot of acrylamide in cigarette smoke. But somehow I doubt that if you’re a dedicated smoker this particular piece of information is going to make much difference.

As the FSA say at the end of their report:

Your toast almost certainly isn't going to kill you.

Your toast almost certainly isn’t going to kill you.

“The dietary acrylamide exposure levels for all age classes are of possible concern for an increased lifetime risk of cancer. The results of the survey do not increase concern with respect to acrylamide in the UK diet but do reinforce FSA advice to consumers and our efforts to support the food industry in reducing acrylamide levels.”

This is not, I would suggest, QUITE the same as “Crunchy toast could give you cancer, FSA warns” but, I suppose, “FSA says risk hasn’t really changed” wouldn’t sell as many newspapers.

One last thing, there’s acrylamide in coffee – it forms when the beans are roasted. There’s more in instant coffee and, perhaps counterintuitively, in lighter-roasted beans. No one seems to have mentioned that today, possibly because having your coffee taken away in January is just too terrifying a prospect to even contemplate. And also perhaps because coffee seems to be associated with more health benefits than negatives. Coffee drinkers are less likely to develop type 2 diabetes, Parkinson’s disease, dementia, suffer fewer cases of some cancers and fewer incidences of stroke. Whether the link is causal or not isn’t clear, but coffee drinking certainly doesn’t seem to be a particularly bad thing, which just goes to show that when it comes to diet, things are rarely clearcut.

Pass the crisps, someone.


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Is it possible to give up sugar completely?

It’s January, a month that’s traditionally marked by cold weather, large credit-card bills and, of course, an awful lot of highly questionable health stuff. Juicing, detox, supplements… it’s all good fun. Until someone gets hurt.

"Refined" sugar is almost entirely made up of a molecule called sucrose.

“Refined” sugar is almost entirely made up of a molecule called sucrose.

One substance that regularly gets a bashing is sugar, particularly so-called “refined” sugar. We’re told it’s toxic (it’s not), it’s more addictive than cocaine (it isn’t) and we should definitely all be trying to give it up.

Now, before I go any further with this, a word about healthy eating. I’m not a dietician. I don’t even claim to be a nutritionist (although I could, if I wanted). However, I think I’m on fairly safe ground if I say that we should all be striving for a healthy, balanced diet. That is, a diet containing a broad range of foods, plenty of fruits and vegetables, healthy amounts of protein and some good fats.

A lot of people have diets that fall short of this ideal. Cutting back on foods which contain a lot of added sugar (cakes, chocolate, fizzy drinks, etc) and eating more vegetables and fruits is a good, and sensible, course of action.

The problem is that bit of common-sense advice doesn’t sell books or make an interesting TV show. It’s all a bit boring and, worse, it’s freely available. Compelling entertainment needs to be more exciting, more dramatic, more… extreme.

Which brings us to ITV’s Sugar Free Farm.

Page 81 of the current issue of Radio Times tells us that the celebrities face a "completely sugar-free regime".

Page 81 of the current issue of Radio Times tells us that the celebrities face a “completely sugar-free regime”.

This is actually the second series of this show, which first aired last year. According to the 7-13th January 2017 issue of the Radio Times:

“Seven celebrities who admit to terrible diets succumb to a few weeks of hard farm labour and a completely sugar-free regime (so no white carbs or fruit, let alone chocolate).”

Hm. Now, I’ve written about sugar more than once before, but to save clicking back and forth, here’s another quick summary:

Sugar is not one thing. The chemistry of sugars is quite complicated, but a human being trying to understand the food they eat probably needs to be aware of three main types, namely: glucose, fructose and sucrose.

180px-Glucose_chain_structure

glucose

Glucose is the sugar that all your cells need. Not having enough glucose in your bloodstream is called hypoglycaemia, and the result is seizure, coma and ultimately death. This isn’t a risk for healthy people without pre-existing conditions (like diabetes, for example) because evolution has put some clever safety-nets in place. First, our bodies are extremely efficient at carrying out the necessary chemistry to turn the molecules we eat into the molecules we need. Should that fail, our bodies are very good at storing nutrients to use in times when our diet doesn’t supply them. If you don’t eat glucose, your body will break down other foods to produce it, then it’ll start on your glycogen stores, move on to fat stores, and eventually start breaking down protein (i.e. the stuff in your muscles). This means that unless you stop eating completely for a fairly long period of time, you’ll survive.

Still, I think it’s important to emphasise the point: glucose is essential for life. The suggestion that this substance is “toxic” and thus should be completely eliminated from our diets is really, when you think about it, a bit odd.

Sucrose ("refined sugar") is a unit of glucose joined to a unit of fructose

Sucrose (“refined sugar”) is a unit of glucose joined to a unit of fructose

Ah but, I hear some people saying, no one is saying that glucose is toxic! They’re talking about refined sugar!

Fine. So what’s “refined” sugar? In simple terms, it’s pure sucrose. And sucrose is just a molecule made from a unit of glucose stuck to a unit of fructose. As I said, our bodies are really good at breaking up the molecules we eat into the molecules we need: our cells can’t use sucrose for energy, so all that happens is that it more or less instantly gets broken up into glucose and fructose.

Refined sugar is, basically, half glucose and half fructose, and it’s no more dangerous or “toxic” than either of those substances. And while I’m here, “natural” sugar options are little different: honey, for example, contains similar ratios of fructose and glucose.

200px-Skeletal_Structure_of_D-Fructose

Fructose

Allrighty then, what’s fructose? Fructose is another simple sugar, and it’s the one that plants produce. For that reason it’s sometimes called “fruit sugar”.

Our cells can’t use fructose for energy, either. But, same thing again: if you eat it your body will still use it. In this case, your liver does the heavy lifting; changing fructose into glucose and other substances, some of which are fats. On the one hand, this is a slower process so you don’t get the blood sugar spike with fructose that you get with glucose. On the other, some of the fructose you eat inevitably ends up being converted into fat.

As I mentioned, fructose is the sugar in plants. It’s found in almost all plant-based foods. For example, the USDA food composition database tells us that 100 g of carrots contains about 0.6 g of fructose. Perhaps surprisingly, broccoli contains slightly more: about 0.7 g per 100 g. Iceberg lettuce contains even more, at 1 g per 100 g, whereas green peas contain a mere 0.4 g.

Even a really small glass of fruit juice contains about 150 g.

Even a small serving of fruit juice usually contains at least 150 g.

None of this comes close to fruit. Apples contain about 6 g of fructose per 100 g, grapes 4 g and bananas 5 g. Dried fruit, as you’d expect, has considerably higher amounts by weight – because the water’s gone. Juices have similar amounts of fructose per unit of weight but, of course, you tend to drink a lot more than 100 g of juice at a time.

Now we understand why “Sugar Free Farm” has banned fruit. But this is why I have a problem with the title: you CAN’T eat an entirely “sugar-free” diet, unless all you eat is meat, fish, eggs and dairy products like cream and butter (but not milk, which contains lots of another sugar: lactose). This would be a far from healthy diet, seriously lacking in fibre as well as a host of vitamins and minerals (even “phase 1” or the “induction” period of the controversial Atkins diet isn’t quite this extreme).

The show hasn’t aired yet, and I admit I didn’t watch it last year, so I don’t know if that’s what they’re doing. But I seriously doubt it – it would be unethical and irresponsible. Plus, the words “white carbs” in the listings blurb make me suspicious. Why specify “white”? Are whole grains included? And what about pulses? Whole grain foods might be relatively low in fructose and glucose before you put them in your mouth, but as soon as saliva hits them the starch they contain is broken down into…. glucose. By the time you swallow that chewed-up food, it contains sugar.

In summary, Sugar Free Farm is almost certainly not sugar free. What they appear to have set up is a place where sugars are restricted and foods with added sugar are banned, and then mixed that with lots of outdoor activities (the celebrities are also expected to work on the farm).

Most people would lose weight following such a regime, because it’s likely that calories in are going to be lower than calories out. It’s a simple calorie deficit.

give-up-sugarWhat bothers me is that the show might go on to conclude that we should all “give up” sugar to lose weight – and some people might misinterpret that and end up embarking on an unbalanced, unhealthy and ultimately unsustainable diet – when in fact the results are simply due to calorie deficit.

There’s no need to try to give up sugar. Cut down, yes, but you can eat some sweet foods and still manage a calorie deficit. In fact you probably should: fruit in particular has lots of nutrients, including fibre. Besides, such a diet will probably be a lot more sustainable in the long term.

Unfortunately, “Eat Fewer Calories And Do Some Exercise Farm” doesn’t have quite the same ring, does it?


EDIT, 11th Jan 2017

Well, the first episode aired last night. No, the diet is not “zero sugar”. It’s very low in sugar, yes, but there are sugars. They used milk (contains lactose), ate wholemeal bread, brown rice and oats (all of which are broken down into glucose) and ate a variety of vegetables which, as I mentioned above, all contain small amounts of sugar. In fact, on their very first morning they eat a strange granola mixture made with sweet potato. The USDA food database tells me that sweet potato contains about 0.4 g of fructose, 0.5 g of glucose, 3.3 g of maltose AND 1.4 g of sucrose per 100 g. Yep. Sucrose. The stuff in “refined” sugar.

There was much talk of “detox” and “detoxing” from sugar. Sigh. That’s not a thing. Most worryingly of all, poor Peter Davison (he was “my” Doctor, you know) was carted off in an ambulance on the second day, suffering with dizzy spells. Everyone immediately started talking about how dreadful it was that “sugar” had caused this. There was only one, in passing, comment shown suggesting that perhaps the 65-year-old might have something else wrong with him. In fact, it turned out that he had labyrinthitis, an inner-ear condition. It’s usually viral. It’s not caused by “sugar withdrawal”. I’m sure they’ll make that clear in the next episode, right?

Speaking of which, the celebrities are on Sugar Free Farm for 15 days. A safe rate of weight loss is generally considered to be 0.5-1 kg (or 1-2 lb) a week. So they should lose about 2 kg, or 4 lb, on the outside. A snippet was shown at the end of the program in which Alison Hammond said she was “pleased” she’d lost 8 lbs. Whether that was after two weeks or a shorter period of time wasn’t clear, but either way, it’s a lot. It suggests that her diet is/was too low in calories, particularly considering all the extra physical activity.  Perhaps some of her so-called “sugar withdrawal” symptoms were actually simply due to the fact that she wasn’t consuming enough to keep up with her energy needs?

That aside, the diet they followed did seem to be fairly balanced, with plenty of vegetables and adequate healthy fats and protein. They had all been eating huge quantities of sugary foods beforehand, and cutting down is no bad thing. I’m just skeptical about exactly how much of the bad, and indeed the good, can be pinned on sugar.

Still, it made good telly I suppose.


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The Chronicles of the Chronicle Flask: 2016

2016 is limping to its painful conclusion, still tossing out last-minute nasty surprises like upturned thumb tacks in the last few metres of a marathon. But the year hasn’t been ALL bad. Some fun, and certainly interesting, things happened too. No, really, they did, honestly.

So with that in mind, let’s have a look back at 2016 for the Chronicle Flask….

January kicked off with a particularly egregious news headline in a well-known broadsheet newspaper: Sugar found in ketchup and Coke linked to breast cancer. Turns out that the sugar in question was fructose. Yes, the sugar that’s in practically everything, and certainly everything that’s come from a plant. So why did the newspaper in question choose ketchup and Coke for their headline instead of, oh, say, fruit juice or honey? Surely not just in an effort to sell a few more newspapers after the overindulgent New Year celebrations. Surely.

octarineThere was something more lighthearted to follow when IUPAC  verified the discoveries of elements 113, 115, 117 and 118. This kicked off lots of speculation about the elements’ eventual names, and the Chronicle Flask suggested that one of them should be named Octarine in honour of the late Sir Terry Pratchett. Amazingly, this suggestion really caught everyone’s imagination. It was picked up in the national press, and the associated petition got over 51 thousand signatures!

In February I wrote a post about the science of statues, following the news that a statue to commemorate Sir Terry Pratchett and his work had been approved by Salisbury City Council. Did you know that there was science in statues? Well there is, lots. Fun fact: the God of metalworking was called Hephaestus, and the Greeks placed dwarf-like statues of him near their Hearths – could this be where the fantasy trope of dwarves as blacksmiths originates?

MCl and MI are common preservatives in cosmetic products

MCl and MI are common preservatives in cosmetic products

My skeptical side returned with a vengeance in March after I read some online reviews criticising a particular shampoo for containing a substance known as methylchloroisothiazolinone. So should you be scared of your shampoo? In short, no. Not unless you have a known allergy or particularly sensitive skin. Otherwise, feel free to the pick your shampoo based on the nicest bottle, the best smell, or the forlorn hope that it will actually thicken/straighten/brighten your hair as promised, even though they never, ever, ever do.

Nature Chemistry published Another Four Bricks in the Wall in April – a piece all about the potential names of new elements, partly written by yours truly. The month also brought a sinus infection. I made the most of this opportunity by writing about the cold cure that’s 5000 years old. See how I suffer for my lovely readers? You’re welcome.

In May I weighed in on all the nonsense out there about glyphosate (and, consequently, learned how to spell and pronounce glyphosate – turns out I’d been getting it wrong for ages). Is it dangerous? Nope, not really. The evidence suggests it’s pretty harmless and certainly a lot safer than most of its alternatives.

may-facebook-postSomething else happened in May: the Chronicle Flask’s Facebook page received this message in which one of my followers told me that my post on apricot kernels had deterred his mother from consuming them. This sort of thing makes it all worthwhile.

In June the names of the new elements were announced. Sadly, but not really very surprisingly, octarine was not among them. But element 118 was named oganesson and given the symbol Og. Now, officially, this was in recognition of the work of Professor Yuri Oganessian, but I for one couldn’t help but see a different reference. Mere coincidence? Surely not.

July brought another return to skepticism. This time, baby wipes, and in particular a brand that promise to be “chemical-free”. They’re not chemical-free. Nothing is chemical-free. This is a ridiculous label which shouldn’t be allowed (and yet, inexplicably, is still in use). It’s all made worse by the fact that Water Wipes contain a ‘natural preservative’ called grapefruit seed extract which, experiments have shown, only actually acts as a preservative when it’s contaminated with synthetic substances. Yep. Turns out some of Water Wipes claims are as stinky as the stuff they’re designed to clean up.

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

August brought the Olympics, and speculation was rife about what, exactly, was causing the swimming pools to turn such strange shades of green. Of course, the Chronicle Flask knew the correct solution…

August also saw MMS and CD reared their ugly heads on social media again. CD (chlorine dioxide) is, lest we forget, a type of bleach solution which certain individuals believe autistic children should be made to drink to ‘cure’ them. Worse, they believe such children should be forced to undergo daily enemas using CD solutions. I wrote a summary page on MMS (master mineral solution) and CD, as straight-up science companion to the commentary piece I wrote in 2015.

mugsSeptember took us back to pesticides, but this time with a more lighthearted feel. Did you know that 99.99% of all the pesticides you consume are naturally-occurring? Well, you do if you regularly read this blog. The Chronicle Flask, along with MugWow, also produced a lovely mug. It’s still for sale here, if you need a late Christmas present… (and if you use the code flask15 you’ll even get a discount!)

In October, fed up with endless arguments about the definition of the word ‘chemical’ I decided to settle the matter once and for all. Kind of. And following that theme I also wrote 8 Things Everyone Gets Wong About ‘Scary’ Chemicals for WhatCulture Science.

Just in case that wasn’t enough, I also wrote a chapter of a book on the missing science of superheroes in October. Hopefully we should see it in print in 2017.

Sparklers are most dangerous once they've gone out.

Sparklers are most dangerous once they’ve gone out.

I decided to mark Fireworks Night in November by writing about glow sticks and sparklers. Which is riskier? The question may not be as straightforward as you’d imagine. This was followed by another WhatCulture Science piece, featuring some genuinely frightening substances: 10 Chemicals You Really Should Be Scared Of.

And that brings us to December, and this little summary. I hope you’ve enjoyed the blog this year – do tell your friends about it! Remember to follow @ChronicleFlask on Twitter and like fb.com/chronicleflask on Facebook – both get updated more or less daily.

Here’s wishing all my lovely readers a very Happy New Year – enjoy a drop of bubbly ethanol solution and be careful with the Armstrong’s mixture…. 

See you on the other side!

new-year-1898553_960_720

What IS a chemical?

a_chemistry_teacher_explaining_an_experiment_8d41253v

You at the back there! Get your nose out of that dictionary and pay attention!

What do we mean when we use the word “chemical”? It seems like a simple enough question, but is it, really? I write about chemicals all the time – in fact my last WhatCulture article was about just that – and I’ve mentioned lots of different definitions before. But I’ll be honest, some of them have bothered me.

I don’t often like the definitions you find in dictionaries. Lexicography and chemistry don’t seem to be common bedfellows, and dictionary compilers haven’t, generally speaking, spent their formative years being incessantly nagged by weary chemistry teachers about their choice of vocabulary.

For example, in the Cambridge Dictionary we find:
any basic substance that is used in or produced by a reaction involving changes to atoms or molecules.”

Hm. Firstly, “basic” has a specific meaning in chemistry. Obviously the definition doesn’t mean to imply that acids aren’t chemicals, but it sort of accidentally does. Then there’s the implication that a chemical reaction has to be involved. So inert substances aren’t chemicals? Admittedly, “used in” doesn’t necessarily imply reacts – it could be some sort of inert solvent, say – but, again, it’s bothersome. Finally, “atoms or molecules”. Ionic substances not chemicals either, then?

Yes, it’s picky, but chemists are picky. Be glad that we are. A misplaced word, or even letter, on a label could have serious consequences. Trust me, you do not want to mix up the methanol with the ethanol if you’re planning cocktails. Similarly, fluorine is a whole other kettle of piranhas compared to fluoride ions. This stuff, excuse the pun, matters.

Dictionary definitions have their problems.

Dictionary definitions have their problems.

Let’s look at some more definitions (of the word as a noun):

The Free Dictionary tells us that a chemical is:
“A substance with a distinct molecular composition that is produced by or used in a chemical process.”

Merriam Webster says:
“of, relating to, used in, or produced by chemistry or the phenomena of chemistry <chemical reactions>”

And Dictionary.com goes with the simple:
“a substance produced by or used in a chemical process.”

That idea that a chemical reaction must be involved somehow seems to be pervasive. It’s understandable, since that’s the way the word is mostly used, but it’s not really right. Helium, after all, is still very much a chemical, despite being stubbornly unreactive.

Possibly the best of the bunch is found in the Oxford Living Dictionary:
“A distinct compound or substance, especially one which has been artificially prepared or purified.”

Not bad. Well done Oxford. No mention of chemical reactions here – it’s just a substance. We do most often think of chemicals as things which have been “prepared” somehow. Which is fair enough, although it can lead to trouble. In particular, ridiculous references to “chemical-free” which actually mean “this alternative stuff is naturally-occurring.” (Except of course it often isn’t: see this article about baby wipes.) The implication, of course, is that thing in question is safe(r), but there are lots and lots of very nasty chemicals in nature: natural does not mean safe.

You keep using that word. I do not think it means what you think it means.

Sometimes people will go the other way and say “everything is chemicals.” We know what this means, but it has its problems, too. Light isn’t a chemical. Sound isn’t a chemical. All right, those are forms of energy. What about neutrinos, then? Or a single proton? Or a single atom? Or, going the other way, some complicated bit of living (or once living) material? In one debate about this someone suggested to me that a “chemical was anything you could put in a jar,” at which point I pedantically said, “I keep coffee in a jar. Is that a chemical?” Obviously there are chemicals in coffee, it works from the “everything is chemicals” perspective, but it’s a single substance that’s not a chemical.

Language is annoying. This is why chemists like symbols and numbers so much.

Anyway, what have we learned? Firstly, something doesn’t necessarily have to be part of a chemical reaction to be a chemical. Secondly, we need to include the idea that it’s something with a defined composition (rather than a complex, variable mixture, like coffee), thirdly that chemical implies matter – light, sound etc don’t count, and fourthly that it also implies a certain quantity of stuff (we probably wouldn’t think of a single atom as a chemical, but collect a bunch together into a sample of gas and we probably would).

So with all that in mind, I think I shall go with:

So what IS a chemical?

A chemical is…

(Drum roll please….)

Any substance made of atoms, molecules and/or ions which has a fixed composition.

I’m not entirely convinced this is perfect, but I think it more or less works.

If you have a better idea, please do comment and let me know!


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8 Things Everyone Gets Wrong About ‘Scary’ Chemicals

scaryChemicals. The word sounds a little bit scary, doesn’t it? For some it probably conjures up memories of school, and that time little Joey heated something up to “see what would happen” and you all had to evacuate the building. Which was actually good fun – what’s not to love about an unplanned fire drill during lesson time?

But for others the word has more worrying associations. What about all those lists of additives in foods, for starters? You know, the stuff that makes it all processed and bad for us. Don’t we need to get rid of all of that? And shouldn’t we be buying organic food, so we can avoid ….

….Read the rest of this article at WhatCulture Science.


This is my first article for WhatCulture Science – please do click the link and read the rest!


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Puzzling pool problems?

We’re half way thorough the Rio 2016 Olypics, and it will have escaped no one’s notice that there have been a few little problems with one of the pools.

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

Maria Lenk Aquatic Enter, Tuesday, Aug. 9, 2016. (AP Photo/Matt Dunham)

First, the water turned a mysterious green colour. Then there were reports of a ‘sulfurous’ smell, with German diver Stephan Feck reported as saying it smelled like a “fart”.

The diving pool seemed to be the worst affected, but the water-polo pool next to it also suffered problems, and competitors complained of stinging eyes.

So what on earth was happening? An early suggestion was that copper salts were contaminating the water. It’s not unheard of for copper compounds to get into water supplies, and it would certainly explain the colour; copper chloride solutions in particular are famously greeny-blue. But what about that sulfurous smell? Copper chloride doesn’t smell of sulfur.

Was the strange pool colour due to algae bloom?

Was the strange pool colour due to an algae bloom, like this one in Lake Erie?

The most likely culprit was some sort of algae bloom – in other words rapid algae growth – with the smell probably coming from dimethyl sulfide, or DMS. There’s a singled-celled phytoplankton called Emiliania huxleyi which is particularly famous for producing this smelly compound. In fact, it actually has more than one very important role in nature: the smell is thought to alert marine life that there’s food nearby, but it also seeps into the atmosphere and helps with cloud formation, helping to control our planet’s temperature. Without these reactions, Earth might not be nearly so habitable.

But how did algae manage to grow in the pool? The pool chemicals should have prevented it, so what had happened? An Olympic official then went on to make the comment that “chemistry is not an exact science,” which of course led to much hilarity all around. Chemistry is, after all, incredibly exact. What chemistry student doesn’t remember all those calculations, with answers to three significant figures? The endless balancing of equations? The careful addition of one solution to another, drop by drop? How much more ‘exact’ would you like it to be?

But I had a bit of sympathy with the official, because I suspect that what they actually meant – if not said – was that swimming pool chemistry is not an exact science. And while that, too, is hardly accurate, it is true that swimming pool chemistry is very complicated and things can easily go wrong, particularly when you’re trying to work on an extremely tight schedule. They could hardly, after all, close down all the pools and spend several days carrying out extensive testing in the middle of the sixteen-day-long Olympic Games.

Rio 2016 Olympics Aquatics Stadium (Image: Myrtha Pools)

Rio 2016 Olympics Aquatics Stadium (Image: Myrtha Pools)

When a pool is first built and filled, things are, theoretically, simple. You know exactly how many cubic litres of water there are, and you know exactly how much of each chemical needs to be added to keep the water free of bacteria and other nasties. Those chemicals are added, possibly (particularly in a pool this size) via some kind of automated system, and the pH is carefully monitored to ensure the water is neither too alkaline (basic) nor too acidic.

There’s a certain amount of proprietary variation of swimming pool chemicals, but it essentially all comes down to chlorine, which has been used to make water safe now for over 120 years.

Originally, water was treated to make it alkaline and then chlorine gas itself was added. This produced compounds which killed bacteria, in particular sodium hypochlorite, but the practice was risky. Chlorine gas is extremely nasty stuff – it has, after all, been used as a chemical weapon – and storing it, not to mention actually using it, was a dangerous business.

However, hundreds of people swimming in untreated water is a recipe for catching all kinds of water-borne disease, so it wasn’t long before alternatives were developed.

The Chemistry of Swimming Pools (Image: Compound Interest - click for more info)

The Chemistry of Swimming Pools (Image: Compound Interest – click graphic for more info)

Those alternatives made use of the chemistry that was happening anyway in the water, but  allowed the dangerous bit, with the elemental chlorine, to happen somewhere else. And so hypochlorite salts began to be manufactured to be used in swimming pools.

As the lovely graphic from Compound Interest illustrates, sodium hypochlorite reacts with water to form hypochlorous acid, which in turn goes on to form hypochlorite ions. These two substances sit in an equilibrium, and both are oxidants, which is good because oxidants are good at blasting bacteria. The equilibria in question are affected by pH though, which is one reason why, quite apart from the potential effects on swimmers, it’s so important to manage the pH of pool water.

There are a couple of different chemicals which can be added to adjust pH. Sodium bicarbonate, for example, can be used to nudge the pH up if needed. On the other hand, sodium bisulfate can be used to lower pH if the water becomes too alkaline.

Open-air pools have particular problems

UV light breaks down the chemicals that are used to keep swimming pool water clean.

This can all be managed extremely precisely in an unused, enclosed pool. But once you open that pool up, things become less simple. Open-air pools have a particular problem with UV light. Chlorine compounds are often sensitive to UV – this is why CFCs are such a problem for the ozone layer – and hypochlorite is no exception. In the presence of UV it breaks down in a process called photolysis to form chloride ions and oxygen. This means that outdoor pools require more frequent treatments, or the addition of extra chemicals to stabilise the ‘free available chlorine’ (FAC) levels.

Sadly, I haven’t managed to make it over to Rio, but from what I’ve seen the Aquatic Centre has a roof which opens up, which means that the pool water is indeed being exposed to UV light.

So perhaps the chemical levels simply dropped too low, which allowed algae to proliferate? Possibly aggravated by environmental conditions? Indeed, initially this seemed to be the explanation. FINA, the international governing body of aquatics, issued a statement on Wednesday afternoon which said:

“FINA can confirm that the reason for the unusual water color observed during the Rio diving competitions is that the water tanks ran out of some of the chemicals used in the water treatment process. As a result, the pH level of the water was outside the usual range, causing the discoloration. The FINA Sport Medicine Committee conducted tests on the water quality and concluded that there was no risk to the health and safety of the athletes, and no reason for the competition to be affected.”

This prompted people to wonder how on earth chemical levels were allowed to run out in an event as significant as the Olympics – did someone forget to click send on the order? – but still, it seemed to explain what had happened.

FINA issued a new statement

FINA issued a new statement on Sunday

Until today (Sunday), when more information surfaced as Olympic officials announced that they were going to drain at least one of the swimming pools and refill it. This is no small feat and will involve considerable cost: after all, we’re talking about millions of gallons of water. But it seems to be necessary. As Rio 2016’s director of venue management Gustavo Nascimento said:

“On the day of the Opening Ceremonies of the Games, 80 litres of hydrogen peroxide was put in the water. This creates a reaction to the chlorine which neutralises the ability of the chlorine to kill organics. This is not a problem for the health of anyone.”

Whoops. Yes indeed. Hydrogen peroxide reacts with chlorine to produce oxygen and hydrochloric acid. In fact, hydrogen peroxide is actually used to dechlorinate water which contains levels of chlorine that are too high. It might not be the very worst thing you could add to the water (when you think of all the things that could end up swimming pools) but it’s definitely up there.

Why and how this happened doesn’t, at the moment, appear to be clear. Presumably someone is for the high jump, and not just on the athletics field.

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Do you really need to worry about baby wipes?

Never mind ingredients, just give me a packet that's not empty!

Never mind ingredients, just give me a packet that’s not empty!

A little while back I wrote a post about shampoo ingredients, and in passing I mentioned baby wipes. Now, these are one of those products which you’ve probably never bought if you’re not a parent, but as soon as you are you find yourself increasingly interested in them. Yes, I know, reusable ‘wipes’ are a thing. But after dealing with a nappy explosion at 2am in the morning, I’m willing to bet that more than one parent’s environmental conscience has gone in the rubbish bin along with a bag of horror they never want to see again, at least for a little while.

But which wipes to buy? The cheapest ones? The nicest-smelling ones? The fragrance-free ones? The ones with the plastic dispenser on the top that allow you to easily grab one wipe at a time? Or not, because those bulky dispensers produce yet more plastic waste? Or just whichever brand you grabbed first at the all-night supermarket at some unpleasant hour that’s too late to be night yet too early to be morning?

All of the above at one time or another, probably. However, I’m going to suggest that one thing you can stop worrying about right now is whether or not your wipes are labelled ‘chemical-free’.

As I’ve explained before, everything is made up of chemicals. By any sensible definition, water is a chemical, and thus the claim that Water Wipes® (“the world’s purest baby wipe”) are “chemical free” is simply incorrect.

These wipes are not, actually, chemical-free.

These wipes are not, actually, chemical-free.

In fact, Water Wipes® aren’t even, as you might imagine, made of some sort of non-woven fabric impregnated with plain water. No, they contain something else: grapefruit seed extract.

Well, that sounds natural, I hear you say. It does, doesn’t it? Grapefruit, that sounds fresh. Seed, well seeds are healthy, aren’t they? And the word ‘extract’ is very natural-sounding. What’s the problem?

Let’s start with what grapefruit seed extract, also called GSE, actually is. It’s made from the seeds, pulp and white membranes of grapefruit. These ingredients are ground up and a drop of glycerin is added. Glycerin, by the way, is otherwise known as glycerol, or propane-1,2,3-triol. It’s naturally-occurring – it’s one of the molecules you get when you break up fats – and it’s usually made from plants such as soybeans or palm (uh oh…), or sometimes from tallow (oh dear…) or as a byproduct of the petroleum industry (yikes! – I wonder if the manufacturers of Water Wipes® enquired about the nature of the glycerin being added to their product…?)

But anyway, back to GSE. Like all plant extracts, grapefruit seed extract is stuffed full of other chemicals that occur naturally. In particular, flavonoids, ascorbic acid (vitamin C), tocopherols, citric acid, limonoids and sterols.

citric acid synthetic vs natural

Can you tell the difference?

So… in short, not chemical-free at all. Not even a bit. The problem here is that, in marketing, the term ‘chemical-free’ is used to mean something that only contains ingredients from ‘natural’ sources. But this is meaningless. Take citric acid, for example. (E330 by the way – E numbers don’t mean something’s deadly, either. In fact, quite the opposite.) There’s no difference between citric acid extracted from a grapefruit and citric acid prepared in a laboratory. They both have exactly the same atoms and the same molecular formula and structure. They both react in the same way.

They’d both be classified as corrosive in high concentrations, and irritant in low concentrations. This isn’t even “might” cause irritation. This is absolutely, definitely, positively WILL cause irritation.

Wait, hang on a minute! There’s a potentially corrosive chemical in the ‘chemical-free’ baby wipes, and unsuspecting parents are putting it on their baby’s skin?!

Yep.

But before anyone runs off to write the next Daily Mail headline, let’s be clear. It’s really not going to burn, alien acid-style, through a new baby’s skin. It’s not even going to slightly redden a baby’s skin, because the quantity is so miniscule that it quite literally has no corrosive properties at all. It’s the same logic as in the old adage that “the dose makes the poison“.

This is where we, as consumers, ought to stop and think. If a fraction of a drop of citric acid is harmless then…. perhaps that small quantity of PEG 40 hydrogenated castor oil or sodium benzoate in most (considerably less expensive, I’m just saying) other brands of baby wipes isn’t as awful as we thought, either…

Indeed, it’s not. But what sodium benzoate in particular IS, is a very effective preservative.

Grapefruit seed extract is marketed as a natural preservative, but studies haven't backed up this claim.

Grapefruit seed extract is allegedly a natural preservative, but studies haven’t backed up this claim.

Why does this matter? Well, without some sort of preservative baby wipes, which sit in a moist environment for weeks or months or even years, might start to grow mould and other nasties. You simply can’t risk selling packets of water-soaked fabric, at a premium price, without any preservative at all, because one day someone might open one of those packets and find it full of mould. At which point they would, naturally, take a photo and post it all over social media. Dis-as-ter.

This is why Water Wipes® include grapefruit seed extract, because it’s a natural preservative. Except…

When researchers studied GSE and its antimicrobial properties they found that most of their samples were contaminated with benzethonium chloride, a synthetic preservative, and some were contaminated with other preservatives, some of which really weren’t very safe at all. And here’s the kicker, the samples that weren’t contaminated had no antimicrobial properties.

In other words, either your ‘natural’ grapefruit seed extract is a preservative because it’s contaminated with synthetic preservatives, or it’s not a preservative at all.

If you're worried, just use cotton wool pads and water.

You can always use cotton wool pads and water.

If you’re worried that baby wipes may be irritating your baby’s skin – I’m not claiming this never happens – then the best, and cheapest, thing to do would be to simply follow the NHS guidelines and use cotton wool and water. It’s actually easier and less messy than you might imagine – packets of flat, cosmetic cotton wool pads are readily available (and pretty cheap). Simply dip one in some clean water, wipe and throw it away. It’s really no more difficult or messy than wipes.

But if you’re choosing a particular brand of wipes on the basis that they’re “chemical-free”, despite the fact that other types have never actually caused irritation, you can stop. Really. Buy the cheap ones. Or the nicest-smelling ones, or the ones that come out of the packet most easily. Because NONE of them are chemical-free, and it’s really not a problem.


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