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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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

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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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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Are you (still) a chemist and you didn’t know it?

I recently wrote a post listing five bits of chemistry you (probably) do every day.  It was surprisingly popular and so, just like the big movie companies, here’s the sequel!

Picture 0151.  Make fresh coffee (or at least drink one someone else made)
Espresso (the basis of most coffee drinks) is made by forcing a small amount of very-nearly boiling water through ground coffee beans.  This handily extracts a number of chemicals including all the ones that produce the lovely coffee flavours and aromas but also, crucially, our friend caffeine, without which many of us simply wouldn’t function on a daily basis.  What you (or your favourite barista) have done here is a form of chemical extraction.  Extraction techniques are extremely important in chemistry, because nature has an annoying habit of stirring up the stuff we want with lots of other things.  Chemists, especially the organic ones (produced with all-natural fertilisers) spend most of their lives carefully and painstakingly extracting things from other things. Some of them probably earn less than baristas, too.

2.  Make toast
You know when you make the perfect slice, and it goes that lovely brown colour, just before black?  That’s the Maillard reaction in action.  It’s the same thing that happens when you brown meat, chips, onions or, well, anything else that goes brown when you cook it.  It’s a reaction between amino acids (the stuff proteins are made of) and sugars.  It’s also responsible for those lovely toasted-biscuity smells and favours.  The surface of the food has to be in contact with dry heat for this reaction to happen, which is why boiled and microwaved food doesn’t brown.  And alkaline conditions help it along, which is the main reason lye is traditionally used on the surface of pretzels and other German breads (that’s always made me a bit nervous).

Haemoglobin3.  Breathe
I mentioned respiration in my previous post but as any 13 year-old pupil will tell you, and most adults have long since forgotten, respiration is not the same as breathing.  Here I’m actually thinking of oxygen exchange (which is also not, technically, the breathing bit but bear with me).  You’re probably aware that you blood has iron in it: in fact that iron is tied up in rather beautifully complicated haemoglobin molecules.  Oxygen molecules bond to four iron atoms in the haemoglobin with something called coordinate, or dative covalent, bonds.  If it weren’t for this nifty bit of chemical bonding, there’s no way our blood could carry enough oxygen around our bodies, delivering it safely to our cells, to keep us going from one minute to the next.

251840969_6404.  Neutralised some excess acid
Taken an indigestion tablet recently?  Did you realise you were doing a chemistry experiment in your very own stomach?  Well you were!  Indigestion tablets contain a variety of substances, but some of the most common ingredients are magnesium hydroxide (also known, when suspended in water, as ‘milk of magnesia’), calcium carbonate, sodium bicarbonate and magnesium carbonate.  These are all bases: they react with acids to form a salt and water and, in the case of the carbonates, carbon dioxide as well.  The acid in your stomach is hydrochloric acid, so for example:

sodium bicarbonate + hydrochloric acid –> sodium chloride + water + carbon dioxide

Now, is that Rennie advert that claims to “turn acid into water and other natural substances” starting to make sense?  They don’t want to use the word salt for some reason…

5.  Used drain cleaner
This is one of my favouritist little bits of chemistry.  Really.  It’s lovely.  Well apart from the horribly caustic chemicals involved obviously.  Drain cleaner is dangerous concoction nasty stuff but it’s main ingredient is often a strong alkali, like sodium hydroxide (there are also acidic drain cleaners; it’s quite important that you don’t mix them).  The stuff that blocks up your plughole is, largely, protein (hair, skin cells, yuck) and and oily dirt.  The strong alkali reacts with these things in a reaction called hydrolysis.  Now this is clever, because soap is made by (virtually) the exact same reaction.  Soap is produced by saponification, where fats are mixed with a strong alkali.  So what are you doing when you put drain cleaner in your stuffed-up plug hole?  You’re not only breaking down the gunk, you’re also effectively making soap in situ, which helps to wash away the remaining dirt.  How brilliant is that?

With thanks to Andrew (@_byronmiller) for his suggestions.