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?



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 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!


10 Chemicals You Really SHOULD Be Scared Of

Some chemicals really ARE scary...

Some chemicals really ARE scary…

People are increasingly worried about chemicals these days (even if they don’t quite know what the word means), but most of that fear is unfounded. The ingredients in cosmetics and foods are actually pretty harmless on the whole, certainly in the quantities you usually meet them.

This is because we’ve had decades of extensive testing and health and safety regulations – the truly nasty stuff simply isn’t allowed anymore. Even, sometimes, in fairly-obviously dangerous things like rat poison.

But the nasty stuff exists. Oh yes it does. You might be unlikely to come across it, but it’s still out there. Locked away. (Or not.)

So, come with me as I take you on a tour of 10 chemicals you really SHOULD be scared of…

Click to continue reading this article at WhatCulture Science

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.


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.


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.


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 - click image for more)

How Light Sticks work (from – 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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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!

Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. In need of a groovy new mug? Check out this page.

MMS and CD chemistry – the facts

The TL:DR version.

The TL:DR version.

About a year ago I wrote a post on the subject of MMS and CD. Many people have since praised that post, but others have complained that it’s rather long (it is) and contains too much opinion.

I believe that anyone that wants them should have easy access to the facts on this subject, and not just the information provided by proponents of MMS/CD use.

With this in mind I’ve written this post as a summary of the basics. I ask only that you credit me if you use this to write an article. A mention of my Twitter account, @chronicleflask, or a link to this page will suffice.

What is MMS?


MMS is usually sold as water purification drops

MMS stands for ‘master mineral solution’ or sometimes ‘miracle mineral solution’. It is a 22.4% solution of sodium chlorite in water. Sodium chlorite has the chemical formula NaClO2. So, MMS is 22.4 grams of NaClO2 dissolved in 100 mls of water. Sodium chlorite/MMS does not, on its own, act as a bleach.

Sodium chlorite’s LD50 (for rats) is 350 mg/kg. This means that, on average, if you feed rats 350 mg of it per kg of body weight, half the rats will die. If we assume its toxicity is similar in humans (and there’s no reason it should not be) that means that 5.25 grams would probably be enough to kill an average 4-year-old child weighing about 15 kg.

MMS is usually sold as ‘water purification drops’. Search for ‘sodium chlorite water purification’ in Google and you will quickly find it (usually alongside an ‘activator’ solution). Bottles for sale are usually 4 oz, or 114 mls. One quarter of one of these bottles would probably be lethal to a 15 kg 4-year-old.

What is CD (or CDS)?

CD is chlorine dioxide (and CDS stands for chlorine dioxide solution). Chlorine dioxide is ClO2. It is a bleach, used industrially to bleach wood pulp. It is also used to purify water and kill pathogens on certain foodstuffs. It is considered more effective than plain chlorine for water purification – it’s less corrosive and is particularly good at destroying legionella bacteria, as well as many viruses and protozoa.

Chlorine dioxide is more toxic than sodium chlorite. It’s LD50 is 292 mg/kg (the lower the number, the more toxic something is). For this reason, the concentrations used in food/water applications are very low. The US Environmental Protection Agency have set a maximum level of 0.8 mg/L chlorine dioxide in drinking water. That’s 0.00008 grams per 100 ml of water.

What’s the connection between MMS and CDS?

The chemistry of sodium chlorite (the substance in MMS) with acids.

The chemistry of sodium chlorite (the substance in MMS) with acids.

Chlorine dioxide evaporates quickly from solution, which means CD solutions cannot be stored – they have be made freshly as they’re needed. When sodium chlorite is mixed with an acid, usually citric acid (the acid in oranges and lemons), it forms chlorine dioxide. In short:
MMS + acid = CDS.

The chemistry behind this is complicated. It’s simpler if the acid used is hydrochloric acid (HCl), and this particular method of ‘activation’ is sometimes recommended by proponents of MMS/CD use.

If sodium chlorite is mixed with citric acid is used the reaction doesn’t happen in one step. Rather, chlorous acid (HClO2) forms, which ultimately breaks down to form ClO2. Several reactions are involved in this process. The concentration of chlorine dioxide in a solution made in this way is likely to be lower than if hydrochloric acid is used. However, it’s important to realise the the resulting solution is a mixture of harmful substances. Less chlorine dioxide does not necessarily mean safer.

How much chlorine dioxide forms when MMS is ‘activated’?

It’s not possible to answer this precisely, because it depends on several different factors. To begin with, it depends on whether hydrochloric acid or another acid (such as citric acid) is used. It further depends on temperature, and how much acid is added. We have no way of knowing exactly what someone mixing up these solutions at home is doing.

A document on acidified sodium chlorite published by the Joint Expert Committee on Food Additives (JECFA) suggests that, at a pH of 2.3, a 50 ppm solution of sodium chlorite would produce 16 ppm chlorous acid (less at higher pHs). Starting with a 22.4% solution (as in MMS), and allowing for the stoichiometry suggested by the equations above, this could produce something in the region of 36 g of chlorine dioxide per litre of water.

The US EPA’s recommended safe limit for chlorine dioxide is 0.00008 grams per litre of water. Compare this to 36 grams per litre. Even if only a fraction is converted to chlorine dioxide, the resulting mixture is likely to be tens of thousands in excess of safe limits.

How are CD solutions used in food & drink production?

Very dilute solutions, with just a few ppm of chlorine dioxide, are used as sprays or dipping solutions for poultry, meats, vegetables fruit and seafood. However, in these applications the chlorine dioxide evaporates from the food long before anyone eats it – it’s not present in the final food product. Chlorine dioxide is also used in water treatment plants, but the concentration in the final water supply is strictly controlled so that it’s less than the recommended safe limits.

How are CD solutions used as ‘alternative treatments’?

There are groups of people who believe that drinking CD solutions, or using them to perform enemas can cure any and all diseases, illnesses and conditions. However, there is no evidence that CDS is at all efficacious, and no reasonable mechanism has ever been given for its supposed mode of action. Jim Humble, who coined the name MMS ten years ago and sparked the use of these ‘treatments’, claimed that he worked with the Red Cross to successfully treat a group of malaria patients in Uganda. The Red Cross strenuously deny these claims. Other commentators have explained very clearly why Humble’s claims are impossible.

There is a large group online, led by Kerri Rivera, who believe that CD solutions can cure autism. This is not true. Autism is a neurodevelopment disorder. There is no cure, although certain therapies may help those on the autistic spectrum to manage better in day-to-day life. The cause of autism is unclear, but it appears to have a strong genetic basis.

Humble and Rivera advocate drinking CD solutions and/or using them in enemas. Protocols for such treatments involve adding drops of CDS to water, milk or other liquids.

The number of drops used varies. Humble reportedly used 18 drops at a time in his malaria treatment. Usually this is added to further liquid, for example in a 250 ml bottle. Assuming a drop is 0.1 mls, this could be as much as 0.065 g of chlorine dioxide in 250 mls, or 0.26 grams per litre. Once again, US EPA’s recommended safe limit for chlorine dioxide is 0.00008 grams per litre.

The amounts recommended by MMS/CD protocols are likely to be at least 3000 times safe limits, and may be considerably more. Protocols exist which recommend drinking these mixtures every one or two hours, eight times a day or even more.

What would happen if someone drank a CD solution?

It would be ironic if it weren't so tragic.

Chlorine dioxide exposure may actually cause delays in the development of the brain.

It would depend on the concentration. The very low levels used in normal water purification are not be harmful (that’s why safe limits exist), however drinking large amounts (such as those usually recommended in MMS/CD protocols) would cause irritation to the mouth, oesophagus, and stomach. There is no evidence that chlorine dioxide causes cancer. The ATSDR‘s (Agency for Toxic Substances and Disease Registry) entry for chlorine dioxide says that “studies in rats have shown that exposure of pregnant animals to chlorine dioxide or exposure of pups shortly after birth can cause delays in the development of the brain” (see also PMID: 2213920).

Why are CDS enemas used, and what would be the effect?

Rivera in particular advocates CDS enemas to kill the ‘parasites’ which she and her followers believe cause autism. There is no evidence for the existence of these ‘parasites’. Photos published online which purport to show them have been condemned as actually showing intestinal lining and mucus, excreted as the direct result of harsh enema procedures.

Enemas, regardless of the liquid used, have risks. Repeated enemas can cause electrolyte imbalance, rupture of the bowel and damage to the rectal tissues. Enemas with CDS are likely to be particularly dangerous since it is corrosive. Proponents of CDS use claim it is ‘selective’ and only kills ‘harmful’ bacteria and parasites. This is not possible; chlorine dioxide is a strong oxidising agent and damages all cells it comes into contact with, regardless of the nature of those cells.

Children have thinner tissues than adults. The risks of regular enemas, particularly with a corrosive agent such as chlorine dioxide, and particularly when carried out at home by someone with no medical training, are likely to be considerably higher for children.

Is there any way to tell if someone has been using CDS in high concentrations?

Unless someone admits to using CDS, there isn’t really any way to tell. For this reason there are very few reported cases of harm caused by CDS, as users tend to be extremely secretive. Unless an enema causes major trauma (which is a real risk) the symptoms are likely to be fairly vague gastrointestinal distress, which could be caused by any number of other things. There is no routine medical test to measure chlorine dioxide or chlorite in the body. There is a special test to measure chlorite in tissues, blood, urine, and feces, but the test cannot tell the extent of the exposure or whether harmful effects will occur. This test wouldn’t be performed unless exposure was expected. In other words, unless someone admits to using CDS on themselves or their child, it’s unlikely anyone will ever find out.

Has MMS/CDS been in the news?

Yes, on several occasions:

If there’s no cure for autism/cancer/some other condition, mightn’t it be worth trying…?

Medicine is all about risks vs. benefits. The benefit of using a particular treatment must always exceed the risk of using that treatment. In this case, there are no proven benefits of using MMS/CDS. There are considerable risks, as described above. The only thing MMS/CDS will do is make you feel sick and generally more unwell than you (or your child) might already. So no, it isn’t worth trying. Please don’t.


Comments will be left open on this page for as long as it takes for me to tire of dealing with “you’re a pharma shill!”, “this is all lies!”, “watch this YouTube video that proves it works!” and “I drink it every day and I’m fine!” type comments.

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Should you be scared of your shampoo?

I was doing some grocery shopping online recently (I have small children, I’ve started to view traditional supermarket shopping in the same way as beating my carpets with a stick and washing clothes in a stream) when I came across some reviews for a particular brand of shampoo.

Most of the reviews were positive, but some were not. In particular, there were a few one star ones complaining about ingredients called methylchloroisothiazolinone and methylisothiazolinone.



What, you may be wondering, are these monstrosities? Surely with names that long they must be huge great big molecules? Actually no, they’re quite small. Methylchloroisothiazolinone (shown in the graphic) has a mere four carbon atoms and an interesting assortment of other elements. They’re part of a group of compounds called isothiazolinones, which are heterocyclic molecules that include a five-membered ring which contains nitrogen, sulfur and a C=O group.

Not surprisingly considering the unwieldy name, methylchloroisothiazolinone is often shortened to MCI. Likewise, the chemically-similar methylisothiazolinone (imagine the molecule above without the -Cl bit) goes by the moniker MI, or sometimes MIT.

MCl and MI are common preservatives in cosmetic products

MCl and MI are common preservatives in cosmetic products.

Why are these things in shampoo? Well, they are very effective preservatives. They’re antibacterial and antifungal, and work against both gram-positive and gram-negative bacteria, as well as yeast and fungi. This is a good thing, because some of these microbes are pretty nasty. The bacteria, for example, include such lovelies as Nocardia (associated with a particular type of respiratory disease), Staphylococcus (associated with various infections) and Listeria (most famous for causing gastrointestinal distress). It may be a small risk, but showers are warm, moist environments – basically the perfect breeding ground for these sorts of things. If these microbes start growing in your shampoo, shower gel and so on, they would then end up on your hair and skin, possibly be inhaled, and might even make their way into your bloodstream if you had a small cut somewhere.


So, that’s why these chemicals are there. That all sounds good, right? Why are people complaining?

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

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

Well, because they also have their hazards. Now, before I go any further, we should remember a very important principle of toxicology, which is that “the dose makes the poison“. Everything, I really mean EVERYTHING, is dangerous if you’re exposed to too much of it. Oxygen is quite crucial if you want to carry on living, for example, but breathe in too much of it for too long and you’re at risk of developing visual disturbances, tinnitus, nausea and muscle spasms. Too much could even be lethal. Similarly, a pinch of salt is quite nice on chips, but try and drink say, seawater, and you’ll soon regret it. Even plain water can be dangerous if you consume too much in too short a time, particularly if you’re also exercising hard.

Many chemicals that are used industrially have scary lists of associated hazards, but it’s important to remember that these warnings are usually aimed at people who use said chemical in an industrial setting. In other words, they might be handling kilograms or even tonnes of the stuff, all day every day, as opposed to the teeny tiny quantity you’re likely to meet a few times a week.

I could pick literally any ingredient in that shampoo bottle and proclaim that it’s dangerous. This would be perfectly true, but also meaningless. A more pertinent question is: is it dangerous in the quantity that you usually use?

Are methylchloroisothiazolinone and methylisothiazolinone in shampoo dangerous? There’s no evidence that they bioaccumulate (build up in the body) or that they’re linked to any kind of cancer (phew). In 2002, there was an in vitro (i.e. outside of living organisms) study of the neurotoxicity of MI which showed that mature neurons in tissue culture could be killed by 4-12 ppm solutions of the chemical. But these experiments were performed on rat brain cells in culture. Lots of things will damage cells in a petri dish: it doesn’t mean that we necessarily have to worry about them in every day life. A shampoo solution pouring straight into your brain might well be harmful, but I suggest that if that’s happening in the shower you have bigger problems. Namely, major head trauma.

However, in high concentrations, MI and MCl are definitely skin and membrane irritants, which can cause chemical burns. They’re known chemical ‘sensitisers‘. This means that exposure to them, even at fairly low levels, might cause an allergic reaction.


A patient who presented to a medical centre following a severe reaction to methylisothiazolinone in a wipe (SA Government – click image for source).

This is where we get into difficult territory, because exactly how a particular individual is going to respond to something like this can be hard to predict. For example, I’ve never had a nasty reaction to methylchloroisothiazolinone. Give me an aspirin, on the other hand, and I’m likely to be in trouble. Allergies are specific to individuals. But there is no doubt that some people do have nasty reactions to MCI and MI; some sources have suggested it might be as many as 15% of the population (and that this number might, worryingly, have increased in recent years).

These chemicals are, or at least have been, also used as preservatives in other products such as sunscreens, moisturisers and wipes (baby wipes, facial wipes and moist toilet tissue, for example), which is a particular concern because you don’t wash off the the residue from these products – that generally being the point of using them – so it lingers on the skin.

A 2014 report from the International Journal of Toxicology concluded that although MI and MCI are sensitisers at concentrations of 50 ppm and above, they weren’t at concentrations of 15 ppm (and below). And therefore they, “may be safely used in ‘rinse-off’ products at a concentration not to exceed 15 ppm and in ‘leave-on’ cosmetic products at a concentration not to exceed 7.5 ppm”.

However, also in 2014, the European Commission Scientific Committee on Consumer Safety argued that: “For leave-on cosmetic products (including ‘wet wipes’), no safe concentrations of MI for induction of contact allergy or elicitation have been adequately demonstrated.”

People have been particularly worried about children, especially with respect to baby wipes. This is not unreasonable, since not only is the contact dermatitis that can occur painful and unpleasant, but once sensitisation has occurred it can’t be reversed: anyone affected will have to read labels extremely carefully for ever after. As a result, consumer groups have campaigned to have MI and MCI removed from any product that’s left on the skin over the last few years.

I happen to have three different brands of baby wipes in my house at the moment (small children you see), and a quick glance at the ingredients tells me that MI and MCI aren’t in any of them, and nor are they ingredients in the packet of flushable moist toilet tissue in the bathroom. This is hardly a comprehensive survey of course, but it suggests that these substances might be falling out of favour. Big companies aren’t really out to get us: pictures of people with nasty skin lesions after using their products doesn’t do them any favours.

Some consumers have complained about the use of MI and MCl in products.

Some consumers have complained about the inclusion of MI and MCl in products.

Do you really need to worry? Were these consumers right to highlight the fact that the shampoo contains MI and MCI in their reviews? Well, if you know you have sensitive skin then these substances probably are best avoided. But is shampoo likely to cause sensitisation if you’re fortunate enough to be blessed with the sort of skin that generally doesn’t erupt into a rash if the wind so much as changes? No one can say for certain, but it seems unlikely because you wash it off: these substances are only in contact with your skin for a few seconds.

So, whilst it doesn’t hurt to be aware of such things, there’s probably no need to panic and throw out all your shampoo just in case. On the other hand, if you’ve been wondering why your skin seems to be permanently irritated, it might be worth checking a few ingredients labels.

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