The Infinite Monkey Cage - Poison

Episode Date: March 6, 2024

Brian Cox and Robin Ince delve into the murky world of historical poisonings. Joining them to add their drops of killer insight are comedian Hugh Dennis, chemist Andrea Sella and Agatha Christie aficionado and former chemist Kathryn Harkup. They find out just how easy poison was to get your hands on and how people literally got away with murder until chemists developed tests for substances like arsenic. Bottles of deadly substances are passed around our expert panel with some trepidation and we learn how seemingly innocuous garden plants can be deadly in the wrong hands.Producer: Melanie Brown Executive Producer: Alexandra Feachem

In our new podcast, Nature Answers, rural stories from a changing planet, we are traveling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers wherever you get your podcasts. This is the first radio ad you can smell. The new Cinnabon pull apart only at Wendy's. It's ooey gooey and just five bucks with a small coffee all day long. Taxes extra at participating Wendy's until May 5th. Terms and conditions apply. BBC Sounds. Music, radio, podcasts.

Hello, I'm Brian Cox. I'm Robert Ince and this is the Infinite Monkey Cage. Now, if there's one thing that the British public absolutely love, it's sitting down on a Sunday evening after a roast beef dinner with Yorkshire pudding and lashings of gravy. And there's the kitchen sink, freshly scoured with vim. The anti-macassars laundered and flat against the armchair, all ready for us to lean back and watch someone being slowly poisoned. On television, generally. Yes, this week we go to the shelf in the medicine cupboard that was strictly out of bounds. The one that Roald Dahl was very careful to say

that George avoided when he was making his marvellous medicine for his awful grandmother, who had... A puckered-up mouth like a dog's bottom, which is one of my favourite lines from literature. If Roald Dahl, if there is one line that must live on, it is, she had a puckered-up mouth like a dog's bottom. And there's someone who studied... Who's Frankie Howard as well?

Oh, yeah, no, I did it with real... I did the full Jackanory on it there. You remember you used to watch Jackanory have that real kind of zeal there. Anyway, so a little sketch of Quentin Blake there at the side. But it was that I would say, puckered-up mouth... If I could have used that in my English... What's going on?

Don't worry. We don't follow the linear narrative of The Now Show, I'm afraid, my friends. Because we realise that now is only a concept in the laws of physics, and now might also be then and also the future, we can't do now. Some call it linear narrative, some call it professionalism. Nah! Brian, if they want professionalism, they listen to Jim Al-Khalili. Anyway, today we are going to be discussing the history of poison,

predominantly in literature, but every now and again in real life. Why was poisoning so popular in the crime novels of authors like Agatha Christie? Is it really the civilised form of murder depicted on screen or on the page? And why did deadly nightshade and arsenic go out of fashion as a method of dispatching one's foes? Yes, sadly, poison went out roughly at the same time as the monocle and the fob watch, which of course I know by saying that immediately means that four listeners in Berkshire go, the monocle! And it drops out of their eyes. They look at their fob watch and go, and it's only 6.31 as well. Disgusting.

I'm very proud of my monocle. I saw a man with a monocle the other day. It can't help but make you look very grumpy, but only on one side, which is a very kind of interesting way. One side is joyous, the other quite furious. It's Patrick Moore. Maybe.

To help us explore the chemistry and culture of poison, we're joined by a celebrated author and former chemist, a comedian and a current chemist. And they so i'm andrea sailor i'm professor of chemistry at ucl and my favorite fictional poisoning is is thallium that was used to poison father brown you'll remember but he survived thanks to prussian blue. Hi, I'm Catherine Harkup. I write science books mostly about chemistry and death and my favourite fictional poisoning is the multiple murders carried out by Aunt Abby and Aunt Martha in Arsenic and Old Lace. I'm Hugh Dennis.

I'm a scientist in the sense that I did physics A-level in which I got an E. Well done, me. I sent it back for remarking because I was predicted an A, and I thought it might be a B, and they'd forgotten to join the ends of the letters up. And they sent it back and they said, no, I'm sorry, it is an E.

But it's a very high E. And my favourite fictional poisoning is Harry Potter. This is because I read all the books to my kids when they were very young. And he gets poisoned by basilisk venom, and he then has to be rescued by the healing tears of a phoenix. And I think, who has got the healing tears of a phoenix in their bathroom cabinet? What I liked was finding out how you also failed your english literature a level as well i thought the e was a b and that's when i realized everything had gone

wrong no exactly this is our panel can i just congratulate katherine by the way on the choice of arsenic and old lace is the most wonderful play in the most brilliant film with carrie grant that's why i just wanted to get that out of the way. Catherine, your first book, which was a huge bestseller, was A is for Arsenic, The Poisons of Agatha Christie. So what was it about poisoning that caught her in your imagination? For me, it was back when I used to work in a lab and I worked with all sorts of dangerous things. Every bottle I touched seemed to have a skull and crossbones on the side. And you start to wonder what that stuff can do to me. So I became a little interested for my own personal safety

and those of my lab mates as to how not to kill myself with this stuff. And I was very lucky to be asked to write a book. And if you want to write about poisonings, then you really can do a lot worse than read to Magatha Christie because she really knew her stuff. She worked as a dispenser in a hospital and she was working at a time when everything was made up by hand and she knew what was too much, what was too little, what could be combined, what shouldn't be combined and she used it extremely well in her novels. So that's why it featured so strongly because she knew. She knew her stuff and she

certainly continued her research even when she wasn't working in a dispensary. So most of her poisons are medicinal or at least they had medicinal applications in the day. Most of them today would not be prescribed although I do occasionally meet people who come up to me after a talk and say oh I was prescribed strychnine when i was a child and recovering from double pneumonia and um so it's still kind of in living memory that this stuff was used do you think that's the most surprising in terms of when we look back historically what are the most surprising things that now we go skull and crossbones but then was like no no this will buck you up don't you think the skull and crossbones itself is rather confusing i mean why is it a skull and crossbones itself is rather confusing?

I mean, why is it a skull and crossbones? Isn't there a danger that the children will think, that bottle is full of pirates? Yeah. Seems quite an attractive thing. There were an awful lot of things that were prescribed, possibly mercury. It was blatantly obvious that was not doing you any good.

Your teeth turned black, you salivated profusely, your hair fell out, and then you died eventually. But they continued to prescribe it for a heck of a long time. When did they stop prescribing mercury? Mercury salts were used for really quite a while as disinfectants. They were wiped, for example, on the gums of children through to the 1920s. Something called pink gum disease. So mercury really lasted a very long time. And one of the things is that because the theory, the background,

you know, how did these things work? The idea of physiology was based on the humors related to hot, cold, dry, wet, those kinds of things. If you took something, right, which suddenly caused you to sweat, which caused you to feel hot or something, then that was clearly having an effect and it was helping to rebalance the humors. And so there were all kinds of things which are known to be very, very toxic, which would have these quite spectacular effects, which were given in the belief, in a sense, you were almost fighting fire with fire. But that's like that amazing thing, you must be getting better because this is making the person vomit so much, they must be vomiting out all the badness as their eyes start bleeding and their fingernails drop out. I mean, it's kind

of that is... Absolutely. And so when do we start to see a modern medicine which accepts that things that kill you might not be making you better? One of the things is, of course, the germ theory of disease becomes incredibly important. And with the arrival of the germ theory of disease, the idea that there are certain organisms which are invisible to the naked eye, which are only visible with a microscope, can then be killed or can be inactivated by using some chemical agent, right? That's when you start to think of being able to treat specific diseases with specific things so one example might be salvar san it was called the the silver bullet which was used against syphilis and it was an arsenic based compound very different from what we call arsenic which i

have here by the way oh Just in case anyone's curious. Could I have a little? I love that it's got a may cause cancer on the side of it. We're keeping the lid on. Do not use heavy machinery after having arsenic. May cause drowsiness. OK, there we are. The good news is it doesn't have a best before date on it.

No. But the bad news is it says the concentration is 99.5% on here. Is that bad news? This stuff is clean. It's properly clean. It's the good stuff. And arsenic's... So for the...

What is arsenic? Is it a metal? So arsenic is an element, yes, a metallic element. But what people call arsenic as a poison, which was used for a very long time as a rat poison and so on, is actually the oxide, arsenic oxide. So it's a white powder. It can be dissolved in water under the right conditions.

And it's not... Hot water, teas, coffees are the way forward. So, tea. And it doesn't taste very strongly. Oh, hang on a minute. I didn't like some of the ohs down there showed a future plan for the end of a marriage. So is that one of Agatha Christie's murders? Is it arsenic in tea? There is arsenic in tea in a few of hers. Arsenic crops up throughout her novels, but it's almost as if it's too obvious too easy so she doesn't actually kill that many characters she still killed four or five of them with arsenic but it's almost cliched it is the it's like the gold standard of poisoning people arsenic is well i mean this is

for no reason at all but how much would you need? It's about 200, 300 milligrams for an adult. Yeah, I mean, you need really quite a lot. It's a good pinch. It's much easier for me in terms of teaspoons. Teaspoons. I would say, yeah, a good teaspoon. Just to be sure. So let's say that we gave someone a teaspoonful of fascination on his face what

would be the process what would what would happen so you have about 15 minutes to establish your alibi um because the symptoms that's roughly when they kick in that's when it's starting to be absorbed into your body and the classic symptoms or initial symptoms of arsenic poisoning are projectile vomiting because this is the body getting rid of a poison which means you have to re-dose until you get the desired effect so it arsenic poisoning is hard work you really have to be dedicated so once he's been filling one cup of tea doesn't do the job well if you add too much to the tea it will curdle the milk so people won't drink it anyway so you really work with oat milk as well or could one use a gray you do have to be quite careful judicious amount of arsenic then clean up all of the vomit obviously because that's the

first thing that gets scooped into an evidence bag when the police arrive and then yet you need to keep redosing which is why it takes days weeks sometimes to accumulate arsenic in your victim's body i see so it's a gradual process anyway but there is there is an interesting thing about it and that is that arsenic you can take in very very small quantities and you can gradually build up resistance this is not something that's for every poison or whatever. Up to a point. But you're all going to be okay,

because I've been collecting the tears of a phoenix. It's a good point, accidentally, I suppose. Is there an antidote? Is there something you should do? Stop eating it for a start. There are ways of extracting it from the body. That mostly came out of the second world war there was a lot of research into poison gases and they looked at antidotes and there were ones uh british

antiluosite which is good for removing arsenic so arsenic seems to be a long-term project right what's the quickest cyanide uh probably. Cyanide is... LAUGHTER For the radio audience, Professor Sellers produced another jar. Potassium cyanide, only 97%. Don't take the top off. I was going to say, it's quite an old bottle. Does it say, this belongs to Herman Goering on it? There are some handwritten notes on the side. I can't decipher.

I'm fascinated by the way it's going to build up in them. Right at the end, you just bring out a little jar of meat paste. So cyanide, what's the delivery mechanism and what happens? That's a very important point because when we talk about poisons, there's no such thing as an absolute poison in a sense. We tend to think about poisons as being rather binary. You know, it's either, you know, you're dead or you're alive. The reality, as in fact Paracelsus spotted in 1538, I think it was, he wrote a phrase which says something like,

the poison is in the dose. Basically, he said everything is a poison if you use enough of it. The second thing is how you administer it and so there's certain poisons which will go through the skin others that won't certainly inhaling or swallowing puts you in a whole different league what are the rules though because you you've brought some of these samples and like where where do you keep them in a plastic bag yeah just between the jam and the peanut butter, I normally keep my jars of them, because they're very safe there. But, I mean, do you...?

No, our poisons are all kept in locked cabinets. These aren't, are they? Yeah. And what is the most dangerous of all the things... Is there anything that you decided not to bring? No, he'll get it out of his bag. That is a bad anthrax. I did look for a few things which weren't available, unfortunately.

Right, go on then. Well, I mean, I couldn't actually get strychnine. We used to have, we found a big box of strychnine many years ago. It was probably about 15 or 18 years ago. A cupboard was found which had several boxes of alkaloids. And alkaloids are biological products which have nitrogen in them. And many of them are really quite toxic. Strychnine is one.

And people used to use it in organic chemistry to be able to separate left-handed from right-handed molecules. And so this box, which had two or three kilos of strychnine, still had written on the outside a list with the name of the student and how much they'd taken and how much they'd returned. So the cry went out, we've got to get rid of this. Then you find, aren't you slightly frightened dealing with poisons? Well, provided you know how they could get into you and you know so if there are things that are absorbed through the skin then clearly you're going to handle them very very different if there are gases that you could inhale you're going to handle them differently

but you know these things here for example they are solids you can weigh them out and so on you avoid getting them on the skin so probably wear gloves if you're worried what while handling the jars no handling the contents katherine so arsenic we've ruled out as a particularly effective poison unless you're patient in terms of cyanide what what happens if someone is poisoned with cyanide so physiologically cyanide is very rapid acting poison you've probably got minutes before you're dead which is why they used to give them to pilots in the second world war in case they were captured you could bite down on the cyanide pill and you would be dead before you could give away any secrets so it is very fast acting and

the reason it's so fast acting is because it disrupts a very fundamental process in your body which is processing oxygen to release energy so the cyanide will stick to the enzyme that processes oxygen in place of oxygen so you can breathe in as much air as you want you cannot use it to make energy and without energy cells die And if enough cells die, you die. So the cells that use most oxygen are the ones that are affected first. So that tends to be nerves. So there will be a blinding headache, convulsions, on top of the vomiting, which is the usual response to poisoning. And then you collapse unconscious on the floor, and you're dead in about 10 minutes.

Have you got any? Oh, it's right there. That's it. It's in the small jar for safety. It's in the small jar because it's, yeah. So how much are we talking about there? Probably similar to arsenic. Yeah, a couple hundred.

A bit less. It is interesting, isn't it? Because in literature and film, poison tends to be almost instant, doesn't it? A very sort of clean way of dispatching someone. But in reality, that's not the case. No, and cyanide is unusual in its speed. Most poisons take hours, and it's a very unpleasant few hours,

which is why they speed things up in TV programmes and films. But I wondered, like Romeo and Juliet, because I know you've written about Shakespeare as well and the deaths in Shakespeare, so spoiler alert, they don't make it through to the end of the play. But Romeo and Juliet, you know, that is this incredibly peaceful, oh, ah, view poison, now I'm poisoned, oh, we're just having a little sleep.

What would the reality be of that? Do we know, because I'm sorry, I'm very ignorant on many things, but it's in terms of what the poison was. There's no poison that is mentioned or named for Juliet, and there's no poison that is named for Romeo either. Juliet's is, she just gets knocked out for a few days and apparently recovers with no side effects whatsoever, no ill, you know, she's not breathed for three days,

but she's fine. Was she anywhere near a phoenix? Possibly. It's a good guess but something that acts that quickly it's got to be probably cyanide which would have been known about at the time but obviously for dramatic purposes shakespeare was more concerned with the play than scientific accuracy so i'm afraid most of his poisons are numb. This is the first radio ad you can smell the new Cinnabon pull apart only at Wendy's. It's ooey gooey and just five bucks for the small coffee all day long. Taxes extra at participating Wendy's until May 5th. Terms and conditions apply. In our new podcast Nature Answers, rural stories from a changing planet we are traveling with you to Uganda and Ghana to meet the people on the front lines of climate change we will share stories of how they

are thriving using lessons learned from nature and good news it is working learn more by listening to Nature Answers wherever you get your podcasts. How was it, because now this is a refined kind of chemical, it's a powder. So back in Shakespeare's time, how was it discovered and how was it produced? Cyanide is a very useful chemical unit. It is part of a huge range of molecules, some of which are biologically available. So the classic we all know about cyanide is that it smells of almonds. Well, almonds smell of cyanide because they contain a cyanide compound.

So if you get bitter almonds or if you get laurel bushes or something, you can distill out cyanide. So the laurel crown that is referred to in Shakespeare had a double meaning because it was like the poison chalice. So they would have known all of that. There are certainly poisoning cases from the 15th, 16th century that refer to cherry water and things like that. You know, to go back to that idea of Paracelsus, it's about the dose mattering. This is really crucial because lots of plants

produce small amounts of, for example, cyanide. The core of peaches, the cores of apricots contain sugar compounds that have cyanides attached to them. And so under the right circumstances, you can, in fact, distill hydrogen cyanide out of them or stuff like that. But we ascribe a kind of moral weight to it because it does us harm. And the reality is that these are just chemical compounds and they interact with us physiologically in a particular way. Now, all the excitement comes, you know, everyone goes, oh, arsenic, oh, cyanide, that kind of thing. But in a way, these are inorganic materials, cyanide that kind of thing but in a way these are inorganic materials which are you know referred to as highly toxic but they're nowhere near as poisonous as biological stuff and the biological world moves you into a league which is a thousand ten thousand times more poisonous than anything

that's on the table here did agatha christie ever use that as well as well as the kind of what you might call the you know the chemical poisons the biological poisons? She did not as often because it wasn't really her expertise but she certainly mentions anthrax, typhoid, bacterial poisons like that, she uses snake venom so she's quite diverse but she did mostly use the medicinal poisons in inverted commas because it's all down to the dose. Well, it's interesting, as you said, Andrea, earlier, that a lot of these compounds were known initially as medicine, and they're coming from plants and the natural world. So is that the root that many of these things got into our culture through medicinal use initially, and then overdosing essentially? Absolutely. I mean, there's an awful lot of what is in our pharmacopoeia today, which really derives ultimately from the biological world. And so the biological world provides an incredible sort of library of starting compounds for doing some kind of therapy with. interesting thing is then to take a known toxic or whatever substance and then tweaking it or

making analogs which are a bit like it which will act on a particular receptor without having the other side effects alternatively you use that but you dose it incredibly carefully so nicely you've mentioned pharmacopoeias and those books are magnificent i don't know if you've ever seen them these you know normally two or three volumes. I've got a few from the 1920s and they make racy reading for what is basically a dictionary because you go through and you go, whoa, this was in the doctor's cabinet.

I mean, do you have favourites, Catherine, when you've been studying these things? Well, one of my favourite books, it's not a pharmacopoeia, but there was a book that Agatha Christie probably had to study to pass her exams, which is called The Art of Dispensing because it really was an art you had to make up the pills by hand nothing was pre-packaged and it goes through all of these stories um spoiler for the

mysterious affair at styles there is a passage in the art of dispensing that says do not mix strychnine from your strychnine tonic which was just dispensed as a pick-me-up to whoever needed it but don't mix that with your bromide powders which your sedatives your go to sleep at night because if you put the two together a chemical reaction occurs and your strychnine precipitates and all of the crystals sink to the bottom of your tonic bottle and you get your lethal dose with the last spoonful and that's useful to know that paragraph is copied pretty much word for word in the mysterious affair at styles because that is how the murder is committed and bromide was is that the thing that was used in summer

camps in in america to uh yeah prevent shenanigans it was also it was also given to soldiers in the first world war for example, supposedly to quiet their urges. Supposedly. But do you want your soldiers sedated? I never really understood the logic behind administering bromide powders in tea, because it just sedates you. I've tasted bromides, but not in sufficient doses to have any physiological effect. You do need quite a bit. Is there anything you haven't tasted? Plenty. There's a whole world out there waiting for me. You know the sort of poisons that my mum, for example, would say, never eat a green potato, never eat a green crisp, all that kind of stuff. Yes. Which I'm sure is true, isn't it? Another alkaloid called solanine. Again, the dose.

Small children need to be careful about green potatoes. Grown-ups, much lesser. It's interesting, isn't it? Nicotine. These things you think of as these kind of complex, strange things that interact with us in a terrible way. But I suppose, you know, they're simple. Hydrogen and cyanide, I mean, it's just carbon, nitrogen, and hydrogen. There's nothing else there. You know, when we think about

poisons, you know, we think about carbon monoxide. You know, carbon monoxide is being a very risky thing. You've got to check your gas boiler if you have one to make sure that it burns cleanly enough. Hydrogen sulfide, the smell of rotten eggs, for example. But these turn out to be signaling molecules. The third one is nitric oxide, NO. And these are incredibly important signaling molecules between cells. And so cells will produce tiny amounts of CO, of H2S, of NO, and so on. And these turn out, we later discovered these are, for example, muscle reluctance. Or, you know, they have different effects,

but it really depends critically on the dose. If you inhale lots of carbon dioxide, guess what? You completely shut down your oxygen-carrying capacity in the blood and curtains. But in tiny quantities, these are incredibly important signaling from one cell to the next. And what, you know, as young parents quite often panic when they look at their own gardens

and take out the plants that might be poisonous. Did you ever do that? No. No. You've made me feel like a very, very bad parent. No, nor did I. And I kind of thought, I kind of, but people were, I'm sort of aware that people were.

Now, I always thought that was probably entirely unnecessary. Is it? Well, let me tell you a story. And I hope that my son, who's in the audience, won't mind. But when I was a... Well, he's still with us. That's good. When he was quite young, he was about two and a half, we went to a botanical garden in the mountains of Italy.

He and his brother, who's two years older than him, went off together. And they walked past a plant. And there were some red berries on both the two plants side by side. And one of them had a big sign with a skull and crossbones saying, you know, beware. And he went and grabbed one of the berries. And his brother said, for God's sake, don't eat the berry. And, of course, it went in his mouth. His brother came hurtling around to us saying, oh, my God, he's eating a red berry.

He's eating a red berry. We went and looked at what the plant was, and I thought, hmm. So we went to the local pharmacy, and when we told them the name of the plant, Daphne Miseram, they said, you get on the phone to the National Toxicity Helpline now, and then you get in the car and you go to the hospital. And so there can be things there. He's here, okay? So, you know, it all ends happily right he was given an enormous dose of charcoal

suspended in water that's a classic way you either make people sort of throw up and and get it back out or alternatively you try and absorb it onto something like charcoal we have a great photograph of him with two big black moustaches on either side. It was a rather fraught night. Catherine, there are some plants in the garden. So foxgloves. Foxgloves. They produce a poison.

They do. But are they poisonous? Yes. If you eat them or make tea from them or something? No, don't do that. That's a bad idea. Yes, they are very, very toxic. They are famous as the source of the heart medicine digitalis digoxin.

And it's very, very effective as a heart medicine if you have certain heart conditions in the appropriate dose. But if you have too much, which is very difficult to judge if you're just picking leaves and bits of the plant. And yes, too much is too much and it can kill you. Hugh you've been in you've been in an Agatha Christie. I have. Which now you can say that because when I said to you when you came in the green room you went have I I don't remember that um but you've been in an Agatha Christie and you've been in a Midsomer Murder so and I know you've did either of those

involve you were Major Philpott I believe which one was that Catherine Major Philpott was that Endless? It's Endless Night wasn't it? I can't actually remember what happened to Major or Captain Philpot. So that probably means there wasn't a demise, but then you did... Well, all that there was. Maybe Catherine... Could you remind him what happened to him? I don't think anything happened to... I think you might have killed someone else.

This is when the regression therapy begins, remember filming it i remember where we filmed it but i couldn't tell you what happened at all in midsummer murders however i can tell you exactly what because the my method of death so i was the third death it's always very important to work out where you are how many advert breaks you make it through and i they said do you want to do midsummer murders and clearly you go how do i die and i said well you get hit around the head with a plank then strangled by a python i thought that is never going to happen to me again in anything i do and i just signed the contract it's brilliant but i made the mistake in that of saying you know when you're filming a thing it's much easier if the thing

actually happens to you rather than sort of having to pretend it was happening and i said to the guy with the plank albeit a rubber plank i said i think you should actually hit me with that plank and he did and it was fine but nine takes later i realized my mistake and then when I'm finally strangled by this python it was an albino python and I realised that I'd worked with him before There is obviously one of the most famous poisonings

is I suppose the asp, Cleopatra and the asp. And that, again, that's kind of not the version that we've sometimes seen happen to Elizabeth Taylor, etc., is it? No, Shakespeare did rewrite things for the benefit of his audience. But the story of Cleopatra being bitten by an asp was certainly a known story. And by all accounts, Cleopatra was a bit of a toxicologist. She wanted a peaceful death, which I think is fair enough. Most of us would want a peaceful death. And so she researched her venoms and her poisons

and she lined up her prisoners who had been condemned to death and she tested different compounds on them and watched the results. Science, yeah. It was probably an Egyptian cobra if she was going to go for a snake. And it gives a slow paralysis. So from the outside, it might look quite peaceful and calm. But on the inside,

it probably is very, very far from that. So she probably didn't have a good time. Is there any, in terms of, again, we see quite often in those kind of, I think even contemporary thrillers, when we do see poison coming back in, there is very often, you won't believe it, it takes only two minutes.

For the first minute, you're writhing in agony, and for the second minute, you're just dead. You appear to be dead. Is there anything that would do that? There are certainly poisons that can give the appearance of death. One of my favourites is tetrodotoxin, which is in pufferfish and lots of other animals, like blue-ringed octopuses and things like that.

It's what's on the tip of the knife of Rosa Klebb's shoe in From Russia With Love, and it's what kills that agent when he gets kicked in the shins. It says, oh, it takes 12 seconds, and lo and behold, 12 seconds later, the guy collapses on the floor. He's probably not dead, but he might as well be because no one's going to help him. So there's probably quite a gap between unconscious and looking dead and actually being dead. But tetrodotoxin, it affects our nerves and it particularly affects the muscles of movement.

So it can slow down your heart as well and it can slow down the muscles that control your breathing. So you look dead, but if you get the dose just right, then your breathing is so low that you're actually alive, but you look dead. So in Japan, where pufferfish is a delicacy, I believe if they thought someone had died of pufferfish poisoning, they would lay them out next to the coffin, just in case. But I mean, it is interesting that a lot of these poisons, in fact, which cause paralysis, what you die of is not necessarily the poisoning, but it's actually

the fact that you asphyxiate, is that you cannot breathe. Your ability to move your muscles just stops. So administering oxygen is an absolutely crucial part of this. So there's an awful lot of conspiracy theories that go around with poisonings. Why didn't they die if this stuff was so toxic, if this was so poisonous? Well, actually, if you get the right medical attention, and particularly if you provide oxygen and other things, you can get people through this. When I was a teenager, I remember hearing from a snake expert. I grew up in Kenya. And I remember hearing this story from a snake expert about a friend of his who in South Africa had been catching spitting cobras or something like that. And one day,

something went wrong and he was bitten. And so he got in his Land Rover and drove as fast as he could to Johannesburg. And he arrived in the hospital, the emergency place, just as this stuff was really getting to him. And he said, for God's sake, I've been bitten by a spitting cobra. You know, I need to go into an iron lung machine, which will keep me breathing. And then you'll just have to be patient. I have a PhD or I am professor of whatever. And so, you know, they went, oh my God, you know, the doctor listened. They put him in the, in the, in the thing. And then they waited one day, two days, three days. He was completely unresponsive. And they decided that he was in a vegetative state,

and he could hear them discussing whether they should pull him out of the iron lung. And his wife said, no, no, he said eight days, up to eight days, whatever. Please wait. And around the eighth day, suddenly there started to be movement. So it's really kind of interesting. We think of these poisons as being something absolute, which will definitely kill you. But in fact, if you have the right medical attention, and because we understand the mechanisms by which some of these things operate, but not all, then it's possible to bring people back. You know, they recover. there are certainly lots of poisons that don't have specific antidotes and you treat symptoms as they present themselves so if your

poison victim if their heart starts to race you give them drugs that slow it down and vice versa if they're struggling to breathe you give them oxygen and you treat symptoms as they present themselves because our bodies are actually very good at clearing out a lot of chemicals that shouldn't be there so you basically support the patient until the venom or whatever it is the poison clears naturally and you know arsenic was untraceable for a long time wasn't it and that's why it was very popular as a murderer's tool but if you were a police pathologist would you be able to recognize all poisons? Asking for a friend. So you want to know if there's an untraceable poison? Well, yes.

And then the dose. How many green crisps would it take? Poisons all have a physical presence, so they are a physical thing, and so they should be traceable. The problem is when poisons are very, very potent, you are looking for a very, very tiny amount in a massive body. So actually finding it, extracting it, establishing that it was the toxin involved, that can be quite difficult. But in terms of an untraceable poison? No, I mean, I don't think there's anything that's really untraceable. The problem is knowing what it is that you're looking for. In fact, arsenic

was really not undetectable for very long. Back in the 1820s, a man called James Marsh, who worked at the London Arsenal, which was the big sort of weapons manufacturing site in South London, he was a chemist. And because there were a lot of poisonings from arsenic, some deliberate, some accidental, because it was widely available as a rat poison, and people wanted to protect, you know, food. It's a time when Britain is industrializing, supply chains from the countryside are getting longer, so, you know, dealing with rats is a big issue. He comes up with a very cunning way of essentially you take the stomach content, say, of the victim, and you add zinc and you add acid. And what that does is it produces a very poisonous, volatile molecule called arsine.

molecule called arsine. And that arsine, you can then visualize, you can make it visible by lighting the stream of gas which is coming out of your apparatus. And then you put a little porcelain dish against it, and you get a beautiful mirror of metallic arsenic. And I've had to do this two or three times for TV programs. And it is absolutely magical. When you decompose the compound, the hydrogen is lost and the arsenic mirror appears. And so that was really the gold standard for arsenic, really up to the early 20th century. And Catherine, going right back to the beginning to the Agatha Christie novels, or indeed across all literature, do you have a favourite intricate poisoning story? My favourite ones from Agatha Christie that I always recommend if you want to read an Agatha

Christie book is The Pale Horse, because it uses Andrea's favourite poison, which is thallium, the poisoner's poison. I knew it. The jar has been revealed. I once worked with this back in the day when I was in the lab, and I very carefully sought out someone who had already used it and learnt what to look for and how to use it safely. So thallium is very tricky because it produces a wide variety of symptoms in the body, so it's very difficult to diagnose. But one of the characteristic symptoms is that your hair falls out this is a very important clue in the pale horse not giving away too much but so little

was known about thallium poisoning when christy wrote the book that actually she was so accurate in her descriptions of what went on that she is credited with saving two lives because people recognized the symptoms and were able to intervene and that person received treatment and they survived thallium poisoning. So in terms of accuracy, but also the intricate way in which thallium is got into Christie's fictional victims is, I think, brilliant. The fact that it saved two lives as well, I think, is even better. Yeah, that jar has got the most little red diamonds on it of all the other ones

with lots of pictures inside and all of them look unpleasant. It's the smallest bottle with the most hazard symbols. What is a GS symbol? Because it has a little symbol that says no GS symbol, so it's a symbol to say the lack of existence of a symbol. GHS it says. GHS.

Guildford High School. So, the subject of poison, obviously, is a tricky one for us to ask a happy-go-lucky question from the audience. Originally, it was going to be, who would you like to poison? And then we raised that. Very negative.

So, instead, we ask our audience who are here, what is your poison? What have you got, Brian? Earl Grey tea, hot. There's a geeky one, Captain Picard. That bottle of creme de menthe tasted as good on the way up as it did on the way down. This one, actually, this is kind of like, you might get this,

a hug without you. It's like a cryptic crossword. Oh, yeah, this is kind of like, you might get this, a hug without you. It's like a cryptic crossword. Oh, yeah. Hug without you. What's the chemical symbol of mercury? Something to do with mercury? Hug without you. Hug without you.

Yeah, mercury, HG. Hydrogyrum. It's one of my favourites. Why has it got the symbol HG? Hydrogyrum, in other words, liquid silver, quicksilver. I'd always assumed it's just no-one could spell mercury. This person's choice is Brian's voice, because it relaxes me so much I fall asleep.

Is there a phone number on it? My favourite poison are secondary metabolites from toadstools because I don't have mushroom for humour and I'm a fungi to be with. Well done for getting that reaction. We don't hear it enough nowadays. Thank you to our panel. Catherine Harkup, Andrea Seller and Hugh Dennis.

Next week, we're going to bring you an episode that will create more fury amongst listeners than any other that we've ever done because we're going to ask, what is better, cats or dogs? Yes! Let's take an initial vote then. Who says cats here? Who says dogs?

Yeah! Let's take an initial vote then. Who says cats here? Who says dogs? Yeah. Brian is, of course, a cat person because that's why he's got such lovely hair because he always actually eats a little bit of that prawn and salmon mousse that he gives to his cat and it makes him all lovely and shiny. Anyway, cats versus dogs, it may well be the end of civilisation as we know it. Goodbye.

Goodbye. Goodbye. Goodbye. Turned out nice again. Planet Monkey Cage! Turned out nice again. Hi, I want to tell you about my podcast from BBC Radio 4. It's called Fed, and it's with me, Chris Van Telleken. It's about one of the most important things that we all do every single day. It's about what we eat. And I'm taking a close look at one food in particular, the most commonly consumed meat in the world.

And it comes from a humble, unremarkable little animal that, as I've been finding out, is actually pretty extraordinary. It's chicken. We eat around 74 billion of them per year. And yet it turns out I know almost nothing about where it comes from, how it's raised or the impact it has on our bodies, our culture and the planet. But I'm going to find out in Fed with me, Chris Van Telleken. Listen now on BBC Sounds. In our new podcast, Nature Answers, rural stories from a changing planet. We are travelling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers

wherever you get your podcasts.