What is toxic?

hello and welcome to technically speaking where  scientists and engineers come together to chat about common interests share knowledge and  satisfy some curiosity i'm laura and in this episode i'm joined by ellie and priyanka to talk  about toxic things and what they do to our bodies ellie your background is in zoology so i think  you probably got quite a lot to contribute here or something like that there are loads  of poisonous and venomous species

in the animal world so i think i'll talk first a  little bit about uh the difference so in my mind something that is poisonous versus something  that is venomous so venomous bites you and you get unwell or potentially even die so that's  venomous and then poisonous is you by it so if an animal eats a toxic animal so it  bites something toxic something poisonous then it gets unwell but if the thing doing the  biting bites something then usually that thing

will then eat the thing that it has bitten so  yeah we'll talk more about that later yeah see i guess you get venomous snakes and poisonous  frogs yeah i guess is the classic example um i also wonder right so if if i become a supervillain  incredible this is a great start already what i do to people that i don't like um if i  decide i'm going to leave something out for them to to ingest i can be like the poison killer yeah  definitely or you want to go real super villain

like animal human hybrid get fangs like a  snake and then you can be venomous and you can bite people that you don't like exactly so  i could be the venomous lady it depends on how i want to kill people exactly it's entirely  your method of delivery i like it i'll bear that in mind if i ever do decide to become a  supervillain you heard her hear first things it doesn't seem very unlikely freehand care your background in biochemistry  is probably going to tell us about what effects

toxins have on our bodies right yeah so basically  we have about six or seven ways toxins can affect you it ranges like throughout all the systems of  the body one of the main processes that i like to talk about is the neurotoxic effects where  essentially toxins can inhibit transition of impulses by binding to enzymes at the synaptic  terminals so like those specific enzymes that are present over there kind of get blocked so the  electrical conduction doesn't go through obviously

there are a lot of processes and i'm going to be  talking about a couple of those a bit later okay so i've heard of neurotoxins and that's just  that's one way in which a chemical can have an effect on the body yes exactly cool  chemical toxins not you know people i guess that means we should define what we mean  by something that is toxic um or what a toxin is specifically i'd read something some weird  definition about a toxin is something that is

made biologically whereas if it's made by humans  it's a toxicant which is a word i'd never come across before yeah i didn't know i've heard that  either i would say yeah definitely something that is toxic is like naturally occurring in the  environment like it's created within itself to be toxic for whatever reason which could be  predator avoidance could be to some people eating it all of those sorts of things but yeah like a  man-made substance could also be toxic i guess

but it's not how i would think of it more  poisonous perhaps well that's it a lot of the dictionary definitions pretty much  said a toxin is something that's poisonous that's not a very helpful definition but i mean  i guess i'd say that it's a substance that causes harm or damage to the body in some way which could  be by damaging cells or as priyanka just gave an example of by interfering with chemical signals  or like the neurons so um the ions that are being

transmitted through pathways um is that what your  lecturer said to you priyanka yeah yes yes we were not too far from the truth um so basically how  it works is that there are acetalcholinesterase enzymes at the synapses which get inhibited by  organophosphorus pesticides sometimes which kind of block transmission of impulses so that's where  the neurotoxic that kind of comes into play but um there's also toxins that affect the sodium  potassium channels for example that can affect the

permeability or they can have block the transport  pumps and just affect the overall enzyme mechanism but yeah that's mostly how it works one other  point that you kind of brought up about like you know how toxins are essentially just poisonous  things it also kind of brings into play like what do we consider poisonous like how it's how do  we classify poisonous things right say i presume someone must have eaten something or been bitten  by something at some point and gotten i want to

say unwell but then there are different levels of  unwell there's like dead in an instant it's pretty extreme or there's just i guess vomiting is that  caused by something that is toxic where i guess you're vomiting to get out of your system maybe  or maybe it's somehow caused a biological response that isn't just get this thing out with me it's  this thing is making some mechanism act that is the thing that says you are now going to  vomit but i'm also thinking in terms of like

you know how we have like compounds that we  can ingest but not specific animals or like vice versa like let's think about like capsaicin  and stuff like the compound present in chilies is that really considered toxic because it's  supposed to be like it's supposed to be toxic towards us it's supposed to be repellent  towards mammals because like birds are supposed to be able to ingest it completely fine because  they don't have the receptors to feel the spice

but do we consider it chili toxic to humans  i mean it is unpleasant isn't it people enjoy eating chili like a little bit of heat in a curry  is nice but it's not it doesn't feel pleasant in like the same way like it makes your mouth  tingle or your lips burn or whatever like it's it's definitely triggering a response there in  your mouth but yeah i guess the concentrations as well because you can build up like a tolerance to  chili you can like train yourself to eat stronger

and stronger chilies like there's people that do  chili eating contests which i could never enter or like the indian genes. They put spice  in every single thing even yogurt

you put spice in yogurt? But the yogurt's what  you need to get rid of that spice no girl we put spice in yogurt as well like  that's a nice slight dish to go with our rice and everything which is also spicy by the  way even the rice is spicy right i could never come to dinner at your house i'm sorry  that's okay i can barely handle it as well but is that true that there would be like  specific genes that would code for something

in the body that would be able to handle a toxin  in a particular way does it depend on genetics or is that one of those sort of myths it's just  that indian people are growing up with a lot of  spice i'm not very sure but i mean  it seems like it right like we have developed the tolerance towards it like i know when i travel  to the uk i'm really sorry to say but food is so bland i carry so many spices from home so i'm not  like starving because i need that spicy but like

i think we just develop a tolerance towards it  i don't think it's i don't think it could be genetic though but then because i'm thinking like  some animals can eat what we would consider like toxic plants because they've had that evolutionary  they call it like an arms race like the plant will develop toxin to stop the animal eating it but  then the animal will develop like some sort of enzyme or like antitoxin so it can get away with  it right and it like just goes back and forth

it doesn't taste toxic to the animal but the  plant might be toxic to someone like you or me wow so to that plant and that animal are pretty  much at war with each other trying to out compete through evolution yeah pretty much like you  can see it in quite a few examples where this has developed this and then the next thing will  develop that and then it's like yeah it's like a little battle of like i will eat you no you won't  i like you have you got any good examples of that

because the first thing i think of is nettles and  i think pretty sure i see cows eating nettles but i'm i break out in hives when i brush against  nettles well you can eat nettles like people can eat nettles you can eat nettle soup you can  i have made nettle soup but you destroy the the irritant the chemical by boiling it don't you yeah  which is i think what must happen like if you chew something a lot you can like change the chemical  compounds that like present it's like sugary

smoothies are much worse for you than like  eating an apple because the blending of the sugar like changes the way the chemicals are so it like  makes it worse it's like more sugary rather than just eating an apple which is a fact that  i find horrible because i love smoothies i find that really weird as well but  just blending it would change the sugars yeah i can't see how that would work but i don't  know about the chemistry of it yes it's funny

as well because in the animal kingdom like and  animals can be both like you could be venomous and also poisonous so you could be like toxic  on two levels which i think is so fun because you create your own venom through your genes  but then what you eat can give you like poisons as well so then your skin becomes  poisonous there's like a species of snake that is both poisonous and venomous which  frankly is just showing off if you ask me

so is that the snake has a tolerance to the poison  it doesn't get poisoned itself but the poison just accumulates in its body yeah so it's the asian  tiger snake so it has like one toxin for its poisonous body sorry one venom a toxic venom and  then it eats poisonous toads and then it stores that poison in its skin so you can both be bitten  by it and eat it and not come out very happy at the other end that is impressive and seemingly  unnecessary i can't be asked to defend myself

i don't need to bite you though it's fine i  just like it exactly but that's the thing like it's duel right it's become a great predator  because it can poison the things it wants to eat and also like no one wants to eat it because then  it's poisonous so it's like it's one basically i'm sure some stuff still tries though usually  everything is trying to eat everything else well yeah otherwise why would it bother trying  to double down on being dangerous yeah exactly

there's got to be an advantage which is the  fact that things don't want to eat it maybe that frog's really tasty yeah that's also  a good point i probably wouldn't try it but it could be great if you're uh asian tiger's  name maybe i feel like i'm kind of missing some more information on what actually happened in  the human body and so your example of blending fruit somehow makes the sugars more potent  which just sounds a bit like magic to me but

aside from the smoothie example there are actual  known ways in which a toxin will act on your body to do harm yeah so we were talking about this  earlier as well like we were thinking about thalidomide which is like a human-made toxin  like it was supposed to be a drug that helps uh women with morning sickness but then since it has  like a teratogenic action it kind of crosses that barrier between mother and fetus and essentially  can affect the development of the baby as well so

they were born without limbs so i guess that's one  of the ways that we can like you know how toxins do harm another way toxins can harm us is they  can take out or like knock off the metal ions in enzymes or proteins so for example in heme we have  like hemoglobin we've got the iron metal kind of bonded to four different groups if that makes  sense so then we have toxins that can knock those off and essentially render hemoglobin useless  which can then affect circulation oxygenation

and they cause oxidative stress and all of that  stuff okay so because hemoglobin needs iron ions tongue twister and it can do something  to remove those ions did you say so you said the ions attached to four different  groups those groups still stayed yeah the groups would technically stay there because they're also  kind of bound to each other but if i'm not wrong but um it's kind of useless because the like the  biggest function was carried out by the iron ions

in here globin because that's what bound  to the um two oxygen groups during like the whole respiration process so if you can't  transport the oxygen yeah i could see how that would create problems yeah or cells with that  there's quite um a horrible one in the back in the snake world there's like boom slang venom  and it's got mela proteinases metalloproteinases in it and they interact with the way blood clots  and they like destroy the capillary blood vessels

so then it's like both causing clots and then like  blocking the blood vessels and then that can cause strokes and heart attack oh my god that just  seems like a horrible way to die slowly having your blood system destroyed by the venom of the  snake wow so if you don't if it destroys your capillaries isn't that what sort of feeds your  skin and everything else it's what it gets what gets your blood into like pretty much everywhere  it needs to go all the little areas yes so you'd

have what like bits of your body just dying  like massive internal bleeding yeah wonderful oh gosh that is grim one question i would want to  be answered is how much of that particular venom do i need in my body for it to have that effect if  i injected a micro liter is that enough to do any damage or would it do a little bit of damage but  i could recover oh that is a really good question i don't know how much boomslang venom like  would like would take to kill like the average

human woman but i'm gonna guess probably  not that much i feel like these animals usually they go harder they go home like they have  a lot of like potency in their venom and they like bite you once and you're you're done but i could  be wrong in that maybe a boomslang is not too bad and you could and then like obviously like  zoos and stuff have dangerous snake species and store anti-venom as well so like if  the keepers get bitten for whatever reason

then you're not automatically whisked off to  an ambulance now so maybe you should be but they yeah they can give you something to help  how does the anti-venom work do you know if the venomous thing has injected you with something  that inhibits some biological function by let's take the example of priyanka gave us  where you knock iron ions off hemoglobin does the anti-venom do something that prevents that  iron from being removed or would it compete so i

think the idea is that it like binds to it so like  the venom is is like the foreign body and then it would like neutralize it by like wrapping around  it like stop it getting to its target i think okay because i can also see that it would  change the chemical structure maybe or make the venom break down in some way yeah i think  it's a little bit like um like a vaccine response in like they'll give a low dose of  the venom to like a sheep or a cow or something

and wait for it to like you know do the white  blood cell thing and generate the antibodies and then that is then used as an antivenom because  it's like already protected like it's already had that sort of situation happening ah because  i guess i think about this more from a chemistry point of view rather than using biomolecules  to fight a chemical biology to fight biology i guess there are things in our own food that  could be considered poisonous or toxic if you

eat enough of it like mercury and seafood or apple  pips contain is it arsenic or cyanide one of the two cyanide wasn't it it's one of those things  i thought i eat apple pips quite a lot and they don't bother me and my tiny little rats quite  happily eat apple pips and they're fine and the apple pip is obviously much bigger to them than  it is to me so it should be a higher concentration so i'm like yeah apple pips are fine they're not  toxic well maybe it's like the potency again like

it differs right like it would be so diluted that  wouldn't affect us if we have like one or two at a time but say we have like 50 or we just make like  an apple seed pie or something how many apple pips do you have stockpiles you need like an entire  orchard's worth of apple pips there's definitely cyanide it can't be that high because otherwise  we won't be able to eat apples right so it must be literally like an orchard full of apple pies or  maybe it's because it depends what that cyanide's

bind to you right if it's bound up in another  molecule in such a way that it can't interact with your body then it might be just one of sort  of urban myths like yeah it contains this thing that could be toxic but in this form it's fine  apparently it would take between 150 to several thousand crushed seeds to cause cyanide poisoning  so i think having an apple a day you'll be all right isn't that one of those things you can uh  build up a resistance to though there are certain

kinds of poisonings that you know notable figures  have allegedly been told to build up a resistance against i don't know how true any of this is i'm  sure there was a guy that like ate mercury every day to build up a resistance because he was like  really terrified of being poisoned by his enemies and then he like you know like ate a little bit  every day and then he did build up a resistance but then he wanted to like commit suicide or  something to avoid being captured so then of

course he took mercury to poison himself but  it didn't work because he'd spent his whole life eating mercury to avoid poisoning  oh my god i can't remember who that was and maybe that is an urban myth but i'm sure  that is a thing that does sound a bit like an odd thing to do like contradictory i've built up this  resistance and now i'll try and kill myself with the same resistance rather than just picking a  different toxin yeah just pick a different poison

there's plenty go and find a bloom slang like  why are you hanging around i guess similar to the intent with the thalidomide example that was  meant to be beneficial but it turned out we had other consequences i guess there are some things  that are considered toxic but do have benefits oh yes actually there are a few chemicals that  can be used as like a benefit for humans so basically there's one that we use for chemotherapy  because it has like a it has what's called like a

cytostatic action what it does is that it inhibits  protein and dna synthesis so hypothetically we stop dna from like replicating causing cell  cycle arrest causing cells to not be able to divide into more cells especially if there are  tumor cells that's the principle behind these chemicals but then the problem is that it has a  lot of off-target effects like any of the cells can like just stop dividing and causes like  tissues to be degraded and things like that

but yeah it is like one of those chemicals that  we can use for chemotherapy and there is like poppy seeds which contain opium those are used  to create morphine and opiates used for you know pain relief after surgeries and everything for  patients with chronic pain even though opioids are technically toxic for us like they are  cardiotoxic we can isolate specific compounds which have the anesthetic properties to provide  that pain relief so it's essentially extracting

like the good qualities out of toxins okay i  always assume with morphine that it was just again it was the concentration a low amount is  anaesthetic a higher amount will kill you but from what you're saying it's not it's that there are  sort of almost different flavors that you can have yeah i guess so basically i was reading this  article and it's like the papaverin group of opium alkaloids are very toxic but then they also  contain anesthetic activity that's separate to

its toxicity so it's kind of like both of them  exist on like you know simultaneously it's just making sure you don't ingest enough to activate  that toxic effect that is amazing that you can like separate it and be like oh i'm just gonna  take this bit and that will you know help someone recover from surgery whereas if you take the  wrong bit you could be in real trouble oh gosh this explains why when i did drugs and alcohol  tests for various employments they always said

don't eat poppy seeds in the days beforehand  because they can show up as a drug you probably shouldn't be taking poppy seeds contain very small  amounts and actually they are culturally they're accepted in a lot of cultures it's one of those  things like they're beneficial as well as harmful so moderation is key it can be all about quantity  can't it like a little bit is fine but if you eat too much then yeah i also find it fascinating  that it's like different toxins like there's

hemotoxins and neurotoxins and cardiotoxins  which i just learned are a thing from priyanka but like it's incredible that they like have  developed over the years to like target you know your nervous system or your circulatory system  or your heart or your brain like it's kind of horrible to think about these so many  different ways that they could hurt you but we still ingest them like we're eating them  anyway a really good example of that is alcohol

and they always say like it's 14 units you should  have in a week but spread over that week and here are the really dire consequences if you consume  too much i was trying to look into what effect alcohol has on the human body and specifically  like what biomechanisms acts on and it sounds like no one knows what all these mechanisms are  they just sort of observed the effects of drinking too much alcohol i mean eventually it's like liver  damage right that's like the main if you come get

you know people with alcoholism and then like  the liver is like the first organ that packs up that's sort of pop culture knowledge more than any  real scientific backing but yeah i never thought of like alcohol being toxic but i guess yeah  it has a negative effect right yeah and you can get alcohol poisoning on a relatively short time  scale like even just like one really heavy night you're drinking where you consume far too much is  enough to knock you unconscious but from the few

papers that i sort of dipped into it didn't really  explain precisely what was happening in the body it sort of alluded that certain mechanisms were  being inhibited but they couldn't really say why which i thought seemed odd because alcohol is  quite a simple molecule or alcohol molecules are quite simple you would think understanding  their action would be quite simple but i guess not the human body is really complicated  right yeah i guess so and it's also been around

for so long to think there's so many studies about  alcohol and like the effect on your brain and your heart and your like health in general like you  thought people would have a better understanding of what it's doing but i guess it's doing maybe  so many things at once but it's hard to get a handle on all of them yeah that's what i figured  if you were gonna do like a really controlled scientific experiment you'd have to isolate  all these things in some way which to me sounds

like you sort of need to artificially create  little bits of cells and bits of the human body i don't know if that's even feasible can you grow  like some heart cells yeah people could do that now right definitely well yeah people feel like  kept that culture tissues that's a thing right i've heard that that is definitely a thing good to  know i'm the least biologically minded person here having not done biology since a levels so you  guys will know more than i do at work i put a

heart cell like a cultured heart cell beating on  our social media if you trawl through ils you can find it they like grew beating heart cells i  don't know how that is a step too far from my biology knowledge but it was really cool it's not  what like a lot of cell cultures are like we have what they call hela cells which are like cancer  cells that we essentially just got once and we just keep regrowing the exact same culture  line again and again for multiple experiments

and it's like one massive culture that people  get shipped to their respective labs and then you culture it even more and they could like perform  experiments like drug experiments and stuff on it is that what that is wow is this where the idea  for like 3d printing organs comes from that they can take those cell cultures and extrude them  through a nozzle this sounds really weird no i think that is like potentially like a future thing  that will happen that they're like trying to like

3d print organs and stuff which is mind-blowing  to me that would be possible but i guess if you can like culture it into a material then why not  i didn't know if that would work you'd beat so much though because you need like muscle and veins  and yeah and you need to solidify all those cells like but then you need to kind of extract the  different functions from stem cells like you need to extract specific lineages which is going to be  another pain and then we need to make sure that

they aren't rejected in the patient's body so  you need like all those biomarkers and stuff maybe someone will come up with some novel way  of using toxins to help that process somehow if toxins act on particular cells in particular  ways then maybe toxins can be used somehow to encourage your cells to do a particular thing  i don't know that sounds like bollocks as well i like the idea of it though i'd  like to think that that was a

thing that could happen in the future it's what  toxins can do for you not what you can do for them some more ways in which they can be beneficial  than uh pain relief and uh cancer therapy i do wonder though does that mean there  is some way that we could get superpowers from ingesting something or being bitten  by something that's gotta be right like if a snake can eat a toad and get poisonous skin  surely i can right like i'm not saying i want

poisonous skin but i would like to have it as an  option hmm spider-man got bitten right over this radioactive yeah which i guess is also sort of  toxic it is toxic right like it has radiotoxic yes general safety assessments i used to do chemotoxic  and radiotoxic effects and again that's all of it again it's all about concentration it's  how much you're exposed to and how quickly does it destroy the cells  before the cells can be repaired

how do i stop it destroying my cells and like get  it to build shooty webs out of my wrists instead i can't answer that but apparently one way  you can protect yourselves is using alcohol so i need to be drunk and also bitten by a  radio toxic spider yeah if you could somehow bathe the correct cells in the  correct concentration of alcohol i feel like i should know how this mechanism  works but i'm presuming the radiation causes the

alcohol to be broken down in a particular way and  maybe the fragments help prepare the dna somehow again that's probably not quite right so  hang on if i was drunk and then i took this it would like break down the alcohol in my  system and therefore make me less junk so it's really the ultimate hanging victim  i have absolutely no idea if that's true actually check with some colleagues in radiation  chemistry before saying that is what happens

wait are we saying that andrew garfield  was drunk when he was bitten by that spider in the lab during his internship my opinion  maybe maybe that was how he actually became spider-man he was just always drunk when he  was peter parker wasn't he a child wasn't he like 16 yeah or something on a school trip  he had a bit of a rough upbringing who knows so what we get from this episode is that peter  parker needs therapy he got over it he was a good

guy right he was spider-man he's right he was  helping people he's in the avengers now right he's happy i remind him of feelings as well  it's slightly more serious but also not serious question for you ali what happens  if a venomous snake bites itself oh my god i mean that is i guess theoretically possible  i think nothing so because they have the venom stored in their mouths and their glands they  could i suppose theoretically die from blood boss

if they bit themselves but they wouldn't die from  the venom because they have that like dna genetic molecular level to be like not affected by their  own venom otherwise that would just be a really really unfortunate day wouldn't it well i mean  what are the chances of a snake biting itself that seems like a really obvious safety mechanism  don't do any harm to yourself yeah what's the chance of any animal like if a lion bites  itself like it's not going to end well is it so

i mean a don't bite yourself in the first place  but yeah if you're venomous as well that is an extra problem but i'm pretty sure they've got like  the antibodies or the anti whatever they need but it's not it's not a problem fair enough so when  you were talking about getting anti-venom one way would be to just extract it from the snake itself  yeah they do this so if you've ever seen like wildlifey shows or like the ones where they like  go out into the bush and poke sticks at snakes and

things they like people in zoos can like extract  venom they get basically they get a jam jar and a like permeable lid and they put the fangs of  the snake through the jam jar and then all the venom like collects at the bottom and then they  can use that venom to like then make antivenom which is cool and yeah like really terrifying when  you see it done yeah i think i just had some idea in my head if the venom is made in particular  glands it's sort of contained away from the rest

of the snake's body so it wouldn't really need  to have its own anti-venom defense mechanism in the rest of its body it would just know not to  bite itself it's like how we know not to bite our you know bite ourselves because apparently  like our fingers have the same consistency as carrots but we can't bite them because we have  the survival instincts not to yeah it makes some sense intuitively but i'd never thought of my  finger as having the same consistency as a carrot

for the reason that you've just said like i'd  never try and deliberately cut through my finger but i chopped carrots up all the time i'm sure  my finger is much more squashy than a carrot that's quite brittle elbow oh yeah i feel like  it would be more difficult to sew through your own finger with a knife than it would be to  cut a carrot up but you just said it's not you can just go one chop and that's it oh it  reminds me that film where the guy cut his arm

off after getting stuck in the ravine oh yeah that  was unpleasant it's a good thing he wasn't bitten by a snake though yeah he survived i mean he lost  his arm but he survived all's well that ends well right yeah i feel like that's probably a  very good point to end the episode as well i feel like i've absolutely no idea what we've  what we've yeah well we've been coming to you guys five different tangents we did we  did indeed we defined what toxic is yes

priyanka gave some examples of what happens in the  body so you talked about binding of metal ions and inhibiting how synapses work i learned that  synapses advisor enzymes in them which i never knew and yeah we did kind of ramble around a bit  about toxins that are beneficial and ways in which human-made toxins have had some unfortunate  consequences in a very weird conversation about how chili's may or may not be toxic to  different animals i think i was always told that

if you don't want cats to mess in your garden  to put chili powder out to like dissuade them whether that's because it's toxic or just smells  bad i'm not entirely sure is there a way you could do an experiment to find out obviously you can't  just leave the chili powder around because how do you prove the hypothesis which one is it yeah if  anyone is looking for a thesis let us know because we've got a question for you yeah how do you tell  what the biological option of chili is on a cat

how would you isolate which cells it  affects oh now that i've summed up we've gone off on a random tangent again we're  back down to like growing cat cells in a lab i think this is probably a very good point to  draw the conversation to your goals so if you want to ask us what the hell are you guys talking  about you can find us on twitter or you can email us there are loads of ways to get in touch and if  you quite liked this utterly ridiculous episode we

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