Naked Science Question and Answer and Polonium Poisoning

Chris - It's been a week or two that's really recreated something that I don't think Ian Fleming could have recreated in the James Bond series; stories about KGB agents knocking off ex-Russian agents and Alexander Litvinenko dying from polonium 210 poisoning. But what actually is polonium 210 and how does it actually do away with people when it gets inside your body? How do you get hold of it and how do you get it inside your body? The editor of Chemistry World from the Royal Society of Chemistry, Mark Peplow, joins us to tell us. What is actually is it, and if I wanted to get some, where would I get it?

Mark - Well this is one of the most bizarre things about this case. It's a very very rare element; a silvery sort of metal. When it was first discovered by Marie and Pierre Curie back in 1897, they did it by trawling through uranium ore, but you only get about 100 micrograms of this stuff in every tonne of uranium ore. So these days you make it by bombarding an element called bismus with neutrons. Now the only way you can do that is in an experimental reactor.

Chris - So that means that somebody must have had access to some pretty high class technology to be able to do this. It's a well-planned and orchestrated attack.

Mark - Absolutely. This is something that you can't just go out and set up yourself. There are maybe only forty facilities around the world that are capable of making this stuff. Funnily enough, Russia actually exports about eight grams of polonium 210 every month, and all of it to the US. It does have a very small use to help discharge static that builds up in certain types of machinery. But other than that, it's not really made very much at all in the world.

Chris - So how much would you need to get inside your body to be harmful?

Mark - The maximum safe dose you could get away with is seven trillionths of a gram. That's a minuscule amount. According to the doctors, the sorts of doses Litvinenko took or was given was substantial enough to cause this very rapid onset of radiation poisoning. That might only be micrograms or milligrams though, so it's the sort of amount that could constitute something smaller than a pea.

Chris - Why do you think someone would have gone for such an exotic way to kill someone? Wouldn't something like lead poisoning in the form of a bullet have been more effective and probably easier?

Mark - Yes, it's very bizarre. This now gets into the realms of a spy thriller and something that is really speculation. From one point of view, it sends out a very powerful message that whoever has done this does have access to some very serious pieces of kit and is able to move radioactive material around the world almost certainly. On the other hand, it may have been a geniuine attempt to try and disguise the mode of poisoning of this guy. Obviously he was sick for quite a few weeks before people realised exactly what had poisoned him, despite the fact that experts at University College London had been testing him and looking at him to treat him. This may have been one of the reasons to use the polonium. It's simply so rare and there's no other documented cases of deliberate poisoning by this metal, that it may have been to cover up the fact that this guy had been poisoned in this way.

Chris - You don't think for instance that this is a KGB calling card. They're saying that you can't prove anything, but it's obvious who's done it.

Mark - Well like I say, it may be a very obvious way to say 'look, we have the technology and we can get to you with some really bizarre stuff that you need serious contacts and power to get hold of.' So yes, that may be one explanation.

Chris - And once you've got this stuff inside your body, why does it actually make you unwell?

Mark - Because it gives out radiation, the type of radiation it gives out is called alpha particles. It's a bundle of two protons and two neutrons; the little particles that make up all the atoms that make up all the different elements in the universe. These alpha particles can work in two ways. Because they're positively charged, they can rip electrons away from the molecules that are found in your body cells that are responsible for doing all the biochemistry needed to keep you living. In doing so, they make things called free radicals, and that can help to break down all the different biochemical reactions that are going on. That can cause you illness. In the longer term, the alpha radiation can damage DNA in your cells. It can damage the DNA to such an extent that the cell realises how badly warped its DNA has become and that can actually make it shut down. The cell will kill itself in a process called apoptosis because the cell has undergone such rapid damage.

A flame goes upwards because of convection. The hot gas created by the flame rises. As you say, there's no up or down in space so the gas just forms a sphere around where it's burning and you just get a sort of circular flame. But actually stuff doesn't really burn very well in space. This is because the process of the gas going upwards (as happens on Earth) gets rid of the carbon dioxide formed in the burning process and sucks in more oxygen to keep the flame stoked. This keeps everything burning quickly. As there's no upward movement of gas in space, you don't have much oxygen getting into the flame and it's quite a poor flame that is formed. So essentially it chokes itself in its own waste products and just goes out.

Spiders are really actually quite clever. Ancestrally they go back a couple of hundred million years, we think. They have glands at the back end of the spider and now it turns out also on their feet that make silk. And what scientists think, is that the glands on the back of their abdomen that make silk are just adapted limbs, where they used to have some legs. Silk is the reaction of proteins. So you have a chemical reaction going on at the back end of the spider that literally spins silk on demand. The spider eats something that has got protein in it. So when it goes and catches something in its web, it injects a venom into that insect that kills it by paralysing it. The insect is paralysed and doesn't die instantly so it remains fresh, the spider injects digestive juices which liquify an insect. And because an insect is like a husk, with a hard skeleton on the outside with the soft bits in the middle, the spider can literally suck the good bits out of the inside leaving behind a dry, wizened up shrivelled skeleton. That's why you see these sort of husks of insects left under spider webs. All the protein and goodness from inside the insect ends up inside the spider, the spider digests that, absorbs it, and then the proteins go to the back end of the spider. And they get turned into new web, amongst other things a spider needs to make. And some spiders have taken this a step further. What they've done is to make the process even more efficient, by eating their own web. This doesn't do them any harm because web is just protein. By eating their own web they're getting the proteins back into their body and they can then reuse them. Spiders' web is incredible stuff and it can absorb immense amounts of energy. It's got the tensile strength of steel. Scientists are now looking at ways of using it for bullet-proof vests, for example. If you can make this artificially in enough quantities you've got something with the tensile strength of a piece of steel, and the ability to stop bullets much better than a bullet-proof vest. Which means rather than police having to go around in these very thick outfits which restrict movement, if you could make it out of spider silk it would be a) lighter, b) a breatheable fabric, so it wouldn't make you so hot and uncomfortable, and c) it wouldn't restrict your movement so much.

其中大部分的工作方式是通过一个小点了tle electric circuit in it. They've got an aerial around the outside of that, and when you walk past one of those detectors, that puts radio frequency energy through you. This powers up the circuit. The little circuit sends a code back to the detector and says "Help, help I'm being stolen" and then the alarm goes off. There are also the solid ones you find in clothes, which are attached, and the reason you might think they're magnetic is the way you deactivate them by using a magnet which allows them to detach without spreading dye all over your nice new clothes. However, the tag will still activate the alarm. The ones which are actually stuck to the things you're buying are deactivated in a slightly different way. What they do is they have a little an electronic thing which puts in such a huge amount of power that it basically melts something in the circuit and causes it to break.

There are a number of things that can determine how long we live. The first thing is the rate of your metabolism. If you compare a mouse with a human, then we're very very genetically similar. But if you look at the heart rate of a mouse it's running along at several hundred beats a minute, whereas our heart's beating at 50 times a minute. So a mouse, in order to survive because it's so small, has to run it's body very very fast. It's almost like you being whipped along by a slave driver. In a mouse, the cells are growing faster, they're dividing more, they're doing everything more quickly, and so the mouse burns itself out more quickly than a bigger animal, like a human. If you compare animals like tortoises, which are cold-blooded, they're big, they're cold blooded, and their metabolism is running much more slowly. Giant tortoises can live for 100, maybe 200 years. So it's down to the speed of your metabolism. Scientists have found whales in the ocean which might even be several hundred years old. There are harpoon tips which have been recovered from the blubber of whales that date back historically to the types of harpoons that haven't been used for several hundred years. Leading scientists to conclude that they really are quite old. The second thing is something called a telomere.These are structures on the ends of each of your chromosomes that are almost like the pieces of cellophane you find around the end of your bootlaces to keep the lace from fraying. Every time a cell divides, it erodes a little piece off of the telomere so it gets shorter and shorter and shorter. If you look at cancer cells that seem to live forever, they have switched on an enzyme that makes telomeres get longer and longer and longer. That seems to be what gives the cells the ability to divide forever. But in a normal cell, the problem is that eventually the telomeres get so short that they run out, and that seems to determine how many times a cell can actually divide. It's called the Hayflick number so there's a limited number of times a cell can divide. But that's not why someone dies. They usually die because something has damaged their DNA and that causes the cells to work less well, and so you get things like cancer.