August 2007

Chemistry World Podcast - August 2007

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Brought to you by the Royal Society of Chemistry: The Chemistry World Pod cast.

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Interviewer - Chris Smith

Hello! Welcome to the August edition of the Chemistry World podcast with Chemistry World's editor Mark Peplow and science correspondent, Victoria Gill, Richard Van Noorden, and James Mitchell Crow.   I am Chris Smith.   On the way, the hi-tech approach to cleaning up polonium contamination in London.

Interviewee - Victoria Gill

They didn't want to be taking out whole bathtubs and whole toilets and whole washbasins and locking them up and burying them deep underground.   So what they did was smash off all the contaminated enamel with hammers.

Interviewer - Chris Smith

And the glow from those workers wasn't down to sweat either.   Also the Chinese have perfected the art of getting energy from a coal seam, but without lifting a pick or shovel.

Interviewee - Mark Peplow

You can turn coal into a kind of fuel gas, called syngas, a mixture of carbon monoxide and hydrogen.   What it involves is pushing steam and air into a coal seam and then at the other end of the coal seam, after this chemical reaction has taken place at nearly 1000 degrees, you get syngas coming out.

Interviewer - Chris Smith

And while we tied in hungry ladybirds planning to eat greenflies feasting on cabbages, because these guys are into chemical warfare.

Interviewee - James Mitchell Crow

They take up a particular chemical that the cabbages produce called glucosinolates and they store that away in their body, if they are attacked, they release an enzyme which breaks down the glucosinolate into mustard oil, so effectively they are releasing a mustard oil bomb.

Interviewer - Chris Smith

The full story of how they do that is coming up shortly plus we got the answer to Ben's question from last month.

Interviewee - Ben

Hello! I'm Ben from Moorhampton.   I just want to ask "why is that the wood changes colour as it ages?"

Interviewer - Chris Smith

That's on the way, but first it was bad news for bathtubs, sushi bars, and Russian spies, I'm of course talking about polonium-210 and the diplomatic row that is now erupting over its use in London last year as a murder weapon.   Only a tiny amount was used, but the clean up has been far from trivial, Victoria.

Interviewee - Victoria Gill

The chemists that I spoke to were staying very much out of the diplomatic row, but they have revealed some of the techniques they used for the mammoth task that was cleaning up London.

Interviewer - Chris Smith

But why was it such a big problem?

Interviewee - Victoria Gill

Well there were 50 venues affected, restaurants, hotels -- all civilian venues and you don't really often get nuclear decontamination needed in civilian venues.

Interviewer - Chris Smith

So when you say it's contaminated, how much was there?   Was this registrable amounts of radiation coming out of these venues and how much must that have been?

Interviewee - Victoria Gill

I'm not sure of the measurements, to be honest, but registrable and its very nasty stuff if you ingest it, but it's nasty enough that it needs completely getting rid off.

Interviewer - Chris Smith

Because it makes alpha particles, doesn't it?

Interviewee - Victoria Gill

Yeah.

Interviewer - Chris Smith

So, they presumably can't get to you very far through air.

Interviewee - Victoria Gill

No.

Interviewer - Chris Smith

So, that's why you're saying it's bad if you eat it?

Interviewee - Victoria Gill

Yeah exactly, which is what happened to Alexander Litvinenko.

Interviewer - Chris Smith

So what did they do to clean up London?

Interviewee - Victoria Gill

Several things that ranged from a bit of a wipe down to smashing of bathrooms.   It was a very.

Interviewer - Chris Smith

Sounds radical.

Interviewee - Victoria Gill

The first thing they revealed was that most of the decontamination could be done with basic detergent, a solid nonporous surface where fixed surface contamination is found, can be wiped down with potassium hydroxide-based detergent and the other thing was that because alpha-particles are so weakly penetrating, they can't get through a layer of glass, a layer of paper or a layer of varnish or paint, so quite often on these solid surfaces, they could be painted over or varnished to seal away the polonium 210.

Interviewer - Chris Smith

Doesn't that mean it's still there, which means, it's still a threat, down the line if someone comes along with the paint stripper.

Interviewee - Victoria Gill

Well no, because it has a very very short half-life of about 130 days, so as long as these surfaces are left sealed from public contacts, then it's perfectly safe.

Interviewer - Chris Smith

And the bathtub?

Interviewee - Victoria Gill

Yes, this is pretty interesting.   The representatives from the Government Decontamination Service talked us through sort of different methods that they used and one of the things was that if the polonium-210 had come into contact with the surface that wasn't solid and nonporous, then the polonium-210 can get within that substance, so.

Interviewer - Chris Smith

Do bathtubs fulfil that criteria?

Interviewee - Victoria Gill

Well exactly! Yes.   Ceramic or enamel on bathtubs and washbasins and toilets is a porous material.   So, the whole of that enamel coated surface is contaminative polonium-210 and not needs to be taken away, but because there was so much other contaminated wastes to be removed, chairs and curtains and carpets and all of this absorbant stuff that had to be gotten rid off, they didn't want to be talking out whole bathtubs and whole toilets and whole washbasins and locking them up and burying them deep underground.   So what they did was smash off all the contaminated enamel with hammers, it was as basic as that.

Interviewer - Chris Smith

But one wonders if that treatment is going to make the stuff go up in the air.

Interviewee - Victoria Gill

Well no, it is.

Interviewer - Chris Smith

This could lead to secondary contamination.

Interviewee - Victoria Gill

No, it is fixed within the substance that it's coming to contact with.

Interviewer - Chris Smith

Well, let's hope its stays there.   But from one kind of mind-bending concept, smashing up of bathtubs to another, Richard, LSD is making a resurgence in terms of whether we think it might be useful for psychotherapy.

Interviewee - Richard Van Noorden

Well we found that LSD, d-lysergic acid diethylamide as chemists would call it, its use in psychiatric therapy could be studied for the first time in almost 3 decades.   There's going to be a trial in Switzerland to determine whether patients with anxiety or relating to advanced stage illnesses or terminal illnesses can be safely given LSD to help them.

Interviewer - Chris Smith

What's the motivation behind doing this?   Why do we think it might be better than the other drugs that the market currently has?   There are lots of drug that can make people feel less anxious about things. Why LSD?

Interviewee - Richard Van Noorden

Well, I mean, reports of LSD use, aside changes in how you feel about the world and your experience in LSD can make you feel less anxious afterwards, say, people say now its often thought that, you know, this is why LSD should be used in a medical setting, but back in the 1970s, when LSD was classed as a Class I drug which meant it had no medical use, all the research was stopped and some of it trickled on into the 80s, but there was no actual legal research into the use of LSD on humans which is why this is really so interesting.

Interviewer - Chris Smith

And so, when are they going to kick off? Is it getting the full green light action or is it going to be more litigation and bureaucracy to get through yet?

Interviewee - Richard Van Noorden

Its had approval from a Swiss Ethics Committee, but to be fully started, it needs to get approval from Swiss Medic, who are the Swiss Drug Regulation Authority, but the president of the Multidisciplinary Association for Psychedelic Studies in the US, MAPS, they are sponsoring the study and they reckon they are going to get approval from this committee by the end of the year, so it's that soon.

Interviewer - Chris Smith

Do you think this is going to open the floodgates, because there are lots of drugs, which fail to find any kind of therapeutic benefit, that become weak drugs of abuse.   Do you think they are going to end back in clinical trials of people looking for functions for these agents?

Interviewee - Richard Van Noorden

Well there does certainly seems to be a core of therapists who were looking to try and find some use for these drugs.   There are studies with Ecstasy with MDMA and DMT and I think people at Harvard Medical School, as I remember, are trying to develop a study to look into the use of LSD to treat cluster headaches, just by asking people who've used psychedelics themselves to treat their cluster headaches, so there is.

Interviewer - Chris Smith

I think they are on aspirin, so their headaches goes away.

Interviewee - Richard Van Noorden

So there is a certain, sort of continuing stress on using these kinds of drugs.

Interviewer - Chris Smith

So, LSD might make a comeback and not just among CPs.   Thanks Richard!   Now most of you would probably have sprayed your carpets, sofas or even your loafers with Scotchgard or perhaps you fry your full English in a Teflon pan, well they work fantastically.   But there is a problem related to the chemicals that are used to make them.   Here's Scott Mabury

Interviewee - Scott Mabury

The problem is that the arctic and humans are significantly contaminated with perfluorinated acids, prefluorocarboxylic acid, perfluorosulphonic acid.   How did that come to be is the question?   Whether or not they are inherently toxic in humans for example, is yet to be determined, but the concentrations are sufficiently high enough to warrant rather significant scientific and regulatory and then thus societal interest in, you know, where do these chemicals come from and how can we cut off exposure both to remote regions like the arctic and to humans in particular.

Interviewer - Chris Smith

What actually are they Scott, and where do they come from?

Interviewee - Scott Mabury

They are long chain, meaning 8, 9, 10 or 11 carbons with fluorine, lots of carbons are bonded to fluorine element and then we either have a carboxylic anion or sulphonic acid anion on the end.   They are surfactants.   Some of them have been used in fire-fighting foams, some as processing agents in making other materials, Teflon for example.   The bulk of the more recent usage has been incorporating the perfluorinated tail into fabric coatings, paper coatings, things that we like to have the properties of water repellency and oils and stain repellency.

Interviewer - Chris Smith

So, what's the scale of the problem?

Interviewee - Scott Mabury

In the arctic, higher up in the food chain, polar bear, seals, the perfluoronated compounds are now either the most common pollutant or certainly vying for top pollutants there.

Interviewer - Chris Smith

And in humans?

Interviewee - Scott Mabury

Pretty much every human blood sample tested, to my knowledge, has P-Phos, perfluorooctane sulphonic acid, also known as Scotchgard and PFOA perfluorooctanoic acid, that a few to tens of micrograms per litre part per billion, so relatively high concentration.

Interviewer - Chris Smith

But you can also find lots of other things washing around in people and polar bears, what's that there? They are not necessarily pathological? So, is there any evidence that we should worry about these things?

Interviewee - Scott Mabury

Certainly the 3M Corporation in 2000, when they announced that they were pulling the 8 carbon version of Scotchgard, they did so unrecognizing that these were ubiquitous universal contaminants globally, that they were found in all human blood samples tested.

Interviewer - Chris Smith

But what are people worried about? What do people think they might be able to do to the body, given that they are there?

Interviewee - Scott Mabury

I think the mechanisms of those kinds of actions are still being worked out.   To me much more of scientific interest is actually the root of exposure itself.   Why do we have these things in our blood and do they come from precursors that we metabolize or transform into the end products like perfluorooctanoic acid, that is pertinent because if we are metabolizing a precursor and the precursors we think are fluorinated telomer alcohol, then some of the intermediates along the way in that metabolic process are actually quite reactive and have the potential to be a quite toxicological interest.

Interviewer - Chris Smith

And presumably these chemicals and the parent compounds are quite stable in the environment, which is why they've accumulated, which suggests that they could be a problem to cleanup and get rid off?

Interviewee - Scott Mabury

Well interestingly, its the perfluorinated acids that are very stable, in fact, are being quoted as saying "they redefine persistence" because the persistent organic pollutants we know DDT, PCB, the perfluorinated acids have no known environmental degradation pathway, thus I can't give you a lifetime because it's so long that we can't measure it.   The precursors themselves are actually much more labile, they are reactive in the atmosphere, in surface water.   In biology, metabolically we can convert them through intermediates into the perfluorinated acids that are so stable.

Interviewer - Chris Smith

So, given that stability, how come we get rid of them, if we decide that we need to?

Interviewee - Scott Mabury

The problem with these compounds are that to my knowledge, nobody has observed under any relevant environmental conditions at all, any degradation.   So I cannot tell you what would ultimately happen, I'd think the eventual fate of these probably would be sedimentation in the ocean.

Interviewer - Chris Smith

So if we do discover that there is a health implication, that's a bit of a problem isn't it?

Interviewee - Scott Mabury

I think, if there is a health implication then we have to look very closely at the roots of exposure, human exposure, and quickly identify how to shut off those roots of exposure.

Interviewer - Chris Smith

The chemical look really isn't biodegradable, Toronto University, Scott Mabury.   Well from making a mess of the environment to a way to do things more cleanly and the Chinese have now mastered the art of getting the energy out of coal without having to dig it out, Mark.

Interviewee - Mark Peplow

It's based on this idea, that you can turn coal into a kind of fuel gas called syngas, a mixture of carbon monoxides and hydrogen.   Now this is a technology that has been around for a long time, it is using the same sort of idea that they used to make coal gas in the 19th century for the early gas lamps.   What it involves in this case is pushing steam and air, deep down a hundred meters below the earth into a coal seam and then at the other end of the coal seam, after this chemical reaction has taken place at nearly 1000 degrees, you get syngas coming out, carbon monoxide and hydrogen.

Interviewer - Chris Smith

What actually is the chemical reaction that produces this?

Interviewee - Mark Peplow

Carbon atoms that are locked up in coal, you are reacting them with oxygen and with water to make CO -- carbon monoxide and H₂ -- hydrogen gas.

Interviewer - Chris Smith

And that then gets funnelled off at the other end of the coal seam.

Interviewee - Mark Peplow

That's right.   Once it comes out, you can use syngas for a variety of things.   In theory you could take away the carbon monoxide and just burn the hydrogen, but probably a more efficient way to use it is to actually use a process called the Fisher Tropsch process, which turns this into liquid fuels, that makes it easier to use the existing pipelines and infrastructure and things like that to transport the fuel around.   This is something that was tried in China both in the '60s and in the '80s and one of the major problems was to try to make it work, you effectively had to make this fast chamber in the middle of the coal seam almost like a big reaction vessel underground and that obviously requires sending people underground, digging it out.   This group that is based in Jiangsu Province, they found a way to make this blast of steam and air, burrow its own reaction vessel inside the coal seam.   It effectively makes a pipe about half a metre wide.

Interviewer - Chris Smith

Are all the coal seams actually amenable to this kind of, I wanted to use the word therapy for some reason, but what's the chances of the gas coming up somewhere else?   It doesn't come out of your collector, sort of finds other ways up to the surface.

Interviewee - Mark Peplow

It's certainly not amenable to every single coal seam that you've got.   Basically you have to alter the conditions depending on the geology locally.   They spent quite a while, sort of fine-tuning the temperature that they did this out, the amounts of steam, and the amounts of air that they put down.   But after a few months of optimization, they found that they were getting out hundreds of cubic metres of syngas every hour.

Interviewer - Chris Smith

I suppose they are from the environmental point of view, it's much better because you are not sending people underground, you are not digging out tons of rock you then chuck away and contaminating the area -- you are just getting the energy out.

Interviewee - Mark Peplow

That's right.   In terms of the heating value, if you like, of syngas, its about a quarter of natural gas, but like you said, you are not wasting lots of energy in sending people down, digging shafts and also 5000 coal miners died in China last year in accidents, so it's potentially also lot of lives saved.

Interviewer - Chris Smith

And there is no risk of some kind of run-away reaction, where the oxygen starts to burn of the coal and it goes out of control.

Interviewee - Mark Peplow

Well, it's very carefully controlled and that's one of the things that they were really looking at in the study, with how you can control the rate of burn, fully enough controlling it and that ways the key to getting the best quality gas out, So, they've really fine-tuned that and got it down the stage where they can keep the fire front moving through the seam at a very controlled slow rate.

Interviewer - Chris Smith

Sounds promising, well that's one seam that we will certainly be hoping to be plump for more information in future, now James, what's all this about aphids, which are using chemical defences to ward off ladybirds.

Interviewee - James Mitchell Crow

Well it could be bad news if you are a veggie batch Chris.   These cabbage aphids have hijacked the chemical defences of the cabbages to defend themselves against ladybirds, which eat the aphids.

Interviewer - Chris Smith

What do they actually do?

Interviewee - James Mitchell Crow

Well they take up a particular chemical that the cabbages produce called glucosinolates which is basically a glucose molecule with sulphur and nitrogen containing side chain and they store that away in their body.   If they are attacked by a ladybird, they release an enzyme which breaks down the glucosinolate into a volatile isothiocyanates which are the major ingredient found in mustard oil, so effectively they are releasing a mustard oil bomb to fend off the attack against the ladybird.

Interviewer - Chris Smith

And why doesn't it harm the aphids?

Interviewee - James Mitchell Crow

Well, it does actually kill the aphid who produces the bomb, but what it does is protect the rest of the colony.

Interviewer - Chris Smith

So it's like an aphid suicide bomber almost?

Interviewee - James Mitchell Crow

It is yes.   But the colonies of aphids reproduce asexually so, effectively they're all the same genetic material in there, so it doesn't affect the gene pool and it doesn't affect those gene's chance of reproducing, because it protects the rest of the colony.

Interviewer - Chris Smith

Do they continue with this behaviour throughout their life cycle or do they switch it on when they most need it, when the ladybirds are most prevalent or something?

Interviewee - James Mitchell Crow

Well, they use this technique throughout the summer, when they are feeding, but then when it comes to the autumn and the colony is dispersing to try and colonize new plants, the aphids grow wings and so they can't afford the energy of keeping this chemical defence system going, so they basically shut that down to use the energy to grow wings and then the ladybirds can get their revenge by feasting away to their hearts content.

Interviewer - Chris Smith

The insects that really are what they eat.

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Interviewer - Chris Smith

And now from life in the undergrowth to life on Mars or at least a new NASA mission to find out whether anything ever did live there?   I spoke with William Boynton about Phoenix, which is due to touch down next year and pick up where previous probes left off?

Interviewee - William Boynton

Several years ago, another instrument that we had built here at the University of Arizona, called the gamma ray spectrometer had actually detected ice buried just beneath the surface.   So this Phoenix lander is going to land in this area, dig up some of the soil that's covering the ice and grind into the ice to remove some samples and will do a chemical analysis on those samples.

Interviewer - Chris Smith

What are you going to be looking for chemically speaking?

Interviewee - William Boynton

We are looking for a variety of minerals, ice is certainly the most important one.   First the sample gets scooped up by a robotic arm and delivered to the instrument called a TAEGA, which stands for Thermal Analyzer and Evolved Gas Analyzer and the thermal analyzer is essentially a very small oven, which is a calorimeter.   So we heat up the sample and very carefully measure the heat it takes to raise the sample by typically 5 or 20 degrees a minute and if there are things in the sample for example, ice, once we run up past 0 degree Celsius, we have to supply extra heat in order to melt the ice, which tells us indeed we must have had ice in the sample.

Interviewer - Chris Smith

Is it just inorganic things you are able to look out with this  bellow or will you be able to probe organic molecules that might be there too?

Interviewee - William Boynton

So far I've only described half of the instrument, the Thermal Analyzer but as the sample is heated up, any gases that are given off are passed through a thin tubing to the Evolved Gas Analyzer which is really a mass spectrometer.   So, we will be able to tell whether organic molecules are present or not present.

Interviewer - Chris Smith

So, say you do strike oil and I mean that in the perspective of finding past vestiges of life.   What's the kind of chemical hallmark that tells you, something was living here once?

Interviewee - William Boynton

We actually are not expecting to necessarily say whether something had been living there in the past or not.   At this point, we are even wanting to find out if the conditions are such that organic molecules can survive.   In the mid '70s there was a mission called Viking, which went to Mars and did a similar experiment, except it wasn't in the Polar Regions and they didn't heat the samples to such high temperatures and they got a negative result saying there was essentially no organic molecules there.   We are going to higher temperature here, close to a 1000 degrees.   What we're hoping for is that very refractory organic molecules that might have survived on Mars, might have been missed by the Viking instrument, which only went to 500 degrees.

Interviewer - Chris Smith

Also you're getting deeper in beneath the surface.   You're scratching further beneath the surface than Viking might have done because it strikes me that if these things were living on Mars, if there were the kinds of things that could've produced organic molecules, they are likely to sub-surfaced.   Anything on the surface might have been destroyed by solar radiation.

Interviewee - William Boynton

Yes.   We have the capabilities of digging substantially deeper than the Viking mission.   But if we reach the solid ice layer 4 or 5 centimetres beneath the surface, we don't expect that we can dig very far into the ice.   We can grind samples out of the ice but we're actually hopeful that because it's in a polar region where it's colder, some things might actually get embedded in the ice, where they might be protected.

Interviewer - Chris Smith

What other experiments are aboard this Phoenix probe?   What else will you be able to do with it?

Interviewee - William Boynton

There are a variety of other things.   There are some cameras of course, that are taking pictures of surroundings as well as some microscopic imagers that are to look at particles.   There is meteorology package measuring temperature and pressure and wind speeds.   The Canadians are providing a Lidar which is essentially a laser that looks up into the air and looks for presence of clouds and scattered light and there's another instrument doing some wet chemistry work, some of the soil is actually put into a little beaker, water is added from earth and stirred and various electrodes like pH electrode which measures the acidity of the soils and ion-specific electrodes that can tell how much salt might be present in the sample, so it's a pretty comprehensive suite of instruments that are going there.

Interviewer - Chris Smith

And there is no way that we could accidentally contaminate Mars with things that come from the earth.

Interviewee - William Boynton

NASA as well as other space-faring nations have pretty rigorous rules about cleanliness, so that we don't contaminate the bodies we are going to visit.   For us it's particularly important that we have very meticulous cleanliness, so that we don't go all the way to Mars and just analyze organic molecules we brought all the way with us.

Interviewer - Chris Smith

So, when are you hoping the touchdown dates are going to be and when will experimentation start?

Interviewee - William Boynton

We expect to touchdown towards the end of May 2008, we'll have to check out the spacecraft and exercise the robotic arm and make sure they would know how to dig and things like that.   So, it'll be some while before we actually get to the point of doing our first analysis.

Interviewer - Chris Smith

Bill Boyton from the University of Arizona.   Back to earth now!   And there is new evidence that the in vitro approach may be a better way to test the safety of drugs and chemicals, Richard.

Interviewee - Richard Van Noorden

Well talking just animal toxicology Chris, which is when you use animals to check chemicals that they are not harmful to human beings, is actually being quite an explosion in the number of non-animal tests, being validated for use by regulators to check chemicals and ECVAM which is the European Centre for the Validation of Alternative Methods has validated 30 in-vitro tests now that tests on cell lines in a test tube instead of using an animal, 14 in the last 18 months and they expect 40 more by 2009.

Interviewer - Chris Smith

How can be we sure that this isn't missing something?   How can we be sure that this is a good representation of what would go on if this was a human body?

Interviewee - Richard Van Noorden

Well, you might think the animal tests are the best chance we've got on working out what's going on in the human body, but actually Thomas Hartung who is the head of ECVAM says that 30% of pharmaceuticals fail in human trials because of the toxicological effect that wasn't picked up by the battery of animal tests they were subjected to.   In fact, most people do agree that animal test to check the safety of a chemical are simply not very predictive of what's going on in the human.

Interviewer - Chris Smith

Which you could look at it the other way, that 60% of tests are successful in animals, what are we going to do to replace that 60% that's picked up at the moment?

Interviewee - Richard Van Noorden

The alternative tests are actually subjected to a much higher regulatory controls than the animal tests they are going to replace.   So, in that way, just looking at the numbers, you can say that the alternative tests are better science.

Interviewer - Chris Smith

So the way that it looks like it's all going, we are going to be repla