Forensic Science Show
Under the microscope this week, the science of forensics. We find out how scientists have exploded the myth about old aged whales thanks to a piece of shrapnel, about a new rice-based vaccine for cholera, and 'whey' to go, how scientists have made edible food wrappers from milk. We investigate what your diet does to your hair, how science can finger forgers and flush out bodies from bogs, and why the key to identifying a torso that washed up in the Thames was rooted in plant science. Plus, in Kitchen Science, we arm Ben with a rifle to find out how fat you'd have to be to stop a speeding bullet with your belly...
In this episode
Whale of a question
A giant bowhead whale caught off northern Alaska recently had a surprise in store for the fisherman who landed it - embedded in its flesh was a piece of a "bomb lance" used by whalers back in the 1880s. And because the weapon was patented it was easy to date, confirming claims that whales can live for 130 years or more. The find joins other "evidence" of whale longevity which has accumulated over the years, including stone harpoon tips thought to be over 100 years old. It was handed over to scientists by native Alaskan Inupiat fisherman who, although commercial whaling is banned, are permitted to carry out a traditional subsistence whale hunt. The meat they catch is shared amongst the residents of their villages.
Cholera vaccine from rice
This week we have promising news for the fight against the dreadful disease cholera, because a team of scientists in Japan are developing a new vaccine against the disease using their national staple food - rice.
Cholera continues to be a huge problem across the developing world, with at least 5000 people a year, and probably a lot more, dying from the severe dehydration caused by chronic diarrhoea that is unleashed by eating food or water contaminated with Vibrio cholerae bacteria. Fortunately it's a disease that's easily treated with clean fluids and antibiotics but sadly there are still millions of people in the world who don't have access to such treatment.
Now, researchers from the University of Tokyo have genetically engineered two strains of domestic rice to contain the CTB gene, which is a major protein of cholera bacteria. The idea is that by introducing these cholera proteins into the body it will trigger an immune response that protects against future attacks of the disease.The scientists have rather nicely called their new rice Mucorice, because cholera is a disease of the mucosal lining of the intestine, and they've shown it to be effective in preventing cholera in mice.Sadly the vaccine can't be taken simply by eating a bowl of steamed rice, because that could give the wrong dosage, but it can easily be made into tablets that are swallowed, getting rid of the need to inject vaccines with needles which can cause other problems like secondary infections and disposal. Another good thing about these tablets is that they don't need to be stored in refrigerators and the rice can easily be grown in areas of the developing world where cholera is still a huge problem.One of the really important breakthroughs with this technique is that the researchers have found a way of delivering the vaccine to the intestine - just where it's needed - without being broken down in the harsh enzyme-laden environment of the stomach. Rice grains survive digestion in the stomach, and even when ground up into tablets the CTB protein is stable enough to pass through the stomach unharmed. So it's hoped that this new technique could be used to develop vaccines for other diseases of the intestine like flu, botulism and maybe even anthrax.
Whey to go! - Scientists make edible food wrapper
Scientists at the US Agricultural Research Service in Wyndmoor, Pennsylvania, have used milk powder and glycerine to produce a water-resistant edible film that could be used to coat or package foods.Peggy Tomasula and her colleagues have found that high-pressure carbon dioxide can be used as a solvent to extract the protein casein from milk. Mixing this with water and glycerol and then leaving it to dry produces a water-repelling, flexible film-like material which can keep food fresh but is also completely safe to eat and unlike most sandwich packs, completely biodegradable. It would also reassure consumers worried about chemicals leaching from plastic wrappers into foods like cheese, because there's nothing in this film that you wouldn't eat normally anyway.
A round up of wildlife trade
For the last couple of weeks, politicians from all around the world have been meeting to talk about endangered species and to try and decide whether trade in certain species should be restricted to prevent them from becoming even more endangered.
Every year millions of wild animals and plants are traded as pets, medicines and food and in 1963 the Convention on International Trade in Endangered Species or CITES, was set up to regulate the trade of wild species between countries to help protect them from becoming extinct.
For a long time the trade in many highly endangered species like tigers and pandas has been completely banned, while other, less endangered species can still be traded but only under strict regulations and controls.
Every two years, members of CITES meet to decide on which species should have their trade banned, which should be regulated and which are doing okay so can be traded as much as anyone wants to.
This year, around 50 species were proposed to either be added to CITES or for their level of protection to be upgraded to a full trade ban and of these there were various successes and a few failures too.
One species that has been added to the list that can't be traded are the sawfish, a bizarre-looking type of shark with a huge long nose or rostrum covered in sharp teeth which are dried and hung on walls as marine curios and in South America the teeth are used in cock-fighting. The trade has also been banned in the slow loris, a cute cuddly primate with huge nocturnal eyes which looks a bit like a gremlin before it gets wet. Slow lorises live in the rainforests of Southeast Asia and are kept by some people as pets. For both sawfish and the slow loris it is likely that other problems such as destruction of their wild habitat and pollution are more important in determining their future than just international trade, but its hoped that the publicity they will get through listing on CITES will help raise their profile so these other problems can also be tackled.
Among the CITES failures this year are two species of shark - the porbeagle and the spiny dogfish - which are threatened by global fisheries for their meat as well as their fins for Asian shark fin soup. And you might think shark meat is not especially attractive to eat, but you could well have eaten spiny dogfish without knowing it because it is sold in fish and chip shops as huss or rock cod.
These two species are in a terrible state with numbers declining around the world, so it's a huge disappointment that they have not been included in CITES which would have been the first international regulation on their exploitation.
And possibly the most controversial decision made at this latest CITES meeting was to allow the one-off sale of stockpiles of Ivory from several southern African countries. Some people think that allowing some legal trade in ivory will stimulate elephant poaching for the illegal trade which continues to be prolific especially in Zimbabwe, but on the plus side, any proceeds made from selling these ivory stock piles must be used for elephant conservation projects - and there will be no more legal trade for at least 9 years.
What is the difference between vaccination and immunization?
Immunisation and Vaccination are two words for the same thing; essentially adding a part of a bacteria, or a whole 'dead' bacteria to our system, so that our immune system is prepared for us contracting the illness. We actually use the term 'vaccination' because the cowpox virus used by Edward Jenner as a preventative treatment for small pox is called vaccinia.
Why does nervousness make me want to pee?
There are many possible reasons, but it may be that your nervous system goes into overdrive when you're nervous. This causes your sympathetic nervous system, the flight or flight mechanism, to kick in. This can cause an increase in blood pressure, which then inspires your kidneys to produce more urine, to try to reduce the volume of blood.
21:30 - Science Update - Future Machines
Science Update - Future Machines
with Chelsea Wald & Bob Hirshon
Bob - This week for the Naked Scientists, we're going to tell you about some surprising skills held by robots and seeds. I'm going to tell you about the future of the domestic robot, but first Chelsea has a surprising report.
Chelsea - The seeds of the wild wheat plant don't just lie around waiting to be planted. Scientists in Germany and Israel have found that like some other plants, they actively crawl on the ground and bury themselves. Chemist Rivka Elbaum, then at the Max Planck Institute in Germany, says the wild wheat uses a technique involving its two antenna-like projections, called awns. The awns contain two types of cellulose fibers: One contracts when the humidity drops, and the other doesn't.
Rivka Elbaum (Max Planck Institute, Germany): So you can imagine that the passive part is similar to a bone and then the active part is pulling it, like a muscle.
Chelsea - As the humidity level fluctuates, the awns flex and extend, muscling the seed along. Elbaum says this mechanism may be used by other plants, and could potentially be copied in tiny, man-made machines.
Bob - Thanks, Chelsea. If robots ever become common household helpers, computer scientist Aaron Edsinger and his colleagues at MIT can take some of the credit. They've designed several generations of robots that are intended to act and respond more like people. The latest is named Domo, a successor to forerunners called Kismet and Cog.
Aaron Edsinger (Massachusetts Institute of Technology): The focus with Domo has been in manipulation. Really being able to do stuff with the arms and hands. A robot like Kismet basically was a head that could display emotion. Cog had a body and arms but it really couldn't do much with them. And really a lot of the advances with Domo have to do with that it can work with a person, and that it can do it someone's home, where it's very unstructured, it's very cluttered, and it's very difficult to predict. So the algorithms that run on Domo try to take into account a lot of that unpredictability, in a way that a lot of robots haven't done yet.
Bob - For example, Domo can find Dr. Edsinger, take an unfamiliar object from him, and set it down on a nearby shelf. While that's simple to us, it's very complex for a robot, which has to assess the size and shape of the object, navigate around obstacles, pass the object between its own hands, remember the shelf's location, and figure out when it's steady enough to let go. Taking an object off a shelf is harder still, and that's what Domo's learning now. Eventually, Edsinger says robots like these may be able to help elderly or disabled people perform household chores.
Chelsea - Thanks, Bob. Next time, we'll tell you want happens when you mix a baby with a trumpet, so definitely tune in. Until then, I'm Chelsea Wald...
Bob - ...and I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists...
24:13 - The Torso in the Thames: Using Plant Remains to Identify a Body
The Torso in the Thames: Using Plant Remains to Identify a Body
with Dr Hazel Wilkinson, Jodrell Laboratory, Kew Gardens
Sabina - In 2001 the torso of a boy aged about 5 was found in the Thames near Tower Bridge, in London. Police believe this was a ritual killing and much forensic work took place to try and identify the boy and lead the Police to his killers. This forensic evidence included taking mineral samples from his bones which matched those in a rural area in south-western Nigeria. Police traveled there to try and obtain further clues as they think the boy, who they've named "Adam", had only been in London for a short time before he was killed.
The contents of Adam's intestine included large amounts of plant matter and so they were sent to Dr Hazel Wilkinson of the Jodrell Laboratory at Kew Gardens for identification.
Hazel - In may 2003, material recovered from the lower intestine of the little boy known as Adam, was sent by the police forensic department. Among the plant remains there were also quartz grains, small particles of gold small fragments of ground down bone. In addition, the police picked up the largest pieces, naturally, of plant material that they could find, and these are very characteristic of tropical bean seeds.
Sabina - The beans which Adam had been fed as part of the ritual had been ground up in a pestle and mortar so the fragments in his gut were extremely small. In order for Hazel to be able to identify the beans under a microscope, she needed some whole beans to compare the sample with.
Hazel - I got some calabar beans from our economic botany department, and I had to ask the herbarium for seeds of other beans; schwarzia, cassia. But when it came to the leaf material, unless I've got stomata, hair and glands on the speciment it's extremely difficult to do anything at all.
Sabina - Those are the bits from the underside of the leaf?
Hazel - Yes, the lower surface of the leaf. I was very fortunate that we had a visitor here from Ibadar in Nigeria, where Adam is believed to have come from and he brought with him some leaf material from one of the Ibadan markets. One of the leaves he gave me fitted exactly, which was so helpful, one of the leaves I found in Adam material. But it is really a very considerable battle to identify anything at all.
Despite the difficulty in identifying the stomach contents, Hazel was able to detect the presence of significant plants.
Hazel - I feel convinced that a small amount of calabar bean was probably in the meal that Adam had, but one of the most frequently found fragments are those of Datura - "Angels Trumpets". It's a member of the solanaceae, the potato and tomato family. Now I have bought, and also obtained from the herbarium, some seeds of datura, ground them up in a pestle and mortar and tried to compare them with the datura in Adams gut. I feel convinced that there is quite a lot of it. Datura is well known historically for being of a sedative, hallucinatory nature, and it's still used for bad purposes today.
Sabina - Hazel needed some clues to help her narrow the search when it came to identifying the rest of the contents. She obtained a book of spells traditionally used in south-western Nigeria to give her an idea of what other plants might be present.
Hazel - "The Use of Plants in Yoruba Society" loads and loads of wonderful receipes supposed to do all sorts of things...
Sabina - "To appease one's spirit counterpart"... "To send smallpox to someone"...
Hazel - Yes, most peculiar. "To kill somebody" - of course I've got a marker in that because I needed to look through these plants to see if there is anything in here.
Sabina - Hazel's findings helped the Police concentrate the investigation into specific channels which assisted in uncovering human trafficking ring between Nigeria and the UK. The Police have as yet, not been able to identify the perpetrators of this crime, but their investigations have further revealed underground sacrificial practices in London.
Hazel - It would seem that Adams sacrifice was to give somebody power and money. Now where is his head, we don't know, but we do know that the head was considered to give the owner of it, especially in a child, youthfulness, extra brain power and above all access to more and more money.
31:13 - Investigating Forensic Science
Investigating Forensic Science
with Dr Trevor Emmett, Anglia Ruskin University
Chris - Thanks for coming in. Tell us what you actually do, how do you use science to solve crimes?
Trevor - Forensic science, strictly is the use of scientific techniques to solve crime, that's the formal definition of forensic science. So basically, it's any scientific information or technique that we can use for that purpose. The sort of thing we teach at Anglia Ruskin is primarily concerned with analytical science, we're analysing small amounts of evidence collected from the crime scene; DNA of course, blood, fibres, glass, residue from gunshots... But any sort of scientific technique at all really!
Chris - Hasn't Anglia set up a system where you actually stage crimes, then people come in and you take them through the various things you investigate and look for.
Trevor - Well the question is "what makes forensic science different from other sciences?" And clearly, it's a matter of context. It's not about what you're doing; using microscopes or chemical analyses, it's about collecting evidence and using that evidence in a court of law. The evidence has to be collected properly. We have to make sure that all the relevant evidence is collected. We have to make sure that evidence is stored properly, accounted for properly and then analysed properly at the end.
To do that most effectively in a teaching environment we can only really simulate a crime scene and send the students in to do what they have to do. It's not just collecting evidence; it's about securing the crime scene, controlling access, and all aspects of quality management of the evidence. If any of these steps are compromised then you can have the best scientific evidence in the world but it will be no good in a court of law, and that isn't good forensic science.
Chris - You've been working on authenticating ancient documents as well, how do you do that?
Trevor - Again, it's purely analytical science.
Chris - What are the give-aways? What are you looking for that says "this is a genuine old document" versus something I made to look old?
Trevor - It's very hard to prove a negative, of course. So what we look for is positive evidence that the document isn't what it purports to be. Some of the work I've been doing with the Fitzwilliam museum [Cambridge] on ancient Egyptian papyrus' If we found on those paintings some pigments or dyes which were only invented in the 19th century then straight away the provenance of that document is called into question.
Chris - How do you know they were only made in the 19th century? What's the chemical hallmark that says "I'm more recent than this ancient Egyptian one"?
Trevor - It's relatively straightforward for ancient Egyptian works. Ancient Egyptian pigments are nearly all geological in character, they represent coloured ores and minerals from the surface of the earth. There are some organic ones, we've all heard of 'imperial purple' which is made from sea shells, and there are one or two others. But in the main what organic colours or dyes were available to ancient Egyptians were very limited. In the 19th century with the development of the chemical industry all sorts of azo-dyes and amino-dyes were developed and a very wide range of colours were developed. SO if you find those materials, those compounds didn't exist at all until they were first made in the 19th century.
Chris - Have you flushed out any fakes?
Trevor - Not from the ancient Egyptian material, I have on one or two other things I've looked at.
Chris - What sorts of things have people tried to fake?
Trevor - They try and fake everything! I did some work on some castings, some statues, which were purportedly 2000 years old, and discovered that they contained an alloy which probably meant they were made in the 19th century. Very straightforward.
Chris - How did you know that? What was the alloy, was it something that people 2000 years ago wouldn't have been able to make?
Trevor - They wouldn't have been able to make it, no, not at all.
Chris - So how do you do this? Do you drill in to it and take samples out? Because if it turned out to be genuine I wouldn't be happy to have you drilling into my beautiful statue that I paid thousands of pounds for.
Trevor - I would never be allowed to drill into anything. I remember in one of my first discussions with a museum, we had a long discussion about what they wanted me to do. I thought asking for ten grams of material would be a very reasonable amount and I could almost hear the conservators on the other end of the phone fainting. Then they said they could send me some drillings and I was expecting to see one of those curly things that come out of your "Black and Decker" when you're drilling some wood. I got about three specks of dust! When I was working in geology, I used to think that half a gram of material was a bit dodgy for analytical work. Now if I get a milligram I think I'm doing pretty well. You get very very small amounts.
Chris - So how do you actually analyse it? Was it a case with the metal of melting it down and doing some chemistry on it. What's the way in which you actually flush out the chemical fingerprint?
Trevor - In that particular case, I took about a milligram of material. A milligram is about a quarter of a grain of sugar, a very small amount of material. I had to develop techniques for handling such a small amount of material, it's very easy to lose it. Then basically we dissolved it in acid and analysed it in the way would analyse any other solution, and the results were conclusive.
Chris - I heard a suggested technique was to fire x-ray beams at things like the statues you mentioned and the scatter pattern is indicative of what's inside, so you don't have to harm them. And because, as you've said, people are using different forms of metals these days compared with historically, this can sometimes be a give-away.
Trevor - Oh Yes. Many years ago I had a colleague who was very interested in looking at Elizabethan methods of lead smelting. We discovered that some of the artefacts that he had actually bought (and that's always a dead give-away if you buy anything) actually contained stainless steel, which is another thing which didn't exist before the 19th century. If you have a statue that has been cast in bronze, the technique will vary with time and location in the world, and you can x-ray it just like you would x-ray a human body for a broken bone. Another thing that happens when you irradiate material with x-rays is that the atoms in the material will radiate their own, characteristic x-rays. That's a technique called x-ray fluorescence, another very sensitive way of determining the composition of the material. The great advantage of x-ray fluorescence is that it's entirely non-destructive, you don't have to take samples of the material.
Chris - I heard that you can even get fingerprints from previously un-fingerprintable things using that technique. If people touch things, they can leave behind traces of sweat which has traces of metal ions in the sweat. If you zap that with highly focused beams of x-rays, you can literally see the fingerprint flashing up again, even on things like skin, which previously wouldn't have shown the print.
Trevor - I've not actually heard of that, it sounds a bit implausible, but then these things often do. I've certainly seen published techniques where people have looked at documents that have been handled. There are no apparent fingerprints but they use something called confocal fluorescence microscopy to be able to see under the surface of the document and actually see the ghostly imprint of a fingerprint on a document that's not actually on a surface. The lipids from the fingerprint, the fatty material and the proteinaceous material, have soaked into the document. This very powerful technique, used a lot in cellular biology, is able to reveal the fingerprint under the surface of the document.
Chris - Finally, talking about things leaching into other things, what about when people try to dispose of bodies in environments like peat bogs, where bodies are very rapidly dissipated. Can you tell from samples of peat if there was a body there?
Trevor - There are several ways this has been attempted, but it's never been particularly successful. You can look for the decomposition products of the human body by organic analysis, but a new technique being developed by colleagues in Northern Ireland is to look for stable isotopes. Stable isotopes of carbon, nitrogen, oxygen in the ground water, and to try and look for bodies by using the natural water system in rivers and swamps and suchlike to try to look for the body itself.
40:38 - "Hair" Pollution: How what you eat and breathe affects the composition of hair
"Hair" Pollution: How what you eat and breathe affects the composition of hair
with Dr Sarah Hall & Dr Karen Scott, Anglia Ruskin University
Sarah - We're going to do the whole of the hair, rather than sections of the hair, so I'll take it at the bottom of your head. I'll try and cut it in the same region so you're not left with too many spikes.
Azi - I've come to Anglia Ruskin University at the Department of Forensic Science and Chemistry, and I'm joined by Dr Sarah Hall, who's a specialist in looking at heavy metal concentrations in hair.
Sarah - I think that'll do. And there we go. OK?
Azi - Oh, right. So you've got a good lump of my hair. Fantastic!
Sarah - It's a fair amount. Sorry!
Azi - No, no, it's fine.
Sarah - OK. Now I'll do mine. I think that'll do. There we go.
Azi - Where would contamination of heavy metals come from?
Sarah - Well it would come from a number of exposures - atmospheric exposure, maybe from your food, your drinking water - but all hopefully low levels.
Azi - Now, it's quite interesting with me, because I've only actually lived in Cambridge for the past three months, and before that I was living in London.
Sarah - I live in Ely [Cambridgeshire, UK], and I've lived in Ely for ten years, and hopefully we may see a difference between yourself and me living in Ely.
Azi - What sort of things would you expect to be exposed to in Ely?
Sarah - Traditionally, you'd think that there may be some exposure from farming practices, maybe herbicides. Traditionally, arsenic tended to be used in herbicides. But again legislation, and changes in farming practices, mean that we may not see that, but we may see a difference because you lived in a more built-up area.
Azi - Fantastic! Well that sounds really exciting. I was also wondering whether you'd be able to tell the difference between somebody's diet, for example, because I don't eat meat at all. I don't even eat fish! But would my hair show up things that, perhaps, somebody who has a different diet practice would not show up, or the other way around?
Sarah - Actually, I've got a research student who I know is a meat-eater. Let's see if we can talk her into taking a bit of hair.
Azi - Could we, please?
Sarah - Yes.
Azi - Excellent.
. . .
Azi - OK, so now that we've got three bits of hair - one from you, one from me and one from Lata - what are we going to do with them then?
Sarah - Well, first I think we should wash them in a soap solution, just basically to remove any sort of conditioner or any hair product. I'm just going to give these a little stir, and then we're going to put them in the sonicator.
. . .
Sarah - All I'm going to do now is just decant the soap solution off, and then wash the hair with some de-ionised water, then a last wash with some methanol, dry it in a bit of filter paper, and then we should be able to easily cut it into smaller sections and get it into our containers.
. . .
Sarah - I've got your hair in the container now, so I'm just going to add nitric acid and hydrogen peroxide, and then pop it in the oven, as they say. And that's it - just leave them for about four hours to digest. Once they've digested, you've got your metals into solution, which then allows us to do the analysis.
Azi - Lovely. Alright, well, what I'll do is, while we wait for everything to cook, I'll pop across the corridor and have a chat with Dr Karen Scott.
Sarah - Yes, okay. And I'll see you soon.
Azi - Yep, excellent. I'll see you in a bit then.
. . .
Karen - Hi, I'm Dr Karen Scott. I work in the Department of Forensic Science and Chemistry at Anglia Ruskin University, and I'm a Forensic Toxicologist.
Azi - So, you look at all the components that get into people's hair, but how do they actually get there to start with?
Karen - Well, basically, anything that is ingested into your body goes into your bloodstream, and our hair grows from components which are retrieved from the bloodstream. As the hair then grows out of the head, the drugs and other substances bind to melanin within your hair, so something that was there, say, a month ago, a month later will be one centimetre away from the point of start of growth of the hair.
Azi - What can hair tell you about a person?
Karen - It can tell you ethnicity. It can tell you which part of the body it's been taken from. It can't tell you whether the donor is male or female, unless you go down the DNA route. It can give you an indication, obviously, if they've dyed or treated their hair in any way. And also, it can tell us if they've ingested drugs in the past. So there are lots of different things that we can tell from the hair sample.
Azi - Dr. Sarah Hall is actually showing me how she can get heavy-metal exposures from hair samples.
Karen - Yes, so that will give you an idea of things like diet. Most people, when they think of forensics, are thinking of crimes being committed - maybe somebody's been poisoned, or someone's been taking drugs - but we can also look at environmental effects in terms of exposure to chemicals which we shouldn't be exposed to.
Azi - Thank you very much. It's been a pleasure.
. . .
Azi - Well, Dr. Hall, you've been looking at these samples and you've got the analysis, so can we have a look and see what you've got?
Sarah - I have to say, we have no cadmium or lead, but Lata had quite an unusual high concentration of nickel. However, she does tell me that her diet is based on a lot of pulses and lentils, and nickel is found in that sort of food.
Azi - But was there anything to differentiate her meat-eating diet with our vegetarian diet?
Sarah - Well, I tried to look at that, so I was looking at iron - because I thought it would be rich in meat and liver - and zinc is quite a lot found in meat, shellfish, dairy foods and cereals. But it doesn't really show in the results much difference between the meat-eaters and vegetarians, I'm afraid.
Azi - So what about the phosphates? Did we find anything that was different between the three of us that perhaps indicated the levels that you might be exposed to in Ely?
Sarah - No. Actually, I had a lower phosphate level than Lata and yourself. In fact, Lata had a higher phosphorus level than both of us, but it might be because of the diet, because there's a fair amount of phosphorus in red meat and fish. So, that might be the difference between the vegetarian and meat-eaters.
Azi - What else has been interesting?
Sarah - The only thing there was an increase on was copper, and, again, Lata had a higher copper level than we had. Copper is found in shellfish and offal. Lata tells me she doesn't eat too much shellfish, but I think she eats a fair amount of red meat, and maybe offal.
Azi - I think you mentioned that Lata has an Asian background. Is that right?
Sarah - That's correct, yes.
Azi - And I know that some Asian families use copper to serve food on or even to cook food in. Would that have something to do with it?
Sarah - Ah, yes. Well, it could do, because a lot of lead pollution years ago came from cooking implements and drinking vessels that were actually made of lead compounds. So yes, that could be true.
Azi - Excellent. Well, thank you very much. It's been absolutely fascinating, and I'm really thrilled that I'm quite healthy and I can carry on with my healthy vegetarian diet. Thank you.
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