We really need to know what the molecular nature of mercury is in fish. If we want to know whether we’re going to be worried about it or not. There is no good just knowing there is methyl mercury something in it, it’s very important to know methyl mercury what. These are the only actual spectral data that I’m going to show you and I’m showing them to you just to give you a flavour of what we look at day in, day out. the little dots here you can see the best perhaps here and here  show what I call a spectrum  and what’s important  are the little  wiggles and  bumps on where there are  and they’re matched against a solid line  which  are like standard  compounds . What age do, the simplest piece of analyse that we do, by no means the only kind is to finger print them. We look at our x-ray absorption spectrum and we match them against a large number, maybe 30, maybe more of reference compounds that are synthetic, chemically characterised small molecules that we really know the structure of already. You can see the top one matches.  Here’s that methyl mercury fragment and it’s revealed to us what the rest is. We now know that mercury in fish is a methyl mercury Sistine species. Among all the possibilities we can underline this one and say this is what it is and this was published in science of last year about a year ago.  Methyl mercury Sistine, a long name, turns out to be much less toxic to fish. Other animals, mammal for instance haven’t been investigate d so we don’t know how toxic it is to mammals but it’s much less toxic fish. A little zebra fish carve which a tiny fresh water fish is found some other methyl mercury molecules.  obviously they haven’t tested all of the methyl mercury molecules  but  this is a strikingly less  toxic form of methyl mercury and many other species and in particular the other species that have been used  in clinical  experiments that have involved move and things to determine how toxic the thing is .

What we suggested was are the recommended safe levels for fish consumption lower than they need to be. We did day that they were because that would be a bit rash, we actually don’t know but there is cause to question it I think. Now that we know the molecular from us can actually move forward. When we started saying these kinds of thing all kinds of fuss happened. We ended up in a lot of newspaper and on the television a lot. The one I likes the best is the BBC coverage and I have to do this from memory, I hope I get it right. You probably know that I’m English from the ay that I’m talking and at the time that I did all these experiments I was at Standard but I subsequently moved to Canada.  They said something like “Canadian scientist report” and then they talk about what we discovered ” but British expert cautioned”. They didn’t say who the experts were.  I thought that as the best quote. The one I actually like the best was the New York Times which had a really nice, balanced article on it.

I’m going to change gears a little bit and deliver a message form our sponsor. This is a commercial break if you like. I want   to advertise the next lecture, the runaway Universe by Roger Branford who is the director of Cava lee Institute for Particular Astrophysics in cosmology. It sounds like a very interesting topic cosmology. I think we had one on slack , one on Singotorum Radiation , one on  anti-matter and matter , one on metals , molecules , death and things and now we’ve   got cosmology which is really a diverse thing. this is  to encourage you to  join slack collections and at this urn  you can find out a lot more about upcoming  lectures and also if you wan please sign up for a  tour of slack and you can  find out more about those right at the top level page there. As ii told you methyl mercury molecules are neuro toxic but there is just a huge amount we don’t know. We don’t know how they work. We have little clues but we are really into the dark about the bulk of the mechanisms about how mercury molecules cause damage to nervous systems.  One of the most curious things is they exhibit latency. A delay between exposure and the onset of toxic effects I’ll say more on that a little bit. It can be as long as 150 days in people, a really long time. This shows you what a creepy and insidious thing some of these mercury compounds are. You can be exposed to them and not know. There can be nothing wrong for ages and ages and then all of a sudden it will hit you out of the blue. Those are best illustrated in the tragic case of Karen Whitterhan. She was a professor of chemistry of Dark Moth College and she was using a substance called dimethyl mercury that I already mentioned. what she  was  doing involved a very small amount  of the material in a glass ample like this one right here and she was  transferring , she got a colleague of hers to  cool the  compound to minimize the vapour pressure and the  possibility of it bursting , the college cut a little nick in the top of it with  a file , they  crack the ample open , she used a little glass dropper like the ones h shown here to transfer a small amount  to a glass sample  tube for a particular  kinds of experiments. The tube was sealed up and with glass blowing torch and labelled. This happened on august 14th 1996.  she used gloves when she was doing this  whole thing ,  she wore latex gloves, she wore  safety spectacles, everything was done  ,  the entire procedure was done in a fume  hood, this is a device that chemist use a lot  when they  are dealing eighth hazardous  materials and there are  strong extractor fans at the tops of it and  it pulls the air rough to minimize exposure to you . you’re wearing gloves , lab  coat , safety spectacles  you’re talking all the recommended precautions at the end of the procedure she noticed that she had  spilled just a few  drops of this stuff onto her gloved  hands so it was on the glove not her skin. At that time she removed the h gloves, she made a b note of it in her log book. After everything was clean and tide she went home to her husband and her children. 5 months later she experienced difficulty walking and talking. She went to her neurologist, lest than a month later she was in a coma, another four months she was dead. There was not a thing they could do for her despite extensive and heroic treatment efforts. They could do nothing for her.

This is dangerous stuff. The point that I’m trying to get across is the latency. You get poisoned, you’re ok for five months and then something bad happens.  We have no idea how this works and to understand how it works we would need to understand the molecular forms of mercury that are involved and how mercury is being modified in the body.

One interesting way, mercury and selenium are linked in quite a curios ay in human metabolism. it’s been know for a  relatively long time that if  you take a dose  of mercury and I have the two together and I  accidentally drink the mercury and I accidentally drink and equal dose of selenium the toxic effects are cancelled  . It’s like your classic antidote. I was reminded of that classical Indiana jones movie where he has an antidote in a little tube and he gets the antidote and drinks it and he’s fine.  This would be the selenium blue he wold have to drink it ratty quickie before the mercury get him. We know a lot about how this works.  if I say “later I know I’m going to have some mercury so I would better have a dose off selenium right now ” so I take the selenium later and then maybe two hours later I have a dose of mercury the toxin effects of the mercury arte not only not cancelled but they are hugely magnified so it’s much more toxic. the  molecular form of the  selenium  is being transformed into  something in our bodies that is combining in the two hours in between and then it gets to  combine with the mercury that you ingest to produce  something that’s absolutely deadly . We have no firm proof or know how this really works.  This is a big mystery and it is one of the major things we are trying to understand. We did have to understand this a little bit.  Never mind the details of this picture the thing I would like you to concentrate on is this thing. when you  take mercury and selenium  together what happens is  you form a  little ball of mercury  and selenium like a ball bearing , maybe 100 atoms  in there surrounded by other molecular fragments never mind what they are and this floats  around the blood stream , its moved to the liver and its stored there forever until you die.

This is how it works, this is how the cancellation of the toxic effects is manifested. We understand this in some details now thanks to experiments done at SSRL.  Quite a curious thing to think you might have these ball bearing things in your blood.

Arsenate and Cen unite are the names of two common molecules that contain arsenic and selenium. There are about as toxic as each other and in isolation by themselves they are each lethal at elevated levels. Remember we need   canines in our diets, we need selenium in our diet. Selenium is pretty important. The level between enough n our diet and the toxic level isn’t very great.  When they are taken together like the mercury but the mechanism is quite different, their toxic effects is surprisingly cancelled. Maybe it’s not surprising because mercury did it but it works in an entirely different way.  It’s a quite an old piece of knowledge. In 1938 it was first published   that rats fed on 11 parts per million selenium I the form of canonized wheat, this is what contaminated with cinnysium. In 60 days fed <inaudible> amount of cilium and they all died.  If they were fed not only on the cenonyzed   wheat but giving the cynonte in their drinking water they all survived. It was later discovered that this was even more effective if you gave exactly equal doses of arsenic and selenium and the thing that emerged over the years was that there was a lethal dose of arsenide or cenunite can be complete counteracted by an equal or otherwise lethal dose of the other one. You could take two lethal doses together and you would be fine.

How does this work? Once again in Singotorum radiation our x-ray reveal the species in bile. This is excreted in the bile. What happens is the arsenic and the selenium comes out together in this cellular entity. We call it they celulobisesculictino arsenic iron. It doesn’t really matter but the important bit is in the idle where the atoms have labels and you can forget about the outside bits and just concentrate on the middle bit.