What's the most toxic chemical?

Ljiljana - Interesting.  Again, plenty of candidates but the most toxic chemical is basically a natural product. There are some chemicals which were made in the lab which can be very tricky but the most toxic according to some scales is the botulinum toxin which is funnily enough used in Botox. But there is a particular scale which is used and it is a lethal dosage that kills 50 percent of subjects. And this is in the case of botulinum toxin, 1 nanogram per kg. That means that you need very low amounts to cause really toxic effects. So it's kind of you know it is a little bit ironic that you can basically use it also in cosmetics today. When we think about synthetic compounds, there are some neurotoxins that have been made. And you know when Haydn was talking about some dangerous stuff and some risks so there may have been lots of chemicals that have been made that are extremely toxic. One of the most toxic ones is the chemical called VX. It's a synthetic poison, a nerve agent. So it basically inhibits signaling between denounced it will cause lots of muscle convulsions and heart attack and it will really kill people instantaneously. It's still less toxic than botulinum. So you would need around three micrograms of this compound to kill the person which means nature has made the most toxic ones.

Chris - I've got something I think can challenge that, Ljiljana. I said there's someone who got in touch and I think that this lady's cooked up something that could give you a run for your money! I just want to read you this letter and you can as the chemist on the team you can tell us what you think of this...

So this is from Mrs. E. Naughton and she's written in and she says she she likes the programme, but she's also a fan of cooking and she was making some stock. She's boiling up some Lamb bones in three independent pots. She didn't have a lid for one of them. So she found instead a frying pan. That was a bit smaller than the top surface of the saucepan, put two wooden skewers across so that the steam could still escape and put the frying pan bottom down on top of the pot because the frying pan was slightly smaller than the diameter of the cooking pot so that way, acted as a lid. But it was a frying pan. She went away for a couple of hours leaving her stock simmering came back coming down some other jobs and she said after two hours of boiling the other pots had this lovely honey-coloured stock in them, delicious. The pot with the frying pan on the top now had this charcoal black or dark green substance. The pan was black on its bottom although it did wash up fine later, I'm pleased to hear. She says she's kept this liquid separate. So should I use it, she’s wondering, or should I chuck it away?

Ljiljana - You know considering that there is a control experiment that she has done and this is this honey colored wonderful stock I would say probably chuck it away.

Chris - What do you think is in it?

Ljiljana - So I'm suspecting that the pan was made of copper.

Chris - She said it was a copper-bottomed pot. 

Ljiljana -  So it's probably copper hydroxide or copper carbonate.

Chris - So why has it come off?

Ljiljana - The copper has oxidized. So the copper pan is made of metallic copper. Copper very easily oxidises. So I think the combination of steam and a combination of maybe some herbs that she has put and some aromatic compounds that were boiling, oxidized the copper, made copper II compounds - carbonate or hydroxide. There are not cases of direct poisoning with a copper II compounds, but there is a certain lethal dose there. But everybody is more or less sensitive to some of the copper ions, so I would just say, chuck it away.

Chris - Probably good advice. It probably wouldn't taste great, and it didn't look that good either compared to what else is on the plate.

Ljiljana - Yeah there is that the interesting thing about food. Usually it does look very good and tasty and then you should eat it. And if it doesn't then yeah think twice.