What are the most common poisons?

Lorna Nisbet answers this tricky toxicology question...

Lorna - When people are trying to, effectively, bump each other off, they either tend to be quite planned out or they generally are just things that are heat of the moment so you don't get a huge amount of poisonings anymore. The instrumentation that we use is now so sensitive that it's detecting way lower concentrations than ever before. So poisoning as a ruse and a way of killing somebody is really quite unfavourable. And the last time that we've really seen somebody doing that would probably be kind of like the Steven Port case where he was using GHB to kill people that he was meeting in Grindr. And that's only because that substance is endogenous in the body so we don't know how long, you know, like how much he had in it to begin with. And so it's not that common anymore.

Chris - Can I ask you a question which is sort of related. Because we've had a lot of issues with people doping in athletics, and that also is putting foreign molecules into the body, which people with instruments, like the ones you're referring to can detect. When people give themselves a big blood transfusion with blood that they banked from say two months ago, so they took some blood out of themselves, froze it down, and then they thaw it out before big race and reinfuse it could you detect that?

Lorna - So yeah, they can detect that, but that's got to get done by a specialist and toxicologist, which is not something that I am capable of doing.

Chris - How do you tell someone's got their own blood?

Lorna - Because they will be looking at, um, the different biomarkers within it, they'll be looking at the different oxygen consumption and various different other telltale signs within it. But that's done by kind of the WADA labs, so Kings College London, for example, and they have to be specialised for that work.

Sam - So I work in the field of obesity and diabetes and I've read insulin being used as a murder weapon in several detective novels. Have you ever come across that and would it still work with modern day insulin preparations?

Lorna - Yes, you could. Nicotine patches is another one. A lot of medication is getting misused and mishandled and so anything can actually kill you. It's just about the dose. So, and we've known that since about the 1600s when it was Paracelsus who said the dose makes the poison. So yeah.

Chris - But I think the, the point that you're referring to Sam is that some of these insulin preparations that we give patients are a little bit different than just the stuff that comes out of your pancreas. So can you tell the difference?

Lorna - Well, you would be able to look at the concentration of insulin within somebody anyway. It's not going to be a small amount of insulin that you're going to have to give somebody. It's not the same as doing like a diabetic injection. So it's about the concentrations. And that's why I love what I do so much because you're working in the grey and you have to put all these different parts together.