Week 7 - 3 Toxins & Biological Poisons

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From the course by Nanyang Technological University, Singapore

Introduction to Forensic Science

349 оценки

Nanyang Technological University, Singapore

Introduction to Forensic Science

349 оценки

We have all seen forensic scientists in TV shows, but how do they really work? What is the science behind their work? The course aims to explain the scientific principles and techniques behind the work of forensic scientists and will be illustrated with numerous case studies from Singapore and around the world. Some questions which we will attempt to address include: How did forensics come about? What is the role of forensics in police work? Can these methods be used in non-criminal areas? Blood. What is it? How can traces of blood be found and used in evidence? Is DNA chemistry really so powerful? What happens (biologically and chemically) if someone tries to poison me? What happens if I try to poison myself? How can we tell how long someone has been dead? What if they have been dead for a really long time? Can a little piece of a carpet fluff, or a single hair, convict someone? Was Emperor Napoleon murdered by the perfidious British, or killed by his wallpaper? *For Nanyang Technological University (NTU) students, please be noted that this course will no longer be eligible for credit transfer.

From the lesson

Toxicology

Week 7 - 1 Introduction to Toxicology16:51

Week 7 - 2 Deliberate & Accidental Poisoning9:36

Week 7 - 3 Toxins & Biological Poisons7:44

Week 7 - 4 LD5012:24

Week 7 - 5 Forensic Toxicology13:54

Week 7 - 6 Alcohol20:06

Week 7 - 7 Inorganic Poisons - Arsenic14:55

Week 7 - 8 Inorganic Poisons - Thallium5:17

Week 7 - 9 Inorganic Poisons - Barium5:00

Week 7 - 10 Nerve Agents13:24

Week 7 - 11 Georgi Markov Case4:16

Week 7 - 12 Alexander Litvinenko Case; Summary6:14

Meet the Instructors

Roderick Bates
Associate Professor
Division of Chemistry & Biological Chemistry | School of Physical & Mathematical Sciences

[MUSIC]

There's a certain group of compounds which are referred to as toxins.

And this is a special group of poisons,

these are natural substances which are produced by living species.

And like the poisons that we already discussed,

they will also attack important biochemical mechanisms.

One example is the poisons produced by jellyfish,

such as this creature here, the box jellyfish.

This is one of the most poisonous of all jellyfish,

and is one of the reasons why that it's dangerous to go swimming

in the waters off Queensland at certain times of the year.

Spiders are also famous for being poisonous.

Here's one of the most famous,

that's the black widow spider.

Technically, these creatures are referred to as being venomous,

rather than poisonous.

However, the substances they produce are indeed poisons,

by the definition we're using in this Course,

and you'll see that definition shortly.

The difference between venomous and poisonous is really one of semantics,

and if you're bitten or stung by one of these creatures,

you're not going to have time to argue about semantics.

And here's a poisonous fish.

This is the Fugu fish,

and there is somewhere 20 to more than 40 cases of Fugu fish poisoning per year.

Now, the Fugu fish is quite interesting as a source of poison,

because it typically only poisons Japanese people,

and this is because this fish is considered a delicacy in Japan.

So how come that there aren't more Fugu poisonings?

And the reason is that the poison, which is a chemical called tetrodotoxin,

is concentrated in the fish's internal organs,

and the amount of tetrodotoxin in the actual meat of the fish is very,

very little indeed.

So Fugu fish chefs go through extensive training

on how to carefully remove all of these highly toxic internal organs,

and those parts are then locked in a special box.

The poisonings that do happen, typically come from amateur Fugu fish chefs,

people who have one of these fish and

want to have a go at cooking it themselves.

Tetrodotoxin is extremely poisonous, but most

of the people who get poisoning in this way don't actually get a lethal dose.

The fatality rate is only a few percent, fortunately.

Well, if we're talking about poisonous creatures,

probably the most famous are the snakes.

Many snakes from all around the world are venomous.

One of the most famous stories concerning poisoning by the snake

concerns the Egyptian queen Cleopatra.

Now, Cleopatra had been seriously playing politics in the Roman Empire.

She had a torrid affair with the Roman dictator Julius Caesar,

even providing him with a son.

After Caesar's assassination, she linked herself up with Mark Antony.

Unfortunately, Mark Antony lost the subsequent Roman Civil War,

and Cleopatra, like him, was on the losing side.

So, what's she going to do?

She's in her palace,

the troops of Augustus Caesar are marching towards the palace to catch her.

Now, in Roman times, in Roman culture, if someone had

gone into politics and lost, then the honourable thing to do

would be to commit suicide and go and meet the gods.

So Cleopatra was going to do this.

But, she thought, according to the legend, that if she was going to

meet her ancestors and to meet her gods, she wanted to look nice.

So according to the legend, what she did was to get her servants to

try out different means of suicide so that she could pick the best one.

And the one she chose was to be bitten by a venomous snake.

In particular, according to the legend, it was this snake, the asp.

So when the Roman soldiers got to her palace, Cleopatra was already dead.

Microorganisms also produce toxins.

This, for instance, is the organism that is responsible for botulism and

it produces one of the most toxic substances on the planet.

Now, ironically, people will pay very large amounts of money

to have this highly toxic substance deliberately injected into their head,

as you can see in the picture here.

And this is the so-called Botox treatment.

So, how come people will actually pay to have this stuff injected into their head

and it doesn't do them any harm?

Well, what Botox does is to paralyze the muscles.

But because it's localized only in the area where the injection is given, and

it is not carried through to the rest of the body,

it only paralyzes that particular region

and doesn't actually paralyze any vital muscles.

Another extremely nasty organism is this one, which is responsible for

the disease anthrax.

Now, even in the Second World War, anthrax was recognized as a potential weapon.

Though it wasn't used in that conflict,

weaponized anthrax has been available to certain people ever since.

So, the most famous outbreak of anthrax poisoning was during the 9/11 crisis.

So at the same time that the World Trade Centre in

New York City was destroyed by airliners,

various people in the United States,

including members of the U.S. Senate, were receiving letters. And

when they opened these letters, white powder would come out.

Several people died died because of this, because that white powder was anthrax.

Well, after a long investigation, suspicion turned to

a man called Bruce Ivins, who was a U.S. Army microbiologist,

and in his lab, he had this kind of anthrax.

Well, this investigation never came to a complete conclusion,

because as the investigators closed in, Bruce Ivins committed suicide.

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