Hello my name is Craig Slattery and I'm
a lecturer in the UCD School of
Biomolecular & Biomedical Science. I'm
delighted to give you this taster
lecture on my own particular area of
interest which is toxicology.
First I'd just like to give you a
little introduction to the School of
Biomolecular & Biomedical Science and
the type of research and teaching that
we're involved in in UCD. The first
question you might have is what is
biomolecular and biomedical science? Really it's about studying biological or
living systems and we look at them at
molecular level, cellular level and then
at whole organism levels. In the
School of Biomolecular & Biomedical
Sciences we do this through different
subjects or different lenses and
different ways of looking at living
systems. We have five different
disciplines within the school.
Biochemistry is concentrating on the
machinery inside the cell, the proteins,
enzymes, how they work and how they
control how the cell behaves. Genetics is
concentrating on the DNA and the genetic
makeup of cells and again how that
can influence how a cell behaves and
how when DNA gets damaged, how that can
manifest as a disease or some sort of
disorder. Microbiology is looking at
microbes, so microscopic organisms like
viruses, bacteria, fungi, looking at how
they exist in our environment, how we
interact with them and ways to limit the
damage that some microorganisms can
cause to human beings. Neuroscience
focuses on the brain and the central
nervous system and the important
functions within the central nervous
system like memory formation, cell-cell
communication,
how they work normally and then what
happens during different types of
diseases that affect humans, diseases
like Alzheimer's disease,
neurodegenerative disorders, different
types of diseases which are very
problematic for humans and where
treatments are quite limited. Then
Pharmacology; is all about the study of
how drugs and molecules interact with
the human body, it's different to
pharmacy, pharmacology is about designing
new drugs and new ways of treating
diseases and trying to prevent diseases.
Ultimately all of these different
subject areas in the school work
together with the aim of increasing our
understanding of health and disease and
then using that knowledge to try and
create new medicines or new treatments
for diseases. My own particular area
of interest is toxicology or the science
of poisons and it is a sub-discipline
within pharmacology. The aim of this
short taster lecture is to give you an
idea of some of the aspects of
toxicology that you might study across
different modules within the UCD science
programmes. There are three modules
listed at the bottom [PHAR30030 - Toxicology, PHAR40160 - Drug Discovery & Development, PHAR40170 - Essential Pharmacology for Toxicologists] that's not all of
them, but they are ones where there would be quite a good focus and a good degree of
toxicology involved in teaching on those
modules. Usually when I mention
toxicology to people these are the sort
of things that spring to mind:
CSI and different television programmes
and really this is forensic toxicology
or it's using toxicology as a means to
solve crimes and of course that is a
very real application for toxicology and
it's probably the most visible one but
it's not what most toxicologists do
and it's not where most of the science
of toxicology is important for the vast
majority of people. Really what
toxicology is all about is protecting
people, protecting the general public, you
me, everybody on the streets, our family,
adults, children, older people, very
young people we have to try and protect
the vast majority of people from quite a
range of different things that they
could possibly be exposed to in the
environment, either through the air that
they breath, the food that they eat,
medicines they might take. Toxicology
is really about protecting the public
from anything that's potentially
dangerous or potentially hazardous to
them. Toxicology hits the news quite
frequently because usually when
something goes wrong with poisoning and
with people being affected by chemicals
or different agents it makes news, and it
seems like a long time ago at this stage,
but if you cast your mind back to just
before Christmas there were a series of
cases in the United States and a smaller
number in other countries of vaping
related injuries and deaths. Almost
3,000 people were confirmed to have this
lung injury in the United States and
68 people unfortunately died and what
happened here really was a contamination,
some sort of a chemical contamination
of the vaping liquid happened and then
when people use that product, they
inhaled it, it went into their lungs and
that contaminant, that chemical that had
shouldn't have been in there damaged
their lungs and unfortunately caused a
number of them to die. Most people in Ireland are very familiar with this guy. [Image shows Bord Gais Carbon Monoxide awareness advertisement]. He's
the canary thats the face of the carbon
monoxide poisoning campaign. Every year
this campaign runs and it's 
really important that it does because
even if we look back to Christmas Day
last year, just before the turn of the
year, 21 people were hospitalised in
France because there was carbon monoxide
poisoning during a Christmas Eve Mass unfortunately. Every year in
Ireland you'll see this and this is
toxicology in action, you know trying to
prevent people being exposed to a
dangerous chemical. Then sometimes
toxicology is not so obvious and
sometimes it's quite subtle and this is
really where they the scientists have to
do the hard work and some of you might
be aware that there is a bit of
controversy and a lot of legal cases in
the United States going on over a weed
killer called Roundup, which we use in
Ireland, and it's used all around the
world and has been for a long time but
there are now question marks over
whether a Roundup could potentially
cause cancer. That's something that
toxicologists are very interested in and
we have to figure out is it true, and
then what do we need to do about it?
As I mentioned toxicology is the science
of poisons and one definition that I
quite like is it's 'the study of how natural
or man-made poisons cause damage to
living organisms and also how safe
limits of exposure to different chemical
agents can be determined'. One big
misconception around toxicology is the
notion of non-toxic and toxic and
sometimes in the media this is
oversimplified and there is an attempt
to try and label things as being either
toxic or non-toxic. So one lesson to
take away from this mini-lecture is that
that's fake news, it's entirely incorrect,
it's impossible to characterise things
as being
toxic or non-toxic because that's an
artificial construct. In reality and in
science we always have big characters
and important individuals who make
discoveries or make observations and in
toxicology it's a guy called Paracelsus,
who was around in the 1500s, and his big
contribution to toxicology, and he's
called the father of toxicology, was the
observation that all things are poison,
nothing's without poison; and that's only
the amount or the dose that makes a
thing not a poison. It seems now like
a very simplistic kind of an observation
but it was pretty profound at the time.
It's basically saying that a little
bit of some things is okay, won't harm
you and if you exceed a safe dose bad things will happen, and that's going to be different for
everything on the planet but everything
has that capacity. He came up with
this concept so everything on the planet,
every chemical, every biological agent at
some level is going to be harmless to a
human being but at some level is going
to be dangerous. For some certain
chemicals and biological agents there is
a Goldilocks zone in the middle where
they may be beneficial and those are
the things that we've usually developed
on to be medicines. They do something
good in the body, at the right dose, but
obviously if you use too much of those
it can be dangerous. Usually if I was
standing in front of you I would ask you
to start naming things that maybe you
thought might break this rule. things
that are quite harmless. What's the least
toxic substance you can think of? Usually
within ten seconds somebody shouts water.
Let's look at water for a moment.
Water does conform to this rule, just
like everything else on the planet, and
when I talk about water damaging the
human body or poisoning the human body
we're not talking about drowning.
Drowning is a mechanical effect, it's
cutting off oxygen getting into the
bloodstream because it's blocking off
the lungs and
or the oxygen can't diffuse across.
What we're talking about here is is
water poisoning or dilutional
hyponatremia and what happens here is if
somebody drinks water too quickly and
drinks too much of it quickly, what will
happen is the blood will get diluted and
all of the important ions like sodium,
chloride and potassium, the salt, the
sugar they'll all get diluted to the
point where there isn't enough in the
system anymore and then excitable cells,
which are the very important cells in
our brain or in our heart, which rely on
electrical signals to work and to make
our heartbeat and to make our lungs
breathe, they start to shut down. In
toxicology we talk about something
called the LD50, which is a lethal dose
in 50% of a population, so for water and
it might surprise you to to know it's
not an awful lot about six to eight
liters for an adult. What that means
is if somebody was to start drinking
right now and they drank six to eight
liters of water within an hour to two hours, something like that, they
would get very seriously sick and if
nothing was done, if they weren't
treated they could potentially die. This is something that has happened,
numerous times unfortunately, so that's
just one example from 2007 where a woman took
part in a water-drinking contest to
win a computer and unfortunately she won
the competition but she had drunk so
much water so quickly that it overloaded
the system and she died. Of course
things like isotonic sports drinks, that
industry came out of this toxicology,
understanding and knowledge because
marathon runners used to go out, they
would run a marathon and then they would
start drinking water to try and prevent
dehydration but they weren't replacing
the lost ions, the sugar, salt
at the same time and they were diluting
the blood and quite often they would
collapse and lose consciousness. It
was quite a common thing in
long-distance runners and that gave
birth to the whole
industry of isotonic sports drinks. So on
the other end of the spectrum then we've
talked about something seemingly
harmless like water and how it's a
poison but let's look at the other end
of the spectrum the things that are the
most poisonous. The most
poisonous chemical that humans have
created is something called VX Nerve
Agent, and as the name suggests, nerve
agent, it interferes with nerve cells and
how they communicate with each other. The amount to kill an average
human being is very small, in this case it's 20 milligrams or 0.02
of a gram, which is a very small
amount. This is the most dangerous
agent that humans have made and of
course nature has been creating
molecules for much longer than we have.
The most poisonous chemical or agent
on the planet, the biological agent is
something called botulinum toxin and the
LD50 for that is 50 nanograms for an
average human being so that's
0.00000005 of a
gram. That's hard to imagine
or picture but if we take a grain of sand
sized piece of botulinum toxin that's
enough to kill 7,000 people. That just
gives you an idea of how poisonous
botulinum toxin is and you might say
well something like that far too
dangerous for contact with humans
obviously but the power of toxicology is
that botulinum toxin has been turned
into a medicine and it can be injected
for cosmetic purposes because it will
stop the cells that
make the muscles in the face contract
and make laughter lines and make
wrinkles. You can inject it and it will
paralyze those those nerves . The
world supply of botulinum toxin is
produced or the medcine Botox is
produced over in Westport.
Ireland have a big part to play in
the safe use of Botox and it's not just
as a cosmetic either because Botox is
very important for the treatment of some
disorders: where you have muscle spasms
or severe migraine or neuropathic pain.
Some people after a car accident they
might a very bad pain which conventional
painkillers just don't deal with.
That really illustrates the power of
toxicology of the science, we can take
the most poisonous agent known to man, the most poisonous thing on the planet and
we can turn it into a medicine, which can
be used safely. It's really
important because all of these products:
medicines, foods, food additives, cosmetics,
personal care products, household
chemicals all of these have chemicals in
them that are potentially dangerous. It's only through the use of toxicology
and understanding how these things could
be damaging to the body that we can
control that and we can make sure that
any of these products are going to be
safe. Hopefully that gives you a
flavour of some of the topics you might
expect to hear about in lectures about
toxicology in UCD. I work in the center
for toxicology and we do lots of
different research projects looking at
better ways of testing chemicals to make
sure that they're safe for
human exposure. Of course on a
broader level I hope it's given you a
bit of a taster for biomolecular and
biomedical science, the sort of things
were interested in, sort of problems that
we try to solve and I hope you
enjoyed this taster lecture.
