How do you know
the chemicals in this stuff you use and eat are safe?
Manufacturers and regulators work hard to ensure that what ends up in the
things you buy isn't harmful.
But it isn't easy. You can't really work out how safe something is by
feeding it to people, and seeing what happens next. Apart from the fact that
it sometimes takes years
for health problems to develop if you're exposed to a hazardous substance,
experimenting on people isn't exactly ethical.
This is why toxicologists use
animals, and cell cultures, and other tests that don't involve people.
They use these to explore what's likely to happen in humans.
But testing a substance thoroughly still takes a long time -
sometimes several years even. Partly because of this, only a few hundred
of the tens of thousands of chemicals we use today have been fully evaluated.
Many the highest priority ones have been tested.
But there is still an awful lot of chemicals in use today
that we don't know that much about.
Of course, responsible manufactures do their best to ensure that products are
safe as possible.
But the slow speed and the cost have many established toxicology tests
mean that companies and regulators alike simply
cannot keep up with evaluating everything they would like to.
They need something better; something faster;
something cheaper. And ideally, something that doesn't involve
using so many animals. Most importantly, they need some way
of triaging the waiting list of untested
chemicals, to see which ones are in most urgent need of attention.
A few years ago, a group really smart people at the US National Academies of Sciences
took this problem head on.
The result was a weighty report with the promising title of
"Toxicity Testing in the 21st Century"
At the heart of the report was a new idea
that would speed up toxicity testing enormously,
while reducing the time and resources needed, as well as the number of
animals used. The idea was quite brilliant.
If we can understand the underlying biological processes that
govern how our bodies work -
what the National Academies called "toxicity pathways" -
we should be able to come up with simple tests that show how much of a given substance
interferes with these processes. And if we could run
hundreds of these tests really fast, we should be able to quickly get an idea of how safe,
or how harmful, a substance is likely to be.
The report was a success. So much so that the Environmental Protection Agency,
the National Institutes of Health,
and the Food and Drug Administration, all got together and formed
a massive new initiative to transform toxicity testing in the United States.
The initiative's called TOX 21 - short for Toxicology in the 21st Century,
and it's now in full swing.
It was launched in 2008 ,with four aims:
First, to better understand the processes or the
pathways that govern how our bodies operate.
Secondly, to develop tests to see how
chemicals interfere with these pathways.
Thirdly, to develop way to predicting how hazardous substances might be.
And forthly, to identify those substances
that are most in need of more detailed safety research.
At the heart of TOX 21 are two really cool emerging technologies:
Hight throughput screening, and computational biology.
High throughput screening runs chemicals through tests
really fast. In fact robots are used to automatically place these substances
in tiny test wells, and observe what happens next.
These tests are designed to indicate how increasing amounts of chemicals
interfere with different toxicity pathways. However,
high throughput screening alone is pretty useless.
It generates a ton of data, but on their own, these tests it uses
can't tell us whether a chemical will in fact cause harm.
For this we need to integrate high throughput screening with some
advanced science, and some powerful computational techniques,
And this is when things get interesting.
By combining high throughput screening with advanced data processing and
computer modeling, TOX 21 is developing tools that are enabling
thousands of substances to be rapidly screened for potential toxicity.
Of course, TOX 21 is just the beginning of transforming how we ensure the safety
of the chemicals we use.
Ironically, despite the name, it doesn't
actually provide information on how toxic a substances is,
just how it may behave in a complex biological system like the human body.
And we're not yet sure how comprehensively
it can represent the full glorious 3-dimensional
messiness of human biology. But, the process
is both highly innovative, and incredibly important for identifying
chemicals that might be harmful.
For these chemicals we still need to use animals to better understand
the actual diseases they're likely to cause. And as always, we
also need to understand how much of something causes harm, not
just its potential to cause harm. But the more research we do on predicting what
happens in animals and humans from high-throughput screening
and computational biology, the more we can refine
reduce, and ultimately replace the use of animals in toxicity testing.
In the meantime, TOX 21 and similar programs around the world are transforming
how we identify chemicals
that have the potential to be harmful, and how to do the research that's necessary to ensure
they are used safely.
For more information on TOX 21, please do check out the
links in the block below.
And as always stay safe.