Chemicals surround us in our air, food, water, clothes and furniture. But which chemicals are harmful? The Environmental Protection Agency’s labs in North Carolina’s Research Triangle Park test them all.
Studying the toxicity of everyday objects
From the air we breathe to the food we eat, we're constantly being exposed to chemicals.
But what are the health risks associated with this exposure?
We go inside the lab at the Environmental Protection Agency and watch as scientists perform chemical toxicology tests to find answers to that very question.
Here's a look.
It doesn't get much cleaner than McCorkle Place, one of the large, grassy, tree-lined squares in the middle of the University of North Carolina Chapel Hill campus.
But grab a bench and look around.
You'll find people interacting with all sorts of chemicals in the midst of all that nature.
Take that person, eating his lunch from a Styrofoam container.
There are lots of people drinking from plastic water bottles, more than a few people sipping from coffee cups and drink cups, not to mention the hundreds of cellphones and earbuds being used.
Um, chemicals, we're exposed to them on a daily basis.
Um, they're in the -- the -- the air we breathe, the water we drink, even the products we use in the -- in the home.
And the -- the, um, the fact that not everybody appreciates is that the potential health risks of many of those chemicals isn't really fully understood.
Rusty Thomas directs the division of the Environmental Protection Agency that tests the safety of chemicals found in the items we use every day.
The labs of the National Center for Computational Toxicology are in Research Triangle Park.
Federal law gives the EPA the authority to test, regulate, and maintain an inventory of all the chemicals used in commerce.
The agency's inventory lists about 75,000 chemicals.
But there are different levels of scrutiny, depending on how the chemical is used.
The computational toxicology division has testing information on about 8,000 chemicals in its library.
We're tending to focus more on understanding the toxicity of single chemicals.
Um, but we do have some research efforts to understanding how they interact, mixtures, um, and how that mixture, the combined effects of chemicals may also be of concern to the agency.
The agency uses robotics and computational modeling to look at the link between the source of chemicals in the environment and negative outcomes, as well as study the health risk a chemical poses.
The new techniques allow researchers to assess the risks of large numbers of chemicals and pinpoint those needing further review, rather than examining individual chemicals one at a time.
And on the top, I've got an example of where will -- would test dozens of chemicals on a single plate.
But we'll test varying concentrations of each chemical.
And this gives us -- We call it concentration response.
We see how the biological response changes with increasing or decreasing concentrations of the test chemical.
There's a couple things.
You gotta see if it reacts and then how much of it --
Or how little -- how -- actually, how little of it is really what we're shooting for.
How little of it is required to actually produce a measurable response.
Weighing the potential toxicity of a chemical, a person's exposure, and the mechanism through which a chemical becomes harmful determines the possible health risk.
It's just not whether that chemical disrupts your hormone systems.
It's how much of a chemical is required to disrupt your hormone systems.
And that's what toxicologists typically refer to as a dose.
Um, and so we, uh, um, determine what dose we need to be concerned about.
And then we compare that dose of which may disrupt your hormone systems and compare it to those predicted exposures.
And the difference between those two is, determine how much we should be concerned about that chemical.
So, like, an example I like to think of, um, so I'm wearing t-shirt that is 100% cotton.
But 100% cotton means the fibers are all cotton.
They're actually -- it is treated with chemicals to keep it from catching on fire, which I appreciate.
But I wear that, I mean, it's all over my skin right now.
And so, knowledge of what the chemical is that's in the shirt, the markers of that chemical might very well also be -- you know, the CDC would be able to see that in us.
And, uh, and so that's the sort of chemical exposure.
And so we've actually tested chemicals like the flame retardant that would keep this shirt from catching on fire in the robot assays.
And then trying to predict whether or not we get exposed, we have to ask questions like, 'Is this in clothing?
Is it in cups?'
So let's go back to McCorkle Place.
The chemicals in different products are regulated differently.
Chemicals that go into pesticides, that are used in pesticides are regulated differently than, um, chemicals that may be in your shampoo or in other cleaning products in your house.
And those are under different levels of scrutiny.
Chemicals that go into a pesticide that are likely to end up on your food, um, are required to submit a whole range of toxicity studies to the agency for approval.
However, for chemicals in many of the products that we encounter on a daily basis, there isn't that requirement.
All companies are required to submit is, uh, what's called a pre-manufacturing notice.
And then the agency has 90 days to sort of demonstrate or determine, uh, whether they can proceed.
And, essentially, the burden is on the agency to determine that a product or a chemical is unsafe.
And so it's a pretty high burden.