0:07
And here in this picture, I want to show you kind of the classical framework,
or exposure pathway schematic it's called,
of how we might be exposed to chemical contaminants in our environment.
And here's a classic case.
So, imagine that's your house there on the left.
0:25
And these days it might not necessarily be a leaking drum of chemical waste,
but perhaps it's something like an oil well.
A fracking location where there is
the use of chemicals as lubricants in fracking operations or, in fact,
some of the byproducts of oil drilling getting into the groundwater.
So here in this picture, it tries to show the big kind of cycle of how things
leak into the environment and leech through the soil
into the groundwater, be carried through the groundwater and
perhaps then ingested either by somebody, who in this case has a well, or
by a population downstream who may drink from a river or a stream.
But if you could kind of follow this, imagine a chemical,
which is synthesized, gets delivered to the environment in some way.
1:20
Or it may travel through the air as a vapor or a mist,
settle down into the soil, then down through the soil into the water,
where it may also be picked up in the water table, not just as a drinking water
contaminant, but it might be picked up by wildlife.
So contamination that is in the water supplies or
the water ways might be taken up by organisms living in those streams and
amplified or brought to us through edible fish for instance.
Or, back to this diagram,
you see the, not that everybody has a cow in the background, but
just imagine you have fallout of a chemical from a smokestack nearby or
from some release nearby, or pesticide spraying.
And you have a cow eating the grass that's growing there.
This was a major concern for instance, when I was a kid.
We were terrified of the fallout from the nuclear bomb tests and
traveling all across the world.
And was our milk contaminated with strontium-90, a radioactive chemical?
So the picture really is to show you it's complicated and
we have to think about exposure.
So this conceptual model is a way to think about the multiple pathways
through air, through ingestion or drinking water, through eating, and
through direct contact that we can be exposed to chemicals.
And so there's the kind of conceptual world.
3:07
This neighborhood is built on a site of an old army base,
where there was a testing of chemical weapon back in 1917.
And unfortunately, an incomplete cleanup before the neighborhood was developed,
way back in 20s.
And unfortunately also, in recent years, unexploded shells were discovered.
And as the EPA and others began to dig to try to remove these hazards,
working with the Department of Defense, widespread contamination of
the environment was revealed, so there's a major clean-up effort.
So take a look at that picture and imagine you live in a house there.
How might you be exposed to chemicals from the environment?
3:51
Well, it could be plants in your backyard that you're growing.
So it could be uptake by vegetation if there's arsenic in the soil.
It could be direct contact if you like to play in the dirt.
So nearby here is the university, and believe me, university students playing
sports in a nearby playing field might have a lot of contact with dirt.
Other ways you might be exposed perhaps are through the sub pump in your house,
perhaps some vapor exposures from other types of chemical contaminants
that might be there.
So, as you can see, it's pretty complicated.
Luckily, in Washington D.C.
they don't have many dairy farms here on the old weapons site.
But the exposure scenarios are complicated, because as you can also see,
when they began to excavate, look in that hole.
What do you see? You see a lot of water, right?
So nature likes to spread things around, and eventually,
anything we bury in the ground ends up in our water supplies one way or another.
It's a long process, but the environment is all interconnected.
So I thought you'd like to see that picture of the real world.
There's another cool thing there.
So you see that big blue tent?
Well, that kind of reminds me of the movie ET,
when they're trying to figure out about this alien from another planet.
It almost looked like that, because imagine I went over and visited that.
The crew working in full protection, digging through what
they had excavated from the ground there to see traces of things that might be
harmful from the old laboratories, little laboratory bottles and other debris.
So they created a pressurized environment to make sure that
off-site exposures didn't happen as they worked to remediate this facility here,
down in, believe it or not, Washington D.C..
Now, there are a lot of exposures that happen everyday that are a lot less
dramatic than chemical weapons from World War I, and a lot more common.
And I wanted to show you a couple of examples of those.
So imagine a newborn infant having a baby bottle, what's the exposure there?
6:11
But, very few people suspected that the plastics and the very fabric
used to make the nipple on that baby bottle nice and soft and
pliable contained a plasticizer that would have some chemical off gassing and
actually would expose that baby to phthalates.
So, there's lots of ways in the chemical world that we live in,
we are exposed to trace chemicals.
6:38
Recently we've had some strong recommendations, and
manufacturers have really tried to think how they manufacture products for kids.
Because we want to avoid the kinds of exposures that we now know about
through many plastics.
And then there are some other classical types of exposure.
I mentioned spraying of insecticides and DDT.
We all hate to get bitten by mosquitoes.
In many places, particularly when we have the emergence of a new threat like
West Nile disease will be at night using a fogger, as you see there on that pickup
truck, to spray certain low lying areas to control pests or control mosquitoes.
That's a good thing, right, but it's also something that might lead to exposure.
7:23
And then there's that thing in the right hand corner there.
What do you think that is?
And how might you be exposed there?
All right, so that's a can of tuna fish, I took the label off and opened it up.
And I know what you're thinking, right, oh tuna,
you read somewhere that there's mercury in tuna.
Okay so that's a chemical exposure, I'll grant you that.
But does anybody know the other potential exposure from canned goods?
8:08
contains a substance calls bisphenol A or BPA.
And we're very concerned that this compound
may have adverse affects on health.
So exposures are complicated.
They could be old traditional types of exposures, but
exposures happen at very low levels in many of the things that we do
in our everyday lives, from eating, to nursing, to breathing the air outside.
Dr. Megan Weil Latshaw, PhDCo-Director of the Masters Programs in Environmental Health
Beth A. Resnick, MPHAssociate Scientist
