How do scientists study contaminants in the environment?


Hello this is Dr.
Kim Anderson, and I’m an environmental chemist
at Oregon State University, studying contaminants
in the environment. One group of chemicals
that we study are the polycyclic aromatic
hydrocarbons, or PAHs. These are chemicals of
concern because some PAHs are toxic, or can cause
cancer in humans and wildlife. PAHs are often found
at superfund sites, and are also one of the
principal contaminants of concern in oil spills,
such as the recent oil spills in the Gulf of Mexico. This video describes passive
sampling devices, or PSDs. A unique tool that
we use to measure contaminants in the
environment, such as PAHs. In the environment only
part of the total amount of chemical present
is potentially available for
uptake by organisms. This concept is known as the
bioavailability of a chemical. It is the bioavailable
fraction that determines potential negative
impact on the health of people, plants, and animals. The BRIDGES project
uses PSDs to study the link between bioavailability
and health impacts. These are called passive,
because they do not need any power, or
maintenance, once they’re set up in the environment. The PSDs contain
a strip or tubing, that looks a lot like a
clear bike inner tube, but it acts like a
high-tech sponge. It absorbs chemicals like a
living creature, such as fish, birds or a person. Animals living in
contaminated waters are exposed to the
bioavailable fraction of water. Contaminants enter
fish and shellfish through their gills
and exposed skin. A contaminant in sediment is
not very bioavailable to fish that does not interact
with the bottom, but is more bioavailable to
shellfish, living or feeding in the sediment. Fish breed by absorbing oxygen
from water through their gills. If present, certain
chemicals can also pass through the thin skin of
the gills and into the fish, and a small amount of
chemical may also observe through the fish’s outer skin. This cartoon shows the
magnified surface of fish gills. Notice that some of the
chemicals enter the cell membrane, and go into the fish. Some are simply too
large to enter the pores. Others that appear to
bounce off the membranes, are not able to enter because
of specific chemical properties that do not allow
these chemicals to pass through the membrane. Once the chemical moves
through the membrane, it will enter the blood
circulation of the organisms, and possibly build
up in its tissue. This cartoon shows the magnified
surface of the PSD membrane. PSDs are able to estimate
the bioavailable amount of contaminant in water, because
they take in contaminants just like fish or shellfish. Like the gill
membrane, PSDs have pores that allow some
contaminants to enter, and block others based
on physical size. Certain contaminants will
be absorbed into the PSD depending on their
chemical properties. Contaminants that build
up in fish and shellfish are also absorbed into the PSD. A big advantage of
using PSDs is that they can remain in the environment
for days, weeks, or months. Collecting
contaminants over time, just like a fish living
in polluted water. This allows us to have a better
idea of bioavailable exposures, over longer periods of time,
instead of just collecting one sample of water on one day. It allows us to measure
very low amounts in water, since the PSDs can
concentrate chemicals over these days,
weeks, and months. To learn how you can be
exposed to contaminants in the environment be sure
to watch the first video on routes of exposure.

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