I once heard
someone say that if you brought a glass down to the Potomac River and took a long
swig of its water, you would have swallowed a small dose of antidepressants.
While drinking Potomac River water is highly discouraged, there may be a hint
of truth to this statement. Thousands of pharmaceuticals and personal care
products are on the market, and many inevitably make their way into rivers and
streams through wastewater discharge or other sources. While we might not
necessarily be chugging river water on a daily basis, many organisms call the
Potomac River home and can’t escape the barrage of these so-called emerging
contaminants. However, “emerging contaminants” is a misleading term for
pharmaceuticals and personal care products, which have been in our waters for
many years. It’s only recently that scientists developed methods sensitive
enough to precisely measure trace quantities of these pollutants.
My part in the OSCAR Summer Team Project, in conjunction
with the Potomac Environmental Research
and Education Center (PEREC), involves using these advanced methods to
determine what pharmaceuticals and personal care products are present in water,
fish, and sediment samples taken from the Potomac River. The ultimate goal is
to determine what risk (if any) they pose to aquatic organisms in the
quantities we detect.
I’m a Chemistry
major with a concentration in Analytical and Environmental Chemistry at George
Mason University. The most common reaction I get to this revelation is a look
of utmost distress and a sympathetic hand on my shoulder; however, I have loved
chemistry since discovering that mixing baking soda and vinegar in just the
right ratio makes the best volcanic eruption for an elementary school project.
While the chemical reactions involved in this project aren’t as visually
dramatic as spewing lava, their results and the data we collect from them could
be earth shaking. Along with my partner Tabitha King, I am analyzing water,
fish, and sediment samples collected downstream from the wastewater treatment
plants in both Gunston Cove and Hunting Creek, looking for 77 different
pharmaceuticals and personal care products, ranging from antidepressants to
high blood pressure medication and even insect repellent and topical creams. All
of our prepared samples will be analyzed by LC-MS/MS, which is a beast of a machine
capable of detecting picograms (one trillionth
of a gram) of a specific chemical.
[Without getting
too technical, LC-MS/MS, liquid chromatography tandem mass spectrometry, works
by separating chemicals in a column (liquid chromatography) and detecting them
by mass (mass spectrometry). Imagine having a whole pile of almost identical
watches, and you want to distinguish which one is a Rolex and which one is a
fake. The first job is to separate them out from each other in the pile, so
you’re only working with one type of watch at a time - this represents liquid
chromatography. The next step is to determine their masses; however, a fake may
have exactly the same mass as a genuine Rolex. The solution to this predicament
is to smash them all to pieces. By smashing each watch with similar amounts of
energy and determining the mass of all the debris, you can come up with a
“smash pattern” for a watch based on how it has fragmented. All the Rolex
watches are made from the same components and will always, theoretically, break
apart the same way if struck by the same amount of energy. The same is true for
chemicals. By finally comparing the unknown patterns to known patterns
determined beforehand, their identities can be revealed just like a
fingerprint. If that’s not already cool enough, we can calculate how many grams
of a compound are in each sample by further analyzing our data.]
Since we can’t just
stick whole fish and a spoonful of mud into the machine, as convenient as that
sounds our samples have to be prepared in such a way that the pharmaceuticals
are extracted into a solvent and can then pass through the machine without
clogging the sensitive interior. Solids to an LC-MS/MS are what cholesterol is
to our arteries; bad things happen if they build up. For this reason, I’ve
spent countless hours in the Shared Research and Instrumentation Facility
(SRIF) lab with Tabitha shaking mud samples and waiting for solvent samples to
evaporate down to fit into a small vial.
This past week
we began our quest to extract our list of pharmaceuticals from Banded Killifish
collected several weeks ago at Gunston Cove and Hunting Creek. These fish were
treated with the most advanced contraption modern science has to offer – a
blender. The blended fish goop took the rest of the day to extract the
chemicals from, and in the words of one of our project advisors and director of
the SRIF lab Dr. Huff, “It doesn’t exactly smell like salmon and dill.” Several
pairs of gloves later, the prepared fish samples were eventually loaded into
the LC-MS/MS, and we patiently waited to see what chemicals the machine detects
in our fish.
Why is our
project important? Previous studies have found that even small levels of emerging contaminants can
severely impact aquatic life; however, information is sparse regarding
pharmaceuticals and personal care products in the Potomac environment. A quick
initial glance at our data showed Venlafaxine, an antidepressant commonly known
as Effexor, was detected in one of our sediment samples. Whether it’s possible for these
pharmaceuticals to make their way back into the food web and end up on our
dinner table along with a beautiful largemouth bass is still unknown. What is
known, however, is that even if we’re not taking our glasses down to the
Potomac, this River is a major source of drinking water and may be filling our
glasses at home. Knowing what’s in our water sources brings us one step closer
to ensuring we have effective water treatment solutions and a healthy river
ecosystem.
With less than
three weeks left in our ten week project, it will be a sprint to the finish
line to organize all our data and finalize risk calculations.
