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.