The United States is home to one of the leading markets for pharmaceutical drugs. Because this is the case, its citizens tend to use a lot of pharmaceutical products in their everyday lives. Some of the compounds present in many of these drugs never completely metabolize out of the body; as much as 90% of a dose can be excreted from the body in urine and enter the sewage system. Pharmaceuticals can also enter wastewater from a number of other potential sources, including landfill sites, direct human disposal of drugs, and from livestock waste.
This, theoretically, should not matter since we have systems in place to monitor the levels of pharmaceuticals in our drinking water, and, according to our government, methods to properly purge all traces of these drugs from our wastewater. However, the majority of countries today do not have any active monitoring programs that routinely test for the presence of pharmaceutical compounds in water supplies. Many studies have detected the presence of pharmaceuticals in water supplies around the world. Although the concentrations are seemingly small, being found only around a few nanograms/liter, they can still have a potential impact on humans and animals alike. The latter category, especially non-mammalian animals like fish, are woefully understudied.
With pharmaceutical pollution already present in the world’s waterways, studies have shown that even very small amounts of these pollutants can have a sizeable effect on fish behavior by disrupting the critical behaviors that help fish survive in their environment. These behavioral disruptions would also magnify damage from existing threats, like more ecologically-fit invasive species and chronic overfishing.
The betta fish (Betta splendens) was a good species of fish to use in the experiment because they are known mainly for their aggressive behavior towards other fish, and even their own reflection, so if the drug had any disruptive effects, it would be readily apparent. Tylenol (or acetaminophen) was the best experimental drug because it was readily available and many people all around the world use it to relieve their pain. In addition, new research into Tylenol has shown that it has a sizeable effect on anxiety, so its global use is likely to be on the rise in the future, and thus it will be more prevalent in the environment. This study should be seen as a foundation for other studies on the effects of pharmaceuticals on wildlife behavior. If enough of an overall detrimental correlation is supported by these studies, then it might lead to federal regulations on pharmaceuticals that would incentivize a more scrupulous level of water filtration, which would not only benefit the wildlife, but also expose us to lesser amounts of potentially damaging chemicals.
David DeMoss, ’19
Aiden Litt, ’19
Huong Quynh Anh Nguyen, ’19
Isabella Blackburn, ’19
Twin Lakes, WI
Sponsor: Tammy Mildenstein