How planarians are affected by mouthwash and cough syrup

Cough syrup and mouthwash are commonly used items and often end up flushed down the drain or toilet. These substances can become dangerously addictive to humans over time and eventually get into freshwater waterways which can be harmful to many marine organisms, such as planarians (aquatic flatworms). To investigate the affects of these substances on planarians, we tested six different concentrations of Listerine mouthwash and its active ingredients and ten different concentrations of Robitussin cough syrup and its active ingredients. We used a behavioral assay to test the effects of mouthwash and cough syrup or their individual active ingredients on planarian behavior. Active ingredients of cough syrup but not mouthwash detrimentally affected planarian behavior. In light of our results, we provide recommendations for the disposal of cough syrup to lessen the environmental effect it can have on aquatic life.