Antidepressants in Stream Waters! Are They in the Fish Too? Completed

Sources/Usage: Public Domain.

More of What the Scientists Found

Average concentrations of antidepressants in water, sediment, and fish neural tissue from Boulder Creek just below the point where wastewater from a sewage treatment plant is discharged (USGS Site ID 400305105103901). Since concentration units differed for each sample type, the concentrations were normalized to the highest single antidepressant concentration in each sample type (highest concentration was set to equal one). The graph shows that fish selectively absorb some antidepressants more than others.

• This study is the first to demonstrate that the concentrations of these antidepressants in stream waters do not necessarily correlate with the concentrations or presence of antidepressants that are found in fish tissue. Other factors come into play that determine which antidepressants are taken up by the fish.
• The most frequently detected antidepressants in wastewater and stream water were venlafaxine, bupropion, and citalopram. In contrast, the most frequently detected antidepressants in fish brains were fluoxetine, norfluoxetine (a transformation product of fluoxetine), sertraline, and norsertraline (a transformation product of sertraline).
• The scientists collected the brains of white suckers because antidepressants are designed to modulate the concentrations of brain chemicals called neurotransmitters (such as serotonin, norepinephrine, and dopamine). Thus, brains are the location in fish most likely to be affected by antidepressants.

"The most important observation in our study is that you cannot necessarily predict which antidepressants are present in aquatic tissue from antidepressant concentrations in the water the organisms are living in. This study clearly documents selective uptake of specific antidepressants into fish brain tissue that were minor components in corresponding water samples. There are many reasons why this selective uptake may occur - including differences in fat versus water solubilities of the targeted antidepressants - but these results suggest other, as yet unidentified mechanisms may also be involved that warrant further study.

We also do not yet fully understand the implications for fish health and populations from exposure to these antidepressants. However, we have collaborated in laboratory experiments (Painter and others, 2009) documenting a slowed predator avoidance behavior in larval fathead minnows exposed to antidepressant concentrations similar to those observed in this study. A slower response to predators is probably not helpful when you are on the lower end of the food chain."

Edward Furlong, USGS research chemist, corresponding author

Sources/Usage: Public Domain.

The study was conducted in collaboration with scientists from the College of Wooster, Ohio; St. Cloud State University, Minnesota; and the University of Colorado at Boulder.