Heiko Schoenfuss, biology professor and director of the Aquatic Toxicology Laboratory.
Fish may be affected by pharmaceuticals entering rivers, streams and lakes through wastewater treatment plant effluents according to a recent study by the St. Cloud State University Aquatic Toxicology Laboratory and the U.S. Geological Survey (USGS).
The study, which included field and laboratory research, was published in November in a special edition of the scientific journal “Environmental Toxicology & Chemistry.”
St. Cloud State Professor Heiko Schoenfuss was the principal investigator of the study titled “Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches.”
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Lesteberg is pursuing a doctorate at Baylor University, Waco, Texas. Rearick is a doctoral candidate at Trent University, Peterborough, Ontario.
The research looked at the effects of nine pharmaceuticals on both larval and mature fathead minnows in the laboratory and at field sites.
It examined the effects both as individual and combined exposures of opioids, agonist opioids, antidepressants, muscle relaxants and sleep aids including:
- Hydrocodone, Opioid
- Methadone, Opioid
- Oxycodone, Opioid
- Tramadol, opioid agonist
- Methocarbamol, muscle relaxant
- Fluoxetine, antidepressant
- Paroxetine, antidepressant
- Venlafaxine, antidepressant
- Temazepam, sleep aid
All the pharmaceuticals examined in the study are all commonly prescribed and have been found in the environment by previous studies.
A comprehensive suite of symptoms of adverse health effects across minnow life stages were assessed to understand how the fish responded to wastewater released in areas that produce these pharmaceuticals.
Juvenile minnows experienced reduced growth and altered escape behaviors. Adult minnows were affected differently by gender. Female minnows experienced an increase in liver size, while males did not defend nests as rigorously and the minnows from the field experiment ended up producing a chemical protein, plasma vitellogenin, associated with egg production in female minnows, an indicator of feminization.
The study involved multiple exposure experiments with fish being exposed for three to four weeks to the pharmaceuticals being studied.
Rearick, Lesteberg and other students ran the day-to-day operations to maintain the fish and the exposure experiments. They did most of the dissections and helped with some of the experiments and analysis.
St. Cloud State has partnered with the USGS to study the effects of pharmaceuticals in fish since 2008. The studies for the current study was conducted in 2012. The work is already being followed up by new studies, which should be published in the next year that look at how quickly the pharmaceutical compounds are taken up by the fish and which organs they appear in.
The studies begin with the USGS finding pharmaceuticals in the environment and then working with the St. Cloud State lab to determine the best way to accurately measure the effect of those pharmaceuticals on the fish. Then the researchers go back to see if the same results are present in fish in the field.
The process goes on as more pharmaceuticals are found and need to be studied. Publication is an important step for graduate and undergraduate students who develop their publication record as they begin their research careers, Schoenfuss said.
Funding for the Aquatic Toxicology Laboratory comes from grants from the National Science Foundation and the U.S. Fish and Wildlife Service.
