Chemicals in Minnesota water supply affecting fish

A recent study published by the St. Cloud State University’s Aquatic Toxicology Laboratory and the U.S. Geological Survey (USGS) is helping to pave the way to broaden knowledge on pharmaceuticals entering the state’s natural water resources.

The issue of pharmaceuticals affecting fish and native wildlife in rivers, streams and lakes has been ongoing throughout the last several years, but the collective work of St. Cloud State professors, students and USGS researchers are drawing attention back to the topic.

Professor Heiko Schoenfuss was the primary investigator of a study published Nov. 13 titled, “Complex mixtures, complex responses: Assessing pharmaceutical mixtures using field and laboratory approaches.” The study was a compilation of research conducted in 2012 that brought to light that fish are being affected by chemicals entering the water.

Schoenfuss said, “We looked at a range of different pharmaceuticals – mostly based on types that colleagues had previously identified as being present in the environment. They are ones that you find in streams and lakes if you look for pharmaceuticals in those environments.”

Photo courtesy of  Flickr.
Photo courtesy of Flickr.

The results proved to be eye opening, as the researchers discovered effects from nine pharmaceuticals in both larval and mature fathead minnows in both their laboratory and field tests.

Schoenfuss explained minnows are the “white lab rats” in aquatic research, as they are found throughout the U.S. and live in a variety of habitats. They are an essential part of the food chain, as they are food for larger predatory fish such as walleye and bass. They make up approximately 80 percent of all aquatic organisms tested.

The effects on the minnows ranged by age and sex, with some facing more drastic changes than others.

One of these major changes was a behavioral effect on male minnows. Males are typically the guards and caretakers of the eggs after the female lays them. They are responsible for protecting the eggs, and if they fail, other fish may eat the brood.

But once the males were exposed to some of the pharmaceuticals in both the lab and field tests, they became significantly less responsive in only 21 days.

Researchers also noticed their livers shrank as well, leaving them more defenseless against toxins.

Interestingly enough, researchers noted the opposite effect on adult female minnows in which their livers grew uniformly larger.

“At first we were surprised by that. We knew from medical literature that if you expose humans in the same way, livers grow similarly. The liver cells [in the female minnows] were much larger than they should be,” Schoenfuss said. “Those effects all suggest these fish were really struggling to adjust to the pharmaceuticals that they were exposed to.”

Schoenfuss said, “Basically, juvenile fish were affected by growth and behavior, males behaviorally became slower and less responsive and had organs shrink and females were mostly affected by their liver being grossly enlarged.”

As the research continues, people may wonder how chemicals like that can even get into the water.

Schoenfuss said it happens a few different ways.

Humans typically excrete the chemicals that goes into waste or treatment plants, which are only designed to remove the nutrients, not pharmaceuticals, which easily pass through the system.

If people have their own septic systems, they typically aren’t hooked up to a wastewater treatment plan, which again, doesn’t break down pharmaceuticals. So chemicals found in excrement can get into the ground water or end up in lakes.

Another common way is through agriculture, as animals such as beef cattle are fed growth-enhancing chemicals that they ingest and excrete. Farmers tend to use their feces for manure for their fields, which wash off into rivers and streams if heavy rain occurs.

All of these findings have not only added to the growing research on the topic of pharmaceuticals in natural resources, but it’s also opening the eyes of various agencies.

As of today, pharmaceuticals in the water supply not regulated by any federal or state agencies. Schoenfuss says, as growing research builds, that may just change.

“Part of the reason we do the research is to see if they [rivers, streams and lakes] need the regulation. The FDA has a basic formula to see if they should look into the environmental impact,” he said. “We are looking at federal agencies starting to investigate some of the compounds to see if they need to be regulated.”

Until then, Schoenfuss and the other researchers will continue their efforts. He said they plan to continue exposing minnows to pharmaceuticals for longer periods of time, maybe even a year, to study the long-term effects. This will aid in determining the pharmaceuticals’ effects on their reproduction, health and longevity.

As for humans, Schoenfuss says they do not have to immediately worry about pharmaceuticals affecting them if they are exposed.

“It is very unlikely that recreational exposure to stream or lake water, or consuming drinking water for that matter, would have any negative effect for Minnesotans.  Similarly, it is unlikely that for the general population consuming fish exposed to pharmaceuticals in the environment would cause problems for humans,” said Schoenfuss. “However, vulnerable groups (young, old, immunocompromised) are of greater concern and long-term studies (including our newest one) are ongoing to examine the risks associated with that environmental exposure to pharmaceuticals.”

The Aquatic Toxicology Laboratory’s research is made possible through grants by the National Science Foundation and the U.S. Fish and Wildlife Service.


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