Endocrine disrupters in Minnesota waters are affecting fish populations.

We are only beginning to learn about many ‘’pollutants of emerging concern’’ that are adversely affecting aquatic organisms in our waters. Dr. Heiko Schoenfuss, a biologist and director of the aquatic toxicology lab at St. Cloud State University, gave an idea of the challenges we face during a presentation at the Hawk Creek Watershed Project’s annual meeting on Feb. 8 in Willmar.
Many of the pollutants are compounds that disrupt the endocrine systems of aquatic organisms, and consequently have gotten lots of press. It may be dramatic to describe them as monster fish, but the adverse effects being seen are scary. In the waters below Boulder, Colorado, only 25 percent of the fish are males. One-fifth of these males have ovaries and produce eggs as well as sperm. ‘’Very much screwed up,’’ is Dr. Schoenfuss’s not-so-scientific but accurate description.
Other effects do not seem so Frankenstein-ish, but damaging all the same. There are flathead minnows that do not have the reflexive, defensive response to curve like a ‘C’ when a predator is near. There are male fish that do not carry out nesting practices that are essential to the survival of progeny.
Scary too is when some of the physical and behavioral changes show up. In many cases it is not the fish initially exposed to the compounds that show the signs, but their progeny one and two generations later. In human terms, that would be a 20 to 50 year lag between exposure and consequence.
In most cases we are still trying to understand the occurrence and the effect of exposure. We are a long ways from knowing the implications to human health, but have every reason to be concerned. The hormones produced by fish are the same as those we produce. All animals share endocrine systems that are unchanged for 300 million years.
It’s only in the last 10 to 15 years that analytical chemistry has allowed us to identify the suspect compounds in our waters. They are often found in dilutions measured in parts per billion or trillion, but don’t be misled. They are potent at these levels.
None of the compounds are regulated, and we create and consume them in large volumes. Detergents, pharmaceuticals, industrial and agricultural chemicals comprise many of the pollutants. Some are natural. People and other animals naturally excrete trace amounts of a compound of estrogen.
What’s not so natural is to discharge the wastes of millions of people into one waterway, such as occurs in the Mississippi River below the Twin Cities. Wastewater treatment plants do not remove these compounds.
Many of the compounds in the pills we swallow are not removed either, and are endocrine disrupters. The active ingredient in the birth control pill and the compounds in many mood altering drugs used to treat depression and other mental health conditions are endocrine disrupters.
Dr. Schoenfuss is concerned because our current water quality testing protocols do not address these compounds for what they are. We test for individual chemicals. These chemicals exist in our waters always as compounds, and only affect organisms as such.
Also, our current procedure is to expose an organism to the chemical, and watch for mortality over the course of a few hours. Yet in the case of endocrine disrupters, we know the serious consequences may not show up for a generation or two.
Add one more reason to be concerned about what is happening. We initially thought that the primary source of these compounds was from wastewater treatment plants. They do discharge large volumes, but so do many other sources. The Grindstone River runs through a heavily forested portion of Minnesota. Failed septic systems along the route have tainted the waters with endocrine disrupters and affected fish no differently than is being seen in urban waters.
Agricultural lands are contributors too. Anti-biotics and growth enhancers fed livestock, and manure, all contribute. We’re also seeing that the chemicals reaching our waterways mix and biologically transform into compounds that can be endocrine disrupters.
Dr. Schoenfuss has tested fish from the length from the Mississippi River in Minnesota, and along portions of the Grindstone, Redwood, and South Fork of the Crow. He’s found the compounds and their effects.

- Tom Cherveny