What’s In Your Wastewater? Intersex Fish and Household Wastewater

chemicalsOver the last few decades, there has been increased concern over commonly used chemicals entering the environment and impacting aquatic life, and possibly even human health. The EPA refers to these compounds as chemicals of emerging concern (CECs) and they include many of the pharmaceuticals and personal care products we use every day.1

Research has shown that several of these chemicals, such as birth control constituent ethinyl estradiol, are known endocrine disruptors (EDCs). These chemicals can alter hormone levels in aquatic organisms leading to detrimental reproductive effects.2 Exposure to low levels of endocrine disruptors have been linked to the development of feminized male fish, referred to as “intersex” fish.

Intersex fish are not hermaphroditic. They don’t have both male and female sexual organs. The affected male fish exhibit “hormonal confusion” by developing eggs in their testes.3,4,5

In a 2008-2010, U.S. Fish and Wildlife Service and U.S. Geological Survey researchers studied largemouth and smallmouth bass found in the waters of 19 different National Wildlife Refuges in several Northeastern states.  The scientists discovered 60-100% of the male smallmouth bass had female egg cells growing in their testes.6pills 2

These findings heightened scientists concern over CEC micropollution in the environment. Discovering such hormonal imbalances in a protected wildlife refuge suggests endocrine disruptor exposure may be more widespread than previously thought.7

Unfortunately, the problem appears to be growing. As of 2016, 37 species of feminized male fish have been discovered in lakes and rivers throughout North America, Europe and other locations around the world.8 The challenge is how to keep CECs out of the environment.

In most urbanized locations, CECs appear in household waste streams in very low concentrations (nanograms per liter) which makes it difficult for traditional wastewater treatment plants (WWTPs) to break down.9 Untreated CECs are generally released back into the environment where they can work their way into vulnerable waterbodies.

Water treatment professionals are well aware of the issue and have been looking for answers. Fortunately, new research from several Universities has revealed possible options for treating many CECs found in wastewaters.

The University of Waterloo in Canada examined how upgrading the Kitchener Wastewater Treatment Plan “from a carbonaceous activated sludge treatment process to a nitrifying activated sludge treatment process” impacted rainbow darters in Ontario’s Grand River.10  These fish are known to be highly sensitive to estrogen and other endocrine receptors.

Over a 10 year study period, they discovered that the new nitrifying activated sludge wastewater treatment process “led to a 70 percent drop in fish that have both male and female characteristics within one year and a full recovery of the fish population within three years.”11

University of Waterloo scientists believe the change in microorganisms used to remove ammonia in the treatment process lowered the levels of the endocrine disrupters which caused the dramatic reduction in the number of intersex fish.12

Researchers at Karlsruhe Institute of Technology (KIT) in Germany have developed a method to eliminate hormones from wastewater by combining ultrafiltration with the adsorption properties of activated carbon.13 The team created a new multi-layered membrane technology which presses wastewater through a polymer membrane separating microorganisms and larger impurities from the smaller hormone molecules.

The hormone-containing wastewater then travels through a special layer of activated carbon, located behind the polymer membrane, which adsorbs the hormone molecules, converting them into other compounds. The KIT scientists have been able to reduce hormone micropollutants by 60% and note that a reduction of up to 90% can be achieved if the thickness of the activated carbon layer is increased.

Kit researchers believe this membrane technology is applicable to both commercial and home use. Planning is now underway for their first industrial project.

Here in the U.S., Stanford University engineers are seeking to change the way wastewater is treated by entirely removing the conventional aerobic process and relying solely on anaerobic digestion of wastewater.14

An exciting new pilot project in Redwood Shores, California will be testing this innovative treatment approach. The Stanford team is working closely with Silicon Valley Clean Water (SWCW) to build and operate a small anaerobic treatment test plant, scheduled to come on-line in the Fall of 2018.

One significant environmental benefit of this new treatment technology is the ability of anaerobic bacteria “to digest pharmaceutical drugs and powerful household and industrial herbicides that have proven difficult for standard aerobic bacteria to digest.”15  Stanford environmental engineer, Perry McCarthy, points out that anaerobic bacteria have “adapted to the harshest environments on Earth.” He believes “they can eat most anything.”16

Clearly viable treatment methods to breakdown CECs and endocrine disrupters are being researched and tested. Yet, full-scale implementation of any one of these technologies is a long way off and would require major changes to wastewater infrastructure. In the meantime, we should all become more aware of what we put into our own household wastewater.


  1. “Contaminants of Emerging Concern Including Pharmaceuticals and Personal Care Products.” EPA, Environmental Protection Agency, 27 Sept. 2016, http://www.epa.gov/wqc/contaminants-emerging-concern-including-pharmaceuticals-and-personal-care-products.
  2. “Endocrine Disrupters and Intersex Fish.” Forester Network, 25 Jan. 2017, foresternetwork.com/daily/water/water-quality-monitoring/endocrine-disrupters-and-intersex-fish/?mqsc=E3867885&utm_source=WhatCountsEmail&utm_medium=Forester FullWater Efficiency Weekly&utm_campaign=Wkly-WE-01192017.
  3. “Why Are These Male Fish Growing Eggs?” National Geographic, National Geographic Society, 3 Feb. 2016, news.nationalgeographic.com/2016/02/160203-feminized-fish-endocrine-disruption-hormones-wildlife-refuges/?beta=true.
  4. “Evidence of Estrogenic Endocrine Disruption in Smallmouth and Largemouth Bass Inhabiting Northeast U.S. National Wildlife Refuge Waters: A Reconnaissance Study.” Egyptian Journal of Medical Human Genetics, Elsevier, 19 Oct. 2015, http://www.sciencedirect.com/science/article/pii/S0147651315301093.
  5. “Emerging Wastewater Contaminant Metformin Causes Intersex and Reduced Fecundity in Fish.” Egyptian Journal of Medical Human Genetics, Elsevier, 18 Apr. 2015, http://www.sciencedirect.com/science/article/pii/S0045653515002830.
  6. “Evidence of Estrogenic Endocrine Disruption in Smallmouth and Largemouth Bass Inhabiting Northeast U.S. National Wildlife Refuge Waters: A Reconnaissance Study”
  7. “Why Are These Male Fish Growing Eggs?”
  8. “Why Are These Male Fish Growing Eggs”
  9. “Water Processing-New Method Eliminates Hormones.” org – News and Articles on Science and Technology, Phys.org, phys.org/news/2018-06-processingnew-method-hormones.html#jCp.
  10. “Endocrine Disrupters and Intersex Fish.”
  11. “Wastewater Treatment Upgrades Result in Major Reduction of Intersex Fish.” ScienceDaily, ScienceDaily, 10 Jan. 2017, http://www.sciencedaily.com/releases/2017/01/170110151418.htm.
  12. “Wastewater Treatment Upgrades Result in Major Reduction of Intersex Fish.”
  13. “Water Processing-New Method Eliminates Hormones.”
  14. Stanford University. “New Plant Tests Energy-Saving Way to Treat Wastewater.” | Stanford News. Stanford University, 10 May 2018, news.stanford.edu/2018/05/10/new-plant-tests-energy-saving-way-treat-wastewater/.
  15. “New Plant Tests Energy-Saving Way to Treat Wastewater.”
  16. “New Plant Tests Energy-Saving Way to Treat Wastewater.”

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