OCT 26, 2020 5:40 AM PDT

When Exposed to Estrogen, Fish Generate Fewer Males

WRITTEN BY: Carmen Leitch

Life on earth relies on the roughly three percent of water on the planet that is drinkable. And clean water sources are being stressed. Researchers have now found that if water is contaminated with even low levels of human hormones, fish that live in that water can suffer profound effects. New work reported in Aquatic Toxicology has used a freshwater fish called least killifish to show that estrogen concentrations of only 5 nanograms per liter resulted in the generation of fewer males and reduced numbers of offspring in general in a laboratory habitat.

UC is using least killifish as a model organism to study the effects of hormones in drinking water. They are among the smallest vertebrates on Earth. / Credit: Andrew Higley/UC Creative

Least killifish are unusual because they have a placenta, and instead of spawning eggs that then get fertilized like most fish, they give birth to live young.

Previous work has indicated that some streams next to sewage plants contain estrogen concentrations of at least 60 nanograms per liter - over ten times higher than the levels used in this study. Fish that live far from sewage plants might still be feeling the effects of hormones that leech from the sewage plant.

"Anything you flush down the toilet or put in the sink will get in the water supply," said study author and biologist Latonya Jackson, a University of Cincinnati assistant professor.

When people use the bathroom, unmetabolized chemicals from their bodies get into the water supply. Unfortunately, people may also improperly dispose of medications by flushing them down the toilet.

UC assistant professor Latonya Jackson is using least killifish as a model organism to study the effects of hormones in drinking water. / Credit: Andrew Higley/UC Creative

"Our wastewater treatment systems are good at removing a lot of things, but they weren't designed to remove pharmaceuticals," Jackson said. "So when women on birth control or hormone therapy go to the bathroom, it gets flushed into wastewater treatment plants."

In this work, Jackson utilized a synthetic estrogen that is used in hormone replacement therapy called 17α-ethinylestradiol. When fish were chronically exposed to this estrogen, the gender ratio of their offspring was skewed; more females than males were produced and the population got smaller.

These impacts aren't only felt by fish, noted Jackson. Chemicals like hormones can build up in water sources and eventually end up in drinking water.

"Our drinking water is not a renewable resource. When we run out of clean drinking water, it's gone," Jackson said. "It's very important that we keep this resource clean."

Jackson is now interested in investigating how hormone exposure in fish parents influences the physiology and health of their offspring.

Sources: AAAS/Eurekalert! via University of Cincinnati, Aquatic Toxicology

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
SEP 08, 2020
Neuroscience
Thyroid Inflammation Linked to Anxiety Disorder
SEP 08, 2020
Thyroid Inflammation Linked to Anxiety Disorder
Findings from a new study suggest that people with autoimmune inflammation in their thyroid may be more likely to develo ...
SEP 13, 2020
Cell & Molecular Biology
RNA Found on the Surface of Human Cells
SEP 13, 2020
RNA Found on the Surface of Human Cells
The surface of a cell carries many features to help it carry out its functions, communicate with other cells, gather inf ...
OCT 08, 2020
Immunology
Immuno Metabolic Complexity and Modulating Metabolites
OCT 08, 2020
Immuno Metabolic Complexity and Modulating Metabolites
Immunometabolism is a relatively new subspecialty of immunology as we’ve begun to unravel the complex metabolic re ...
OCT 15, 2020
Neuroscience
Neurometabolism: A bold, new frontier
OCT 15, 2020
Neurometabolism: A bold, new frontier
Billions of neurons communicate with each other through trillions of synapses to create a functioning, unique system we ...
OCT 18, 2020
Genetics & Genomics
'Silent' Mutations Might Have Given SARS-CoV-2 an Edge
OCT 18, 2020
'Silent' Mutations Might Have Given SARS-CoV-2 an Edge
The pandemic virus SARS-CoV-2 is thought to have originated in bats, like many viruses. To make the leap and infect anot ...
NOV 19, 2020
Cardiology
Examining a Possible Link Between Atherosclerosis and Inflammation
NOV 19, 2020
Examining a Possible Link Between Atherosclerosis and Inflammation
The immune system’s primary duty is to protect the body from dangerous invaders. Many don’t know that it als ...
Loading Comments...