Contraceptive pills in urban sewage could cause freshwater ecosystem collapse

Ingredients from oral contraceptives in sewage triggered a chain reaction that nearly wiped out a species of freshwater fish in a lake, according to a new study by Canadian researchers, whose lead researcher called for improvements to Canada's wastewater treatment facilities.

The study found that adding small amounts of female hormones to lakes caused fathead minnows to nearly die because their ability to reproduce was disrupted. Lead researcher Karen Kidd from the University of New Brunswick said the research began in the 1990s, when British researchers found that when female hormones were added to lakes, male fish began to form eggs.

Kidd said they plan to conduct research to determine whether estrogen affects the fathead minnows' ability to reproduce and whether it has a greater impact on the lake's ecosystem.

In 2001, researchers began putting small amounts of female hormones into a freshwater lake at a research facility in Ontario. "The male fish immediately started responding to the female hormones," Kidd said. "They started producing yolk protein and very quickly they started producing eggs."

Soon after the estrogen was introduced, the fathead minnows began to decline, with the population decreasing by 1%. "It was unexpected how fast and how dramatic the response was," she said. "The decline was very significant and directly related to the addition of the estrogen."

Kidd said this had a domino effect, causing lake trout, the fathead minnow's main predator, to decline and insects, its main food, to increase. Kidd said the feminization of male fish has occurred in several parts of Canada because of municipal wastewater being discharged into waterways.

Kidd believes that this problem can definitely be solved by optimizing wastewater treatment facilities. She said: "There is evidence that removing these chemicals from our wastewater will have downstream effects on fish." Experiments have also confirmed that after removing estrogen, the population of fathead minnows returned to the level before the study began.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.