Fish devastated by sex-changing chemicals in municipal ...(broader class of sex-changing chemical c...),Health

To better understand the impacts of estrogen on fish, the researchers conducted a seven-year, whole-lake study at the Experimental Lakes Area in northwestern Ontario. Over three summers, they added tiny amounts low parts per trillion of the synthetic estrogen used in birth control pills to the lake to recreate concentrations measured in municipal wastewater.

During that period, they observed that chronic exposure to estrogen led to the near extinction of the lakes fathead minnow population as well significant declines in larger fish, such as pearl dace and lake trout.

Generally, the smaller the fish, the more vulnerable they are to estrogen, remarks Kidd.

Part of the reason, she adds, is that smaller fish have a shorter lifespan and will often die after reproducing only once.

The researchers used synthetic estrogen because it tends to persist longer in the environment than natural estrogens. Yet the problem with estrogen is not its environmental persistence but rather its persistent discharge in municipal wastewater into surface waters.

Kidd says the risk is greatest for aquatic ecosystems downstream from municipalities that either discharge untreated wastewater or maintain only primary treatment facilities. On the flipside, the problem is of less concern near cities that remove a wide range of chemical contaminants, including estrogens, from wastewater using secondary and tertiary treatment processes.

It is now understood, she says, that removing estrogen through wastewater treatment can reverse the adverse impact of this substance/hormone on wild fish. In fact, three years after halting additions of synthetic estrogen to the e
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