A controlled study involving brook trout exposed to varying amounts of effluent Montreal water over a three-month period at the University of Montreal showed that fish exposed to antidepressants in the water showed a reduction in brain activity. Significant quantities of antidepressants are finding their way into the water around Montreal and affecting the fishes’ tissue and brain activity. The study also showed that antidepressant drugs accumulate in fish tissues.
The study revealed ozone treatment reduces the level of antidepressants in the waste water as it leaves the plant. Montreal is experimenting with ozone wastewater treatment. The study shows the phenomenon is likely found around many cities in the world because Montreal has a typical sewage-treatment system.
While antidepressant levels in wastewater do not pose a risk to human it does have an impact on fish in particular and the ecosystem in general. This should be a concern for everyone. Other pharmaceuticals like hormones have been shown to change the gender of fish. The wastewater treatment system for Las Vegas is adopting ozone to minimize the risk of these compounds. Other cities, like Montreal, are looking into this as well.