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I find some hope for the future of our planet in the emergence of millions of unconnected environmental and social movements. The leaderless Anarchy of this mass phenomenon and its macro scale means that its cells will not be centrally controlled or turned aside by profit motives. It seems to be a genuine grass roots response to the global threat which our planet faces. —Paul Hawken

Headwaters of Smith River Protected

Emerging wastewater contaminant metformin causes intersex and reduced fecundity in fish

Nicholas J. Niemuth, Rebecca D. Klaper


  • Fish were exposed to metformin at concentrations relevant to wastewater effluent.
  • Exposure from early life stages to adulthood caused intersex in male fish.
  • Exposure caused a reduction in fecundity and in overall size of male fish.
  • Results suggest that metformin is a potential endocrine disruptor in the environment.
  • Metformin may be another cause of intersex fish seen globally.


The occurrence of intersex fish, where male reproductive tissues show evidence of feminization, have been found in freshwater systems around the world, indicating the potential for significant endocrine disruption across species in the ecosystem. Estrogens from birth control medications in wastewater treatment plant effluent have been cited as the likely cause, but research has shown that endocrine disruption is not solely predictable based on hormone receptor interactions. Many other non-hormone pharmaceuticals are found in effluent at concentrations orders of magnitude higher than estrogens, yet there is little data indicating the impacts of these other medications. The widely prescribed anti-diabetic metformin is among the most abundant of pharmaceuticals found in effluent and is structurally dissimilar from hormones. However, we show here that exposing fathead minnows (Pimephales promelas) to a concentration of metformin found in wastewater effluent causes the development of intersex gonads in males, reduced size of treated male fish, and reduction in fecundity for treated pairs. Our results demonstrate that metformin acts as an endocrine disruptor at environmentally relevant concentrations. The complete study can be found at:


Message from KS Wild

Cheers to wild rivers! Today, we are extremely excited to announce that Public Land Order 7859 was signed by Obama officials protecting the headwaters of the Smith and Illinois Rivers and Hunter Creek for 20 years from the threat of industrial strip mining!

We could not have done it without your outstanding support by signing petitions, attending public hearings, and supporting all the efforts leading to this momentous occasion. Thank you! 

We also extend a huge thank you to our coalition partners and our river champions, especially Representatives Defazio and Huffman, and Senators Merkley and Wyden. If you are as excited as we are, please take a minute to thank them too!

What's next for the Kalmiopsis Rivers? These spectacular rivers provide clean drinking water to dowstream communities. They are are home to healthy salmon and steelhead runs, and the rives are surrounded by some of the most unique plant habitat in the West. We will continue to work hard to defend this victory against attack, and for more permanent protection from mining in the years to come. 

Please continue to follow updates, and consider supporting our ongoing work for wild rivers. Let the mountains talk, let the river run. Once more, and forever.  - David Brower


Jeanine Moy, Outreach Director
KS Wild