A He Fish? A She Fish. A (S)He fish?

Most of us have heard of birth control pills causing sex changes in native fish. Few of us have pondered whether it’s also happening to us….

We already know Birth control pills and herbicides wreak all kinds of havoc on the sexual development of aquatic life.. and perhaps even our children. Now the University of Wisconsin-Milwaukee has discovered a new nasty.  It’s the medicine ‘metformin’, which is taken for Type II diabetes and found in freshwater worldwide, has been shown to cause male fish that can produce eggs.

We already know that pharmaceuticals are  found in wastewater and surface waters around the world, usually due to incomplete metabolism in humans and subsequent excretion, resulting in discharge into surface waters by wastewater treatment plant effluent.

It’s now common. Intersex fish are very common downstream from wastewater treatment plants, and there has been a lot of research looking at the effect of hormones from birth control pills.

A study of chemicals prevalent in water samples collected from Lake Michigan, found high levels of metformin. It was the pharmaceutical with the highest levels in the samples – even higher than caffeine.

The affected fish were also smaller than normal species.

The search revealed that in fact, metformin may be a potential endocrine disruptor. It is also prescribed to women with the hormonal disease, and polycystic ovary syndrome.

Metformin is the most commonly prescribed medicine for Type II diabetes. In 2013, some 70 million prescriptions were dispensed with sales of more than $23 billion. And with diabetes rates skyrocketing – between 1980 and 2008, the number of diabetics worldwide more than doubled from 153 million to 347 million – the gender-bending drug will likely become ever more prevalent.