Andreas Späth

Prozac is not for the birds

2014-10-28 09:29

Andreas Wilson-Späth

Physics is simple.

Take Newton’s famous Third Law of Motion: for every action there is an equal but opposite reaction. This makes for a perfectly foreseeable world in which one’s activities lead to outcomes which can be predicted with mathematical accuracy.

Ecology is complicated.

The natural environment is an exceedingly complex network of large numbers of multiply interconnected organisms, physical objects, processes and relationships, much of which is best described by chaos theory and in which end results are often sensitively dependent on initial conditions – the metaphorical butterfly beating its wings in the Amazon and affecting future weather conditions on the other side of the globe.

It’s often extremely difficult to forecast exactly what impact our actions today will have on the state of the environment tomorrow. Which is one of the reasons why meteorologists tend to shy away from making definitive predictions about what global warming and climate change will actually mean for the weather in your backyard in years to come.

Another good example is the impact a variety of pharmaceutical products are having on the natural world, a subject scientists are only beginning to understand.

Used by millions of people on a daily basis, these chemicals make their way into the greater biosphere via our toilets, emerging as part of the effluent from sewage treatment plants and on agricultural fields fertilised with sewage sludge. In some places there is more direct pollution from the factories which produce them.

The fact that environmental concentrations of these pharmaceutical pollutants are often minute does not mean that they have no effects on plants and animals. Their impacts were certainly never expected or intended by manufacturers or users. Earlier this month, the scientific journal Philosophical Transactions of the Royal Society B dedicated an entire issue to research papers on the topic.

One of the studies considers what happens to birds when they are exposed to fluoxetine, the antidepressant better known by its trade name Prozac, in concentrations encountered in their natural habitat.

While starlings administered with the drug didn’t show a change in mood (if birds can be accused of having such a thing), but experienced detrimental changes in physiology and behaviour as a result of a noticeable drop in libido and a loss of appetite.

Reviewing the effects of waterborne pharmaceuticals which influence the workings of sex hormones and the reproductive cycle, including synthetic oestrogen and progestogens, a team of Swedish researchers found that they can inhibit reproduction in frogs and other amphibians.

A study conducted in Canada confirms that ethynyl oestradiol, an artificial oestrogen used as an active ingredient in many birth control pills, can have a significant impact on lake ecosystems. The substance virtually eradicated flathead minnows in an experimental lake, leading to an increase in zooplankton and insects previously controlled by this species of fish as well as a decrease in the body size and a 23-42% decline in the population of its main predator, the lake trout.

It’s clear then, that individual pharmaceutical pollutants can have a negative effect on ecosystems, even at low concentrations. It’s likely that exposure to a combination of drugs will have an additional array of impacts.

I’m not suggesting, of course, that as an eco-conscious consumer you should stop using pharmaceutical drugs. These products immeasurably improve the lives of millions of people around the globe every day. Their broader impact beyond our own bodies does, however, offer a rather poignant illustration of the kinds of consequences our actions as a species are having on the natural world we so casually co-inhabit.

- Andreas is a freelance writer with a PhD in geochemistry. Follow him on Twitter: @Andreas_Spath
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