Fluoxetine and the environment

Back in 2004 I read an article about a UK study that had found traces of drugs such as analgesics, antibiotics and antidepressants in both sewage water and drinking water.

The author wrote: “… it seems like it won’t be very long at all before these prescription drug pollutants start showing up in shrimp, crab, lobsters and perhaps someday, even in seaweed. If you thought mercury poisoning was bad, just wait until you hear the announcement that shrimp is contaminated with Prozac [fluoxetine].”

Alas, this prediction has come true all too soon. But instead of finding ourselves eating tainted shrimps, we may find there are no shrimps left to eat.

Fluoxetine reaches our coastal waters by passing through our bodies unchanged and entering waterways in the effluent discharged by sewage processing plants. A new UK study has shown that the fluoxetine levels in British rivers and estuaries can be high enough to alter the behaviour of Prozac-happy shrimps in a way that puts them at greater danger of predation.

According to a report published in the journal Aquatic Toxicology, and widely taken up by the popular press, a research team at Portsmouth University has discovered that shrimps exposed to fluoxetine at levels similar to those found in waste water are five times more likely to swim towards light rather than away from it, increasing their risk of being eaten by fish or birds.

Not widely reported was the fact that the researchers chose a selective serotonin reuptake inhibitor for their study because it was already known that the behaviour of marine organisms can be changed by parasites that alter brain serotonin levels. The researchers hope to extend their studies to other drugs that modulate serotonin levels.

Fluoxetine is just one of many drugs and drug metabolites that find their way into our coastal waters. Until now, it has been generally assumed that they are found in too low a concentration to threaten the balance of the ecosystem, but the Portsmouth research shows that further studies are urgently needed.