Drugs Down the Drain: The Impact on Wildlife
by Karen Lourdes
MSc in Applied Wildlife Conservation, ARU
We might be facing Earth’s sixth mass extinction today, having already lost over half the world’s wildlife species in the last 40 years (Barnosky et al 2011, WWF 2016). Pharmaceuticals polluting our water bodies may be contributing to this, affecting our wildlife in unimaginable ways.
Which Drugs and How?
Drugs meant for human consumption are getting washed down our sewage system. Some of the different types of drugs involved are antibiotics, painkillers, anti-depressants and hormones which include contraceptive pills (Kuster and Adler 2014).
How exactly can drugs ingested by humans end up in sewage and still be harmful?
All pictures from Pixabay and WikiCommons
Although drugs pass through our digestive tract, trace amounts are still present in our excrement. These then gets flushed down the sewage system and enter our natural water system. However, it is not just through waste-water that these pharmaceuticals affect wildlife. Factories are also responsible for the release of drugs into water bodies like lakes and rivers (Larsson 2014). So animals living in lakes and rivers (e.g. fish and amphibians) are usually more exposed to contamination.
Species Affected
Amphibians
Pharmaceutical “cocktails" have been shown to cause sterility frogs and sex reversal in frogs (Walton 2003, Uppsala University 2007). Tadpoles swimming in contaminated water, all of them develop ovaries, instead of, half developing testicals (males) and the other half ovaries (females).
Amphibians, which usually breed in water, are vulnerable to pharmaceuticals especially during the fertilisation of eggs in the water and early stages of tadpole development (Safholm et al 2014).
Fish
Synthetic estrogen (birth control pill compound) can result in the feminization of the longnose dace (Rhinichthys cataractae), in Canada (University of Calgary 2010). The feminized males have high protein levels, that are normally found only in females for egg production..
This can have serious consequences in terms of reproduction, as you can imagine. How would one expect the longdace minnow population to survive in the long run without healthy males?
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Solutions?
Why these chemicals are not being removed from wastewater? Well, pharmaceuticals are often resistant to standard water treatment processes used by local wastewater plants. However, new approaches to improve wastewater output have been in the works for years (Zupanc et al 2013). Recent investigations include the use of intermittent electrocoagulation to remove pharmaceuticals from wastewater (Ensano et al 2017). This complex electrochemical process removes drug particles in the water by adsorbing them to the electrodes and aggregating larger particles on the bottom, like sediment. It is said to be far more efficiently than current biological water treatment processes..
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Unfortunately, more comprehensive data is required on the impact of drugs in the environment to improve legislation. Kuster and Adler (2014) touch on some challenges for regulation in Germany in their paper.
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Other ideas on reducing the amount of drugs prescribed and to prevent drugs from entering the environment in the first place are discussed in this article by Burns (2014). Studying the effects of drugs on animals is often ethically debated, and can prove challenging to conduct research on animals humanely.
Aquatic Invertebrates
Antidepressants disrupt spawning and larval release, locomotion and reproduction in various types of molluscs and crustaceans (Fong and Ford 2014). Some species affected include marine snails (Tritonea diomedea), freshwater snails (Lymnaea stagnalis), zebra mussels (Dreissena polymorpha), the Pacific white shrimp (Litopanaeus vannamei) and lobsters (Homarus americanus).
Birds
Gyps vultures (Gyps indicus) in India are an extreme example of the effects of drugs in natural systems (Cuthbert et al. 2014). These vultures feed on cattle carcasses in special disposal grounds due to social and religious constraints on cattle consumption in India. The cattle however, are dosed with diclofenac (anti-inflammatory drug), when old and lame. Diclofenac causes visceral gout and kidney failure in vultures, resulting in a painful, rapid death. Over 97% of the Gyps vulture population in South Asia has disappeared in the last 12 years .
These are just some of the many, many wildlife species being affected out there. There are also potentially many that we have not yet discovered.
The presence of drugs in wastewater is not a recent discovery. There are plenty of research papers that go back decades on this issue and its impact on wildlife species. Moreover, the knock-on effects on other wildlife species in the ecosystem has not yet been fully explored. Recently in the UK, diclofenac was found on otter fur (Richards et al 2011). This is the first instance of human drugs in mammals and the consequences are still unknown.
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Wildlife known to be affected today are part of an incomplete picture. We are yet to uncover how many other species are compromised and in what ways. These implications could affect food chains and result in trophic cascades in various ecosystems.
Responsible chemical disposal by factories is often very costly. Hence, irresponsible factories that pollute the environment cover-up their actions as they may be fined if discovered. However, here have been ideas on improving wastewater treatment facilities and efforts to reduce the pollution by manufacturing factories. This is a great as it nips the problem at the bud, rather than dealing with the chemicals once in open water.
However, as much pharmaceuticals in the environment is recognised as a threat to wildlife, not much tangible action has been taken over the years. This needs to change, and soon, if this issue is to be prevented from spiralling further out of control.
REFERENCES
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Burns, C. (2014). What happens to the excreted drugs you flush down the toilet? The Guardian. Available at: https://www.theguardian.com/science/blog/2014/aug/08/drugs-toilet-pharmaceutical-pollution
Fong, P P and Ford, A T. (2014). The biological effects of antidepressants on the molluscs and crustaceans: A review, Aquatic Toxicology, 151: 4-13. doi: 10.1016/j.aquatox.2013.12.003.
University of Calgary. (2010). Chemicals are likely cause of feminization of fish present in two rivers in Alberta, Canada, researchers find. Science Daily. Available at: www.sciencedaily.com/releases/2010/07/100729122332.htm
Uppsala University. (2007). Sex Reversal In Frogs An Effect Of Drugs In The Environment. Science Daily. Available at: www.sciencedaily.com/releases/2007/02/070228091721.htm
Walton, M. (2003). Frogs, fish and pharmaceuticals a troubling brew, CNN: Science and space. Available at: http://edition.cnn.com/2003/TECH/science/11/14/coolsc.frogs.fish/
WWF (2016). Living Planet Report. Available at: http://wwf.panda.org/about_our_earth/all_publications/lpr_2016/