Beyond traditional pollutants

By Prof Sigal Balshine

Prof Balshine spent a year collaborating with us at Project Seahorse in 2014/2015. This blog is about her research in Hamilton, Ontario.

Flush!  The first show to ever feature a flushing toilet was “All in the Family”. Back in the early 1970s bathroom business was still considered a highly taboo subject, and a fairly unsuitable or risky topic for network television. But we all use the toilet.  In Hamilton alone, toilets are flushed about 2 million times a day.  That is about 1500 flushes per minute.  And when the 720, 000 people, who live and work all over the Greater Hamilton metropolitan area, use their bathrooms, it’s not just water that is being flushed down that sink, bath or toilet. The wastewater or “sewage” in Hamilton is treated by three large wastewater treatment plants that collectively “clean” over 520 million liters of wastewater each day. All three of these plants are extremely well equipped to deal with our bodies’ natural wastes, feces and urine. 

But these treatment plants have a much more challenging time filtering out pharmaceuticals such as antibiotics, aspirin, and birth control pills or personal care products like sunscreen and deodorants, compounds that unfortunately also end up in wastewater whenever we use the toilet, shower, sink or laundry. The drugs we take are not entirely absorbed by our bodies so they and the cosmetics, perfumes and soaps that we use are passed into the wastewater stream. 

But why should we care if there are small residues of pharmaceuticals and personal care products in our wastewater?

Well, once our wastewater is treated and cleaned up, the liquid component, known as effluent, is pumped right back into our rivers, lakes and oceans.  In Hamilton, this treated wastewater gets discharged into Hamilton Harbour, and into Cootes Paradise Marsh. All of the City of Burlington’s wastewater is also discharged into Hamilton Harbour. Many different fish, amphibians, reptiles, birds and even mammals live in these aquatic habitats.  And these water bodies are where we swim and play, and they are connected to Lake Ontario, where we get our drinking water.

How does the treated effluent in these areas impact the wildlife and the ecology of the Bay? The truth is we don’t really know.  It is likely that many aquatic animals encounter treated wastewater everyday.  Cootes Paradise, for example, is an environmentally sensitive wetland, is used by over 25000 water birds as an annual migratory stopover spot and by over 60 species of fish as a breeding and nursery ground (with over 10 million young produced there each year). Unfortunately, removing the removal of pharmaceuticals and personal care products (PPCPs) from wastewater is technologically challenging and prohibitively costly to filter out, so more and more of these compounds are ending up in our watersheds.

More worryingly still is that when many PPCPs mix together they produce a complex cocktail and the impacts on wildlife exposed to these mixtures are really not very well understood. Recently in Sweden, Brodin and his colleagues [link to reference?] showed that European perch exposed to just one of these compounds, a mood-altering drug, were far less social. Fish that are less social won’t group together and without the protection from schooling together are at much higher risk of predation. 

In my laboratory (ABEL), we too have found that fish from highly impacted sites in Hamilton Harbour, move less and take unnecessary risks in the presence of predators (Marentette & Balshine 2012). Changes to animal behaviour or physiology can be thought of as a type of early warning system.  The fish may not die but if they look or act strangely something might be wrong.  Fish and other aquatic organisms can be used as firstline indicators.  They are the canaries in the coal mine, for compounds that might affect the health of our aquatic habitats and the quality of our drinking water. But first we really need to understand how precisely wastewater effluent influences biological function in animals that encounter it regularly.

To this end, my research group at McMaster University, the Aquatic Behavioural Ecology Laboratory (ABEL), has begun a research study.  Joining forces with Dr. Graham Scott’s research group from the McMaster Biology Department, the Royal Botanical Gardens, and the City of Hamilton’s Wastewater division, we are examining how treated wastewater effluent influences fish behaviour and physiology. Graduate students Erin McCallum and Sherry Du, and their research assistants, are caging fish in locations ranging from the wastewater plant’s treatment ponds and next to the effluent discharge pipes all the way to a distant clean site far away from the wastewater effluent. The fish are exposed to different amounts of wastewater effluent in these cages for a month. We then test their behaviour and their physiology, looking at traits that are important for reproduction and survival.  We are using two species of fish, the round goby and pumpkinseed sunfish, both ecologically and economically important species in Canada and the Great Lakes.  We want to understand if treated wastewater effluent, even at very low doses, can alter biological function of the animals that encounter it. 

So what can you do about the problem of pharmaceuticals and personal care product contamination? First, always make sure to take advantage of drug take-back programs at your local pharmacy or local waste collection station. Never flush remaining drugs into the toilet or wash unused pills down the sink. Second, whenever possible use less harmful organic cosmetics and cleaning products.  If there is a choice between several different drug options, consider the respective environmental impact and pick the most ecofriendly compound. Third, encourage the city and the province to more strongly protect our natural lands and water bodies. Eventually there will be further advances in removal technology, and possibly even legislation that will better protect our oceans, rivers and lakes. Until then we need to make sure that we know how to accurately detect and measure these chemicals in water, in sediment and in the organisms that live in aquatic habitats.  And of course we really to figure out what the consequences of PPCPs are on ecosystem function and on human health. 

So the next time you flush, take a minute to think about how we can all work to protect water, our most precious renewable resource.  

Dr. Sigal Balshine is a professor at McMaster University.  She is in the Department of Psychology, Neuroscience & Behaviour and studies fish behaviour, ecology and evolution.  She received her B.Sc. from the University of Toronto and her Ph.D. from the University of Cambridge and did postdoctoral fellowships in Israel, Austria and England before joining the faculty at McMaster.  She and her students have been working on round goby behaviour and the effects of contaminants on their behaviour since 2002.  She thanks to the Royal Bank of Canada for a Blue Water Research Grant and to McMaster University for their generous support of this research project.