Shampoos, soaps, perfumes, cosmetics and cleaning supplies, along with a combination of medications can be found in every kitchen and bathroom cupboard in Canada. All these products have something in common: they’re putting a wide variety of relatively unstudied chemicals down our drains and, ultimately, into our oceans.
Pharmaceuticals hitch a ride with every flush of the toilet, while other chemicals are making their way to the nearest harbour through your sink and shower drains. These are “Chemicals of Emerging Concern” or CECs and the concern is well warranted, as Karen Kidd and Angella Mercer noted in a recent BoFEP report.
“There are no regulations or guidelines for the discharge of CECs into the aquatic environment from municipal wastewater treatment plants. In addition, little is known about how long these chemicals persist in the environment and the effects they have on fish and other aquatic life”
In the report below, BoFEP focused on 31 of the hundreds of CECs which have been found in household wastewater, including antibiotics, antidepressants, fragrances, preservatives, sunscreens, and insect repellents. The effects of these chemicals on fish and other wildlife depends on several factors: Is the chemical easily dissolved in water? Is it persistent in the environment? If the chemical does degrade, what are the products?
A persistent substance cannot be degraded by sunlight or bacteria. Instead, it sticks around often becoming part of a marine organism’s next meal. On the other hand, a chemical that degrades rapidly may not always be good news; Kidd and Mercer explain, “Degradation can result in new chemicals in the environment which can be more or less toxic than the original ones.”
So far, research suggests that the CECs frequently found in surface water and sediment are, indeed, more persistent. Since they remain in the ecosystem, these chemicals find their way into the food chain, taking up residence in the bodies of fish and other animals. Antidepressants, antimicrobials, anti-epileptics, and fragrances have all been found in the tissues of fish downstream from Canadian and US sewage treatment plants. The cumulative and long-term effects of this exposure is still unknown.
Sewage Treatment
Between our drains and the oceans, these chemicals have a stopover in sewage treatment plants (STP) or home septic systems. However, even the most efficient STPs were designed to remove bacteria, solids, and nutrients. They aren’t very effective at preventing CECs from reaching our rivers, lakes, streams and harbours.
Recent studies show that a small fraction of CECs may be removed by conventional sewage treatment, and that the higher levels of treatment are slightly more successful. Unfortunately, tertiary treatment (the highest level) is rare in Atlantic Canada. Only 8% of Nova Scotia waste and 4% of New Brunswick waste flows through a tertiary STP (as measured in m3/day of sewage flow) before entering the environment. At the low end of the sewage treatment spectrum is lagoon treatment, which process sewage through open, aerated pools and sand filters. Lagoons account for 35% of waste treatment in Nova Scotia and 48% in New Brunswick, granting a virtual free pass for CECs on a trip from our drains to our coastlines.
Missing Information
. One crucial piece of information that is missing from CEC research to date is an examination of how different mixtures of these chemicals impact the ecosystem. Waste-waters contain complex combinations of chemicals from thousands of households, constantly interacting with each other as well as the surrounding ecosystem. Unfortunately, as Kidd and Mercer point out, “the science is not advanced enough to be able to assess the total effects of these mixtures. For this reason, risks are examined using individual chemicals, maximum environmental exposures (worst-case scenarios), and lab toxicity experiments.”
To learn more, read the whole report here: CECs-Kidd-Mercer-2012 Final
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