Vince Palace is a senior research scientist for the IISD Experimental Lakes Area.
You know the drill. Nowadays, it seems like every email, conversation and Zoom or Skype meeting starts the same way: “I hope you are coping with the new reality well and staying safe.”
Implied in that latter phrase, of course, is the understanding that we all are doing our part to reduce the spread of the coronavirus by physically distancing, washing our hands and being vigilant by cleaning high-traffic areas and high-touch surfaces. What we may not yet have fully considered, however, is how these practices of our new normal may go on to impact our earth’s resources – including our fresh water.
One of the greatest concerns for the environment comes in the form of enhanced cleaning protocols, which mean that we are all using a larger volume of cleaning products. It has been estimated that hospitals have recently doubled their already rigorous sanitizing routines. Indeed, a visit to the cleaning products aisle of any local supermarket will provide enough evidence that household cleaners are now in high demand. But many of those contain chemicals that can then find their way into the environment.
Take quaternary ammonium compounds (QACs), for example. QACs are one of the most common active ingredients in sanitizing and disinfecting products, especially among products recommended by the U.S. Environmental Protection Agency and the Canadian government to prevent the spread of COVID-19.
QACs are what the Organisation for Economic Co-operation and Development calls high-consumption chemicals, with worldwide annual usage estimated at 500,000 tonnes. QACs can find their way into the aquatic environment when they are released in wastewaters. Typically, wastewater treatment plants remove the majority of biodegradable components in sewage, but some contaminants are not completely degraded, and a percentage can be discharged at the end of the process into the environment.
Such is the case with QACs: an estimated 25 per cent of their consumed volume is annually discharged into the environment. Wastewater treatment facilities remove about 90 per cent of those compounds but measurable concentrations can still invariably be found in rivers and lakes that are downstream from these facilities and that receive their effluent. And some of the highest concentrations have been measured in waters that receive wastewater from hospitals.
What makes QACs effective as cleaning agents also makes them potentially toxic to non-target organisms if they reach fresh water. Cleaning products contain QACs because they can effectively disinfect by disrupting the cell membranes of bacteria and lipid coats of viruses. This is rather handy when combatting a viral pandemic, but it’s potentially deadly for algae and more complex animals, including bottom-dwelling invertebrates, fish and even mammals, because they can interact with membranes and disrupt normal cell functioning in these organisms. Some of these effects have even been reported at QAC concentrations that are similar to those already detected in the environment.
Even so, there are still some unknowns that could modify the toxicity of QACs to freshwater organisms. For example, when QACs are present in combination with contaminants like oil, their combined toxicity can be intensified; on the other hand, in environments with more sediment, QACs may be sequestered and unavailable, thus reducing toxicity.
What we need to do now, then, is learn more. All these questions and uncertainties need to be teased out using holistic experimental approaches that consider not just QACs’ toxicity to individual organisms, but also the interactions of environmental factors and between species.
Our continued use of cleaning and sanitizing products is an important part of combating the spread of the COVID-19 pandemic. But that doesn’t mean we should delay doing more research into the potential environmental threats posed by the QACs to the freshwaters into which they discharge, and the fauna who reside within – a world that we need to ensure survives and thrives for long after this pandemic is over.
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