How the Way We Clean Could Impact our Fresh Water: The case of QACs

You may have heard that the past few years have been marked by a little-known phenomenon called COVID-19.

Collectively, we discovered just how quickly we could adapt to new cleaning habits when given a good enough reason. But the question remains: what are the effects of our zealous spraying, scrubbing, and wiping on the environment—and our freshwater supplies?

Here at IISD Experimental Lakes Area, scientists are undertaking a large collaborative study to investigate the impact of a commonly used class of chemicals in disinfectants called quaternary ammonium compounds (QACs) on fresh water.

What Are QACs?

QACs are a group of human-made cationic surfactants that contain a quaternary ammonium ion.

QACs are formed by a central nitrogen atom surrounded by four clusters of atoms—hence, “quaternary.” They’re cationic, meaning they carry an overall positive charge.

This enables easy binding to the negatively charged surfaces of most microbes. In turn, this disrupts the cell membranes of bacteria and lipid coats of viruses, making QACs an excellent antimicrobial disinfectant.

Examples of QAC-based disinfectants include hand sanitizer, cleaning sprays, surface wipes, and pretty much any product adorned with “kills 99.9% of germs.” QACs are also used in goods such as fabric softeners, hair care products, and air fresheners. Another good tell that a product contains QACs is when the ingredient list features chemicals ending in “ammonium chloride.” Even before the pandemic, QACs were classified as a high-consumption chemical with an annual usage of around 500,000 tons.

From Wipes to Water

So, how do QACs get from wipes into freshwater systems? The answer is down the drain and into wastewater!

Treatment systems typically remove around 90% of QAC from wastewater, but every year around 25% of QACs consumed are discharged into the environment. For instance, significant concentrations of QACs can be found in rivers and lakes that are downstream from facilities such as hospitals, where disinfectants are frequently used in large quantities and may overwhelm treatment facilities.

What We Still Need to Learn About QACs

Even though QACs are widely used, not much is known about their effects on fresh water and its inhabiting organisms.

Though we know that the chemical composition of QACs makes them great at disinfecting, we still don’t fully understand the extent of harm they pose to algae, bottom-dwelling invertebrates, fish, and even mammals.

What Exactly Are Scientists Doing?

Well, as part of a 4-year whole ecosystem experiment, scientists at IISD-ELA are working in mesocosms—a kind of enclosure within a lake—to look at the impact of a specific class of QACs called alkyl dimethyl benzyl ammonium chloride (ADBAC).

They’re looking at many different factors, like how ADBACs interact with species of the lower trophic levels of the food web and how they move through the water column and sediment. Biota—the plants and animals of the region—are also an area of investigation.

Additionally, concerns about the widespread use of QACs and microorganisms developing resistance are being addressed with help from two Scottish universities that are studying the evolution of antimicrobial resistance.

Over 4 years, scientists at the world’s freshwater laboratory are working in mesocosms to discover what a specific class of QACs do to fresh water.

The pandemic is an example of how difficult it can be to balance our immediate needs with the possible long-term consequences of the future. The work being done at IISD-ELA on QACs is helping to contribute to a richer understanding of the human impact on fresh water. In doing so, policy-makers, industries, and many others will be more equipped to make better and more informed decisions going forward.

For instance, this could mean changes to the way that the cleaning product industry formulates its sanitizers. Additionally, wastewater treatment plants could adapt their processes to reduce the amount of QACs released into freshwater systems.

And overall, this research on QACs can lead to shifts—both big and small—that will reduce the mark they leave on our environment.