Reports of alligators living in sewers should, by and large, be treated with skepticism. Likewise, flushing your goldfish down the toilet and hoping he makes it to the freedom of the open sea is pretty unlikely. But caffeine from your favourite beverage? That’s a problem.

The drug of choice

Caffeine, the legal psychoactive drug found in coffee, tea, pop, chocolate, and some medications, is one of the most widely used drugs on the planet.

Over the last few years, researchers on the Washington coast and in Montreal have found elevated levels of caffeine in natural waterways. Showing up in rivers, lakes, ocean and even drinking water.

It’s not the only ingredient in the pharmaceutical soup stewing in our waterways.

“Anything that’s being sold in the drugstore and anything that’s being sold in the street is ending up in our waterways,” says chemistry Professor Sébastien Sauvé at the University of Montreal.

Not everyone is taking estrogen supplements, anti-epileptic drugs, anti-depressants or methamphetamines, but loads of people consume caffeine.

“If you look at caffeine as a medication, 95% of people would be medicated with caffeine. How many people do you know who don’t drink tea, coffee, Coke or chocolate?” says Sauvé.

That’s what makes it special.

There’s something in the water

Because of its popularity, caffeine is a good indicator that any number of drugs are in the water. It’s the first one to look for is caffeine. If it’s there, chances are you’ll find other contaminants.

A recent study done by McGill University in Montreal found cocaine, oxycodone, morphine, and other drugs in the Grand River in southern Ontario.

Innocently paddling the Grand River where traces of drugs were found. Photo by Sean Marshall.

One possible pathway from your coffee cup to river goes like this: brew your coffee, drink it, go to the washroom, flush, watch as caffeine flows through the sewers to the water treatment plant, out into the closest body of water. If that waterbody also happens to be your drinking water supply, watch as caffeine returns to your tap, back into your cup. For the next cup of coffee.

That’s the simple explanation.

Here’s the technical explanation. We know part of the caffeine will metabolize in your body and only part will travel out in urine to the treatment plant. Depending on the level of treatment at your specific wastewater treatment plant, most or none of the caffeine and other drugs, will be removed. What’s left will exit the plant and then either disperse, degrade, or be taken up again into the drinking supply.

Old infrastructure is to blame

Many people assume local wastewater treatment plants completely remove caffeine and other drugs from the system. Removing very high percentages of drugs is possible, but it’s also very expensive advanced technology. Most treatment plants in use were built decades ago, and never designed to extract drugs from the water.

A little bit of a lot of things

Sauvé stresses that though the drugs are in the water, the concentrations are exceedingly small.

“If you were to drink 2 L a day for your lifetime, for most pharmaceuticals, you would probably consume one or two percent of one pill.”

But it isn’t just a question of one pill in isolation. Elise Granek, marine ecologist and associate professor at Portland State University in Oregon has been studying caffeine and other contaminants in intertidal mussels and Olympia oysters.

“There are thousands of these contaminants or chemical compounds in the environment and hundreds in the water. In reality, it’s going to be incredibly rare when you would see only one of these compounds. It’s more likely that you’re going to see a whole suite of these compounds at any one location.”

The element of the unknown

While little is known about the effects on humans, Granek and other are publishing work on aquatic species.

“We are finding in study after study, that even the very low levels of these compounds have effects on freshwater and marine organisms. For example, low levels of antidepressants cause snails to suffer from foot detachment (they have trouble holding onto the substrate). Other compounds affect the behaviour of prey species around their predators. Making them more bold, and thus more susceptible to predation.”

The simplest question in all this: should we be concerned about caffeine in our drinking water? Granek says that generally speaking we don’t want our kids ingesting caffeine. And there’s guidelines for how much caffeine pregnant women should be taking.

Photo by Matthew Kenwrick

“If there is caffeine that is coming back into our pipes from incomplete water treatment, these populations are getting caffeine in their ‘diet’ from drinking water,” says Granek.

The consequences of these trace amounts of caffeine are unknown, not to mention the consequences of exposure to all the other drugs and toxic chemicals that are also in the water.

It’s almost enough to make you long for the days when alligators were the scariest things in your city sewers.

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