What Is Emerging Contaminant Classifying?

Since the turn of the millennia, the scientific and environmental communities have focused more and more of their attention on emerging contaminants or contaminants of emerging concern (CECs). This vague catch-all term refers to a multitude of chemicals which may be naturally occurring or manmade and which are present in our environment at various (but generally low) concentrations – but about which we know very little.

Given that there are literally tens of thousands of chemicals circulating through the natural world – with more and more new ones entering the environment all the time – it’s a difficult task to classify which of these substances should be defined as emerging contaminants. Let’s take a closer look at the challenges and processes involved in doing so below.

Keeping up with the chemicals

According to the Environment Protection Agency (EPA) in the USA, there are currently over 86,000 chemicals in use around the world. Some of these are naturally occurring substances that have been present in our environment for millennia, while many others are synthetic chemicals that have only entered the picture relatively recently.

With such an astronomically high number of chemicals to keep tabs on, it’s only logical that a mere fraction of these have been defined as contaminants of emerging concern by the EPA. At present, their list is comprised of around 1,000 CECs, though the actual figure is projected to be at least ten times that amount. Given the restraints of time and labour involved in classifying CECs, we do not yet have a clear or comprehensive picture of their makeup.

Emerging contaminant vs emerging concern

From the term emerging contaminant, you may think that the chemicals referred to are newly manufactured and only just now circulating in our environment. While that may be true for some CECs (especially since new chemicals are being produced on a near daily basis), there are a plethora of contaminants which have been around for decades, centuries or even millennia – but about which we have only received discovered potentially harmful properties.

Take lead, for example. Widely used by the Ancient Greek and Roman Empires, lead contamination is probably the oldest CEC in the world – but our awareness of the damage it can do to ecosystems and organisms is a relatively recent phenomenon. The same goes with arsenic, which was used as a pesticide over a thousand years ago. Once its long-term toxicity was understood, it was outlawed in favour of more modern substances such as DDT – which in turn, was subsequently banned for its harmful effects. Something similar is now happening with neonicotinoids, glyphosate and other substances, indicating the constantly changing landscape of CECs.

What classifies a chemical as a CEC?

With that in mind, it begs the question: how do we classify what is and what isn’t a CEC? Well, the truth is that the science is an imperfect one, since there remains much we do not know about the majority of the chemicals in our environment. However, the ability to persist over extremely long periods in the natural world can lead to bioaccumulation. Over time, miniscule concentrations can build to levels sufficient to threaten the health of the biosphere around them.

As such, scientists are developing new methods of analysing water samples (where most CECs are found) and conducting new studies into their potential effects on flora, fauna and human life. In such a fluid realm of research, where new chemicals enter the market on a continual basis, the goalposts are constantly moving to classify CECs.