Addressing the ‘paradigm problem’ for better emerging chemical management

RPS PFAS specialist, Dr Karl Bowles and Janina Beyer from the NSW Department of Planning and Environment recently co-authored a paper that was published in the CSIRO journal Environmental Chemistry.

22 Nov 2022

‘Examining the utility of existing chemical hazard paradigms to predict future global-scale impacts from emerging chemicals’ was published as part of a tribute issue for Dr Graeme Batley, an important and pioneering figure in the development of environmental chemistry and ecotoxicology in Australia and internationally. 

It explores problems that can arise from relying too heavily on existing chemical hazard paradigms, and how lessons from the past can help us better protect people and the environment.

Here, Karl provides an overview.

Paradigms, and their problems

When it comes to evaluating the safety of new chemical compounds, communities rely on scientific enquiry, process, and testing to determine risk vs reward.

We use what we’ve learned about chemicals in the past to inform our understanding (and interrogation) of how ‘new’ compounds will behave. What impact do we expect them to have on people or ecosystems? What does experience tell us about how they might travel or accumulate in the environment?

These become our scientific and policy paradigms – the commonly accepted lenses through which we look at potential problems. But if contamination issues of the past have taught us anything, it’s that environmental science is a job that’s never quite finished.

Science – environmental or otherwise - evolves because things don’t always go down as we expect. The hypotheses we formed at the beginning are challenged. And new information reveals that we need to look at things through a new lens. To evolve our paradigm.

Paradigms are important. They help us investigate consistently and apply useful knowledge. But over-reliance on paradigms can also obscure our perceptions of causality and hide connections from view.

OCPs and PFAS as a case in point

Over the twentieth century, a few groups of chemicals have caused environmental and health issues that were so profound as to spark a global response.

A common factor for these chemicals was that they had been used for decades and were in widespread (global) use before the environmental issues they caused were understood scientifically.

One of these chemical groups was organochlorine pesticides (OCPs) which had been in widespread use since the 1940s and includes the well-known pesticide DDT. They were believed to be ‘safe’, with low human toxicity in agricultural and domestic settings.

It wasn’t until Rachel Carson and others observed and reported environmental effects that they attributed to OCP use – in particular a lack of birds in the wild – that the safety of these chemicals really came into question.

In the beginning, the prevailing paradigm stood firm. Scientists and industry reasoned that OCPs had low acute toxicity and so couldn’t be responsible for the type of changes that people were seeing.

Later it was revealed that the impact was more indirect. Rather than killing higher order animals quickly through chemical exposure, OCP compounds were accumulating in their bodies via their food and eventually affecting their reproduction.

As this was something not typically observed for pesticides the causal connection was not made. In fact, the assertion was staunchly opposed for some time.

Understanding of the science behind OCPs impact – the ability of these chemicals to accumulate in fat tissue and biomagnify as a result – came some years after environmental changes were first observed. OCPs were in use for decades before any action was taken.     

It’s a similar case for per- and polyfluroalkyl substances (PFAS). While concerns about their impact have emerged more recently than OCPs, PFAS has been used extensively from about the same time − from the mid-twentieth century onwards. PFAS have similar chemical hazard characteristics – persistence in the environment, tendency to bioaccumulate, and toxicity to animals above defined thresholds.

However, the chemical properties leading to these hazards are not the same as for OCPs, so applying the paradigm for OCPs failed to identify the concerns for PFAS that have since emerged through environmental observations.

Why challenging paradigms is vital

Examples like OCPs, PFAS, and others that we discussed in the paper demonstrate that there will be more instances where current paradigms for chemical hazards will not be enough to predict future problems.

They also show that waiting for large-scale impacts to prove our paradigms wrong can have serious consequences. We will forever be reacting to negative impacts, rather than preventing them.

So, what do we do?

Three steps to prevention rather than cure

There are some programs in place to search for the early warning signs of chemical contamination issues. But if we want to prevent impacts that require a large-scale global response, we need to expand on these and move our practice beyond reliance on the ‘paradigm of the day’. Janina and I point to three key things that could help.

1. Transparent data for chemical production
More transparency about chemical production, which chemicals are used to make products, how these products are then used and disposed of could help us to better understand potential pathways into the environment.

While commercial interests will continue to be a roadblock to information sharing, greater commitment to lifecycle assessment and detailed examination of all potential routes into the environment would provide a much better platform for spotting issues before they become problems.

2. Multiple lines of evidence
Targeted and untargeted monitoring programs for environments and people (biomonitoring) that draw on the latest advancements in chemical analysis, biomonitoring and toxicity testing could help us identify risks much earlier, and act far sooner to stop widespread impact.

3. Global data sharing

While there are online databases and public information sources for chemical hazards, there is little consistency of data, search functionality is a challenge, and few platforms focus on the environmental monitoring of chemicals.

By investing in data consistency, broadening the scope of information available and sharing our results, we would be in a better position to observe patterns and identify risks.

Not knowing what you don’t know is a difficult hurdle to overcome.

But as chemical contamination risks emerge, we are constantly learning and evolving the scientific paradigms through which we investigate and address them.

If we commit to continually testing our assumptions, look for potential gaps in our knowledge, and develop more effective mechanisms for data sharing, we can maximise our chances of identifying early warning signs before major environmental or human impacts develop.


Learn more

Read Karl and Janina’s full article ‘Examining the utility of existing chemical hazard paradigms to predict future global-scale impacts from emerging chemicals’ (inclusive of references) in Environmental Chemistry.

Karl Bowles, Senior Project Manager

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