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Rivers, lakes and coastal waters are increasingly burdened with the by-products of modern living. From the pesticide-soaked fields of intensive agriculture to the microplastics in our laundry wastewater, today’s contaminants are more diverse, persistent and widespread than ever. Analysts face the task of not only detecting these pollutants at trace levels but also helping society understand the risks, and responsibilities, of living in a chemically complex world.

Crucially, this also means designing safer, non-toxic alternatives and developing effective remediation approaches to mitigate the damage already done. One group of toxic chemicals in particular, per- and polyfluoroalkyl substances (PFAS), has become emblematic of the wider problem: useful, invisible and alarmingly durable.

The challenge of PFAS detection and removal

PFAS are synthetic chemicals used in everything from firefighting foams to water-resistant clothing, non-stick pans and fast-food packaging. What makes them invaluable in manufacturing – their chemical stability and resistance to water, oil and heat – also makes them a nightmare for the environment.

These “forever chemicals” do not readily break down, accumulating in soil, water and wildlife. They’ve been detected in rainfall and polar ice caps, but PFAS don’t just contaminate water, they embed themselves in us. These chemicals stick to proteins in our blood, and once they’re in the body, they stay there for a long time.

“That’s why we’re now finding PFAS in nearly everyone’s blood around the world. It’s not just a water issue anymore, it’s a public health concern.” said Prof. Graham Peaslee, a nuclear physicist at the University of Notre Dame.

“These substances are so persistent that archaeologists of the future may identify the ‘PFAS layer’ in sediments, just like we mark the asteroid impact or the Industrial Revolution in past sediments.”

Peaslee continued, “That’s how deeply embedded these chemicals have become in our environment. We’ve created a signature that will last for thousands of years, and future generations will be able to pinpoint recent centuries by the traces of fluorinated compounds we’ve left behind.”

For analysts, PFAS present a unique technical challenge. They require highly sensitive and selective detection methods, often pushing the limits of liquid chromatography with tandem mass spectrometry (LC-MS/MS) or high-resolution mass spectrometry. Regulatory thresholds are frequently in the parts-per-trillion range, demanding robust sampling protocols and extreme care to avoid contamination during analysis.

“The problem isn’t just that PFAS are everywhere, it’s that they’re often invisible to conventional methods,” said Peaslee. “Most labs are equipped to detect maybe a few dozen PFAS compounds, but there are thousands out there. The ones we’re missing are often the ultra-short chains, which are water-soluble and hard to trap. We’ve had to build entirely new tools just to see what’s really there.”

The regulatory landscape for PFAS is also evolving quickly. Across Europe, the UK and the US, policymakers are beginning to restrict production and monitor presence more closely. However, with thousands of structurally diverse PFAS compounds in circulation, and many yet to be studied, regulation often lags behind discovery.

“We’re essentially in a game of regulatory whack-a-mole, ban one PFAS, and the industry just shifts to another. There are nearly 15,000 variants out there,” Peaslee explained. “The trouble is, we’re still regulating chemicals one at a time. Until we tackle the whole class of PFAS collectively, we’ll never be able to stem the tide.”

PFAS removal remains technically and economically demanding; traditional methods like activated carbon or reverse osmosis are effective but costly and energy-intensive. Research is now exploring methods for chemical degradation and targeted remediation, ranging from photocatalysis to emerging biotechnologies.

Detecting pesticides, pharmaceuticals and microplastics

While PFAS dominate headlines, pesticides and herbicides also remain a threat, regularly entering surface waters through agricultural runoff. Glyphosate, atrazine and neonicotinoids are frequently detected, some even in protected wetlands and drinking water sources.

Though many legacy pesticides have been banned, their residues can persist for years. Meanwhile, newer formulations bring their own risks, sometimes breaking down into unknown or poorly understood by-products. Analysts rely on a combination of targeted screening and untargeted high-resolution MS approaches to track these substances and their metabolites across complex matrices.

Not all water pollutants come from industrial smokestacks, treated fields or chemical plants, many originate in our homes, our wardrobes and our daily routines. What begins as a rinse, a wash or a flush can often end up in rivers, lakes and eventually the sea.

Pharmaceuticals and personal care products (PPCPs) are among the fastest-growing classes of environmental contaminants. Medications, cosmetics, soaps and sunscreens frequently pass through wastewater treatment systems intact, entering aquatic ecosystems where they can persist, accumulate and interact with other chemicals in complex ways.

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Compounds such as active pharmaceutical ingredients, parabens and UV filters have been detected in sediments, aquatic wildlife and even treated drinking water. Even at nanogram-per-liter levels, these compounds have been linked to endocrine disruption, behavioral changes in fish and bioaccumulation.

Around the world, aging wastewater infrastructure and the growing diversity of synthetic chemicals are placing increasing pressure on aquatic ecosystems. Identifying which compounds pose the greatest risk is a complex task. Wastewater is a constantly shifting mixture of natural and synthetic substances, and harmful chemicals may be present in trace amounts or altered through environmental processes by the time they’re detected.

Detection often relies on LC-MS/MS, but the sheer variety of compounds, and their tendency to appear in mixtures, has driven the use of multi-residue screening methods and bioanalytical assays that assess biological impact rather than chemical identity alone.

Meanwhile, microplastics and nanoplastics, less visible but no less pervasive, have emerged as another major concern. These particles originate from degraded packaging, textiles, tire wear and other consumer products. Their diversity in size, shape and polymer type poses major challenges for analysts. Sampling protocols must avoid contamination, and identification often requires a combination of physical and chemical techniques. To address this, researchers are increasingly developing novel materials and sensor platforms that improve selectivity, reduce background interference, and enable more accurate characterization in complex environmental matrices.

Chemical traps which look to select established contaminants based on the molecular size or its chemical properties offer an exciting approach to specifically detect or immobilize contaminants thus eradicating their environmental damage.

“We’re developing metal-organic cages that can operate in water and be tailored to trap specific pollutants from pharmaceutical and personal care waste,” said Dr. Imogen Riddell, a Royal Society University Research Fellow at the University of Manchester. “Recent developments enabling application of these cages in water, rather than organic solvents, have demonstrated capture of established wastewater contaminants originating from medicinal and personal care streams.”

Fourier-transform infrared (FTIR) and Raman spectroscopy remain central tools for identifying plastic fragments, while pyrolysis-GC-MS is used for detailed chemical profiling. However, standardized reference materials and harmonized methods are still being developed, with international collaboration playing a growing role.

“Diversity in all its forms is vital to scientific progress,” explained Riddell. “Collaborating across borders and disciplines brings fresh perspectives and approaches, and often leads to creative solutions neither team would have reached alone.”

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From contamination to conversation

Tackling water contamination isn’t solely a technical challenge, it’s a cultural and political one. The work of analysts feeds directly into policymaking, environmental justice debates and public health strategies.

Recent regulations in the EU and UK have begun to include a broader array of pollutants on watchlists. Citizen science projects are also growing in popularity, allowing the public to engage in water sampling and awareness-raising campaigns. However, with thousands of emerging contaminants yet to be regulated, or even studied, there is a clear need for more integrated, interdisciplinary action.

An investigation by Consumer Reports tested food packaging from major US restaurant chains and found widespread PFAS contamination. Peaslee explained that measuring total organic fluorine is a simple and effective way to screen for PFAS. The story gained widespread media attention and demonstrated how clear scientific evidence, when well communicated, can drive real-world policy change.

“Scientists can sound the alarm, but real change only happens when policymakers act on the evidence,” said Peaslee. “We’ve seen it work before. When science, public awareness, and regulation align, big problems become solvable. The ozone layer is healing. Lead was removed from petrol. PFAS could be next, if we move quickly, together.”

Innovation and collaboration are turning the tide

Despite the scale of the challenge, progress is being made. New tools, new policies and new public awareness are reshaping how we think about environmental contamination. Research groups are developing faster, greener methods of detection. Universities are embedding sustainability into science education. Industry is under pressure to reformulate products or adopt safer manufacturing processes.

“Every threat is also an opportunity,” Peaslee reflected. “The world came together to fix the ozone layer, we can do the same with PFAS. It starts with smart science and honest policy.”

“New environmental problems will continue to be identified,” said Riddell, “however continued investment in science, supporting increases in instrument capability and training of the next generation of scientists, will ensure we have the tools to tackle these challenges in new and innovative ways”.

Perhaps most importantly, scientists and policymakers are now beginning to work more closely together, translating analytical findings into real-world action. The pollutants may be complex, but the goal is clear: to ensure clean, safe water for people and ecosystems alike.