UK's toxic waste crisis extends far beyond documented sites, scientists warn

Stephen Constance was 61 when he decided to speak publicly about what he had buried. For three years in the 1990s, he worked at Monsanto's Newport factory, and his job was straightforward and grim: dig trenches around mounds of toxic waste, seal them with plastic sheets and liquid clay, and move on. The protective equipment was cheap. Nobody told him what was actually in the ground. Looking back, he said the whole operation felt "absolutely dreadful."

Constance came forward after the BBC aired a documentary investigation into Monsanto's legacy in Wales, one that traced decades of industrial dumping and regulatory inaction. But what the film revealed—14 identified toxic waste sites—is merely the visible portion of a much larger problem. According to Dr. David Megson, a chemist and environmental forensics researcher at Manchester Metropolitan University who led the scientific work for the documentary, there are approximately 20,000 high-concern sites across the UK that require investigation. The scale is staggering, and most remain untouched.

The chemical at the center of the story is polychlorinated biphenyl, or PCB—a compound so toxic that Constance's colleague Douglas Gowan, a researcher and whistleblower, spent 50 years trying to convince authorities it needed urgent attention. PCBs were widely used throughout the 20th century in everything from lipstick to refrigerators. They were banned in the UK in the 1970s and have since been prohibited by 151 countries. Yet Monsanto knew the dangers early. A 1972 internal memo, revealed in the documentary, showed the company understood PCBs posed a threat to human health. The company closed its American operations under legal pressure from an affected town—then increased production at its Newport plant. The UK government, the documentary's journalists found, had told industry there would be no restrictions on importing PCBs. Hundreds of tonnes arrived from around the world.

When Megson analyzed contamination levels at these sites, the results alarmed him. He found concentrations "pretty much the highest I've ever seen in anything we've tested." The data showed not isolated problems but widespread leakage from multiple locations, each containing a chemical cocktail of unknown composition. PCBs are suspected carcinogens. Megson said plainly: "The country is in a really dire place. Public pressure is the only thing that's going to make this action happen."

One specific site illustrates the regulatory paralysis. The acid tar lagoon near Ruabon in Wales has been known to be contaminated since 1979. A 2006 environmental report identified 93,100 tonnes of acid sludge from Burmah Castrol and barrels of unknown substances believed to originate from Monsanto. The same report documented 105 possible pathways through which contamination could reach people, wildlife, water supplies, or property—including three uncapped mine shafts beneath the lagoon. In the 27 years since that report, there have been 18 investigations, two remediation proposals, and five treatment trials. As of 2026, the lagoon remains untouched. Ralph Davies, a chemical remediation specialist with 35 years of experience, proposed a cleanup plan in 2007. He never heard back from Wrexham council. When he visited the site nearly two decades ago, he was struck by how close it sat to residential homes. "The fact it is still there, untouched, is mind blowing," he said.

Constance is in remission from follicular lymphoma. He does not claim a direct link to his work at Monsanto, but the thought has crossed his mind. Sue Jordan, an emeritus professor at Swansea University, has noted that certain health outcomes—congenital anomalies, stillbirths—appear elevated in Wales compared to other UK regions, though researchers do not yet fully understand why. She is calling for Public Health Wales to investigate whether historical pollution plays a role. Public Health Wales has countered that based on available evidence, there is no indication that environmental contamination has increased cancer risk or other disease in these areas. Natural Resources Wales stated that the acid tar lagoon does not meet the legal definition of contaminated land. Wrexham council said ongoing monitoring has shown no significant changes and there is no statutory requirement for remediation.

John Browne, a lawyer specializing in industrial disease claims, acknowledged that cases involving historical contamination are difficult to prove but not impossible. Time erodes evidence and memory, he said, yet scientific, forensic, and medical evidence can establish what occurred and whether exposure caused harm. The central question, he emphasized, is not what the law permitted at the time but what was known about the risks. "Communities affected by contamination deserve transparency and clear answers," he said. The Welsh government has acknowledged the scale of the problem—a 2015 survey identified more than 9,000 potential sites requiring investigation—and says it intends to develop a Wales-wide strategy for restoring post-industrial land. Whether that strategy will materialize, and whether public pressure will finally force action, remains uncertain.