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Environment & Climate

Documentary highlights legacy of toxic waste sites across Wales and the UK

Researchers and former workers raised concerns over historical chemical dumping, though public health officials maintain there is no current evidence of increased disease risk.

Updated Aug 25, 2026 · 22:18 UTC1 reports

The short version

  • A BBC documentary hosted by Michael Sheen highlighted 14 historical toxic waste sites in Wales, including chemical dumping by Monsanto and an acid tar lagoon containing sludge from Burmah Castrol.
  • A participating scientist estimated there are around 20,000 high-concern sites across the UK and stated scientific data shows the identified Welsh sites are actively leaking contaminants.
  • Public Health Wales stated its surveillance data shows no evidence linking historical pollution to an increased risk of cancer or other diseases in these areas.
  • The Welsh government announced plans to create a nationwide strategy to restore post-industrial land, following a 2015 survey that identified more than 9,000 potential sites needing investigation.

Key facts

  • The BBC documentary 'Buried with Michael Sheen' detailed the historical dumping of industrial chemicals, including polychlorinated biphenyls (PCBs), at multiple sites in Wales.[BBC News]
  • Stephen Constance, a former worker at Monsanto's Newport factory during the 1990s, reported that staff lacked proper information about the buried materials and were provided with inadequate protective equipment.[BBC News]
  • Dr. David Megson of Manchester Metropolitan University stated that the UK contains roughly 20,000 high-concern sites, describing the documentary's 14 featured locations as leaking chemical mixtures.[BBC News]
  • An environmental engineering report from 2006 documented 93,100 tonnes of acid sludge dumped at the Llwyneinion acid tar lagoon, alongside barrels of unverified origin.[BBC News]
  • Natural Resources Wales and Wrexham County Council stated that tests in 2006 and 2008 concluded the Llwyneinion acid tar lagoon did not meet the legal threshold requiring statutory remediation.[BBC News]
  • Public Health Wales stated that data from its cancer surveillance unit since the 1970s shows no indication that historical environmental pollution has increased disease risks in the affected areas.[BBC News]
  • A 2015 survey carried out by Natural Resources Wales found over 9,000 potential sites that require further investigation by local authorities.[BBC News]

What remains uncertain

  • Academic researchers note it remains unclear whether historical industrial pollution is connected to elevated rates of certain health conditions in Wales, such as congenital anomalies and stillbirths.[BBC News]
  • Former site workers expressed uncertainty over whether plastic membranes and clay seals used at disposal sites prevented contaminants from leaking into local groundwater.[BBC News]

Sources