Michael Sheen has welcomed the strong public response to his documentary on Wales’ toxic waste legacy and hopes it prompts authorities to take practical action. The programme examined allegations that Monsanto disposed of PCBs, persistent industrial chemicals, at sites across Wales, raising concerns about historical contamination and its possible effects on communities.

Dozens of people contacted BBC Wales after the documentary, including former Monsanto worker Stephen Constance, who said staff sealing underground waste in the 1990s had inadequate protective equipment and were not told what they were burying. Researcher Douglas Gowan had raised concerns about 14 sites, 12 in Wales, before his death; Natural Resources Wales says historic industrial waste is difficult to investigate because records are often incomplete, while the Welsh government has described contaminated land as a priority.