Experts say that controversial proposals to drill for coalbed methane could result in discharges of three times as much radioactivity as that at the Rosyth naval base, where seven defunct nuclear submarines are moored. The proposals should be rejected, they argue.
But the company behind the development, Dart Energy, dismisses the claims as misleading, erroneous and sensationalist. The impact of any radioactivity released would be "insignificant", it says.
Dart has applied for planning permission to drill 22 wells at Airth on the Forth to extract up to 60 billion cubic feet of gas from underground coal seams. The application attracted over 2,500 objections, and was the subject of a public inquiry in March and April.
Evidence submitted to the inquiry by Dart says that "predicted annual discharges" of untreated water from the development could contain up to 1.7 billion becquerels of radioactivity.
Now anti-nuclear local authorities have pointed out that this is much higher than the annual discharges from the Rosyth Royal Dockyard. An official report from UK government regulators put Rosyth's liquid discharges in 2012 at 0.6 billion becquerels of radioactivity.
"Dart Energy has applied for permission to discharge almost three times the amount of radioactivity into the Forth estuary compared with what Rosyth discharged in 2012," said Pete Roche, radiation adviser to the 50-strong group of Nuclear-Free Local Authorities (NFLA).
"This is not a small amount. We should be asking ourselves if this is really a sustainable way to be generating our energy."
NFLA is advising local authorities on how to respond to a government consultation on naturally occurring radioactive wastes.
NFLA's Scotland's convener, the Glasgow councillor and former Labour MSP, Bill Butler, also expressed concern about Dart's pollution. "Such levels of radioactive contamination into the local environment are a high price to pay for the methane gas produced," he said.
Dart's predicted radioactive discharges were highlighted in a submission to the public inquiry by Dr Ian Fairlie, a radiation expert hired by local objectors. He didn't present his evidence because Dart objected to inaccuracies in his submission.
But a corrected version suggests that annual emissions of radium-226, radon-222 and other "radiotoxic" isotopes will be significant. Additional radioactivity would also end up in waste sludges that would have to be transported to licenced dumps.
Dart Energy, however, pointed to the submissions made to the public inquiry by its radiation expert, Shehu Saleh. He criticised Fairlie's submission as "not an accurate interpretation" of the company's information.
A treatment facility planned by Dart would remove 99 per cent of the particulate matter, he argued.
Saleh also attacked Fairlie's submission as "sensationalist and out of context".