The WA Department of Minerals and Petroleum Resources confirmed it was still considering how to dispose of the waste on a rig at BHP Billiton's Griffin Venture, 68km north-west of Onslow.

The department took over responsibility from the WA Radiological Council last month after uncertainty over whether disposing of the material might have breached legislation prohibiting radioactive waste produced in international waters being brought into WA.

Acting petroleum division director Richard Craddock said that low-level radiation was the result of scale that built up naturally in pipework on the rigs over a period of years and was not hazardous to people or the environment.

"Radiation is in everything around us - a kilo of bananas has traceable amounts of radiactivity," Mr Craddock said.

"The radiation in the pipework comes from the produced formation water."

He said the majority of offshore facilities in WA have zero to minimal scale accumulation.

BHP Billiton spokesman Malcolm Garrett said the company was keen for the State Government to decide what should be done with the waste.

"We are constantly monitoring this waste and while it is not a hazard, we would like the issue resolved," Mr Garrett said.