from ABC

Work has resumed at five of the 12 coal seam gas drilling sites in southern Queensland shut down by CSG company Origin after an asbestos contamination was detected.

The drill sites were shut down in mid-March and an investigation is currently underway to find out how asbestos came to be in the drilling fluid additive called Nutplug and what the implications are.

Origin Energy spokesman Phil Craig says the company has found an alternative to Nutplug and testing has cleared a number of worksites of contamination.

"We continue to work through a very comprehensive and systematic process of both airborne and surface testing making sure each and every rig has no trace of asbestos and is verified as safe to resume operation," he said.

"This issue is really a supply chain issue. It’s a problem with an additive product. It actually has nothing to do with the CSG operations or their sustainability."

However, an environmental group says it’s concerned by reports of contamination at the coal seam gas project.

Dr Merryn Redenbach, of Doctors for the Environment Australia, says more work needs to be done to ensure workers and the public aren’t exposed to danger.

"We do know that only a handful of chemicals used in the industry have any sort of assessment by our national chemical regulator and in this case we’ve seen that even products that were supposedly innocuous contain compounds that are a serious health risk."