Concern has been raised about the continued use of a cancer-linked herbicide.

The World Health Organisation has warned that glyphosate is probably carcinogenic, and the chemical safety is under review by the Australian Pesticides and Veterinary Medicines Authority (APVMA).

The European Union is in the process of banning glyphosate, and its use is already banned or restricted in much of Europe and in Sri Lanka.

The APVMA says its investigations are taking longer than expected, but in the meantime, it appears that glyphosate is still being sprayed.

The state-owned Forest Products Commission (FPC) has been spraying glyphosate over pine plantations in Balingup in WA.

Locals say it could drift over to Southampton Homestead, a nearby organic farm.

Conservationists say Australian companies should at least wait for the findings of the review before continuing to use the controversial chemical.

But WA Nationals leader and Warren-Blackwood MP, Terry Redman, maintains that it can be safe.

“FPC's done everything it possibly can in terms of managing its relationship with neighbours in proximity to its plantation forestry,” he told ABC reporters.

“I'm very confident that everything's been done to work through the issues.

“I'm aware of the concerns from the organic farmer and I'd like to think that over time those issues won't be something that impedes [their] capacity to manage their farming business.”

Mr Redman said the FPC would continue to use the chemical until it was officially deemed unsafe.

“It's assessed as a safe chemical to use under the conditions that it's prescribed, and therefore that's what we abide by if we are using them in Australia,” he said.

“If anything changes in that assessment of course we have to respond to it.”