A researcher is warning new herbicides used within the Queensland sugarcane industry could be just as damaging to the environment as the ones they're replacing.

The industry has been gradually reducing its reliance on a group of herbicides known as photosystem II inhibitors (PSIIs), which includes products such as diuron and atrazine.

Usage restrictions were placed on some of these chemicals in the Great Barrier Reef catchment during 2009, with the industry encouraged to move towards another group of mostly non-PSII herbicides.

However, James Cook University researcher Dr Aaron Davis says a desktop study of 25 'alternatives' shows many could be just as harmful as the regulated chemicals.

"Some of the alternative herbicides in fact did come out as posing, in a lot of ways, more risk to the environment, I guess, due to their proneness to movement offsite in runoff water," he said.

"Also their toxicity [is greater] than some of the regulated herbicides now that have been red-flagged to a certain extent.

"Virtually any herbicide can cause problems if it moves off-farm, and I guess there's not too many that tick the box of working really well at killing weeds, but also causing no problems if they run off the farm.

"But a number of those which may pose additional, we think, or comparable risks to regulated herbicides include things like metribuzin, pendimethalin and terbutryn.

"And some of the shorter lived herbicides, the ones that have had the sales pitch of being shorter lived and friendly for the environment, they may also pose problems down the track, glyphosate and 2-4-D.

"It's not to say they're quite as bad environmentally, but there's lots of different issues, not just from an environmental perspective."

Implications for canegrowers

The research findings were published in May, but will only go before the Australian Pesticides and Veterinary Medicines Authority for consideration later this month.

In a statement, APWMA executive director Dr Raj Bhula says 'it's too early to tell what the regulatory response may be'.

Dr Davis says regulation was an 'ad hoc' reaction to the reef health issue, and is cautioning against further restrictions being placed on the industry.

"I think we may be doing the industry a bit of a disservice if we push them in a certain direction, when we're not really even sure ourselves about what are the long term implications of almost forcing that shift in some ways," he said.

"There's a need for a broad range of herbicides in certain industries and a lot of the ones that growers have used in the past, they use because they work well.

"I don't personally think [more] regulation is necessarily the best way to go, and I don't think the APVMA or the industry thinks that either."

Industry 'supports the science' behind chemical regulation

While the long-term implications of the findings remain unclear, the industry has thrown its support behind the research effort.

Manager of Canegrowers Herbert River and Ingham, Peter Sheedy, says if additional regulations are imposed as a result of the study, growers will simply have to adapt.

"We support the science that enables us to keep on doing things better and better," he said.

"With the chemicals people do use, they've all been through an evaluation and approval process, through the APVMA.

"I guess what we're hearing is that JCU might have some good information to pass onto that process, and I guess that's where that effort really needs to be directed."

The Queensland Department of Environment and Heritage Protection says that, since 2009, $5.4 million has been invested to support graziers and cane growers develop best management programs to prevent sediments, fertilisers and pesticides entering the reef.

Almost $9 million has also been spent on research projects to give graziers and cane growers more information and tools to develop property action plans.

The Department says its latest Reef Report Card (released in June) showed the decline in the quality of water entering the Great Barrier Reef had halted and reversed.

It also says 49 per cent of Queensland sugarcane growers had adopted improved land management practices by June last year, with a 28 per cent drop in pesticides now entering the reef.