Which Pesticides Should be Banned?

NICK Heath is worried about the future of the Great Barrier Reef.  He has a Bachelor of Commerce and after ten years in business and consulting, moved into political and policy advice for government.  He’s now the national program leader for water at WWF-Australia.   He’s been spearheading the ongoing WWF campaign to ‘Save the Great Barrier Reef’. [1]

As part of this campaign WWF wants the herbicide Diuron banned.  Heath recently told journalist Brian Williams at the Courier Mail that he accepted that government would probably ban Diuron, but he was disappointed about further delays. [2]

Why does Heath want Diuron banned?

Recently, on ABC Radio National he said, “Don’t ask WWF for an endorsement of what a safe pesticide is.  I’m not qualified.  But that is why we need a better regulatory system.” [3]

As part of the same program, Munro Mortimer from the National Research Centre for Environmental Toxicology said, “Some of the chemicals that have been banned in overseas countries particularly in Europe…  some of these bans probably relate more to politics and popular perceptions rather than science.  Because that is the way that these things tend to happen. Quite often governments respond to political pressure regardless of whether they are supported by science or not.”

Mortimer made many other relevant and insightful comments during the program but they were mostly ignored by Paul Barclay, the host of the show.  Barclay seemed more interested in encouraging Nick, who apparently has no idea what a safe pesticide is, to suggest more be banned.

And this has been about the level of the discussion for about the last ten years – since WWF first launched its ‘Safe the Great Barrier Reef Campaign’ in 2001.   And not just the public discussion, but from my experience also much of the technical discussion.

John Abbot, a research chemist at Central Queensland University, and I recently reviewed the work of Norm Duke who published peer-reviewed papers and reports claiming Diuron killed mangroves.  Our paper has just come out in the international peer-reviewed journal Human and Ecological Risk Assessment, Volume 17, pages 1077-1094.   In the paper we explain that while Duke’s work influenced government policies to ‘Save the Great Barrier Reef’ this same research is fundamentally flawed. [4]

If you would like a pdf copy of our paper and don’t have access to a technical library, please email me at jennifermarohasy@jennifermarohasy.com.

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References/Links

1. Nick Heath at Linked In.  Accessed October 5, 2011.

2. Williams B. 2011. Farm chemical diuron found in Great Barrier Reef catchment at levels 50 times higher than those considered safe.  Courier Mail.  http://www.couriermail.com.au/news/queensland/farm-toxins-flow-to-reef/story-e6freoof-1226143002578

3. Barclay P. 2011. Our waterways: are we poisoning them and ourselves? Australia Talks, ABC Radio National. June 28, 2011.  http://www.abc.net.au/rn/australiatalks/stories/2011/3243560.htm

4. Abbot J., Marohasy J. 2011.  Has the herbicide Diuron caused mangrove dieback? A re-examination of the evidence.  Human and Ecological Risk Assessment. Volume 17,  Pages 1077-1094.

Abstract of our paper…

The claim that the herbicide Diuron in agricultural runoff caused dieback of the grey mangrove (Avicennia marina) in Central Queensland, Australia, has influenced government policies including programs to save the Great Barrier Reef. Several investigations on mangrove dieback in Central Queensland river estuaries have been published during the past decade.However, proof of a causal link between mangrove dieback and Diuron remains inconclusive. This study presents a systematic review of the evidence using Hill’s Criteria of Causation. Our review shows that using concentrations of the chemical bound to sediment as a measure for biological availability in either glasshouse or field studies is inappropriate. The appropriate measure is Diuron concentration in solution and this parameter bears no simple relationship to concentration bound to sediment, and is not strongly correlated with mangrove health. Only when the herbicide is applied in experimental investigations at many orders of magnitude higher thanmeasured in rivers has an impact on A. marina been demonstrated. Evidence from field studies suggests burial of pneumatophores, the plant’s breathing roots, following flood events is a more likely causal factor in mangrove dieback, whereas any contribution from Diuron remains unproven.